Research Article Photocatalytic Degradation of Rhodamine B by C and N Codoped TiO 2 Nanoparticles under Visible-Light Irradiation Thuy Thi Thanh Le 1 and Trinh Dinh Tran 2 1 Department of Chemistry, Faculty of Science, Qui Nhon University, No. 170 an Duong Vuong Street, Qui Nhon, Vietnam 2 VNU Key Laboratory of Advanced Materials for Green Growth, Faculty of Chemistry, University of Science, Vietnam National University, No. 334 Nguyen Trai Street, Hanoi, Vietnam Correspondence should be addressed to uy i anh Le; [email protected] and Trinh DinhTran; [email protected] Received 18 April 2020; Revised 6 June 2020; Accepted 18 June 2020; Published 9 July 2020 Guest Editor: Tapan Sarkar Copyright©2020uyianhLeandTrinhDinhTran.isisanopenaccessarticledistributedundertheCreativeCommons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. CandNcodopedTiO 2 nanoparticles were synthesized via a solvothermal method. e degradation of Rhodamine B by the photocatalyst C, N-TiO 2 was investigated under visible-light irradiation generated by using a 36W compact fluorescent lamp which is characterized by wavelengths from 400 to 650nm. e structure and properties of the obtained photocatalyst have been systematically investigated using X-ray diffraction, TEM, UV-Vis, FT-IR, and BET techniques. e experimental results revealed that C, N codoped TiO 2 nanoparticles were successfully synthesized, with an average diameter of 9.1nm. C, N-TiO 2 nanoparticles exhibited an energy band gap of 2.90eV, which were lower than pristine TiO 2 (3.34eV), C-TiO 2 (3.2eV), and N-TiO 2 (3.03eV). e degradation of Rhodamine B by C, N-TiO 2 indicated that, under visible-light irradiation, the optimal dose of the photocatalyst was 1.8 g/L, and the removal of Rhodamine B was almost complete after 3 hours of reaction. e photocatalytic degradation of Rhodamine B in the range of 5–100mg/L showed that the process followed the first-order kinetics according to the Langmuir–Hinshelwood model. e highest apparent rate constant (0.0427 min −1 ) was obtained when the initial concentration of Rhodamine B was 5 mg/L, whereas the former decreased with the increase in the initial concentration of Rhodamine B. Moreover, C and N codoped TiO 2 nanoparticles presented a high potential for recycling, which was characterized by a removal efficiency of more than 86% after three cycles. 1. Introduction TiO 2 is one of the well-known photocatalysts because of its nontoxicity, chemical stability, ease of processing, low cost, and multiple reusability. However, TiO 2 is only active under the ultraviolet light (Eg∼3.2 eV in the anatase phase), which prevents it from various applications. e doping of non- metals such as N, C, S, P, and halogens in TiO 2 would lead to an increase in catalytic activities in the visible-light region [1–5]. Particularly, the modification of TiO 2 by carbon in- creases the photosensitivity of the obtained materials [1, 2]. It has been reported that N-doping TiO 2 could result in a significant decrease in the energy band gap and an increase in catalytic activity in the visible-light region [3, 4]. Rhodamine B (RhB) has been widely used in histologic specimens; textile, paper, and cosmetics industries; RhB is also a well-known water tracer fluorescent [6]. RhB is harmful to humans and animals. Expose to RhB was re- ported to cause acute symptoms such as burning of the eyes, excessive tearing, nasal burning and itching, chest pain/ tightness and burning, rhinorrhea, cough, burning of the throat, headache, and nausea [7]. e carcinogenicity and reproductive and developmental toxicity of RhB to humans and animals have been experimentally proven [8, 9]. erefore, a number of efforts to remove RhB from the aqueous medium have been made. Several techniques have been deployed to deal with RhB residues in waters such as flotation [10, 11], activated sludge process [12], chemical Hindawi Journal of Chemistry Volume 2020, Article ID 4310513, 8 pages https://doi.org/10.1155/2020/4310513
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Research ArticlePhotocatalytic Degradation of Rhodamine B by C and N CodopedTiO2 Nanoparticles under Visible-Light Irradiation
Thuy Thi Thanh Le 1 and Trinh Dinh Tran 2
1Department of Chemistry Faculty of Science Qui Nhon University No 170 an Duong Vuong Street Qui Nhon Vietnam2VNU Key Laboratory of Advanced Materials for Green Growth Faculty of Chemistry University of ScienceVietnam National University No 334 Nguyen Trai Street Hanoi Vietnam
Correspondence should be addressed to uy i anh Le lethithanhthuyqnueduvn andTrinh Dinh Tran trinhtdvnueduvn
Received 18 April 2020 Revised 6 June 2020 Accepted 18 June 2020 Published 9 July 2020
Guest Editor Tapan Sarkar
Copyright copy 2020uyianh Le and TrinhDinh Tranis is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in anymedium provided the original work isproperly cited
C andN codopedTiO2 nanoparticles were synthesized via a solvothermalmethodedegradation of Rhodamine B by the photocatalystC N-TiO2was investigated under visible-light irradiation generated by using a 36W compact fluorescent lampwhich is characterized bywavelengths from 400 to 650nme structure and properties of the obtained photocatalyst have been systematically investigated usingX-ray diffraction TEM UV-Vis FT-IR and BET techniques e experimental results revealed that C N codoped TiO2 nanoparticleswere successfully synthesized with an average diameter of 91nm C N-TiO2 nanoparticles exhibited an energy band gap of 290 eVwhich were lower than pristine TiO2 (334 eV) C-TiO2 (32 eV) and N-TiO2 (303 eV) e degradation of Rhodamine B by C N-TiO2indicated that under visible-light irradiation the optimal dose of the photocatalyst was 18 gL and the removal of Rhodamine B wasalmost complete after 3 hours of reaction e photocatalytic degradation of Rhodamine B in the range of 5ndash100mgL showed that theprocess followed the first-order kinetics according to the LangmuirndashHinshelwood model e highest apparent rate constant(00427minminus1) was obtainedwhen the initial concentration of Rhodamine Bwas 5mgL whereas the former decreasedwith the increasein the initial concentration of Rhodamine B Moreover C and N codoped TiO2 nanoparticles presented a high potential for recyclingwhich was characterized by a removal efficiency of more than 86 after three cycles
1 Introduction
TiO2 is one of the well-known photocatalysts because of itsnontoxicity chemical stability ease of processing low costand multiple reusability However TiO2 is only active underthe ultraviolet light (Egsim32 eV in the anatase phase) whichprevents it from various applications e doping of non-metals such as N C S P and halogens in TiO2 would lead toan increase in catalytic activities in the visible-light region[1ndash5] Particularly the modification of TiO2 by carbon in-creases the photosensitivity of the obtained materials [1 2]It has been reported that N-doping TiO2 could result in asignificant decrease in the energy band gap and an increasein catalytic activity in the visible-light region [3 4]
Rhodamine B (RhB) has been widely used in histologicspecimens textile paper and cosmetics industries RhB isalso a well-known water tracer fluorescent [6] RhB isharmful to humans and animals Expose to RhB was re-ported to cause acute symptoms such as burning of the eyesexcessive tearing nasal burning and itching chest paintightness and burning rhinorrhea cough burning of thethroat headache and nausea [7] e carcinogenicity andreproductive and developmental toxicity of RhB to humansand animals have been experimentally proven [8 9]erefore a number of efforts to remove RhB from theaqueous medium have been made Several techniques havebeen deployed to deal with RhB residues in waters such asflotation [10 11] activated sludge process [12] chemical
HindawiJournal of ChemistryVolume 2020 Article ID 4310513 8 pageshttpsdoiorg10115520204310513
oxidation [13 14] adsorption [15ndash17] and membrane fil-tration [18 19] Recently advanced oxidation processes(AOPs) in a particular photocatalytic approach have beenwidely applied for the degradation of RhB in waters Forinstance Phuruangrat et al [20 21] studied parametersinfluencing RhB degradation in a solution by Bi2WO6-basedcatalysts and found that at optimal conditions RhB deg-radation efficiency could reach more than 98 SimilarlyLee et al [22] reported that a photocatalyst based on apolydimethylsiloxane (PDMS)-TiO2-gold (Au) compositewas able to degrade about 85 of RhB after 90min of visible-light irradiation at photocatalytic system also presented ahigh potential of recyclability with a degradation efficiencyof more than 80 after four cycles of RhB treatment Le et al[23] revealed synergic effects in the Fe-C-TiO2AC photo-catalytic system and reported a very good catalytic activity ofthe system for the degradation of RhB in solutions undervisible-light irradiation After five cycles there were stillmore than 80 of RhB in solutions degraded by the Fe-C-TiO2AC photocatalytic system Similar results were re-ported by previous studies [24 25] Until now no workreports on the degradation of RhB by the C N-TiO2photocatalyst
In this work C and N codoped TiO2 was prepared bycombination of the sol-gel and hydrothermal methods emain objective is to shift light absorption from the UVregion to the visible-light region apart from the increase inphotocatalytic activity of as-synthesized photocatalystsDifferent parameters influencing the photodegradation ofRhB by C and N codoped TiO2 photocatalysts were studiedwhile the photodegradation of C and N codoped TiO2 wasdescribed by using the LangmuirndashHinshelwood equation
2 Experimental
21 Catalyst Preparation Chemicals TIOT (tetraisopropylorthotitanate 98) nitric acid (HNO3 68) ethyl alcohol(C2H5OH 997) and ammonium chloride (NH4Cl) pureand Rhodamine B (C28H31ClN2O3) were used Synthesis ofC N-TiO2 firstly two solutions A and B were preparedseparately Solution A was obtained by well mixing 6mLTIOT with 50mL C2H5OH while solution B contained amixture of 28mL C2H5OH 04mL HNO3 (68) 16mL ofdistilled water and 850mg NH4Cl Solution A was droppedinto the solution B under vigorous agitation at room tem-perature for 2 hours to form a uniform and transparent solsolution Sol was then aged for 2 days at room temperature toform gel which was then placed into a Teflon-lined stainlesssteel autoclave and heated at 180degC for 10 hours After thehydrothermal treatment the obtained solid was washedusing distilled water prior to being dried at 100degC for 24hours e C N-TiO2 catalyst was collected after beingpulverized in an agate mortar [26ndash28]
22 Photocatalytic Degradation Experiment To investigatethe optimal catalyst dosage 100mL RhB (20mgL) wasfirstly poured into a beaker (250mL) which was then addedwith x (gL) of the catalyst (x 14 18 26 and 30 gL)
en the obtained solution was stirred with a constant speedfor 30min in the black light to reach the absorption equi-librium Finally the solution was irradiated by a 36Wcompact fluorescent lamp and the decomposition time wascounted since then e RhB concentration during the re-action was measured by the photometry method e re-moval efficiency of the RhB bay photocatalyst (H) iscalculated based on the initial concentration of RhB (C0) andconcentration of RhB (Ct) at time (t) according to thefollowing equation
H() 100 middotC0 minus Ct( 1113857
C0 (1)
e effect of irradiation conditions on the RhB de-composition was also investigated e experiments werecarried out in the dark natural light at noon and lights froma 36W compact fluorescent lampe light characteristics ofthe deployed compact lamp were examined by using a PMS-50 spectrophotocolorimeter which showed that the deployedcompact lamp emitted light in the region of 400minus650 nm(Figure S1)
23 Characterization Techniques Crystallite phases of theobtained materials were identified by X-ray diffraction(XRD) measurements (D8 Advance 5005) A scanningelectron microscope (SEM Hitachi S4800) and a trans-mission electron microscope (TEM JEOL JEM-1010 elec-tron microscope) have been used to investigate the particlesize and morphology of the samples Wavelength absorptionwas conducted by UV-Vis (Jasco-V670 photospectrometer)Elemental composition of the catalyst was determined byenergy-dispersive X-ray spectroscopy EDX (JEOL-JSM6490) Functional groups were identified by IR spectroscopy(IR prestige 21) Nitrogen isothermal adsorption (Bru-nauerndashEmmettndashTeller (BET)) was done by TriStar 3000V607 A RhB concentrations were determined by UV-Vis at553 nm (the absorption maximum wavelength of RhB)
3 Results and Discussion
31 Characterization of C and N Codoped TiO2 As can beseen in Figure 1 unmodified TiO2 exhibits the characteristicpeaks of both anatase (A) and rutile (R) crystal phases whilemodified TiO2 only shows the characteristics peaks of theanatase crystal phase at 2θ of 2526deg 3778deg 3856deg 4800deg5390deg and 6392deg is indicates that the C and N codopingin TiO2 has an effect on the phase formation of the obtainedmaterial which may be attributed to an increase in itscatalytic activity [27] e average crystallite size of CN-TiO2 calculated by using Scherrerrsquos equation is 91 nmis is in good agreement with the results of TEM (Figure 2)measurement It is noted that the average crystallite size of CandN codoped TiO2 is smaller than that of unmodified TiO2
e UV-Vis spectra of the prepared photocatalysts arepresented in Figures 3 and 4 e results show that theabsorption band of C and N codoping TiO2 (C N-TiO2) wassignificantly expanded to the visible region compared to the
2 Journal of Chemistry
absorption bands of C-TiO2 N-TiO2 and pristine TiO2(Figure 3)
e band gap energies estimated by using the Taucmethod are 334 320 303 and 290 eV for pristine TiO2C-TiO2 N-TiO2 and C N-TiO2 respectively (Figure 4) edecrease in the energy band gap can be explained as follows(i) when adding the carbon element a part of carbon atomswill occupy the interstitial site in the crystal structure whichis attributed to the decrease in the energy band gap [26] (ii)N substitutes O leading to a significant decrease in theenergy band gap [3 27] Moreover a part of carbon atomscover on the surface of TiO2 in the form of graphite orcarbonate groups which would increase the photosentivity[3 29] e absorption edge shifts to the visible regionswould be promising for the application of photocatalystsunder sunlight irradiation
e IR spectra showing a broad peak appearing ataround 3450 cmminus1 could be assigned to vibrations of hy-droxyl groups on the surface of TiO2 in the form of Ti-OH(Figure 5) In addition the peak at 1647 cmminus1 is likely due tovibrations of hydroxyl groups in the form of Ti-O-OH erelatively weak peaks at 1540 cmminus1 and around 1385 cmminus1
could be attributed to the vibration of CO and C-O in thecarbonate group respectively (Figure 5) e presence ofthose functional groups on the TiO2 surface would lead to anincrease in photosensitivity of the as-synthesized catalysts[26]
e presence of the N element in the catalyst obtained isapproved by the peak at 1400 cmminus1 which is likely due tovibrations of N-H bonds In addition multiple bands at theregion of 536ndash484 cmminus1 are assigned to vibrations of Ti-Oand Ti-O-C bonds is is in agreement with the results ofEDX analysis (Figure 6) which reveal the presence of Ti OC and N elements in the samples It is noted that theformation of bonds between C and N elements and TiO2could be examined by using the X-ray photoelectronspectroscopy (XPS) method [24 25]
880nm 830nm
859nm
863nm
126nm117nm
788nm
929nm
20nm
Figure 2 TEM image of C N-TiO2
300 400 500 600 70000
02
04
06
08
10
Abso
rban
ce
TiO2C-TiO2
N-TiO2CN-TiO2
Wavelength (nm)
Figure 3 UV-VIS spectra of TiO2 (a) and C N-TiO2 (b)
25 30 35 40 450
20
40
60
80
100
334 eV
320 eV303 eV
Energy (eV)
290 eV
(αhv
)2 (eV
cmndash1
)2
TiO2C-TiO2
N-TiO2CN-TiO2
Figure 4 Plot of [αh]]2 vs h] for pristine TiO2 C-TiO2 N-TiO2and CN-TiO2
20 30 40 50 60 70 80
R
R
R
AAAA
A
AAAA
AA
Lin
(Cps
)
2-theta
A
R
(a)
(b)
Figure 1 XRD patterns of TiO2 (a) and C N-TiO2 (b)
Journal of Chemistry 3
BETanalysis was carried out under nitrogen atmosphereto figure out the porous features of the prepared synthesizedmaterials which is presented in Figure 7 e adsorptiondesorption plots of C N-TiO2 show a common type IVisotherm with a H3 hysteresis loop Furthermore the BJHanalysis shows a wide distribution of hierarchical pores withdiameters in the range of meso-macro pores (Figure S2) thepore volume for C N-TiO2 is 0040 cm3g
It is noted that the BET specific surface area of theprepared C N-TiO2 is 203m2gis figure is slightly higherwhen compared to the values previously reported forpristine TiO2 For instance Hussain et al [30] reported thatTiO2 commercial (anatasetechnical) could present a BETspecific surface area in the range of 10ndash15m2g while theincrease in rutile percentage could lead to an augmentationof the surface area of TiO2 Similarly Shi et al [31] revealedthat anatase TiO2 exhibited a BET surface area lower than5m2g and the latter would decrease when the treatmenttemperature increases Mahlambi et al [32] synthesized
TiO2 nanoparticles and found that at 550degC their specificsurface areas were 2272m2g and this value decreased to778m2g when the treatment temperature increased to600degC
32 Photocatalytic Performance of C N-TiO2 towards RhBDegradation e results in Figure 8 indicate that the RhBdegradation efficiency under visible-light condition of CN-TiO2 is higher than that of pure TiO2 As for C N-TiO2the degradation efficiency reached up to 94 after 90min ofirradiation is is consistent with the characteristics of theobtained catalyst
Studying the effect of the C N-TiO2 content on the RhBdegradation efficiency (Figure 9) suggests that the optimalamount of the catalyst is 18 gL Using a large amount ofcatalyst caused the photoresist resulting in a decrease incatalytic activity
According to the results obtained from liquid UV-Vismeasurements of the RhB solution by C N-TiO2 as afunction of treatment time (Figure 10) RhB changed overtime As for the initial RhB solution of 920mgL thecharacteristic peak at 533 nm moved to the peaks of theintermediate organic compounds e peak intensity ofthese compounds decreases with increasing treatment timeand is extremely low (near zero) after 3 hours of treatmentis suggests that the role of C N-TiO2 in the RhB deg-radation is different from the normal absorption processes[33 34]
It should be noted that the RhB degradation efficiency isextremely low in the dark (Figure 11) indicating that thecatalyst obtained is a photocatalyst e RhB degradationefficiency under compact lamp and natural light irradiationis almost the same because of the 36W compact lampcontaining wavelength at 450 nm near absorption maximumof the catalyst Hence the obtained catalyst works well invisible light and natural light and it is in agreement withprevious reported works [35ndash37]
4000 3600 3200 2800 2400 2000 1600 1200 800 4000
10
20
30
40
50
60
70
80
T
TiO2CN-TiO2
Wavenumber (cmndash1)
Figure 5 IR spectra of TiO2 (a) and C N-TiO2 (b)
1 2 3 4 5 6 7 8 9 10 11Energy (keV)
Cps
Figure 6 EDX analysis of C N-TiO2
0
5
10
15
20
25
30
0 02 04 06 08 1
Qua
ntity
adso
rbed
(cm
3 g S
TP)
Relative pressure (pp0)
AdsorptionDesorption
Figure 7 Nitrogen adsorption-desorption isotherms for the C N-TiO2 photocatalyst
4 Journal of Chemistry
33 Kinetics of RhB Degradation by C N-TiO2 under Visible-Light Irradiation Kinetics of the RhB degradation reactionwas studied by using different initial concentrations of RhB(0ndash100mgL) while keeping the catalyst load constant at18 gL
RhB decomposition reaction can be described by theLangmuirndashHinshelwood kinetics equation that is expressedas follows [27]
r minusdC
dt k
KC
1 + KC (2)
where k is the reaction rate constant K is the adsorptioncoefficient t is the time and C is the reactant concentration(the target organic compound) In the case of low initialconcentrations KCltlt 1 equation (2) can be rewritten as thefollowing
r minusdC
dt k middot KC kprime middot C (3)
where krsquo is the apparent rate constant which is also known asthe reduced first-order reaction en the following equa-tion is derived
lnCo
Ct
kprime middot t (4)
where Co and Ct are the reactant concentrations at t 0 and t(min) respectively Figure 12 shows the dependence of lnCoCt on time during the degradation of RhB by the C N-TiO2photocatalyst
As can be seen in Figures 12 and 13 when the initialconcentrations of RhB were in the range of 0ndash100mgL thephotodegradation was divided into 3 distinct groups whichwere characterized by the corresponding distinct apparent rateconstants e decomposition of RhB was observed unstablewhen the initial concentration was relatively low (0ndash10mgL)is is due to the degradationmainly affected by the absorption
0
20
40
60
80
100
120
0 30 60 90 120Time (min)
Rem
oval
effic
ienc
y of
RhB
()
(a)
(b)
Figure 8 Comparison of degradation efficiency as a function oflight irradiation time of TiO2 (a) and C N-TiO2 (b)
0
20
40
60
80
100
0 30 60 90Time (min)
Rem
oval
effic
ienc
y of
RhB
()
18 gl26 gl14 gl3 gl
Figure 9 Effect of catalyst concentration on the RhB degradationefficiency of C N-TiO2
0
05
1
15
2
25
3
35
ABS
Wavelength (nm)
Rhodamine B (t = 0)Rhodamine B (t = 1 (h))Rhodamine B (t = 15 (h))
Rhodamine B (t = 2 (h))Rhodamine B (t = 3 (h))
546
524
497
380
392
404
416
428
440
452
464
476
488
500
512
524
536
548
560
572
584
596
608
620
632
644
656
668
680
692
704
716
728
740
554
Figure 10 Liquid UV-Vis spectra of the RhB solution as a functionof treatment time
0
20
40
60
80
100
0 30 60 90Time (min)
Rem
oval
effic
ienc
y of
RhB
()
DarknessCompact lampNatural light
Figure 11 RhB degradation efficiency of C N-TiO2 under differentirradiation conditions
Journal of Chemistry 5
process e corresponding apparent rate constant krsquo is00427minminus1 In contrast when the initial concentration wasrelatively high (gt10mgL) the RhB decomposition occurredvery slowly resulting in smaller apparent rate constants(krsquo 00041minminus1 for 100mgL) is is because the bold colorof RhB causes the photoresist [23 27] e suitable initialconcentration for stable decomposition is about 20ndash40mgLe optimal initial concentration of RhB is 20mgL at whichthe apparent rate constant krsquo is 00205minminus1 e results ob-tained in this work is in agreement with previous studies[27 32] Hence with the RhB initial concentration of 20mgLequation (4) can be expressed by the following
lnCo
Ct
00205 times t (5)
Similarly the relation between CoCt and t for other initialconcentrations of RhB could be plotted as in Figure 13
e photocatalytic degradation of RhB by the C N-TiO2system can be explained by the following mechanism(Figure 14) (1) once h]ge (ECndashEVprime) electrons would beexcited in the valence band of TiO2 by the process TiO2 + h]
(UV)⟶TiO2 (eCBminus+ hVB+) (2) the departed electrons andholes subsequently migrate to the surface of the catalysts andreact with adsorbed H2O and O2 molecules forming bullOHand bullO2
minus respectively according to equations (6)ndash(8)
H2O + hVB+⟶ bullOH + H+
(6)
HOadminus
+ hVB+⟶ bullOHad (7)
eCBminus
+ O2⟶bullO2
minus(8)
and (3) bullOH and bullO2minus radicals are mainly responsible for the
degradation of RhB in solutions [38]emechanism for thedegradation of RhB in solutions by the C N-TiO2 system isproposed in Figure 14
34 Recoverability andReusability of CN-TiO2 Photocatalyste catalytic stability in RhB decomposition under visible-lightirradiation was studied After each decomposition cycle thecatalyst was centrifuged washed with distilled water and thenused for further treatment of RhB in solutions As can be seen inFigure 15 C and N codoped TiO2 exhibited good catalytic
000E + 00
100E ndash 02
200E ndash 02
300E ndash 02
400E ndash 02
500E ndash 02
0 20 40 60 80 100Co (mgl)
kprime(1
min
)
Figure 13 e apparent rate constant krsquo as a function of initialconcentrations of RhB
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140Time (min)
Ln(C
oC t
)
5 mgl y = 00427x
10 mgl y = 00345x
20 mgl y = 00205x30 mgl y = 00147x40 mgl y = 00136x
80 mgl y = 00080x90 mgl y = 00069x100 mgl y = 00041x
60 mgl y = 00110x
Figure 12 First-order kinetics for RhB degradation at differentinitial concentrations
UV light
TiO2VB
CB
334
eV
EC
EV
CN-TiO2
EprimeV
h+
h+
endash
endash endash
Visible light
290
eV
O2
bullO2ndash
OHndash
bullOH
Figure 14 Schematic mechanism of photocatalytic degradation ofRhB by C N-TiO2
0
02
04
06
08
1
0 30 60 90 120 150 180 210 240 270Time (min)
C tC
o
(a) (b) (c)
Figure 15 Catalystrsquos reuse results (a) first cycle (b) second cycle(c) third cycle
6 Journal of Chemistry
activity with the degradation efficiency of above 86 after threecycles and the obtained results were in agreement with previousstudies [39] It is noted that the absence of RhB and othersubstances on the surface of the catalyst and no release ofcatalysts to the water medium need to be proved prior to eachsubsequent cycle is could be revealed by using TEM FT-IRBET and extinction spectrum change of the water solution [22]In this work the photocatalytic performance is still very highafter three cycles (86) suggesting that the presence of sub-stances on the catalystrsquos surfaces is insignificant
4 Conclusions
In this work C and N codoped TiO2 nanoparticles aresuccessfully prepared by solvothermal synthesis and thenused for the study on their catalytic activities regardingRhB degradation in solutions under visible-light irradi-ation e obtained results showed that the as-synthesizednanoparticles mainly contained anatase crystallites withan average particle diameter of 91 nm C N-TiO2 pre-sented a high catalytic activity in the RhB degradationunder visible-light irradiation e optimal catalyst dos-age was 18 gL while optimal initial concentration of RhBwas 5mgL e photocatalytic degradation kinetics wasfound to follow the first-order rate law of the Lang-muirndashHinshelwood model e apparent rate constantdepended on the initial concentration of RhB which washigher at more diluted solutions of RhB
Data Availability
All the data used to support the findings of this study areprovided within the manuscript
Conflicts of Interest
e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
is work was partly supported by the Team Project ofVLIR-UOS with the code number ZEIN2016PR431 eauthors would like to thank the OEPAC project for theutilization of instruments
Supplementary Materials
Figure S1 energy spectra of the deployed compact lampFigure S2 BJH adsorption analysis for the C N-TiO2photocatalyst (Supplementary Materials)
References
[1] H Liu Y Wu and J Zhang ldquoA new approach toward carbon-modified vanadium-doped titanium dioxide photocatalystsrdquoACS Applied Materials amp Interfaces vol 3 no 5 pp 1757ndash17642011
[2] S Jafari B Tryba E Kusiak-Nejman J Kapica-KozarA W Morawski and M Sillanpaa ldquoe role of adsorption inthe photocatalytic decomposition of Orange II on carbon-
modified TiO2rdquo Journal of Molecular Liquids vol 220pp 504ndash512 2016
[3] Y Taga ldquoTitanium oxide based visible light photocatalystsmaterials design and applicationsrdquo ltin Solid Films vol 517no 10 pp 3167ndash3172 2009
[4] S Hosseini H Jahangirian T J Webster S M Soltani andM K Aroua ldquoSynthesis characterization and performanceevaluation of multilayered photoanodes by introducing meso-porous carbon and TiO2 for humic acid adsorptionrdquo Interna-tional Journal of Nanomedicine vol 11 pp 3969ndash3978 2016
[5] G Zhang Y C Zhang M Nadagouda et al ldquoVisible light-sensitized S N and C co-doped polymorphic TiO2 for pho-tocatalytic destruction of microcystin-LRrdquo Applied CatalysisB Environmental vol 144 pp 614ndash621 2014
[6] S D Richardson C S Willson and K A Rusch ldquoUse ofrhodamine water tracer in the marshland upwelling systemrdquoGround Water vol 42 no 5 pp 678ndash688 2004
[7] D J Dire and J A Wilkinson ldquoAcute exposure to rhodamineBrdquo Journal of Toxicology Clinical Toxicology vol 25 no 7pp 603ndash607 1987
[8] D Kornbrust and T Barfknecht ldquoTesting of 24 food drugcosmetic and fabric dyes in the in vitro and the in vivoinvitro rat hepatocyte primary culture DNA repair assaysrdquoEnvironmental Mutagenesis vol 7 no 1 pp 101ndash120 1985
[9] E R Nestmann G R Douglas T I Matula C E Grant andD J Kowbel ldquoMutagenic activity of rhodamine dyes and theirimpurities as detected by mutation induction in Salmonellaand DMA damage in Chinese hamster ovary cellsrdquo CancerResearch vol 39 pp 4412ndash4417 1979
[10] S Zodi B Merzouk O Potier F Lapicque and J-P LeclercldquoDirect red 81 dye removal by a continuous flow electro-coagulationflotation reactorrdquo Separation and PurificationTechnology vol 108 pp 215ndash222 2013
[11] Y-M Zheng R F Yunus K G N Nanayakkara andJ P Chen ldquoElectrochemical decoloration of syntheticwastewater containing rhodamine 6G behaviors and mech-anismrdquo Industrial amp Engineering Chemistry Research vol 51no 17 pp 5953ndash5960 2012
[12] H K Shon S Vigneswaran I S Kim et al ldquoPreparation oftitanium dioxide (TiO2) from sludge produced by titaniumtetrachloride (TiCl4) flocculation of wastewaterrdquo Environ-mental Science amp Technology vol 41 no 4 pp 1372ndash13772007
[13] X Chen Z Xue Y Yao W Wang F Zhu and C HongldquoOxidation degradation of rhodamine B in aqueous by UVS2O82- treatment systemrdquo International Journal of Photo-energy vol 2012 Article ID 754691 9 pages 2012
[14] W Griffith ldquoOzonolysis in coordination chemistry and ca-talysis recent advancesrdquo Coordination Chemistry Reviewsvol 219ndash221 pp 259ndash281 2001
[15] K Shen and M A Gondal ldquoRemoval of hazardous Rhoda-mine dye from water by adsorption onto exhausted coffeegroundrdquo Journal of Saudi Chemical Society vol 21pp S120ndashS127 2017
[16] T A Khan M Nazir and E A Khan ldquoAdsorptive removal ofrhodamine B from textile wastewater using water chestnut(Trapa natans L) peel adsorption dynamics and kineticstudiesrdquo Toxicological amp Environmental Chemistry vol 95no 6 pp 919ndash931 2013
[17] A A Oyekanmi A Ahmad K Hossain and M RafatullahldquoAdsorption of Rhodamine B dye from aqueous solution ontoacid treated banana peel response surface methodology ki-netics and isotherm studiesrdquo PLoS ONE vol 14 no 5 ArticleID e0216878 2019
Journal of Chemistry 7
[18] S Elumalai and G Muthuraman ldquoComparative study ofliquidndashliquid extraction and bulk liquid membrane for rho-damine Brdquo International Journal of Engineering and Inno-vative Technology vol 3 no 2 pp 387ndash392 2013
[19] M E Ersahin H Ozgun R K Dereli I Ozturk K Roest andJ B van Lier ldquoA review on dynamic membrane filtrationmaterials applications and future perspectivesrdquo BioresourceTechnology vol 122 pp 196ndash206 2012
[20] A Phuruangrat A Maneechote P DumrongrojthanathN Ekthammathat S ongtem and T ongtem ldquoEffect ofpH on visible-light-driven Bi2WO6 nanostructured catalystsynthesized by hydrothermal methodrdquo Superlattices andMicrostructures vol 78 pp 106ndash115 2015
[21] P Dumrongrojthanath T ongtem A Phuruangrat andS ongtem ldquoSynthesis and characterization of hierarchicalmultilayered flower-like assemblies of Ag doped Bi2WO6 andtheir photocatalytic activitiesrdquo Superlattices and Microstruc-tures vol 64 pp 196ndash203 2013
[22] S Y Lee D Kang S Jeong H T Do and J H KimldquoPhotocatalytic degradation of rhodamine B dye by TiO2 andgold nanoparticles supported on a floating porous poly-dimethylsiloxane sponge under ultraviolet and visible lightirradiationrdquo ACS Omega vol 5 no 8 pp 4233ndash4241 2020
[23] T T T Le T L Nguyen D T Tran and V N NguyenldquoEnhanced photocatalytic degradation of rhodamine B usingCFe Co-doped titanium dioxide coated on activated carbonrdquoJournal of Chemistry vol 2019 Article ID 2949316 8 pages2019
[24] J ShaoW Sheng MWang et al ldquoIn situ synthesis of carbon-doped TiO 2 single-crystal nanorods with a remarkablyphotocatalytic efficiencyrdquoApplied Catalysis B Environmentalvol 209 pp 311ndash319 2017
[25] Y Zhang J Chen L Hua et al ldquoHigh photocatalytic activityof hierarchical SiO2C-doped TiO2 hollow spheres in UVand visible light towards degradation of rhodamine BrdquoJournal of Hazardous Materials vol 340 pp 309ndash318 2017
[26] C Chen M Long H Zeng et al ldquoPreparation character-ization and visible-light activity of carbon modified TiO2 withtwo kinds of carbonaceous speciesrdquo Journal of MolecularCatalysis A Chemical vol 314 no 1-2 pp 35ndash41 2009
[27] W Xiaoping and T-T Lim ldquoSolvothermal synthesis of C-Ncodoped TiO2 and photocatalytic evaluation for bisphenol Adegradation using a visible-light irradiation LED photo-reactorrdquo Applied Catalysis B Environmental vol 100pp 355ndash364 2010
[28] U G Akpan and B H Hameed ldquoe advancements in sol-gelmethod of doped-TiO2 photocatalystsrdquo Applied Catalysis AGeneral vol 375 no 1 pp 1ndash11 2010
[29] H J Yun H Lee J B Joo N D Kim M Y Kang and J YildquoFacile preparation of high performance visible light sensitivephoto-catalystsrdquo Applied Catalysis B Environmental vol 94no 3-4 pp 241ndash247 2010
[30] M Hussain R Ceccarelli D L Marchisio D Fino N Russoand F Geobaldo ldquoSynthesis characterization and photo-catalytic application of novel TiO2 nanoparticlesrdquo ChemicalEngineering Journal vol 157 no 1 pp 45ndash51 2010
[31] T Shi Y Duan K Lv et al ldquoPhotocatalytic oxidation ofacetone over high thermally stable TiO2 nanosheets withexposed (001) facetsrdquo Frontiers in Chemistry vol 6 p 1752018
[32] M M Mahlambi A K Mishra S B Mishra R W KrauseB B Mamba and A M Raichur ldquoComparison of rhodamineB degradation under UV irradiation by two phases of titania
nano-photocatalystrdquo Journal of ltermal Analysis and Calo-rimetry vol 110 no 2 pp 847ndash855 2012
[33] W Zhang Y Li C Wang and P Wang ldquoKinetics of het-erogeneous photocatalytic degradation of Rhodamine B byTiO2-coated activated carbon roles of TiO2 content and lightintensityrdquo Desalination vol 266 no 1-3 pp 40ndash45 2011
[34] Y Xiao X Sun l Li et al ldquoSimultaneous formation of a CN-TiO2 hollow photocatalyst with efficient photocatalytic per-formance and recyclabilityrdquo Chinese Journal of Catalysisvol 40 no 5 pp 765ndash775 2019
[35] Y Wu J Zhang L Xiao and F Chen ldquoProperties of carbonand iron modified TiO2 photocatalyst synthesized at lowtemperature and photodegradation of acid orange 7 undervisible lightrdquo Applied Surface Science vol 256 no 13pp 4260ndash4268 2010
[36] X Cheng X Yu and Z Xing ldquoSynthesis and characterizationof C-N-S-tridoped TiO2 nano-crystalline photocatalyst and itsphotocatalytic activity for degradation of rhodamine BrdquoJournal of Physics and Chemistry of Solids vol 74 no 5pp 684ndash690 2013
[37] H Huang Y Song N Li et al ldquoOne-step in-situ preparationof N-doped TiO2C derived fromTi3C2MXene for enhancedvisible-light driven photodegradationrdquo Applied Catalysis BEnvironmental vol 251 pp 154ndash161 2019
[38] L Youji Z Xiaoming C Wei et al ldquoPhotodecolorization ofRhodamine B on tungsten-doped TiO2activated carbonunder visible-light irradiationrdquo Journal of Hazardous Mate-rials vol 227-228 pp 25ndash33 2012
[39] A Y Shan T I M Ghazi and S A Rashid ldquoImmobilisationof titanium dioxide onto supporting materials in heteroge-neous photocatalysis a reviewrdquo Applied Catalysis A Generalvol 389 no 1-2 pp 1ndash8 2010
8 Journal of Chemistry
oxidation [13 14] adsorption [15ndash17] and membrane fil-tration [18 19] Recently advanced oxidation processes(AOPs) in a particular photocatalytic approach have beenwidely applied for the degradation of RhB in waters Forinstance Phuruangrat et al [20 21] studied parametersinfluencing RhB degradation in a solution by Bi2WO6-basedcatalysts and found that at optimal conditions RhB deg-radation efficiency could reach more than 98 SimilarlyLee et al [22] reported that a photocatalyst based on apolydimethylsiloxane (PDMS)-TiO2-gold (Au) compositewas able to degrade about 85 of RhB after 90min of visible-light irradiation at photocatalytic system also presented ahigh potential of recyclability with a degradation efficiencyof more than 80 after four cycles of RhB treatment Le et al[23] revealed synergic effects in the Fe-C-TiO2AC photo-catalytic system and reported a very good catalytic activity ofthe system for the degradation of RhB in solutions undervisible-light irradiation After five cycles there were stillmore than 80 of RhB in solutions degraded by the Fe-C-TiO2AC photocatalytic system Similar results were re-ported by previous studies [24 25] Until now no workreports on the degradation of RhB by the C N-TiO2photocatalyst
In this work C and N codoped TiO2 was prepared bycombination of the sol-gel and hydrothermal methods emain objective is to shift light absorption from the UVregion to the visible-light region apart from the increase inphotocatalytic activity of as-synthesized photocatalystsDifferent parameters influencing the photodegradation ofRhB by C and N codoped TiO2 photocatalysts were studiedwhile the photodegradation of C and N codoped TiO2 wasdescribed by using the LangmuirndashHinshelwood equation
2 Experimental
21 Catalyst Preparation Chemicals TIOT (tetraisopropylorthotitanate 98) nitric acid (HNO3 68) ethyl alcohol(C2H5OH 997) and ammonium chloride (NH4Cl) pureand Rhodamine B (C28H31ClN2O3) were used Synthesis ofC N-TiO2 firstly two solutions A and B were preparedseparately Solution A was obtained by well mixing 6mLTIOT with 50mL C2H5OH while solution B contained amixture of 28mL C2H5OH 04mL HNO3 (68) 16mL ofdistilled water and 850mg NH4Cl Solution A was droppedinto the solution B under vigorous agitation at room tem-perature for 2 hours to form a uniform and transparent solsolution Sol was then aged for 2 days at room temperature toform gel which was then placed into a Teflon-lined stainlesssteel autoclave and heated at 180degC for 10 hours After thehydrothermal treatment the obtained solid was washedusing distilled water prior to being dried at 100degC for 24hours e C N-TiO2 catalyst was collected after beingpulverized in an agate mortar [26ndash28]
22 Photocatalytic Degradation Experiment To investigatethe optimal catalyst dosage 100mL RhB (20mgL) wasfirstly poured into a beaker (250mL) which was then addedwith x (gL) of the catalyst (x 14 18 26 and 30 gL)
en the obtained solution was stirred with a constant speedfor 30min in the black light to reach the absorption equi-librium Finally the solution was irradiated by a 36Wcompact fluorescent lamp and the decomposition time wascounted since then e RhB concentration during the re-action was measured by the photometry method e re-moval efficiency of the RhB bay photocatalyst (H) iscalculated based on the initial concentration of RhB (C0) andconcentration of RhB (Ct) at time (t) according to thefollowing equation
H() 100 middotC0 minus Ct( 1113857
C0 (1)
e effect of irradiation conditions on the RhB de-composition was also investigated e experiments werecarried out in the dark natural light at noon and lights froma 36W compact fluorescent lampe light characteristics ofthe deployed compact lamp were examined by using a PMS-50 spectrophotocolorimeter which showed that the deployedcompact lamp emitted light in the region of 400minus650 nm(Figure S1)
23 Characterization Techniques Crystallite phases of theobtained materials were identified by X-ray diffraction(XRD) measurements (D8 Advance 5005) A scanningelectron microscope (SEM Hitachi S4800) and a trans-mission electron microscope (TEM JEOL JEM-1010 elec-tron microscope) have been used to investigate the particlesize and morphology of the samples Wavelength absorptionwas conducted by UV-Vis (Jasco-V670 photospectrometer)Elemental composition of the catalyst was determined byenergy-dispersive X-ray spectroscopy EDX (JEOL-JSM6490) Functional groups were identified by IR spectroscopy(IR prestige 21) Nitrogen isothermal adsorption (Bru-nauerndashEmmettndashTeller (BET)) was done by TriStar 3000V607 A RhB concentrations were determined by UV-Vis at553 nm (the absorption maximum wavelength of RhB)
3 Results and Discussion
31 Characterization of C and N Codoped TiO2 As can beseen in Figure 1 unmodified TiO2 exhibits the characteristicpeaks of both anatase (A) and rutile (R) crystal phases whilemodified TiO2 only shows the characteristics peaks of theanatase crystal phase at 2θ of 2526deg 3778deg 3856deg 4800deg5390deg and 6392deg is indicates that the C and N codopingin TiO2 has an effect on the phase formation of the obtainedmaterial which may be attributed to an increase in itscatalytic activity [27] e average crystallite size of CN-TiO2 calculated by using Scherrerrsquos equation is 91 nmis is in good agreement with the results of TEM (Figure 2)measurement It is noted that the average crystallite size of CandN codoped TiO2 is smaller than that of unmodified TiO2
e UV-Vis spectra of the prepared photocatalysts arepresented in Figures 3 and 4 e results show that theabsorption band of C and N codoping TiO2 (C N-TiO2) wassignificantly expanded to the visible region compared to the
2 Journal of Chemistry
absorption bands of C-TiO2 N-TiO2 and pristine TiO2(Figure 3)
e band gap energies estimated by using the Taucmethod are 334 320 303 and 290 eV for pristine TiO2C-TiO2 N-TiO2 and C N-TiO2 respectively (Figure 4) edecrease in the energy band gap can be explained as follows(i) when adding the carbon element a part of carbon atomswill occupy the interstitial site in the crystal structure whichis attributed to the decrease in the energy band gap [26] (ii)N substitutes O leading to a significant decrease in theenergy band gap [3 27] Moreover a part of carbon atomscover on the surface of TiO2 in the form of graphite orcarbonate groups which would increase the photosentivity[3 29] e absorption edge shifts to the visible regionswould be promising for the application of photocatalystsunder sunlight irradiation
e IR spectra showing a broad peak appearing ataround 3450 cmminus1 could be assigned to vibrations of hy-droxyl groups on the surface of TiO2 in the form of Ti-OH(Figure 5) In addition the peak at 1647 cmminus1 is likely due tovibrations of hydroxyl groups in the form of Ti-O-OH erelatively weak peaks at 1540 cmminus1 and around 1385 cmminus1
could be attributed to the vibration of CO and C-O in thecarbonate group respectively (Figure 5) e presence ofthose functional groups on the TiO2 surface would lead to anincrease in photosensitivity of the as-synthesized catalysts[26]
e presence of the N element in the catalyst obtained isapproved by the peak at 1400 cmminus1 which is likely due tovibrations of N-H bonds In addition multiple bands at theregion of 536ndash484 cmminus1 are assigned to vibrations of Ti-Oand Ti-O-C bonds is is in agreement with the results ofEDX analysis (Figure 6) which reveal the presence of Ti OC and N elements in the samples It is noted that theformation of bonds between C and N elements and TiO2could be examined by using the X-ray photoelectronspectroscopy (XPS) method [24 25]
880nm 830nm
859nm
863nm
126nm117nm
788nm
929nm
20nm
Figure 2 TEM image of C N-TiO2
300 400 500 600 70000
02
04
06
08
10
Abso
rban
ce
TiO2C-TiO2
N-TiO2CN-TiO2
Wavelength (nm)
Figure 3 UV-VIS spectra of TiO2 (a) and C N-TiO2 (b)
25 30 35 40 450
20
40
60
80
100
334 eV
320 eV303 eV
Energy (eV)
290 eV
(αhv
)2 (eV
cmndash1
)2
TiO2C-TiO2
N-TiO2CN-TiO2
Figure 4 Plot of [αh]]2 vs h] for pristine TiO2 C-TiO2 N-TiO2and CN-TiO2
20 30 40 50 60 70 80
R
R
R
AAAA
A
AAAA
AA
Lin
(Cps
)
2-theta
A
R
(a)
(b)
Figure 1 XRD patterns of TiO2 (a) and C N-TiO2 (b)
Journal of Chemistry 3
BETanalysis was carried out under nitrogen atmosphereto figure out the porous features of the prepared synthesizedmaterials which is presented in Figure 7 e adsorptiondesorption plots of C N-TiO2 show a common type IVisotherm with a H3 hysteresis loop Furthermore the BJHanalysis shows a wide distribution of hierarchical pores withdiameters in the range of meso-macro pores (Figure S2) thepore volume for C N-TiO2 is 0040 cm3g
It is noted that the BET specific surface area of theprepared C N-TiO2 is 203m2gis figure is slightly higherwhen compared to the values previously reported forpristine TiO2 For instance Hussain et al [30] reported thatTiO2 commercial (anatasetechnical) could present a BETspecific surface area in the range of 10ndash15m2g while theincrease in rutile percentage could lead to an augmentationof the surface area of TiO2 Similarly Shi et al [31] revealedthat anatase TiO2 exhibited a BET surface area lower than5m2g and the latter would decrease when the treatmenttemperature increases Mahlambi et al [32] synthesized
TiO2 nanoparticles and found that at 550degC their specificsurface areas were 2272m2g and this value decreased to778m2g when the treatment temperature increased to600degC
32 Photocatalytic Performance of C N-TiO2 towards RhBDegradation e results in Figure 8 indicate that the RhBdegradation efficiency under visible-light condition of CN-TiO2 is higher than that of pure TiO2 As for C N-TiO2the degradation efficiency reached up to 94 after 90min ofirradiation is is consistent with the characteristics of theobtained catalyst
Studying the effect of the C N-TiO2 content on the RhBdegradation efficiency (Figure 9) suggests that the optimalamount of the catalyst is 18 gL Using a large amount ofcatalyst caused the photoresist resulting in a decrease incatalytic activity
According to the results obtained from liquid UV-Vismeasurements of the RhB solution by C N-TiO2 as afunction of treatment time (Figure 10) RhB changed overtime As for the initial RhB solution of 920mgL thecharacteristic peak at 533 nm moved to the peaks of theintermediate organic compounds e peak intensity ofthese compounds decreases with increasing treatment timeand is extremely low (near zero) after 3 hours of treatmentis suggests that the role of C N-TiO2 in the RhB deg-radation is different from the normal absorption processes[33 34]
It should be noted that the RhB degradation efficiency isextremely low in the dark (Figure 11) indicating that thecatalyst obtained is a photocatalyst e RhB degradationefficiency under compact lamp and natural light irradiationis almost the same because of the 36W compact lampcontaining wavelength at 450 nm near absorption maximumof the catalyst Hence the obtained catalyst works well invisible light and natural light and it is in agreement withprevious reported works [35ndash37]
4000 3600 3200 2800 2400 2000 1600 1200 800 4000
10
20
30
40
50
60
70
80
T
TiO2CN-TiO2
Wavenumber (cmndash1)
Figure 5 IR spectra of TiO2 (a) and C N-TiO2 (b)
1 2 3 4 5 6 7 8 9 10 11Energy (keV)
Cps
Figure 6 EDX analysis of C N-TiO2
0
5
10
15
20
25
30
0 02 04 06 08 1
Qua
ntity
adso
rbed
(cm
3 g S
TP)
Relative pressure (pp0)
AdsorptionDesorption
Figure 7 Nitrogen adsorption-desorption isotherms for the C N-TiO2 photocatalyst
4 Journal of Chemistry
33 Kinetics of RhB Degradation by C N-TiO2 under Visible-Light Irradiation Kinetics of the RhB degradation reactionwas studied by using different initial concentrations of RhB(0ndash100mgL) while keeping the catalyst load constant at18 gL
RhB decomposition reaction can be described by theLangmuirndashHinshelwood kinetics equation that is expressedas follows [27]
r minusdC
dt k
KC
1 + KC (2)
where k is the reaction rate constant K is the adsorptioncoefficient t is the time and C is the reactant concentration(the target organic compound) In the case of low initialconcentrations KCltlt 1 equation (2) can be rewritten as thefollowing
r minusdC
dt k middot KC kprime middot C (3)
where krsquo is the apparent rate constant which is also known asthe reduced first-order reaction en the following equa-tion is derived
lnCo
Ct
kprime middot t (4)
where Co and Ct are the reactant concentrations at t 0 and t(min) respectively Figure 12 shows the dependence of lnCoCt on time during the degradation of RhB by the C N-TiO2photocatalyst
As can be seen in Figures 12 and 13 when the initialconcentrations of RhB were in the range of 0ndash100mgL thephotodegradation was divided into 3 distinct groups whichwere characterized by the corresponding distinct apparent rateconstants e decomposition of RhB was observed unstablewhen the initial concentration was relatively low (0ndash10mgL)is is due to the degradationmainly affected by the absorption
0
20
40
60
80
100
120
0 30 60 90 120Time (min)
Rem
oval
effic
ienc
y of
RhB
()
(a)
(b)
Figure 8 Comparison of degradation efficiency as a function oflight irradiation time of TiO2 (a) and C N-TiO2 (b)
0
20
40
60
80
100
0 30 60 90Time (min)
Rem
oval
effic
ienc
y of
RhB
()
18 gl26 gl14 gl3 gl
Figure 9 Effect of catalyst concentration on the RhB degradationefficiency of C N-TiO2
0
05
1
15
2
25
3
35
ABS
Wavelength (nm)
Rhodamine B (t = 0)Rhodamine B (t = 1 (h))Rhodamine B (t = 15 (h))
Rhodamine B (t = 2 (h))Rhodamine B (t = 3 (h))
546
524
497
380
392
404
416
428
440
452
464
476
488
500
512
524
536
548
560
572
584
596
608
620
632
644
656
668
680
692
704
716
728
740
554
Figure 10 Liquid UV-Vis spectra of the RhB solution as a functionof treatment time
0
20
40
60
80
100
0 30 60 90Time (min)
Rem
oval
effic
ienc
y of
RhB
()
DarknessCompact lampNatural light
Figure 11 RhB degradation efficiency of C N-TiO2 under differentirradiation conditions
Journal of Chemistry 5
process e corresponding apparent rate constant krsquo is00427minminus1 In contrast when the initial concentration wasrelatively high (gt10mgL) the RhB decomposition occurredvery slowly resulting in smaller apparent rate constants(krsquo 00041minminus1 for 100mgL) is is because the bold colorof RhB causes the photoresist [23 27] e suitable initialconcentration for stable decomposition is about 20ndash40mgLe optimal initial concentration of RhB is 20mgL at whichthe apparent rate constant krsquo is 00205minminus1 e results ob-tained in this work is in agreement with previous studies[27 32] Hence with the RhB initial concentration of 20mgLequation (4) can be expressed by the following
lnCo
Ct
00205 times t (5)
Similarly the relation between CoCt and t for other initialconcentrations of RhB could be plotted as in Figure 13
e photocatalytic degradation of RhB by the C N-TiO2system can be explained by the following mechanism(Figure 14) (1) once h]ge (ECndashEVprime) electrons would beexcited in the valence band of TiO2 by the process TiO2 + h]
(UV)⟶TiO2 (eCBminus+ hVB+) (2) the departed electrons andholes subsequently migrate to the surface of the catalysts andreact with adsorbed H2O and O2 molecules forming bullOHand bullO2
minus respectively according to equations (6)ndash(8)
H2O + hVB+⟶ bullOH + H+
(6)
HOadminus
+ hVB+⟶ bullOHad (7)
eCBminus
+ O2⟶bullO2
minus(8)
and (3) bullOH and bullO2minus radicals are mainly responsible for the
degradation of RhB in solutions [38]emechanism for thedegradation of RhB in solutions by the C N-TiO2 system isproposed in Figure 14
34 Recoverability andReusability of CN-TiO2 Photocatalyste catalytic stability in RhB decomposition under visible-lightirradiation was studied After each decomposition cycle thecatalyst was centrifuged washed with distilled water and thenused for further treatment of RhB in solutions As can be seen inFigure 15 C and N codoped TiO2 exhibited good catalytic
000E + 00
100E ndash 02
200E ndash 02
300E ndash 02
400E ndash 02
500E ndash 02
0 20 40 60 80 100Co (mgl)
kprime(1
min
)
Figure 13 e apparent rate constant krsquo as a function of initialconcentrations of RhB
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140Time (min)
Ln(C
oC t
)
5 mgl y = 00427x
10 mgl y = 00345x
20 mgl y = 00205x30 mgl y = 00147x40 mgl y = 00136x
80 mgl y = 00080x90 mgl y = 00069x100 mgl y = 00041x
60 mgl y = 00110x
Figure 12 First-order kinetics for RhB degradation at differentinitial concentrations
UV light
TiO2VB
CB
334
eV
EC
EV
CN-TiO2
EprimeV
h+
h+
endash
endash endash
Visible light
290
eV
O2
bullO2ndash
OHndash
bullOH
Figure 14 Schematic mechanism of photocatalytic degradation ofRhB by C N-TiO2
0
02
04
06
08
1
0 30 60 90 120 150 180 210 240 270Time (min)
C tC
o
(a) (b) (c)
Figure 15 Catalystrsquos reuse results (a) first cycle (b) second cycle(c) third cycle
6 Journal of Chemistry
activity with the degradation efficiency of above 86 after threecycles and the obtained results were in agreement with previousstudies [39] It is noted that the absence of RhB and othersubstances on the surface of the catalyst and no release ofcatalysts to the water medium need to be proved prior to eachsubsequent cycle is could be revealed by using TEM FT-IRBET and extinction spectrum change of the water solution [22]In this work the photocatalytic performance is still very highafter three cycles (86) suggesting that the presence of sub-stances on the catalystrsquos surfaces is insignificant
4 Conclusions
In this work C and N codoped TiO2 nanoparticles aresuccessfully prepared by solvothermal synthesis and thenused for the study on their catalytic activities regardingRhB degradation in solutions under visible-light irradi-ation e obtained results showed that the as-synthesizednanoparticles mainly contained anatase crystallites withan average particle diameter of 91 nm C N-TiO2 pre-sented a high catalytic activity in the RhB degradationunder visible-light irradiation e optimal catalyst dos-age was 18 gL while optimal initial concentration of RhBwas 5mgL e photocatalytic degradation kinetics wasfound to follow the first-order rate law of the Lang-muirndashHinshelwood model e apparent rate constantdepended on the initial concentration of RhB which washigher at more diluted solutions of RhB
Data Availability
All the data used to support the findings of this study areprovided within the manuscript
Conflicts of Interest
e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
is work was partly supported by the Team Project ofVLIR-UOS with the code number ZEIN2016PR431 eauthors would like to thank the OEPAC project for theutilization of instruments
Supplementary Materials
Figure S1 energy spectra of the deployed compact lampFigure S2 BJH adsorption analysis for the C N-TiO2photocatalyst (Supplementary Materials)
References
[1] H Liu Y Wu and J Zhang ldquoA new approach toward carbon-modified vanadium-doped titanium dioxide photocatalystsrdquoACS Applied Materials amp Interfaces vol 3 no 5 pp 1757ndash17642011
[2] S Jafari B Tryba E Kusiak-Nejman J Kapica-KozarA W Morawski and M Sillanpaa ldquoe role of adsorption inthe photocatalytic decomposition of Orange II on carbon-
modified TiO2rdquo Journal of Molecular Liquids vol 220pp 504ndash512 2016
[3] Y Taga ldquoTitanium oxide based visible light photocatalystsmaterials design and applicationsrdquo ltin Solid Films vol 517no 10 pp 3167ndash3172 2009
[4] S Hosseini H Jahangirian T J Webster S M Soltani andM K Aroua ldquoSynthesis characterization and performanceevaluation of multilayered photoanodes by introducing meso-porous carbon and TiO2 for humic acid adsorptionrdquo Interna-tional Journal of Nanomedicine vol 11 pp 3969ndash3978 2016
[5] G Zhang Y C Zhang M Nadagouda et al ldquoVisible light-sensitized S N and C co-doped polymorphic TiO2 for pho-tocatalytic destruction of microcystin-LRrdquo Applied CatalysisB Environmental vol 144 pp 614ndash621 2014
[6] S D Richardson C S Willson and K A Rusch ldquoUse ofrhodamine water tracer in the marshland upwelling systemrdquoGround Water vol 42 no 5 pp 678ndash688 2004
[7] D J Dire and J A Wilkinson ldquoAcute exposure to rhodamineBrdquo Journal of Toxicology Clinical Toxicology vol 25 no 7pp 603ndash607 1987
[8] D Kornbrust and T Barfknecht ldquoTesting of 24 food drugcosmetic and fabric dyes in the in vitro and the in vivoinvitro rat hepatocyte primary culture DNA repair assaysrdquoEnvironmental Mutagenesis vol 7 no 1 pp 101ndash120 1985
[9] E R Nestmann G R Douglas T I Matula C E Grant andD J Kowbel ldquoMutagenic activity of rhodamine dyes and theirimpurities as detected by mutation induction in Salmonellaand DMA damage in Chinese hamster ovary cellsrdquo CancerResearch vol 39 pp 4412ndash4417 1979
[10] S Zodi B Merzouk O Potier F Lapicque and J-P LeclercldquoDirect red 81 dye removal by a continuous flow electro-coagulationflotation reactorrdquo Separation and PurificationTechnology vol 108 pp 215ndash222 2013
[11] Y-M Zheng R F Yunus K G N Nanayakkara andJ P Chen ldquoElectrochemical decoloration of syntheticwastewater containing rhodamine 6G behaviors and mech-anismrdquo Industrial amp Engineering Chemistry Research vol 51no 17 pp 5953ndash5960 2012
[12] H K Shon S Vigneswaran I S Kim et al ldquoPreparation oftitanium dioxide (TiO2) from sludge produced by titaniumtetrachloride (TiCl4) flocculation of wastewaterrdquo Environ-mental Science amp Technology vol 41 no 4 pp 1372ndash13772007
[13] X Chen Z Xue Y Yao W Wang F Zhu and C HongldquoOxidation degradation of rhodamine B in aqueous by UVS2O82- treatment systemrdquo International Journal of Photo-energy vol 2012 Article ID 754691 9 pages 2012
[14] W Griffith ldquoOzonolysis in coordination chemistry and ca-talysis recent advancesrdquo Coordination Chemistry Reviewsvol 219ndash221 pp 259ndash281 2001
[15] K Shen and M A Gondal ldquoRemoval of hazardous Rhoda-mine dye from water by adsorption onto exhausted coffeegroundrdquo Journal of Saudi Chemical Society vol 21pp S120ndashS127 2017
[16] T A Khan M Nazir and E A Khan ldquoAdsorptive removal ofrhodamine B from textile wastewater using water chestnut(Trapa natans L) peel adsorption dynamics and kineticstudiesrdquo Toxicological amp Environmental Chemistry vol 95no 6 pp 919ndash931 2013
[17] A A Oyekanmi A Ahmad K Hossain and M RafatullahldquoAdsorption of Rhodamine B dye from aqueous solution ontoacid treated banana peel response surface methodology ki-netics and isotherm studiesrdquo PLoS ONE vol 14 no 5 ArticleID e0216878 2019
Journal of Chemistry 7
[18] S Elumalai and G Muthuraman ldquoComparative study ofliquidndashliquid extraction and bulk liquid membrane for rho-damine Brdquo International Journal of Engineering and Inno-vative Technology vol 3 no 2 pp 387ndash392 2013
[19] M E Ersahin H Ozgun R K Dereli I Ozturk K Roest andJ B van Lier ldquoA review on dynamic membrane filtrationmaterials applications and future perspectivesrdquo BioresourceTechnology vol 122 pp 196ndash206 2012
[20] A Phuruangrat A Maneechote P DumrongrojthanathN Ekthammathat S ongtem and T ongtem ldquoEffect ofpH on visible-light-driven Bi2WO6 nanostructured catalystsynthesized by hydrothermal methodrdquo Superlattices andMicrostructures vol 78 pp 106ndash115 2015
[21] P Dumrongrojthanath T ongtem A Phuruangrat andS ongtem ldquoSynthesis and characterization of hierarchicalmultilayered flower-like assemblies of Ag doped Bi2WO6 andtheir photocatalytic activitiesrdquo Superlattices and Microstruc-tures vol 64 pp 196ndash203 2013
[22] S Y Lee D Kang S Jeong H T Do and J H KimldquoPhotocatalytic degradation of rhodamine B dye by TiO2 andgold nanoparticles supported on a floating porous poly-dimethylsiloxane sponge under ultraviolet and visible lightirradiationrdquo ACS Omega vol 5 no 8 pp 4233ndash4241 2020
[23] T T T Le T L Nguyen D T Tran and V N NguyenldquoEnhanced photocatalytic degradation of rhodamine B usingCFe Co-doped titanium dioxide coated on activated carbonrdquoJournal of Chemistry vol 2019 Article ID 2949316 8 pages2019
[24] J ShaoW Sheng MWang et al ldquoIn situ synthesis of carbon-doped TiO 2 single-crystal nanorods with a remarkablyphotocatalytic efficiencyrdquoApplied Catalysis B Environmentalvol 209 pp 311ndash319 2017
[25] Y Zhang J Chen L Hua et al ldquoHigh photocatalytic activityof hierarchical SiO2C-doped TiO2 hollow spheres in UVand visible light towards degradation of rhodamine BrdquoJournal of Hazardous Materials vol 340 pp 309ndash318 2017
[26] C Chen M Long H Zeng et al ldquoPreparation character-ization and visible-light activity of carbon modified TiO2 withtwo kinds of carbonaceous speciesrdquo Journal of MolecularCatalysis A Chemical vol 314 no 1-2 pp 35ndash41 2009
[27] W Xiaoping and T-T Lim ldquoSolvothermal synthesis of C-Ncodoped TiO2 and photocatalytic evaluation for bisphenol Adegradation using a visible-light irradiation LED photo-reactorrdquo Applied Catalysis B Environmental vol 100pp 355ndash364 2010
[28] U G Akpan and B H Hameed ldquoe advancements in sol-gelmethod of doped-TiO2 photocatalystsrdquo Applied Catalysis AGeneral vol 375 no 1 pp 1ndash11 2010
[29] H J Yun H Lee J B Joo N D Kim M Y Kang and J YildquoFacile preparation of high performance visible light sensitivephoto-catalystsrdquo Applied Catalysis B Environmental vol 94no 3-4 pp 241ndash247 2010
[30] M Hussain R Ceccarelli D L Marchisio D Fino N Russoand F Geobaldo ldquoSynthesis characterization and photo-catalytic application of novel TiO2 nanoparticlesrdquo ChemicalEngineering Journal vol 157 no 1 pp 45ndash51 2010
[31] T Shi Y Duan K Lv et al ldquoPhotocatalytic oxidation ofacetone over high thermally stable TiO2 nanosheets withexposed (001) facetsrdquo Frontiers in Chemistry vol 6 p 1752018
[32] M M Mahlambi A K Mishra S B Mishra R W KrauseB B Mamba and A M Raichur ldquoComparison of rhodamineB degradation under UV irradiation by two phases of titania
nano-photocatalystrdquo Journal of ltermal Analysis and Calo-rimetry vol 110 no 2 pp 847ndash855 2012
[33] W Zhang Y Li C Wang and P Wang ldquoKinetics of het-erogeneous photocatalytic degradation of Rhodamine B byTiO2-coated activated carbon roles of TiO2 content and lightintensityrdquo Desalination vol 266 no 1-3 pp 40ndash45 2011
[34] Y Xiao X Sun l Li et al ldquoSimultaneous formation of a CN-TiO2 hollow photocatalyst with efficient photocatalytic per-formance and recyclabilityrdquo Chinese Journal of Catalysisvol 40 no 5 pp 765ndash775 2019
[35] Y Wu J Zhang L Xiao and F Chen ldquoProperties of carbonand iron modified TiO2 photocatalyst synthesized at lowtemperature and photodegradation of acid orange 7 undervisible lightrdquo Applied Surface Science vol 256 no 13pp 4260ndash4268 2010
[36] X Cheng X Yu and Z Xing ldquoSynthesis and characterizationof C-N-S-tridoped TiO2 nano-crystalline photocatalyst and itsphotocatalytic activity for degradation of rhodamine BrdquoJournal of Physics and Chemistry of Solids vol 74 no 5pp 684ndash690 2013
[37] H Huang Y Song N Li et al ldquoOne-step in-situ preparationof N-doped TiO2C derived fromTi3C2MXene for enhancedvisible-light driven photodegradationrdquo Applied Catalysis BEnvironmental vol 251 pp 154ndash161 2019
[38] L Youji Z Xiaoming C Wei et al ldquoPhotodecolorization ofRhodamine B on tungsten-doped TiO2activated carbonunder visible-light irradiationrdquo Journal of Hazardous Mate-rials vol 227-228 pp 25ndash33 2012
[39] A Y Shan T I M Ghazi and S A Rashid ldquoImmobilisationof titanium dioxide onto supporting materials in heteroge-neous photocatalysis a reviewrdquo Applied Catalysis A Generalvol 389 no 1-2 pp 1ndash8 2010
8 Journal of Chemistry
absorption bands of C-TiO2 N-TiO2 and pristine TiO2(Figure 3)
e band gap energies estimated by using the Taucmethod are 334 320 303 and 290 eV for pristine TiO2C-TiO2 N-TiO2 and C N-TiO2 respectively (Figure 4) edecrease in the energy band gap can be explained as follows(i) when adding the carbon element a part of carbon atomswill occupy the interstitial site in the crystal structure whichis attributed to the decrease in the energy band gap [26] (ii)N substitutes O leading to a significant decrease in theenergy band gap [3 27] Moreover a part of carbon atomscover on the surface of TiO2 in the form of graphite orcarbonate groups which would increase the photosentivity[3 29] e absorption edge shifts to the visible regionswould be promising for the application of photocatalystsunder sunlight irradiation
e IR spectra showing a broad peak appearing ataround 3450 cmminus1 could be assigned to vibrations of hy-droxyl groups on the surface of TiO2 in the form of Ti-OH(Figure 5) In addition the peak at 1647 cmminus1 is likely due tovibrations of hydroxyl groups in the form of Ti-O-OH erelatively weak peaks at 1540 cmminus1 and around 1385 cmminus1
could be attributed to the vibration of CO and C-O in thecarbonate group respectively (Figure 5) e presence ofthose functional groups on the TiO2 surface would lead to anincrease in photosensitivity of the as-synthesized catalysts[26]
e presence of the N element in the catalyst obtained isapproved by the peak at 1400 cmminus1 which is likely due tovibrations of N-H bonds In addition multiple bands at theregion of 536ndash484 cmminus1 are assigned to vibrations of Ti-Oand Ti-O-C bonds is is in agreement with the results ofEDX analysis (Figure 6) which reveal the presence of Ti OC and N elements in the samples It is noted that theformation of bonds between C and N elements and TiO2could be examined by using the X-ray photoelectronspectroscopy (XPS) method [24 25]
880nm 830nm
859nm
863nm
126nm117nm
788nm
929nm
20nm
Figure 2 TEM image of C N-TiO2
300 400 500 600 70000
02
04
06
08
10
Abso
rban
ce
TiO2C-TiO2
N-TiO2CN-TiO2
Wavelength (nm)
Figure 3 UV-VIS spectra of TiO2 (a) and C N-TiO2 (b)
25 30 35 40 450
20
40
60
80
100
334 eV
320 eV303 eV
Energy (eV)
290 eV
(αhv
)2 (eV
cmndash1
)2
TiO2C-TiO2
N-TiO2CN-TiO2
Figure 4 Plot of [αh]]2 vs h] for pristine TiO2 C-TiO2 N-TiO2and CN-TiO2
20 30 40 50 60 70 80
R
R
R
AAAA
A
AAAA
AA
Lin
(Cps
)
2-theta
A
R
(a)
(b)
Figure 1 XRD patterns of TiO2 (a) and C N-TiO2 (b)
Journal of Chemistry 3
BETanalysis was carried out under nitrogen atmosphereto figure out the porous features of the prepared synthesizedmaterials which is presented in Figure 7 e adsorptiondesorption plots of C N-TiO2 show a common type IVisotherm with a H3 hysteresis loop Furthermore the BJHanalysis shows a wide distribution of hierarchical pores withdiameters in the range of meso-macro pores (Figure S2) thepore volume for C N-TiO2 is 0040 cm3g
It is noted that the BET specific surface area of theprepared C N-TiO2 is 203m2gis figure is slightly higherwhen compared to the values previously reported forpristine TiO2 For instance Hussain et al [30] reported thatTiO2 commercial (anatasetechnical) could present a BETspecific surface area in the range of 10ndash15m2g while theincrease in rutile percentage could lead to an augmentationof the surface area of TiO2 Similarly Shi et al [31] revealedthat anatase TiO2 exhibited a BET surface area lower than5m2g and the latter would decrease when the treatmenttemperature increases Mahlambi et al [32] synthesized
TiO2 nanoparticles and found that at 550degC their specificsurface areas were 2272m2g and this value decreased to778m2g when the treatment temperature increased to600degC
32 Photocatalytic Performance of C N-TiO2 towards RhBDegradation e results in Figure 8 indicate that the RhBdegradation efficiency under visible-light condition of CN-TiO2 is higher than that of pure TiO2 As for C N-TiO2the degradation efficiency reached up to 94 after 90min ofirradiation is is consistent with the characteristics of theobtained catalyst
Studying the effect of the C N-TiO2 content on the RhBdegradation efficiency (Figure 9) suggests that the optimalamount of the catalyst is 18 gL Using a large amount ofcatalyst caused the photoresist resulting in a decrease incatalytic activity
According to the results obtained from liquid UV-Vismeasurements of the RhB solution by C N-TiO2 as afunction of treatment time (Figure 10) RhB changed overtime As for the initial RhB solution of 920mgL thecharacteristic peak at 533 nm moved to the peaks of theintermediate organic compounds e peak intensity ofthese compounds decreases with increasing treatment timeand is extremely low (near zero) after 3 hours of treatmentis suggests that the role of C N-TiO2 in the RhB deg-radation is different from the normal absorption processes[33 34]
It should be noted that the RhB degradation efficiency isextremely low in the dark (Figure 11) indicating that thecatalyst obtained is a photocatalyst e RhB degradationefficiency under compact lamp and natural light irradiationis almost the same because of the 36W compact lampcontaining wavelength at 450 nm near absorption maximumof the catalyst Hence the obtained catalyst works well invisible light and natural light and it is in agreement withprevious reported works [35ndash37]
4000 3600 3200 2800 2400 2000 1600 1200 800 4000
10
20
30
40
50
60
70
80
T
TiO2CN-TiO2
Wavenumber (cmndash1)
Figure 5 IR spectra of TiO2 (a) and C N-TiO2 (b)
1 2 3 4 5 6 7 8 9 10 11Energy (keV)
Cps
Figure 6 EDX analysis of C N-TiO2
0
5
10
15
20
25
30
0 02 04 06 08 1
Qua
ntity
adso
rbed
(cm
3 g S
TP)
Relative pressure (pp0)
AdsorptionDesorption
Figure 7 Nitrogen adsorption-desorption isotherms for the C N-TiO2 photocatalyst
4 Journal of Chemistry
33 Kinetics of RhB Degradation by C N-TiO2 under Visible-Light Irradiation Kinetics of the RhB degradation reactionwas studied by using different initial concentrations of RhB(0ndash100mgL) while keeping the catalyst load constant at18 gL
RhB decomposition reaction can be described by theLangmuirndashHinshelwood kinetics equation that is expressedas follows [27]
r minusdC
dt k
KC
1 + KC (2)
where k is the reaction rate constant K is the adsorptioncoefficient t is the time and C is the reactant concentration(the target organic compound) In the case of low initialconcentrations KCltlt 1 equation (2) can be rewritten as thefollowing
r minusdC
dt k middot KC kprime middot C (3)
where krsquo is the apparent rate constant which is also known asthe reduced first-order reaction en the following equa-tion is derived
lnCo
Ct
kprime middot t (4)
where Co and Ct are the reactant concentrations at t 0 and t(min) respectively Figure 12 shows the dependence of lnCoCt on time during the degradation of RhB by the C N-TiO2photocatalyst
As can be seen in Figures 12 and 13 when the initialconcentrations of RhB were in the range of 0ndash100mgL thephotodegradation was divided into 3 distinct groups whichwere characterized by the corresponding distinct apparent rateconstants e decomposition of RhB was observed unstablewhen the initial concentration was relatively low (0ndash10mgL)is is due to the degradationmainly affected by the absorption
0
20
40
60
80
100
120
0 30 60 90 120Time (min)
Rem
oval
effic
ienc
y of
RhB
()
(a)
(b)
Figure 8 Comparison of degradation efficiency as a function oflight irradiation time of TiO2 (a) and C N-TiO2 (b)
0
20
40
60
80
100
0 30 60 90Time (min)
Rem
oval
effic
ienc
y of
RhB
()
18 gl26 gl14 gl3 gl
Figure 9 Effect of catalyst concentration on the RhB degradationefficiency of C N-TiO2
0
05
1
15
2
25
3
35
ABS
Wavelength (nm)
Rhodamine B (t = 0)Rhodamine B (t = 1 (h))Rhodamine B (t = 15 (h))
Rhodamine B (t = 2 (h))Rhodamine B (t = 3 (h))
546
524
497
380
392
404
416
428
440
452
464
476
488
500
512
524
536
548
560
572
584
596
608
620
632
644
656
668
680
692
704
716
728
740
554
Figure 10 Liquid UV-Vis spectra of the RhB solution as a functionof treatment time
0
20
40
60
80
100
0 30 60 90Time (min)
Rem
oval
effic
ienc
y of
RhB
()
DarknessCompact lampNatural light
Figure 11 RhB degradation efficiency of C N-TiO2 under differentirradiation conditions
Journal of Chemistry 5
process e corresponding apparent rate constant krsquo is00427minminus1 In contrast when the initial concentration wasrelatively high (gt10mgL) the RhB decomposition occurredvery slowly resulting in smaller apparent rate constants(krsquo 00041minminus1 for 100mgL) is is because the bold colorof RhB causes the photoresist [23 27] e suitable initialconcentration for stable decomposition is about 20ndash40mgLe optimal initial concentration of RhB is 20mgL at whichthe apparent rate constant krsquo is 00205minminus1 e results ob-tained in this work is in agreement with previous studies[27 32] Hence with the RhB initial concentration of 20mgLequation (4) can be expressed by the following
lnCo
Ct
00205 times t (5)
Similarly the relation between CoCt and t for other initialconcentrations of RhB could be plotted as in Figure 13
e photocatalytic degradation of RhB by the C N-TiO2system can be explained by the following mechanism(Figure 14) (1) once h]ge (ECndashEVprime) electrons would beexcited in the valence band of TiO2 by the process TiO2 + h]
(UV)⟶TiO2 (eCBminus+ hVB+) (2) the departed electrons andholes subsequently migrate to the surface of the catalysts andreact with adsorbed H2O and O2 molecules forming bullOHand bullO2
minus respectively according to equations (6)ndash(8)
H2O + hVB+⟶ bullOH + H+
(6)
HOadminus
+ hVB+⟶ bullOHad (7)
eCBminus
+ O2⟶bullO2
minus(8)
and (3) bullOH and bullO2minus radicals are mainly responsible for the
degradation of RhB in solutions [38]emechanism for thedegradation of RhB in solutions by the C N-TiO2 system isproposed in Figure 14
34 Recoverability andReusability of CN-TiO2 Photocatalyste catalytic stability in RhB decomposition under visible-lightirradiation was studied After each decomposition cycle thecatalyst was centrifuged washed with distilled water and thenused for further treatment of RhB in solutions As can be seen inFigure 15 C and N codoped TiO2 exhibited good catalytic
000E + 00
100E ndash 02
200E ndash 02
300E ndash 02
400E ndash 02
500E ndash 02
0 20 40 60 80 100Co (mgl)
kprime(1
min
)
Figure 13 e apparent rate constant krsquo as a function of initialconcentrations of RhB
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140Time (min)
Ln(C
oC t
)
5 mgl y = 00427x
10 mgl y = 00345x
20 mgl y = 00205x30 mgl y = 00147x40 mgl y = 00136x
80 mgl y = 00080x90 mgl y = 00069x100 mgl y = 00041x
60 mgl y = 00110x
Figure 12 First-order kinetics for RhB degradation at differentinitial concentrations
UV light
TiO2VB
CB
334
eV
EC
EV
CN-TiO2
EprimeV
h+
h+
endash
endash endash
Visible light
290
eV
O2
bullO2ndash
OHndash
bullOH
Figure 14 Schematic mechanism of photocatalytic degradation ofRhB by C N-TiO2
0
02
04
06
08
1
0 30 60 90 120 150 180 210 240 270Time (min)
C tC
o
(a) (b) (c)
Figure 15 Catalystrsquos reuse results (a) first cycle (b) second cycle(c) third cycle
6 Journal of Chemistry
activity with the degradation efficiency of above 86 after threecycles and the obtained results were in agreement with previousstudies [39] It is noted that the absence of RhB and othersubstances on the surface of the catalyst and no release ofcatalysts to the water medium need to be proved prior to eachsubsequent cycle is could be revealed by using TEM FT-IRBET and extinction spectrum change of the water solution [22]In this work the photocatalytic performance is still very highafter three cycles (86) suggesting that the presence of sub-stances on the catalystrsquos surfaces is insignificant
4 Conclusions
In this work C and N codoped TiO2 nanoparticles aresuccessfully prepared by solvothermal synthesis and thenused for the study on their catalytic activities regardingRhB degradation in solutions under visible-light irradi-ation e obtained results showed that the as-synthesizednanoparticles mainly contained anatase crystallites withan average particle diameter of 91 nm C N-TiO2 pre-sented a high catalytic activity in the RhB degradationunder visible-light irradiation e optimal catalyst dos-age was 18 gL while optimal initial concentration of RhBwas 5mgL e photocatalytic degradation kinetics wasfound to follow the first-order rate law of the Lang-muirndashHinshelwood model e apparent rate constantdepended on the initial concentration of RhB which washigher at more diluted solutions of RhB
Data Availability
All the data used to support the findings of this study areprovided within the manuscript
Conflicts of Interest
e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
is work was partly supported by the Team Project ofVLIR-UOS with the code number ZEIN2016PR431 eauthors would like to thank the OEPAC project for theutilization of instruments
Supplementary Materials
Figure S1 energy spectra of the deployed compact lampFigure S2 BJH adsorption analysis for the C N-TiO2photocatalyst (Supplementary Materials)
References
[1] H Liu Y Wu and J Zhang ldquoA new approach toward carbon-modified vanadium-doped titanium dioxide photocatalystsrdquoACS Applied Materials amp Interfaces vol 3 no 5 pp 1757ndash17642011
[2] S Jafari B Tryba E Kusiak-Nejman J Kapica-KozarA W Morawski and M Sillanpaa ldquoe role of adsorption inthe photocatalytic decomposition of Orange II on carbon-
modified TiO2rdquo Journal of Molecular Liquids vol 220pp 504ndash512 2016
[3] Y Taga ldquoTitanium oxide based visible light photocatalystsmaterials design and applicationsrdquo ltin Solid Films vol 517no 10 pp 3167ndash3172 2009
[4] S Hosseini H Jahangirian T J Webster S M Soltani andM K Aroua ldquoSynthesis characterization and performanceevaluation of multilayered photoanodes by introducing meso-porous carbon and TiO2 for humic acid adsorptionrdquo Interna-tional Journal of Nanomedicine vol 11 pp 3969ndash3978 2016
[5] G Zhang Y C Zhang M Nadagouda et al ldquoVisible light-sensitized S N and C co-doped polymorphic TiO2 for pho-tocatalytic destruction of microcystin-LRrdquo Applied CatalysisB Environmental vol 144 pp 614ndash621 2014
[6] S D Richardson C S Willson and K A Rusch ldquoUse ofrhodamine water tracer in the marshland upwelling systemrdquoGround Water vol 42 no 5 pp 678ndash688 2004
[7] D J Dire and J A Wilkinson ldquoAcute exposure to rhodamineBrdquo Journal of Toxicology Clinical Toxicology vol 25 no 7pp 603ndash607 1987
[8] D Kornbrust and T Barfknecht ldquoTesting of 24 food drugcosmetic and fabric dyes in the in vitro and the in vivoinvitro rat hepatocyte primary culture DNA repair assaysrdquoEnvironmental Mutagenesis vol 7 no 1 pp 101ndash120 1985
[9] E R Nestmann G R Douglas T I Matula C E Grant andD J Kowbel ldquoMutagenic activity of rhodamine dyes and theirimpurities as detected by mutation induction in Salmonellaand DMA damage in Chinese hamster ovary cellsrdquo CancerResearch vol 39 pp 4412ndash4417 1979
[10] S Zodi B Merzouk O Potier F Lapicque and J-P LeclercldquoDirect red 81 dye removal by a continuous flow electro-coagulationflotation reactorrdquo Separation and PurificationTechnology vol 108 pp 215ndash222 2013
[11] Y-M Zheng R F Yunus K G N Nanayakkara andJ P Chen ldquoElectrochemical decoloration of syntheticwastewater containing rhodamine 6G behaviors and mech-anismrdquo Industrial amp Engineering Chemistry Research vol 51no 17 pp 5953ndash5960 2012
[12] H K Shon S Vigneswaran I S Kim et al ldquoPreparation oftitanium dioxide (TiO2) from sludge produced by titaniumtetrachloride (TiCl4) flocculation of wastewaterrdquo Environ-mental Science amp Technology vol 41 no 4 pp 1372ndash13772007
[13] X Chen Z Xue Y Yao W Wang F Zhu and C HongldquoOxidation degradation of rhodamine B in aqueous by UVS2O82- treatment systemrdquo International Journal of Photo-energy vol 2012 Article ID 754691 9 pages 2012
[14] W Griffith ldquoOzonolysis in coordination chemistry and ca-talysis recent advancesrdquo Coordination Chemistry Reviewsvol 219ndash221 pp 259ndash281 2001
[15] K Shen and M A Gondal ldquoRemoval of hazardous Rhoda-mine dye from water by adsorption onto exhausted coffeegroundrdquo Journal of Saudi Chemical Society vol 21pp S120ndashS127 2017
[16] T A Khan M Nazir and E A Khan ldquoAdsorptive removal ofrhodamine B from textile wastewater using water chestnut(Trapa natans L) peel adsorption dynamics and kineticstudiesrdquo Toxicological amp Environmental Chemistry vol 95no 6 pp 919ndash931 2013
[17] A A Oyekanmi A Ahmad K Hossain and M RafatullahldquoAdsorption of Rhodamine B dye from aqueous solution ontoacid treated banana peel response surface methodology ki-netics and isotherm studiesrdquo PLoS ONE vol 14 no 5 ArticleID e0216878 2019
Journal of Chemistry 7
[18] S Elumalai and G Muthuraman ldquoComparative study ofliquidndashliquid extraction and bulk liquid membrane for rho-damine Brdquo International Journal of Engineering and Inno-vative Technology vol 3 no 2 pp 387ndash392 2013
[19] M E Ersahin H Ozgun R K Dereli I Ozturk K Roest andJ B van Lier ldquoA review on dynamic membrane filtrationmaterials applications and future perspectivesrdquo BioresourceTechnology vol 122 pp 196ndash206 2012
[20] A Phuruangrat A Maneechote P DumrongrojthanathN Ekthammathat S ongtem and T ongtem ldquoEffect ofpH on visible-light-driven Bi2WO6 nanostructured catalystsynthesized by hydrothermal methodrdquo Superlattices andMicrostructures vol 78 pp 106ndash115 2015
[21] P Dumrongrojthanath T ongtem A Phuruangrat andS ongtem ldquoSynthesis and characterization of hierarchicalmultilayered flower-like assemblies of Ag doped Bi2WO6 andtheir photocatalytic activitiesrdquo Superlattices and Microstruc-tures vol 64 pp 196ndash203 2013
[22] S Y Lee D Kang S Jeong H T Do and J H KimldquoPhotocatalytic degradation of rhodamine B dye by TiO2 andgold nanoparticles supported on a floating porous poly-dimethylsiloxane sponge under ultraviolet and visible lightirradiationrdquo ACS Omega vol 5 no 8 pp 4233ndash4241 2020
[23] T T T Le T L Nguyen D T Tran and V N NguyenldquoEnhanced photocatalytic degradation of rhodamine B usingCFe Co-doped titanium dioxide coated on activated carbonrdquoJournal of Chemistry vol 2019 Article ID 2949316 8 pages2019
[24] J ShaoW Sheng MWang et al ldquoIn situ synthesis of carbon-doped TiO 2 single-crystal nanorods with a remarkablyphotocatalytic efficiencyrdquoApplied Catalysis B Environmentalvol 209 pp 311ndash319 2017
[25] Y Zhang J Chen L Hua et al ldquoHigh photocatalytic activityof hierarchical SiO2C-doped TiO2 hollow spheres in UVand visible light towards degradation of rhodamine BrdquoJournal of Hazardous Materials vol 340 pp 309ndash318 2017
[26] C Chen M Long H Zeng et al ldquoPreparation character-ization and visible-light activity of carbon modified TiO2 withtwo kinds of carbonaceous speciesrdquo Journal of MolecularCatalysis A Chemical vol 314 no 1-2 pp 35ndash41 2009
[27] W Xiaoping and T-T Lim ldquoSolvothermal synthesis of C-Ncodoped TiO2 and photocatalytic evaluation for bisphenol Adegradation using a visible-light irradiation LED photo-reactorrdquo Applied Catalysis B Environmental vol 100pp 355ndash364 2010
[28] U G Akpan and B H Hameed ldquoe advancements in sol-gelmethod of doped-TiO2 photocatalystsrdquo Applied Catalysis AGeneral vol 375 no 1 pp 1ndash11 2010
[29] H J Yun H Lee J B Joo N D Kim M Y Kang and J YildquoFacile preparation of high performance visible light sensitivephoto-catalystsrdquo Applied Catalysis B Environmental vol 94no 3-4 pp 241ndash247 2010
[30] M Hussain R Ceccarelli D L Marchisio D Fino N Russoand F Geobaldo ldquoSynthesis characterization and photo-catalytic application of novel TiO2 nanoparticlesrdquo ChemicalEngineering Journal vol 157 no 1 pp 45ndash51 2010
[31] T Shi Y Duan K Lv et al ldquoPhotocatalytic oxidation ofacetone over high thermally stable TiO2 nanosheets withexposed (001) facetsrdquo Frontiers in Chemistry vol 6 p 1752018
[32] M M Mahlambi A K Mishra S B Mishra R W KrauseB B Mamba and A M Raichur ldquoComparison of rhodamineB degradation under UV irradiation by two phases of titania
nano-photocatalystrdquo Journal of ltermal Analysis and Calo-rimetry vol 110 no 2 pp 847ndash855 2012
[33] W Zhang Y Li C Wang and P Wang ldquoKinetics of het-erogeneous photocatalytic degradation of Rhodamine B byTiO2-coated activated carbon roles of TiO2 content and lightintensityrdquo Desalination vol 266 no 1-3 pp 40ndash45 2011
[34] Y Xiao X Sun l Li et al ldquoSimultaneous formation of a CN-TiO2 hollow photocatalyst with efficient photocatalytic per-formance and recyclabilityrdquo Chinese Journal of Catalysisvol 40 no 5 pp 765ndash775 2019
[35] Y Wu J Zhang L Xiao and F Chen ldquoProperties of carbonand iron modified TiO2 photocatalyst synthesized at lowtemperature and photodegradation of acid orange 7 undervisible lightrdquo Applied Surface Science vol 256 no 13pp 4260ndash4268 2010
[36] X Cheng X Yu and Z Xing ldquoSynthesis and characterizationof C-N-S-tridoped TiO2 nano-crystalline photocatalyst and itsphotocatalytic activity for degradation of rhodamine BrdquoJournal of Physics and Chemistry of Solids vol 74 no 5pp 684ndash690 2013
[37] H Huang Y Song N Li et al ldquoOne-step in-situ preparationof N-doped TiO2C derived fromTi3C2MXene for enhancedvisible-light driven photodegradationrdquo Applied Catalysis BEnvironmental vol 251 pp 154ndash161 2019
[38] L Youji Z Xiaoming C Wei et al ldquoPhotodecolorization ofRhodamine B on tungsten-doped TiO2activated carbonunder visible-light irradiationrdquo Journal of Hazardous Mate-rials vol 227-228 pp 25ndash33 2012
[39] A Y Shan T I M Ghazi and S A Rashid ldquoImmobilisationof titanium dioxide onto supporting materials in heteroge-neous photocatalysis a reviewrdquo Applied Catalysis A Generalvol 389 no 1-2 pp 1ndash8 2010
8 Journal of Chemistry
BETanalysis was carried out under nitrogen atmosphereto figure out the porous features of the prepared synthesizedmaterials which is presented in Figure 7 e adsorptiondesorption plots of C N-TiO2 show a common type IVisotherm with a H3 hysteresis loop Furthermore the BJHanalysis shows a wide distribution of hierarchical pores withdiameters in the range of meso-macro pores (Figure S2) thepore volume for C N-TiO2 is 0040 cm3g
It is noted that the BET specific surface area of theprepared C N-TiO2 is 203m2gis figure is slightly higherwhen compared to the values previously reported forpristine TiO2 For instance Hussain et al [30] reported thatTiO2 commercial (anatasetechnical) could present a BETspecific surface area in the range of 10ndash15m2g while theincrease in rutile percentage could lead to an augmentationof the surface area of TiO2 Similarly Shi et al [31] revealedthat anatase TiO2 exhibited a BET surface area lower than5m2g and the latter would decrease when the treatmenttemperature increases Mahlambi et al [32] synthesized
TiO2 nanoparticles and found that at 550degC their specificsurface areas were 2272m2g and this value decreased to778m2g when the treatment temperature increased to600degC
32 Photocatalytic Performance of C N-TiO2 towards RhBDegradation e results in Figure 8 indicate that the RhBdegradation efficiency under visible-light condition of CN-TiO2 is higher than that of pure TiO2 As for C N-TiO2the degradation efficiency reached up to 94 after 90min ofirradiation is is consistent with the characteristics of theobtained catalyst
Studying the effect of the C N-TiO2 content on the RhBdegradation efficiency (Figure 9) suggests that the optimalamount of the catalyst is 18 gL Using a large amount ofcatalyst caused the photoresist resulting in a decrease incatalytic activity
According to the results obtained from liquid UV-Vismeasurements of the RhB solution by C N-TiO2 as afunction of treatment time (Figure 10) RhB changed overtime As for the initial RhB solution of 920mgL thecharacteristic peak at 533 nm moved to the peaks of theintermediate organic compounds e peak intensity ofthese compounds decreases with increasing treatment timeand is extremely low (near zero) after 3 hours of treatmentis suggests that the role of C N-TiO2 in the RhB deg-radation is different from the normal absorption processes[33 34]
It should be noted that the RhB degradation efficiency isextremely low in the dark (Figure 11) indicating that thecatalyst obtained is a photocatalyst e RhB degradationefficiency under compact lamp and natural light irradiationis almost the same because of the 36W compact lampcontaining wavelength at 450 nm near absorption maximumof the catalyst Hence the obtained catalyst works well invisible light and natural light and it is in agreement withprevious reported works [35ndash37]
4000 3600 3200 2800 2400 2000 1600 1200 800 4000
10
20
30
40
50
60
70
80
T
TiO2CN-TiO2
Wavenumber (cmndash1)
Figure 5 IR spectra of TiO2 (a) and C N-TiO2 (b)
1 2 3 4 5 6 7 8 9 10 11Energy (keV)
Cps
Figure 6 EDX analysis of C N-TiO2
0
5
10
15
20
25
30
0 02 04 06 08 1
Qua
ntity
adso
rbed
(cm
3 g S
TP)
Relative pressure (pp0)
AdsorptionDesorption
Figure 7 Nitrogen adsorption-desorption isotherms for the C N-TiO2 photocatalyst
4 Journal of Chemistry
33 Kinetics of RhB Degradation by C N-TiO2 under Visible-Light Irradiation Kinetics of the RhB degradation reactionwas studied by using different initial concentrations of RhB(0ndash100mgL) while keeping the catalyst load constant at18 gL
RhB decomposition reaction can be described by theLangmuirndashHinshelwood kinetics equation that is expressedas follows [27]
r minusdC
dt k
KC
1 + KC (2)
where k is the reaction rate constant K is the adsorptioncoefficient t is the time and C is the reactant concentration(the target organic compound) In the case of low initialconcentrations KCltlt 1 equation (2) can be rewritten as thefollowing
r minusdC
dt k middot KC kprime middot C (3)
where krsquo is the apparent rate constant which is also known asthe reduced first-order reaction en the following equa-tion is derived
lnCo
Ct
kprime middot t (4)
where Co and Ct are the reactant concentrations at t 0 and t(min) respectively Figure 12 shows the dependence of lnCoCt on time during the degradation of RhB by the C N-TiO2photocatalyst
As can be seen in Figures 12 and 13 when the initialconcentrations of RhB were in the range of 0ndash100mgL thephotodegradation was divided into 3 distinct groups whichwere characterized by the corresponding distinct apparent rateconstants e decomposition of RhB was observed unstablewhen the initial concentration was relatively low (0ndash10mgL)is is due to the degradationmainly affected by the absorption
0
20
40
60
80
100
120
0 30 60 90 120Time (min)
Rem
oval
effic
ienc
y of
RhB
()
(a)
(b)
Figure 8 Comparison of degradation efficiency as a function oflight irradiation time of TiO2 (a) and C N-TiO2 (b)
0
20
40
60
80
100
0 30 60 90Time (min)
Rem
oval
effic
ienc
y of
RhB
()
18 gl26 gl14 gl3 gl
Figure 9 Effect of catalyst concentration on the RhB degradationefficiency of C N-TiO2
0
05
1
15
2
25
3
35
ABS
Wavelength (nm)
Rhodamine B (t = 0)Rhodamine B (t = 1 (h))Rhodamine B (t = 15 (h))
Rhodamine B (t = 2 (h))Rhodamine B (t = 3 (h))
546
524
497
380
392
404
416
428
440
452
464
476
488
500
512
524
536
548
560
572
584
596
608
620
632
644
656
668
680
692
704
716
728
740
554
Figure 10 Liquid UV-Vis spectra of the RhB solution as a functionof treatment time
0
20
40
60
80
100
0 30 60 90Time (min)
Rem
oval
effic
ienc
y of
RhB
()
DarknessCompact lampNatural light
Figure 11 RhB degradation efficiency of C N-TiO2 under differentirradiation conditions
Journal of Chemistry 5
process e corresponding apparent rate constant krsquo is00427minminus1 In contrast when the initial concentration wasrelatively high (gt10mgL) the RhB decomposition occurredvery slowly resulting in smaller apparent rate constants(krsquo 00041minminus1 for 100mgL) is is because the bold colorof RhB causes the photoresist [23 27] e suitable initialconcentration for stable decomposition is about 20ndash40mgLe optimal initial concentration of RhB is 20mgL at whichthe apparent rate constant krsquo is 00205minminus1 e results ob-tained in this work is in agreement with previous studies[27 32] Hence with the RhB initial concentration of 20mgLequation (4) can be expressed by the following
lnCo
Ct
00205 times t (5)
Similarly the relation between CoCt and t for other initialconcentrations of RhB could be plotted as in Figure 13
e photocatalytic degradation of RhB by the C N-TiO2system can be explained by the following mechanism(Figure 14) (1) once h]ge (ECndashEVprime) electrons would beexcited in the valence band of TiO2 by the process TiO2 + h]
(UV)⟶TiO2 (eCBminus+ hVB+) (2) the departed electrons andholes subsequently migrate to the surface of the catalysts andreact with adsorbed H2O and O2 molecules forming bullOHand bullO2
minus respectively according to equations (6)ndash(8)
H2O + hVB+⟶ bullOH + H+
(6)
HOadminus
+ hVB+⟶ bullOHad (7)
eCBminus
+ O2⟶bullO2
minus(8)
and (3) bullOH and bullO2minus radicals are mainly responsible for the
degradation of RhB in solutions [38]emechanism for thedegradation of RhB in solutions by the C N-TiO2 system isproposed in Figure 14
34 Recoverability andReusability of CN-TiO2 Photocatalyste catalytic stability in RhB decomposition under visible-lightirradiation was studied After each decomposition cycle thecatalyst was centrifuged washed with distilled water and thenused for further treatment of RhB in solutions As can be seen inFigure 15 C and N codoped TiO2 exhibited good catalytic
000E + 00
100E ndash 02
200E ndash 02
300E ndash 02
400E ndash 02
500E ndash 02
0 20 40 60 80 100Co (mgl)
kprime(1
min
)
Figure 13 e apparent rate constant krsquo as a function of initialconcentrations of RhB
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140Time (min)
Ln(C
oC t
)
5 mgl y = 00427x
10 mgl y = 00345x
20 mgl y = 00205x30 mgl y = 00147x40 mgl y = 00136x
80 mgl y = 00080x90 mgl y = 00069x100 mgl y = 00041x
60 mgl y = 00110x
Figure 12 First-order kinetics for RhB degradation at differentinitial concentrations
UV light
TiO2VB
CB
334
eV
EC
EV
CN-TiO2
EprimeV
h+
h+
endash
endash endash
Visible light
290
eV
O2
bullO2ndash
OHndash
bullOH
Figure 14 Schematic mechanism of photocatalytic degradation ofRhB by C N-TiO2
0
02
04
06
08
1
0 30 60 90 120 150 180 210 240 270Time (min)
C tC
o
(a) (b) (c)
Figure 15 Catalystrsquos reuse results (a) first cycle (b) second cycle(c) third cycle
6 Journal of Chemistry
activity with the degradation efficiency of above 86 after threecycles and the obtained results were in agreement with previousstudies [39] It is noted that the absence of RhB and othersubstances on the surface of the catalyst and no release ofcatalysts to the water medium need to be proved prior to eachsubsequent cycle is could be revealed by using TEM FT-IRBET and extinction spectrum change of the water solution [22]In this work the photocatalytic performance is still very highafter three cycles (86) suggesting that the presence of sub-stances on the catalystrsquos surfaces is insignificant
4 Conclusions
In this work C and N codoped TiO2 nanoparticles aresuccessfully prepared by solvothermal synthesis and thenused for the study on their catalytic activities regardingRhB degradation in solutions under visible-light irradi-ation e obtained results showed that the as-synthesizednanoparticles mainly contained anatase crystallites withan average particle diameter of 91 nm C N-TiO2 pre-sented a high catalytic activity in the RhB degradationunder visible-light irradiation e optimal catalyst dos-age was 18 gL while optimal initial concentration of RhBwas 5mgL e photocatalytic degradation kinetics wasfound to follow the first-order rate law of the Lang-muirndashHinshelwood model e apparent rate constantdepended on the initial concentration of RhB which washigher at more diluted solutions of RhB
Data Availability
All the data used to support the findings of this study areprovided within the manuscript
Conflicts of Interest
e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
is work was partly supported by the Team Project ofVLIR-UOS with the code number ZEIN2016PR431 eauthors would like to thank the OEPAC project for theutilization of instruments
Supplementary Materials
Figure S1 energy spectra of the deployed compact lampFigure S2 BJH adsorption analysis for the C N-TiO2photocatalyst (Supplementary Materials)
References
[1] H Liu Y Wu and J Zhang ldquoA new approach toward carbon-modified vanadium-doped titanium dioxide photocatalystsrdquoACS Applied Materials amp Interfaces vol 3 no 5 pp 1757ndash17642011
[2] S Jafari B Tryba E Kusiak-Nejman J Kapica-KozarA W Morawski and M Sillanpaa ldquoe role of adsorption inthe photocatalytic decomposition of Orange II on carbon-
modified TiO2rdquo Journal of Molecular Liquids vol 220pp 504ndash512 2016
[3] Y Taga ldquoTitanium oxide based visible light photocatalystsmaterials design and applicationsrdquo ltin Solid Films vol 517no 10 pp 3167ndash3172 2009
[4] S Hosseini H Jahangirian T J Webster S M Soltani andM K Aroua ldquoSynthesis characterization and performanceevaluation of multilayered photoanodes by introducing meso-porous carbon and TiO2 for humic acid adsorptionrdquo Interna-tional Journal of Nanomedicine vol 11 pp 3969ndash3978 2016
[5] G Zhang Y C Zhang M Nadagouda et al ldquoVisible light-sensitized S N and C co-doped polymorphic TiO2 for pho-tocatalytic destruction of microcystin-LRrdquo Applied CatalysisB Environmental vol 144 pp 614ndash621 2014
[6] S D Richardson C S Willson and K A Rusch ldquoUse ofrhodamine water tracer in the marshland upwelling systemrdquoGround Water vol 42 no 5 pp 678ndash688 2004
[7] D J Dire and J A Wilkinson ldquoAcute exposure to rhodamineBrdquo Journal of Toxicology Clinical Toxicology vol 25 no 7pp 603ndash607 1987
[8] D Kornbrust and T Barfknecht ldquoTesting of 24 food drugcosmetic and fabric dyes in the in vitro and the in vivoinvitro rat hepatocyte primary culture DNA repair assaysrdquoEnvironmental Mutagenesis vol 7 no 1 pp 101ndash120 1985
[9] E R Nestmann G R Douglas T I Matula C E Grant andD J Kowbel ldquoMutagenic activity of rhodamine dyes and theirimpurities as detected by mutation induction in Salmonellaand DMA damage in Chinese hamster ovary cellsrdquo CancerResearch vol 39 pp 4412ndash4417 1979
[10] S Zodi B Merzouk O Potier F Lapicque and J-P LeclercldquoDirect red 81 dye removal by a continuous flow electro-coagulationflotation reactorrdquo Separation and PurificationTechnology vol 108 pp 215ndash222 2013
[11] Y-M Zheng R F Yunus K G N Nanayakkara andJ P Chen ldquoElectrochemical decoloration of syntheticwastewater containing rhodamine 6G behaviors and mech-anismrdquo Industrial amp Engineering Chemistry Research vol 51no 17 pp 5953ndash5960 2012
[12] H K Shon S Vigneswaran I S Kim et al ldquoPreparation oftitanium dioxide (TiO2) from sludge produced by titaniumtetrachloride (TiCl4) flocculation of wastewaterrdquo Environ-mental Science amp Technology vol 41 no 4 pp 1372ndash13772007
[13] X Chen Z Xue Y Yao W Wang F Zhu and C HongldquoOxidation degradation of rhodamine B in aqueous by UVS2O82- treatment systemrdquo International Journal of Photo-energy vol 2012 Article ID 754691 9 pages 2012
[14] W Griffith ldquoOzonolysis in coordination chemistry and ca-talysis recent advancesrdquo Coordination Chemistry Reviewsvol 219ndash221 pp 259ndash281 2001
[15] K Shen and M A Gondal ldquoRemoval of hazardous Rhoda-mine dye from water by adsorption onto exhausted coffeegroundrdquo Journal of Saudi Chemical Society vol 21pp S120ndashS127 2017
[16] T A Khan M Nazir and E A Khan ldquoAdsorptive removal ofrhodamine B from textile wastewater using water chestnut(Trapa natans L) peel adsorption dynamics and kineticstudiesrdquo Toxicological amp Environmental Chemistry vol 95no 6 pp 919ndash931 2013
[17] A A Oyekanmi A Ahmad K Hossain and M RafatullahldquoAdsorption of Rhodamine B dye from aqueous solution ontoacid treated banana peel response surface methodology ki-netics and isotherm studiesrdquo PLoS ONE vol 14 no 5 ArticleID e0216878 2019
Journal of Chemistry 7
[18] S Elumalai and G Muthuraman ldquoComparative study ofliquidndashliquid extraction and bulk liquid membrane for rho-damine Brdquo International Journal of Engineering and Inno-vative Technology vol 3 no 2 pp 387ndash392 2013
[19] M E Ersahin H Ozgun R K Dereli I Ozturk K Roest andJ B van Lier ldquoA review on dynamic membrane filtrationmaterials applications and future perspectivesrdquo BioresourceTechnology vol 122 pp 196ndash206 2012
[20] A Phuruangrat A Maneechote P DumrongrojthanathN Ekthammathat S ongtem and T ongtem ldquoEffect ofpH on visible-light-driven Bi2WO6 nanostructured catalystsynthesized by hydrothermal methodrdquo Superlattices andMicrostructures vol 78 pp 106ndash115 2015
[21] P Dumrongrojthanath T ongtem A Phuruangrat andS ongtem ldquoSynthesis and characterization of hierarchicalmultilayered flower-like assemblies of Ag doped Bi2WO6 andtheir photocatalytic activitiesrdquo Superlattices and Microstruc-tures vol 64 pp 196ndash203 2013
[22] S Y Lee D Kang S Jeong H T Do and J H KimldquoPhotocatalytic degradation of rhodamine B dye by TiO2 andgold nanoparticles supported on a floating porous poly-dimethylsiloxane sponge under ultraviolet and visible lightirradiationrdquo ACS Omega vol 5 no 8 pp 4233ndash4241 2020
[23] T T T Le T L Nguyen D T Tran and V N NguyenldquoEnhanced photocatalytic degradation of rhodamine B usingCFe Co-doped titanium dioxide coated on activated carbonrdquoJournal of Chemistry vol 2019 Article ID 2949316 8 pages2019
[24] J ShaoW Sheng MWang et al ldquoIn situ synthesis of carbon-doped TiO 2 single-crystal nanorods with a remarkablyphotocatalytic efficiencyrdquoApplied Catalysis B Environmentalvol 209 pp 311ndash319 2017
[25] Y Zhang J Chen L Hua et al ldquoHigh photocatalytic activityof hierarchical SiO2C-doped TiO2 hollow spheres in UVand visible light towards degradation of rhodamine BrdquoJournal of Hazardous Materials vol 340 pp 309ndash318 2017
[26] C Chen M Long H Zeng et al ldquoPreparation character-ization and visible-light activity of carbon modified TiO2 withtwo kinds of carbonaceous speciesrdquo Journal of MolecularCatalysis A Chemical vol 314 no 1-2 pp 35ndash41 2009
[27] W Xiaoping and T-T Lim ldquoSolvothermal synthesis of C-Ncodoped TiO2 and photocatalytic evaluation for bisphenol Adegradation using a visible-light irradiation LED photo-reactorrdquo Applied Catalysis B Environmental vol 100pp 355ndash364 2010
[28] U G Akpan and B H Hameed ldquoe advancements in sol-gelmethod of doped-TiO2 photocatalystsrdquo Applied Catalysis AGeneral vol 375 no 1 pp 1ndash11 2010
[29] H J Yun H Lee J B Joo N D Kim M Y Kang and J YildquoFacile preparation of high performance visible light sensitivephoto-catalystsrdquo Applied Catalysis B Environmental vol 94no 3-4 pp 241ndash247 2010
[30] M Hussain R Ceccarelli D L Marchisio D Fino N Russoand F Geobaldo ldquoSynthesis characterization and photo-catalytic application of novel TiO2 nanoparticlesrdquo ChemicalEngineering Journal vol 157 no 1 pp 45ndash51 2010
[31] T Shi Y Duan K Lv et al ldquoPhotocatalytic oxidation ofacetone over high thermally stable TiO2 nanosheets withexposed (001) facetsrdquo Frontiers in Chemistry vol 6 p 1752018
[32] M M Mahlambi A K Mishra S B Mishra R W KrauseB B Mamba and A M Raichur ldquoComparison of rhodamineB degradation under UV irradiation by two phases of titania
nano-photocatalystrdquo Journal of ltermal Analysis and Calo-rimetry vol 110 no 2 pp 847ndash855 2012
[33] W Zhang Y Li C Wang and P Wang ldquoKinetics of het-erogeneous photocatalytic degradation of Rhodamine B byTiO2-coated activated carbon roles of TiO2 content and lightintensityrdquo Desalination vol 266 no 1-3 pp 40ndash45 2011
[34] Y Xiao X Sun l Li et al ldquoSimultaneous formation of a CN-TiO2 hollow photocatalyst with efficient photocatalytic per-formance and recyclabilityrdquo Chinese Journal of Catalysisvol 40 no 5 pp 765ndash775 2019
[35] Y Wu J Zhang L Xiao and F Chen ldquoProperties of carbonand iron modified TiO2 photocatalyst synthesized at lowtemperature and photodegradation of acid orange 7 undervisible lightrdquo Applied Surface Science vol 256 no 13pp 4260ndash4268 2010
[36] X Cheng X Yu and Z Xing ldquoSynthesis and characterizationof C-N-S-tridoped TiO2 nano-crystalline photocatalyst and itsphotocatalytic activity for degradation of rhodamine BrdquoJournal of Physics and Chemistry of Solids vol 74 no 5pp 684ndash690 2013
[37] H Huang Y Song N Li et al ldquoOne-step in-situ preparationof N-doped TiO2C derived fromTi3C2MXene for enhancedvisible-light driven photodegradationrdquo Applied Catalysis BEnvironmental vol 251 pp 154ndash161 2019
[38] L Youji Z Xiaoming C Wei et al ldquoPhotodecolorization ofRhodamine B on tungsten-doped TiO2activated carbonunder visible-light irradiationrdquo Journal of Hazardous Mate-rials vol 227-228 pp 25ndash33 2012
[39] A Y Shan T I M Ghazi and S A Rashid ldquoImmobilisationof titanium dioxide onto supporting materials in heteroge-neous photocatalysis a reviewrdquo Applied Catalysis A Generalvol 389 no 1-2 pp 1ndash8 2010
8 Journal of Chemistry
33 Kinetics of RhB Degradation by C N-TiO2 under Visible-Light Irradiation Kinetics of the RhB degradation reactionwas studied by using different initial concentrations of RhB(0ndash100mgL) while keeping the catalyst load constant at18 gL
RhB decomposition reaction can be described by theLangmuirndashHinshelwood kinetics equation that is expressedas follows [27]
r minusdC
dt k
KC
1 + KC (2)
where k is the reaction rate constant K is the adsorptioncoefficient t is the time and C is the reactant concentration(the target organic compound) In the case of low initialconcentrations KCltlt 1 equation (2) can be rewritten as thefollowing
r minusdC
dt k middot KC kprime middot C (3)
where krsquo is the apparent rate constant which is also known asthe reduced first-order reaction en the following equa-tion is derived
lnCo
Ct
kprime middot t (4)
where Co and Ct are the reactant concentrations at t 0 and t(min) respectively Figure 12 shows the dependence of lnCoCt on time during the degradation of RhB by the C N-TiO2photocatalyst
As can be seen in Figures 12 and 13 when the initialconcentrations of RhB were in the range of 0ndash100mgL thephotodegradation was divided into 3 distinct groups whichwere characterized by the corresponding distinct apparent rateconstants e decomposition of RhB was observed unstablewhen the initial concentration was relatively low (0ndash10mgL)is is due to the degradationmainly affected by the absorption
0
20
40
60
80
100
120
0 30 60 90 120Time (min)
Rem
oval
effic
ienc
y of
RhB
()
(a)
(b)
Figure 8 Comparison of degradation efficiency as a function oflight irradiation time of TiO2 (a) and C N-TiO2 (b)
0
20
40
60
80
100
0 30 60 90Time (min)
Rem
oval
effic
ienc
y of
RhB
()
18 gl26 gl14 gl3 gl
Figure 9 Effect of catalyst concentration on the RhB degradationefficiency of C N-TiO2
0
05
1
15
2
25
3
35
ABS
Wavelength (nm)
Rhodamine B (t = 0)Rhodamine B (t = 1 (h))Rhodamine B (t = 15 (h))
Rhodamine B (t = 2 (h))Rhodamine B (t = 3 (h))
546
524
497
380
392
404
416
428
440
452
464
476
488
500
512
524
536
548
560
572
584
596
608
620
632
644
656
668
680
692
704
716
728
740
554
Figure 10 Liquid UV-Vis spectra of the RhB solution as a functionof treatment time
0
20
40
60
80
100
0 30 60 90Time (min)
Rem
oval
effic
ienc
y of
RhB
()
DarknessCompact lampNatural light
Figure 11 RhB degradation efficiency of C N-TiO2 under differentirradiation conditions
Journal of Chemistry 5
process e corresponding apparent rate constant krsquo is00427minminus1 In contrast when the initial concentration wasrelatively high (gt10mgL) the RhB decomposition occurredvery slowly resulting in smaller apparent rate constants(krsquo 00041minminus1 for 100mgL) is is because the bold colorof RhB causes the photoresist [23 27] e suitable initialconcentration for stable decomposition is about 20ndash40mgLe optimal initial concentration of RhB is 20mgL at whichthe apparent rate constant krsquo is 00205minminus1 e results ob-tained in this work is in agreement with previous studies[27 32] Hence with the RhB initial concentration of 20mgLequation (4) can be expressed by the following
lnCo
Ct
00205 times t (5)
Similarly the relation between CoCt and t for other initialconcentrations of RhB could be plotted as in Figure 13
e photocatalytic degradation of RhB by the C N-TiO2system can be explained by the following mechanism(Figure 14) (1) once h]ge (ECndashEVprime) electrons would beexcited in the valence band of TiO2 by the process TiO2 + h]
(UV)⟶TiO2 (eCBminus+ hVB+) (2) the departed electrons andholes subsequently migrate to the surface of the catalysts andreact with adsorbed H2O and O2 molecules forming bullOHand bullO2
minus respectively according to equations (6)ndash(8)
H2O + hVB+⟶ bullOH + H+
(6)
HOadminus
+ hVB+⟶ bullOHad (7)
eCBminus
+ O2⟶bullO2
minus(8)
and (3) bullOH and bullO2minus radicals are mainly responsible for the
degradation of RhB in solutions [38]emechanism for thedegradation of RhB in solutions by the C N-TiO2 system isproposed in Figure 14
34 Recoverability andReusability of CN-TiO2 Photocatalyste catalytic stability in RhB decomposition under visible-lightirradiation was studied After each decomposition cycle thecatalyst was centrifuged washed with distilled water and thenused for further treatment of RhB in solutions As can be seen inFigure 15 C and N codoped TiO2 exhibited good catalytic
000E + 00
100E ndash 02
200E ndash 02
300E ndash 02
400E ndash 02
500E ndash 02
0 20 40 60 80 100Co (mgl)
kprime(1
min
)
Figure 13 e apparent rate constant krsquo as a function of initialconcentrations of RhB
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140Time (min)
Ln(C
oC t
)
5 mgl y = 00427x
10 mgl y = 00345x
20 mgl y = 00205x30 mgl y = 00147x40 mgl y = 00136x
80 mgl y = 00080x90 mgl y = 00069x100 mgl y = 00041x
60 mgl y = 00110x
Figure 12 First-order kinetics for RhB degradation at differentinitial concentrations
UV light
TiO2VB
CB
334
eV
EC
EV
CN-TiO2
EprimeV
h+
h+
endash
endash endash
Visible light
290
eV
O2
bullO2ndash
OHndash
bullOH
Figure 14 Schematic mechanism of photocatalytic degradation ofRhB by C N-TiO2
0
02
04
06
08
1
0 30 60 90 120 150 180 210 240 270Time (min)
C tC
o
(a) (b) (c)
Figure 15 Catalystrsquos reuse results (a) first cycle (b) second cycle(c) third cycle
6 Journal of Chemistry
activity with the degradation efficiency of above 86 after threecycles and the obtained results were in agreement with previousstudies [39] It is noted that the absence of RhB and othersubstances on the surface of the catalyst and no release ofcatalysts to the water medium need to be proved prior to eachsubsequent cycle is could be revealed by using TEM FT-IRBET and extinction spectrum change of the water solution [22]In this work the photocatalytic performance is still very highafter three cycles (86) suggesting that the presence of sub-stances on the catalystrsquos surfaces is insignificant
4 Conclusions
In this work C and N codoped TiO2 nanoparticles aresuccessfully prepared by solvothermal synthesis and thenused for the study on their catalytic activities regardingRhB degradation in solutions under visible-light irradi-ation e obtained results showed that the as-synthesizednanoparticles mainly contained anatase crystallites withan average particle diameter of 91 nm C N-TiO2 pre-sented a high catalytic activity in the RhB degradationunder visible-light irradiation e optimal catalyst dos-age was 18 gL while optimal initial concentration of RhBwas 5mgL e photocatalytic degradation kinetics wasfound to follow the first-order rate law of the Lang-muirndashHinshelwood model e apparent rate constantdepended on the initial concentration of RhB which washigher at more diluted solutions of RhB
Data Availability
All the data used to support the findings of this study areprovided within the manuscript
Conflicts of Interest
e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
is work was partly supported by the Team Project ofVLIR-UOS with the code number ZEIN2016PR431 eauthors would like to thank the OEPAC project for theutilization of instruments
Supplementary Materials
Figure S1 energy spectra of the deployed compact lampFigure S2 BJH adsorption analysis for the C N-TiO2photocatalyst (Supplementary Materials)
References
[1] H Liu Y Wu and J Zhang ldquoA new approach toward carbon-modified vanadium-doped titanium dioxide photocatalystsrdquoACS Applied Materials amp Interfaces vol 3 no 5 pp 1757ndash17642011
[2] S Jafari B Tryba E Kusiak-Nejman J Kapica-KozarA W Morawski and M Sillanpaa ldquoe role of adsorption inthe photocatalytic decomposition of Orange II on carbon-
modified TiO2rdquo Journal of Molecular Liquids vol 220pp 504ndash512 2016
[3] Y Taga ldquoTitanium oxide based visible light photocatalystsmaterials design and applicationsrdquo ltin Solid Films vol 517no 10 pp 3167ndash3172 2009
[4] S Hosseini H Jahangirian T J Webster S M Soltani andM K Aroua ldquoSynthesis characterization and performanceevaluation of multilayered photoanodes by introducing meso-porous carbon and TiO2 for humic acid adsorptionrdquo Interna-tional Journal of Nanomedicine vol 11 pp 3969ndash3978 2016
[5] G Zhang Y C Zhang M Nadagouda et al ldquoVisible light-sensitized S N and C co-doped polymorphic TiO2 for pho-tocatalytic destruction of microcystin-LRrdquo Applied CatalysisB Environmental vol 144 pp 614ndash621 2014
[6] S D Richardson C S Willson and K A Rusch ldquoUse ofrhodamine water tracer in the marshland upwelling systemrdquoGround Water vol 42 no 5 pp 678ndash688 2004
[7] D J Dire and J A Wilkinson ldquoAcute exposure to rhodamineBrdquo Journal of Toxicology Clinical Toxicology vol 25 no 7pp 603ndash607 1987
[8] D Kornbrust and T Barfknecht ldquoTesting of 24 food drugcosmetic and fabric dyes in the in vitro and the in vivoinvitro rat hepatocyte primary culture DNA repair assaysrdquoEnvironmental Mutagenesis vol 7 no 1 pp 101ndash120 1985
[9] E R Nestmann G R Douglas T I Matula C E Grant andD J Kowbel ldquoMutagenic activity of rhodamine dyes and theirimpurities as detected by mutation induction in Salmonellaand DMA damage in Chinese hamster ovary cellsrdquo CancerResearch vol 39 pp 4412ndash4417 1979
[10] S Zodi B Merzouk O Potier F Lapicque and J-P LeclercldquoDirect red 81 dye removal by a continuous flow electro-coagulationflotation reactorrdquo Separation and PurificationTechnology vol 108 pp 215ndash222 2013
[11] Y-M Zheng R F Yunus K G N Nanayakkara andJ P Chen ldquoElectrochemical decoloration of syntheticwastewater containing rhodamine 6G behaviors and mech-anismrdquo Industrial amp Engineering Chemistry Research vol 51no 17 pp 5953ndash5960 2012
[12] H K Shon S Vigneswaran I S Kim et al ldquoPreparation oftitanium dioxide (TiO2) from sludge produced by titaniumtetrachloride (TiCl4) flocculation of wastewaterrdquo Environ-mental Science amp Technology vol 41 no 4 pp 1372ndash13772007
[13] X Chen Z Xue Y Yao W Wang F Zhu and C HongldquoOxidation degradation of rhodamine B in aqueous by UVS2O82- treatment systemrdquo International Journal of Photo-energy vol 2012 Article ID 754691 9 pages 2012
[14] W Griffith ldquoOzonolysis in coordination chemistry and ca-talysis recent advancesrdquo Coordination Chemistry Reviewsvol 219ndash221 pp 259ndash281 2001
[15] K Shen and M A Gondal ldquoRemoval of hazardous Rhoda-mine dye from water by adsorption onto exhausted coffeegroundrdquo Journal of Saudi Chemical Society vol 21pp S120ndashS127 2017
[16] T A Khan M Nazir and E A Khan ldquoAdsorptive removal ofrhodamine B from textile wastewater using water chestnut(Trapa natans L) peel adsorption dynamics and kineticstudiesrdquo Toxicological amp Environmental Chemistry vol 95no 6 pp 919ndash931 2013
[17] A A Oyekanmi A Ahmad K Hossain and M RafatullahldquoAdsorption of Rhodamine B dye from aqueous solution ontoacid treated banana peel response surface methodology ki-netics and isotherm studiesrdquo PLoS ONE vol 14 no 5 ArticleID e0216878 2019
Journal of Chemistry 7
[18] S Elumalai and G Muthuraman ldquoComparative study ofliquidndashliquid extraction and bulk liquid membrane for rho-damine Brdquo International Journal of Engineering and Inno-vative Technology vol 3 no 2 pp 387ndash392 2013
[19] M E Ersahin H Ozgun R K Dereli I Ozturk K Roest andJ B van Lier ldquoA review on dynamic membrane filtrationmaterials applications and future perspectivesrdquo BioresourceTechnology vol 122 pp 196ndash206 2012
[20] A Phuruangrat A Maneechote P DumrongrojthanathN Ekthammathat S ongtem and T ongtem ldquoEffect ofpH on visible-light-driven Bi2WO6 nanostructured catalystsynthesized by hydrothermal methodrdquo Superlattices andMicrostructures vol 78 pp 106ndash115 2015
[21] P Dumrongrojthanath T ongtem A Phuruangrat andS ongtem ldquoSynthesis and characterization of hierarchicalmultilayered flower-like assemblies of Ag doped Bi2WO6 andtheir photocatalytic activitiesrdquo Superlattices and Microstruc-tures vol 64 pp 196ndash203 2013
[22] S Y Lee D Kang S Jeong H T Do and J H KimldquoPhotocatalytic degradation of rhodamine B dye by TiO2 andgold nanoparticles supported on a floating porous poly-dimethylsiloxane sponge under ultraviolet and visible lightirradiationrdquo ACS Omega vol 5 no 8 pp 4233ndash4241 2020
[23] T T T Le T L Nguyen D T Tran and V N NguyenldquoEnhanced photocatalytic degradation of rhodamine B usingCFe Co-doped titanium dioxide coated on activated carbonrdquoJournal of Chemistry vol 2019 Article ID 2949316 8 pages2019
[24] J ShaoW Sheng MWang et al ldquoIn situ synthesis of carbon-doped TiO 2 single-crystal nanorods with a remarkablyphotocatalytic efficiencyrdquoApplied Catalysis B Environmentalvol 209 pp 311ndash319 2017
[25] Y Zhang J Chen L Hua et al ldquoHigh photocatalytic activityof hierarchical SiO2C-doped TiO2 hollow spheres in UVand visible light towards degradation of rhodamine BrdquoJournal of Hazardous Materials vol 340 pp 309ndash318 2017
[26] C Chen M Long H Zeng et al ldquoPreparation character-ization and visible-light activity of carbon modified TiO2 withtwo kinds of carbonaceous speciesrdquo Journal of MolecularCatalysis A Chemical vol 314 no 1-2 pp 35ndash41 2009
[27] W Xiaoping and T-T Lim ldquoSolvothermal synthesis of C-Ncodoped TiO2 and photocatalytic evaluation for bisphenol Adegradation using a visible-light irradiation LED photo-reactorrdquo Applied Catalysis B Environmental vol 100pp 355ndash364 2010
[28] U G Akpan and B H Hameed ldquoe advancements in sol-gelmethod of doped-TiO2 photocatalystsrdquo Applied Catalysis AGeneral vol 375 no 1 pp 1ndash11 2010
[29] H J Yun H Lee J B Joo N D Kim M Y Kang and J YildquoFacile preparation of high performance visible light sensitivephoto-catalystsrdquo Applied Catalysis B Environmental vol 94no 3-4 pp 241ndash247 2010
[30] M Hussain R Ceccarelli D L Marchisio D Fino N Russoand F Geobaldo ldquoSynthesis characterization and photo-catalytic application of novel TiO2 nanoparticlesrdquo ChemicalEngineering Journal vol 157 no 1 pp 45ndash51 2010
[31] T Shi Y Duan K Lv et al ldquoPhotocatalytic oxidation ofacetone over high thermally stable TiO2 nanosheets withexposed (001) facetsrdquo Frontiers in Chemistry vol 6 p 1752018
[32] M M Mahlambi A K Mishra S B Mishra R W KrauseB B Mamba and A M Raichur ldquoComparison of rhodamineB degradation under UV irradiation by two phases of titania
nano-photocatalystrdquo Journal of ltermal Analysis and Calo-rimetry vol 110 no 2 pp 847ndash855 2012
[33] W Zhang Y Li C Wang and P Wang ldquoKinetics of het-erogeneous photocatalytic degradation of Rhodamine B byTiO2-coated activated carbon roles of TiO2 content and lightintensityrdquo Desalination vol 266 no 1-3 pp 40ndash45 2011
[34] Y Xiao X Sun l Li et al ldquoSimultaneous formation of a CN-TiO2 hollow photocatalyst with efficient photocatalytic per-formance and recyclabilityrdquo Chinese Journal of Catalysisvol 40 no 5 pp 765ndash775 2019
[35] Y Wu J Zhang L Xiao and F Chen ldquoProperties of carbonand iron modified TiO2 photocatalyst synthesized at lowtemperature and photodegradation of acid orange 7 undervisible lightrdquo Applied Surface Science vol 256 no 13pp 4260ndash4268 2010
[36] X Cheng X Yu and Z Xing ldquoSynthesis and characterizationof C-N-S-tridoped TiO2 nano-crystalline photocatalyst and itsphotocatalytic activity for degradation of rhodamine BrdquoJournal of Physics and Chemistry of Solids vol 74 no 5pp 684ndash690 2013
[37] H Huang Y Song N Li et al ldquoOne-step in-situ preparationof N-doped TiO2C derived fromTi3C2MXene for enhancedvisible-light driven photodegradationrdquo Applied Catalysis BEnvironmental vol 251 pp 154ndash161 2019
[38] L Youji Z Xiaoming C Wei et al ldquoPhotodecolorization ofRhodamine B on tungsten-doped TiO2activated carbonunder visible-light irradiationrdquo Journal of Hazardous Mate-rials vol 227-228 pp 25ndash33 2012
[39] A Y Shan T I M Ghazi and S A Rashid ldquoImmobilisationof titanium dioxide onto supporting materials in heteroge-neous photocatalysis a reviewrdquo Applied Catalysis A Generalvol 389 no 1-2 pp 1ndash8 2010
8 Journal of Chemistry
process e corresponding apparent rate constant krsquo is00427minminus1 In contrast when the initial concentration wasrelatively high (gt10mgL) the RhB decomposition occurredvery slowly resulting in smaller apparent rate constants(krsquo 00041minminus1 for 100mgL) is is because the bold colorof RhB causes the photoresist [23 27] e suitable initialconcentration for stable decomposition is about 20ndash40mgLe optimal initial concentration of RhB is 20mgL at whichthe apparent rate constant krsquo is 00205minminus1 e results ob-tained in this work is in agreement with previous studies[27 32] Hence with the RhB initial concentration of 20mgLequation (4) can be expressed by the following
lnCo
Ct
00205 times t (5)
Similarly the relation between CoCt and t for other initialconcentrations of RhB could be plotted as in Figure 13
e photocatalytic degradation of RhB by the C N-TiO2system can be explained by the following mechanism(Figure 14) (1) once h]ge (ECndashEVprime) electrons would beexcited in the valence band of TiO2 by the process TiO2 + h]
(UV)⟶TiO2 (eCBminus+ hVB+) (2) the departed electrons andholes subsequently migrate to the surface of the catalysts andreact with adsorbed H2O and O2 molecules forming bullOHand bullO2
minus respectively according to equations (6)ndash(8)
H2O + hVB+⟶ bullOH + H+
(6)
HOadminus
+ hVB+⟶ bullOHad (7)
eCBminus
+ O2⟶bullO2
minus(8)
and (3) bullOH and bullO2minus radicals are mainly responsible for the
degradation of RhB in solutions [38]emechanism for thedegradation of RhB in solutions by the C N-TiO2 system isproposed in Figure 14
34 Recoverability andReusability of CN-TiO2 Photocatalyste catalytic stability in RhB decomposition under visible-lightirradiation was studied After each decomposition cycle thecatalyst was centrifuged washed with distilled water and thenused for further treatment of RhB in solutions As can be seen inFigure 15 C and N codoped TiO2 exhibited good catalytic
000E + 00
100E ndash 02
200E ndash 02
300E ndash 02
400E ndash 02
500E ndash 02
0 20 40 60 80 100Co (mgl)
kprime(1
min
)
Figure 13 e apparent rate constant krsquo as a function of initialconcentrations of RhB
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140Time (min)
Ln(C
oC t
)
5 mgl y = 00427x
10 mgl y = 00345x
20 mgl y = 00205x30 mgl y = 00147x40 mgl y = 00136x
80 mgl y = 00080x90 mgl y = 00069x100 mgl y = 00041x
60 mgl y = 00110x
Figure 12 First-order kinetics for RhB degradation at differentinitial concentrations
UV light
TiO2VB
CB
334
eV
EC
EV
CN-TiO2
EprimeV
h+
h+
endash
endash endash
Visible light
290
eV
O2
bullO2ndash
OHndash
bullOH
Figure 14 Schematic mechanism of photocatalytic degradation ofRhB by C N-TiO2
0
02
04
06
08
1
0 30 60 90 120 150 180 210 240 270Time (min)
C tC
o
(a) (b) (c)
Figure 15 Catalystrsquos reuse results (a) first cycle (b) second cycle(c) third cycle
6 Journal of Chemistry
activity with the degradation efficiency of above 86 after threecycles and the obtained results were in agreement with previousstudies [39] It is noted that the absence of RhB and othersubstances on the surface of the catalyst and no release ofcatalysts to the water medium need to be proved prior to eachsubsequent cycle is could be revealed by using TEM FT-IRBET and extinction spectrum change of the water solution [22]In this work the photocatalytic performance is still very highafter three cycles (86) suggesting that the presence of sub-stances on the catalystrsquos surfaces is insignificant
4 Conclusions
In this work C and N codoped TiO2 nanoparticles aresuccessfully prepared by solvothermal synthesis and thenused for the study on their catalytic activities regardingRhB degradation in solutions under visible-light irradi-ation e obtained results showed that the as-synthesizednanoparticles mainly contained anatase crystallites withan average particle diameter of 91 nm C N-TiO2 pre-sented a high catalytic activity in the RhB degradationunder visible-light irradiation e optimal catalyst dos-age was 18 gL while optimal initial concentration of RhBwas 5mgL e photocatalytic degradation kinetics wasfound to follow the first-order rate law of the Lang-muirndashHinshelwood model e apparent rate constantdepended on the initial concentration of RhB which washigher at more diluted solutions of RhB
Data Availability
All the data used to support the findings of this study areprovided within the manuscript
Conflicts of Interest
e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
is work was partly supported by the Team Project ofVLIR-UOS with the code number ZEIN2016PR431 eauthors would like to thank the OEPAC project for theutilization of instruments
Supplementary Materials
Figure S1 energy spectra of the deployed compact lampFigure S2 BJH adsorption analysis for the C N-TiO2photocatalyst (Supplementary Materials)
References
[1] H Liu Y Wu and J Zhang ldquoA new approach toward carbon-modified vanadium-doped titanium dioxide photocatalystsrdquoACS Applied Materials amp Interfaces vol 3 no 5 pp 1757ndash17642011
[2] S Jafari B Tryba E Kusiak-Nejman J Kapica-KozarA W Morawski and M Sillanpaa ldquoe role of adsorption inthe photocatalytic decomposition of Orange II on carbon-
modified TiO2rdquo Journal of Molecular Liquids vol 220pp 504ndash512 2016
[3] Y Taga ldquoTitanium oxide based visible light photocatalystsmaterials design and applicationsrdquo ltin Solid Films vol 517no 10 pp 3167ndash3172 2009
[4] S Hosseini H Jahangirian T J Webster S M Soltani andM K Aroua ldquoSynthesis characterization and performanceevaluation of multilayered photoanodes by introducing meso-porous carbon and TiO2 for humic acid adsorptionrdquo Interna-tional Journal of Nanomedicine vol 11 pp 3969ndash3978 2016
[5] G Zhang Y C Zhang M Nadagouda et al ldquoVisible light-sensitized S N and C co-doped polymorphic TiO2 for pho-tocatalytic destruction of microcystin-LRrdquo Applied CatalysisB Environmental vol 144 pp 614ndash621 2014
[6] S D Richardson C S Willson and K A Rusch ldquoUse ofrhodamine water tracer in the marshland upwelling systemrdquoGround Water vol 42 no 5 pp 678ndash688 2004
[7] D J Dire and J A Wilkinson ldquoAcute exposure to rhodamineBrdquo Journal of Toxicology Clinical Toxicology vol 25 no 7pp 603ndash607 1987
[8] D Kornbrust and T Barfknecht ldquoTesting of 24 food drugcosmetic and fabric dyes in the in vitro and the in vivoinvitro rat hepatocyte primary culture DNA repair assaysrdquoEnvironmental Mutagenesis vol 7 no 1 pp 101ndash120 1985
[9] E R Nestmann G R Douglas T I Matula C E Grant andD J Kowbel ldquoMutagenic activity of rhodamine dyes and theirimpurities as detected by mutation induction in Salmonellaand DMA damage in Chinese hamster ovary cellsrdquo CancerResearch vol 39 pp 4412ndash4417 1979
[10] S Zodi B Merzouk O Potier F Lapicque and J-P LeclercldquoDirect red 81 dye removal by a continuous flow electro-coagulationflotation reactorrdquo Separation and PurificationTechnology vol 108 pp 215ndash222 2013
[11] Y-M Zheng R F Yunus K G N Nanayakkara andJ P Chen ldquoElectrochemical decoloration of syntheticwastewater containing rhodamine 6G behaviors and mech-anismrdquo Industrial amp Engineering Chemistry Research vol 51no 17 pp 5953ndash5960 2012
[12] H K Shon S Vigneswaran I S Kim et al ldquoPreparation oftitanium dioxide (TiO2) from sludge produced by titaniumtetrachloride (TiCl4) flocculation of wastewaterrdquo Environ-mental Science amp Technology vol 41 no 4 pp 1372ndash13772007
[13] X Chen Z Xue Y Yao W Wang F Zhu and C HongldquoOxidation degradation of rhodamine B in aqueous by UVS2O82- treatment systemrdquo International Journal of Photo-energy vol 2012 Article ID 754691 9 pages 2012
[14] W Griffith ldquoOzonolysis in coordination chemistry and ca-talysis recent advancesrdquo Coordination Chemistry Reviewsvol 219ndash221 pp 259ndash281 2001
[15] K Shen and M A Gondal ldquoRemoval of hazardous Rhoda-mine dye from water by adsorption onto exhausted coffeegroundrdquo Journal of Saudi Chemical Society vol 21pp S120ndashS127 2017
[16] T A Khan M Nazir and E A Khan ldquoAdsorptive removal ofrhodamine B from textile wastewater using water chestnut(Trapa natans L) peel adsorption dynamics and kineticstudiesrdquo Toxicological amp Environmental Chemistry vol 95no 6 pp 919ndash931 2013
[17] A A Oyekanmi A Ahmad K Hossain and M RafatullahldquoAdsorption of Rhodamine B dye from aqueous solution ontoacid treated banana peel response surface methodology ki-netics and isotherm studiesrdquo PLoS ONE vol 14 no 5 ArticleID e0216878 2019
Journal of Chemistry 7
[18] S Elumalai and G Muthuraman ldquoComparative study ofliquidndashliquid extraction and bulk liquid membrane for rho-damine Brdquo International Journal of Engineering and Inno-vative Technology vol 3 no 2 pp 387ndash392 2013
[19] M E Ersahin H Ozgun R K Dereli I Ozturk K Roest andJ B van Lier ldquoA review on dynamic membrane filtrationmaterials applications and future perspectivesrdquo BioresourceTechnology vol 122 pp 196ndash206 2012
[20] A Phuruangrat A Maneechote P DumrongrojthanathN Ekthammathat S ongtem and T ongtem ldquoEffect ofpH on visible-light-driven Bi2WO6 nanostructured catalystsynthesized by hydrothermal methodrdquo Superlattices andMicrostructures vol 78 pp 106ndash115 2015
[21] P Dumrongrojthanath T ongtem A Phuruangrat andS ongtem ldquoSynthesis and characterization of hierarchicalmultilayered flower-like assemblies of Ag doped Bi2WO6 andtheir photocatalytic activitiesrdquo Superlattices and Microstruc-tures vol 64 pp 196ndash203 2013
[22] S Y Lee D Kang S Jeong H T Do and J H KimldquoPhotocatalytic degradation of rhodamine B dye by TiO2 andgold nanoparticles supported on a floating porous poly-dimethylsiloxane sponge under ultraviolet and visible lightirradiationrdquo ACS Omega vol 5 no 8 pp 4233ndash4241 2020
[23] T T T Le T L Nguyen D T Tran and V N NguyenldquoEnhanced photocatalytic degradation of rhodamine B usingCFe Co-doped titanium dioxide coated on activated carbonrdquoJournal of Chemistry vol 2019 Article ID 2949316 8 pages2019
[24] J ShaoW Sheng MWang et al ldquoIn situ synthesis of carbon-doped TiO 2 single-crystal nanorods with a remarkablyphotocatalytic efficiencyrdquoApplied Catalysis B Environmentalvol 209 pp 311ndash319 2017
[25] Y Zhang J Chen L Hua et al ldquoHigh photocatalytic activityof hierarchical SiO2C-doped TiO2 hollow spheres in UVand visible light towards degradation of rhodamine BrdquoJournal of Hazardous Materials vol 340 pp 309ndash318 2017
[26] C Chen M Long H Zeng et al ldquoPreparation character-ization and visible-light activity of carbon modified TiO2 withtwo kinds of carbonaceous speciesrdquo Journal of MolecularCatalysis A Chemical vol 314 no 1-2 pp 35ndash41 2009
[27] W Xiaoping and T-T Lim ldquoSolvothermal synthesis of C-Ncodoped TiO2 and photocatalytic evaluation for bisphenol Adegradation using a visible-light irradiation LED photo-reactorrdquo Applied Catalysis B Environmental vol 100pp 355ndash364 2010
[28] U G Akpan and B H Hameed ldquoe advancements in sol-gelmethod of doped-TiO2 photocatalystsrdquo Applied Catalysis AGeneral vol 375 no 1 pp 1ndash11 2010
[29] H J Yun H Lee J B Joo N D Kim M Y Kang and J YildquoFacile preparation of high performance visible light sensitivephoto-catalystsrdquo Applied Catalysis B Environmental vol 94no 3-4 pp 241ndash247 2010
[30] M Hussain R Ceccarelli D L Marchisio D Fino N Russoand F Geobaldo ldquoSynthesis characterization and photo-catalytic application of novel TiO2 nanoparticlesrdquo ChemicalEngineering Journal vol 157 no 1 pp 45ndash51 2010
[31] T Shi Y Duan K Lv et al ldquoPhotocatalytic oxidation ofacetone over high thermally stable TiO2 nanosheets withexposed (001) facetsrdquo Frontiers in Chemistry vol 6 p 1752018
[32] M M Mahlambi A K Mishra S B Mishra R W KrauseB B Mamba and A M Raichur ldquoComparison of rhodamineB degradation under UV irradiation by two phases of titania
nano-photocatalystrdquo Journal of ltermal Analysis and Calo-rimetry vol 110 no 2 pp 847ndash855 2012
[33] W Zhang Y Li C Wang and P Wang ldquoKinetics of het-erogeneous photocatalytic degradation of Rhodamine B byTiO2-coated activated carbon roles of TiO2 content and lightintensityrdquo Desalination vol 266 no 1-3 pp 40ndash45 2011
[34] Y Xiao X Sun l Li et al ldquoSimultaneous formation of a CN-TiO2 hollow photocatalyst with efficient photocatalytic per-formance and recyclabilityrdquo Chinese Journal of Catalysisvol 40 no 5 pp 765ndash775 2019
[35] Y Wu J Zhang L Xiao and F Chen ldquoProperties of carbonand iron modified TiO2 photocatalyst synthesized at lowtemperature and photodegradation of acid orange 7 undervisible lightrdquo Applied Surface Science vol 256 no 13pp 4260ndash4268 2010
[36] X Cheng X Yu and Z Xing ldquoSynthesis and characterizationof C-N-S-tridoped TiO2 nano-crystalline photocatalyst and itsphotocatalytic activity for degradation of rhodamine BrdquoJournal of Physics and Chemistry of Solids vol 74 no 5pp 684ndash690 2013
[37] H Huang Y Song N Li et al ldquoOne-step in-situ preparationof N-doped TiO2C derived fromTi3C2MXene for enhancedvisible-light driven photodegradationrdquo Applied Catalysis BEnvironmental vol 251 pp 154ndash161 2019
[38] L Youji Z Xiaoming C Wei et al ldquoPhotodecolorization ofRhodamine B on tungsten-doped TiO2activated carbonunder visible-light irradiationrdquo Journal of Hazardous Mate-rials vol 227-228 pp 25ndash33 2012
[39] A Y Shan T I M Ghazi and S A Rashid ldquoImmobilisationof titanium dioxide onto supporting materials in heteroge-neous photocatalysis a reviewrdquo Applied Catalysis A Generalvol 389 no 1-2 pp 1ndash8 2010
8 Journal of Chemistry
activity with the degradation efficiency of above 86 after threecycles and the obtained results were in agreement with previousstudies [39] It is noted that the absence of RhB and othersubstances on the surface of the catalyst and no release ofcatalysts to the water medium need to be proved prior to eachsubsequent cycle is could be revealed by using TEM FT-IRBET and extinction spectrum change of the water solution [22]In this work the photocatalytic performance is still very highafter three cycles (86) suggesting that the presence of sub-stances on the catalystrsquos surfaces is insignificant
4 Conclusions
In this work C and N codoped TiO2 nanoparticles aresuccessfully prepared by solvothermal synthesis and thenused for the study on their catalytic activities regardingRhB degradation in solutions under visible-light irradi-ation e obtained results showed that the as-synthesizednanoparticles mainly contained anatase crystallites withan average particle diameter of 91 nm C N-TiO2 pre-sented a high catalytic activity in the RhB degradationunder visible-light irradiation e optimal catalyst dos-age was 18 gL while optimal initial concentration of RhBwas 5mgL e photocatalytic degradation kinetics wasfound to follow the first-order rate law of the Lang-muirndashHinshelwood model e apparent rate constantdepended on the initial concentration of RhB which washigher at more diluted solutions of RhB
Data Availability
All the data used to support the findings of this study areprovided within the manuscript
Conflicts of Interest
e authors declare that there are no conflicts of interestregarding the publication of this paper
Acknowledgments
is work was partly supported by the Team Project ofVLIR-UOS with the code number ZEIN2016PR431 eauthors would like to thank the OEPAC project for theutilization of instruments
Supplementary Materials
Figure S1 energy spectra of the deployed compact lampFigure S2 BJH adsorption analysis for the C N-TiO2photocatalyst (Supplementary Materials)
References
[1] H Liu Y Wu and J Zhang ldquoA new approach toward carbon-modified vanadium-doped titanium dioxide photocatalystsrdquoACS Applied Materials amp Interfaces vol 3 no 5 pp 1757ndash17642011
[2] S Jafari B Tryba E Kusiak-Nejman J Kapica-KozarA W Morawski and M Sillanpaa ldquoe role of adsorption inthe photocatalytic decomposition of Orange II on carbon-
modified TiO2rdquo Journal of Molecular Liquids vol 220pp 504ndash512 2016
[3] Y Taga ldquoTitanium oxide based visible light photocatalystsmaterials design and applicationsrdquo ltin Solid Films vol 517no 10 pp 3167ndash3172 2009
[4] S Hosseini H Jahangirian T J Webster S M Soltani andM K Aroua ldquoSynthesis characterization and performanceevaluation of multilayered photoanodes by introducing meso-porous carbon and TiO2 for humic acid adsorptionrdquo Interna-tional Journal of Nanomedicine vol 11 pp 3969ndash3978 2016
[5] G Zhang Y C Zhang M Nadagouda et al ldquoVisible light-sensitized S N and C co-doped polymorphic TiO2 for pho-tocatalytic destruction of microcystin-LRrdquo Applied CatalysisB Environmental vol 144 pp 614ndash621 2014
[6] S D Richardson C S Willson and K A Rusch ldquoUse ofrhodamine water tracer in the marshland upwelling systemrdquoGround Water vol 42 no 5 pp 678ndash688 2004
[7] D J Dire and J A Wilkinson ldquoAcute exposure to rhodamineBrdquo Journal of Toxicology Clinical Toxicology vol 25 no 7pp 603ndash607 1987
[8] D Kornbrust and T Barfknecht ldquoTesting of 24 food drugcosmetic and fabric dyes in the in vitro and the in vivoinvitro rat hepatocyte primary culture DNA repair assaysrdquoEnvironmental Mutagenesis vol 7 no 1 pp 101ndash120 1985
[9] E R Nestmann G R Douglas T I Matula C E Grant andD J Kowbel ldquoMutagenic activity of rhodamine dyes and theirimpurities as detected by mutation induction in Salmonellaand DMA damage in Chinese hamster ovary cellsrdquo CancerResearch vol 39 pp 4412ndash4417 1979
[10] S Zodi B Merzouk O Potier F Lapicque and J-P LeclercldquoDirect red 81 dye removal by a continuous flow electro-coagulationflotation reactorrdquo Separation and PurificationTechnology vol 108 pp 215ndash222 2013
[11] Y-M Zheng R F Yunus K G N Nanayakkara andJ P Chen ldquoElectrochemical decoloration of syntheticwastewater containing rhodamine 6G behaviors and mech-anismrdquo Industrial amp Engineering Chemistry Research vol 51no 17 pp 5953ndash5960 2012
[12] H K Shon S Vigneswaran I S Kim et al ldquoPreparation oftitanium dioxide (TiO2) from sludge produced by titaniumtetrachloride (TiCl4) flocculation of wastewaterrdquo Environ-mental Science amp Technology vol 41 no 4 pp 1372ndash13772007
[13] X Chen Z Xue Y Yao W Wang F Zhu and C HongldquoOxidation degradation of rhodamine B in aqueous by UVS2O82- treatment systemrdquo International Journal of Photo-energy vol 2012 Article ID 754691 9 pages 2012
[14] W Griffith ldquoOzonolysis in coordination chemistry and ca-talysis recent advancesrdquo Coordination Chemistry Reviewsvol 219ndash221 pp 259ndash281 2001
[15] K Shen and M A Gondal ldquoRemoval of hazardous Rhoda-mine dye from water by adsorption onto exhausted coffeegroundrdquo Journal of Saudi Chemical Society vol 21pp S120ndashS127 2017
[16] T A Khan M Nazir and E A Khan ldquoAdsorptive removal ofrhodamine B from textile wastewater using water chestnut(Trapa natans L) peel adsorption dynamics and kineticstudiesrdquo Toxicological amp Environmental Chemistry vol 95no 6 pp 919ndash931 2013
[17] A A Oyekanmi A Ahmad K Hossain and M RafatullahldquoAdsorption of Rhodamine B dye from aqueous solution ontoacid treated banana peel response surface methodology ki-netics and isotherm studiesrdquo PLoS ONE vol 14 no 5 ArticleID e0216878 2019
Journal of Chemistry 7
[18] S Elumalai and G Muthuraman ldquoComparative study ofliquidndashliquid extraction and bulk liquid membrane for rho-damine Brdquo International Journal of Engineering and Inno-vative Technology vol 3 no 2 pp 387ndash392 2013
[19] M E Ersahin H Ozgun R K Dereli I Ozturk K Roest andJ B van Lier ldquoA review on dynamic membrane filtrationmaterials applications and future perspectivesrdquo BioresourceTechnology vol 122 pp 196ndash206 2012
[20] A Phuruangrat A Maneechote P DumrongrojthanathN Ekthammathat S ongtem and T ongtem ldquoEffect ofpH on visible-light-driven Bi2WO6 nanostructured catalystsynthesized by hydrothermal methodrdquo Superlattices andMicrostructures vol 78 pp 106ndash115 2015
[21] P Dumrongrojthanath T ongtem A Phuruangrat andS ongtem ldquoSynthesis and characterization of hierarchicalmultilayered flower-like assemblies of Ag doped Bi2WO6 andtheir photocatalytic activitiesrdquo Superlattices and Microstruc-tures vol 64 pp 196ndash203 2013
[22] S Y Lee D Kang S Jeong H T Do and J H KimldquoPhotocatalytic degradation of rhodamine B dye by TiO2 andgold nanoparticles supported on a floating porous poly-dimethylsiloxane sponge under ultraviolet and visible lightirradiationrdquo ACS Omega vol 5 no 8 pp 4233ndash4241 2020
[23] T T T Le T L Nguyen D T Tran and V N NguyenldquoEnhanced photocatalytic degradation of rhodamine B usingCFe Co-doped titanium dioxide coated on activated carbonrdquoJournal of Chemistry vol 2019 Article ID 2949316 8 pages2019
[24] J ShaoW Sheng MWang et al ldquoIn situ synthesis of carbon-doped TiO 2 single-crystal nanorods with a remarkablyphotocatalytic efficiencyrdquoApplied Catalysis B Environmentalvol 209 pp 311ndash319 2017
[25] Y Zhang J Chen L Hua et al ldquoHigh photocatalytic activityof hierarchical SiO2C-doped TiO2 hollow spheres in UVand visible light towards degradation of rhodamine BrdquoJournal of Hazardous Materials vol 340 pp 309ndash318 2017
[26] C Chen M Long H Zeng et al ldquoPreparation character-ization and visible-light activity of carbon modified TiO2 withtwo kinds of carbonaceous speciesrdquo Journal of MolecularCatalysis A Chemical vol 314 no 1-2 pp 35ndash41 2009
[27] W Xiaoping and T-T Lim ldquoSolvothermal synthesis of C-Ncodoped TiO2 and photocatalytic evaluation for bisphenol Adegradation using a visible-light irradiation LED photo-reactorrdquo Applied Catalysis B Environmental vol 100pp 355ndash364 2010
[28] U G Akpan and B H Hameed ldquoe advancements in sol-gelmethod of doped-TiO2 photocatalystsrdquo Applied Catalysis AGeneral vol 375 no 1 pp 1ndash11 2010
[29] H J Yun H Lee J B Joo N D Kim M Y Kang and J YildquoFacile preparation of high performance visible light sensitivephoto-catalystsrdquo Applied Catalysis B Environmental vol 94no 3-4 pp 241ndash247 2010
[30] M Hussain R Ceccarelli D L Marchisio D Fino N Russoand F Geobaldo ldquoSynthesis characterization and photo-catalytic application of novel TiO2 nanoparticlesrdquo ChemicalEngineering Journal vol 157 no 1 pp 45ndash51 2010
[31] T Shi Y Duan K Lv et al ldquoPhotocatalytic oxidation ofacetone over high thermally stable TiO2 nanosheets withexposed (001) facetsrdquo Frontiers in Chemistry vol 6 p 1752018
[32] M M Mahlambi A K Mishra S B Mishra R W KrauseB B Mamba and A M Raichur ldquoComparison of rhodamineB degradation under UV irradiation by two phases of titania
nano-photocatalystrdquo Journal of ltermal Analysis and Calo-rimetry vol 110 no 2 pp 847ndash855 2012
[33] W Zhang Y Li C Wang and P Wang ldquoKinetics of het-erogeneous photocatalytic degradation of Rhodamine B byTiO2-coated activated carbon roles of TiO2 content and lightintensityrdquo Desalination vol 266 no 1-3 pp 40ndash45 2011
[34] Y Xiao X Sun l Li et al ldquoSimultaneous formation of a CN-TiO2 hollow photocatalyst with efficient photocatalytic per-formance and recyclabilityrdquo Chinese Journal of Catalysisvol 40 no 5 pp 765ndash775 2019
[35] Y Wu J Zhang L Xiao and F Chen ldquoProperties of carbonand iron modified TiO2 photocatalyst synthesized at lowtemperature and photodegradation of acid orange 7 undervisible lightrdquo Applied Surface Science vol 256 no 13pp 4260ndash4268 2010
[36] X Cheng X Yu and Z Xing ldquoSynthesis and characterizationof C-N-S-tridoped TiO2 nano-crystalline photocatalyst and itsphotocatalytic activity for degradation of rhodamine BrdquoJournal of Physics and Chemistry of Solids vol 74 no 5pp 684ndash690 2013
[37] H Huang Y Song N Li et al ldquoOne-step in-situ preparationof N-doped TiO2C derived fromTi3C2MXene for enhancedvisible-light driven photodegradationrdquo Applied Catalysis BEnvironmental vol 251 pp 154ndash161 2019
[38] L Youji Z Xiaoming C Wei et al ldquoPhotodecolorization ofRhodamine B on tungsten-doped TiO2activated carbonunder visible-light irradiationrdquo Journal of Hazardous Mate-rials vol 227-228 pp 25ndash33 2012
[39] A Y Shan T I M Ghazi and S A Rashid ldquoImmobilisationof titanium dioxide onto supporting materials in heteroge-neous photocatalysis a reviewrdquo Applied Catalysis A Generalvol 389 no 1-2 pp 1ndash8 2010
8 Journal of Chemistry
[18] S Elumalai and G Muthuraman ldquoComparative study ofliquidndashliquid extraction and bulk liquid membrane for rho-damine Brdquo International Journal of Engineering and Inno-vative Technology vol 3 no 2 pp 387ndash392 2013
[19] M E Ersahin H Ozgun R K Dereli I Ozturk K Roest andJ B van Lier ldquoA review on dynamic membrane filtrationmaterials applications and future perspectivesrdquo BioresourceTechnology vol 122 pp 196ndash206 2012
[20] A Phuruangrat A Maneechote P DumrongrojthanathN Ekthammathat S ongtem and T ongtem ldquoEffect ofpH on visible-light-driven Bi2WO6 nanostructured catalystsynthesized by hydrothermal methodrdquo Superlattices andMicrostructures vol 78 pp 106ndash115 2015
[21] P Dumrongrojthanath T ongtem A Phuruangrat andS ongtem ldquoSynthesis and characterization of hierarchicalmultilayered flower-like assemblies of Ag doped Bi2WO6 andtheir photocatalytic activitiesrdquo Superlattices and Microstruc-tures vol 64 pp 196ndash203 2013
[22] S Y Lee D Kang S Jeong H T Do and J H KimldquoPhotocatalytic degradation of rhodamine B dye by TiO2 andgold nanoparticles supported on a floating porous poly-dimethylsiloxane sponge under ultraviolet and visible lightirradiationrdquo ACS Omega vol 5 no 8 pp 4233ndash4241 2020
[23] T T T Le T L Nguyen D T Tran and V N NguyenldquoEnhanced photocatalytic degradation of rhodamine B usingCFe Co-doped titanium dioxide coated on activated carbonrdquoJournal of Chemistry vol 2019 Article ID 2949316 8 pages2019
[24] J ShaoW Sheng MWang et al ldquoIn situ synthesis of carbon-doped TiO 2 single-crystal nanorods with a remarkablyphotocatalytic efficiencyrdquoApplied Catalysis B Environmentalvol 209 pp 311ndash319 2017
[25] Y Zhang J Chen L Hua et al ldquoHigh photocatalytic activityof hierarchical SiO2C-doped TiO2 hollow spheres in UVand visible light towards degradation of rhodamine BrdquoJournal of Hazardous Materials vol 340 pp 309ndash318 2017
[26] C Chen M Long H Zeng et al ldquoPreparation character-ization and visible-light activity of carbon modified TiO2 withtwo kinds of carbonaceous speciesrdquo Journal of MolecularCatalysis A Chemical vol 314 no 1-2 pp 35ndash41 2009
[27] W Xiaoping and T-T Lim ldquoSolvothermal synthesis of C-Ncodoped TiO2 and photocatalytic evaluation for bisphenol Adegradation using a visible-light irradiation LED photo-reactorrdquo Applied Catalysis B Environmental vol 100pp 355ndash364 2010
[28] U G Akpan and B H Hameed ldquoe advancements in sol-gelmethod of doped-TiO2 photocatalystsrdquo Applied Catalysis AGeneral vol 375 no 1 pp 1ndash11 2010
[29] H J Yun H Lee J B Joo N D Kim M Y Kang and J YildquoFacile preparation of high performance visible light sensitivephoto-catalystsrdquo Applied Catalysis B Environmental vol 94no 3-4 pp 241ndash247 2010
[30] M Hussain R Ceccarelli D L Marchisio D Fino N Russoand F Geobaldo ldquoSynthesis characterization and photo-catalytic application of novel TiO2 nanoparticlesrdquo ChemicalEngineering Journal vol 157 no 1 pp 45ndash51 2010
[31] T Shi Y Duan K Lv et al ldquoPhotocatalytic oxidation ofacetone over high thermally stable TiO2 nanosheets withexposed (001) facetsrdquo Frontiers in Chemistry vol 6 p 1752018
[32] M M Mahlambi A K Mishra S B Mishra R W KrauseB B Mamba and A M Raichur ldquoComparison of rhodamineB degradation under UV irradiation by two phases of titania
nano-photocatalystrdquo Journal of ltermal Analysis and Calo-rimetry vol 110 no 2 pp 847ndash855 2012
[33] W Zhang Y Li C Wang and P Wang ldquoKinetics of het-erogeneous photocatalytic degradation of Rhodamine B byTiO2-coated activated carbon roles of TiO2 content and lightintensityrdquo Desalination vol 266 no 1-3 pp 40ndash45 2011
[34] Y Xiao X Sun l Li et al ldquoSimultaneous formation of a CN-TiO2 hollow photocatalyst with efficient photocatalytic per-formance and recyclabilityrdquo Chinese Journal of Catalysisvol 40 no 5 pp 765ndash775 2019
[35] Y Wu J Zhang L Xiao and F Chen ldquoProperties of carbonand iron modified TiO2 photocatalyst synthesized at lowtemperature and photodegradation of acid orange 7 undervisible lightrdquo Applied Surface Science vol 256 no 13pp 4260ndash4268 2010
[36] X Cheng X Yu and Z Xing ldquoSynthesis and characterizationof C-N-S-tridoped TiO2 nano-crystalline photocatalyst and itsphotocatalytic activity for degradation of rhodamine BrdquoJournal of Physics and Chemistry of Solids vol 74 no 5pp 684ndash690 2013
[37] H Huang Y Song N Li et al ldquoOne-step in-situ preparationof N-doped TiO2C derived fromTi3C2MXene for enhancedvisible-light driven photodegradationrdquo Applied Catalysis BEnvironmental vol 251 pp 154ndash161 2019
[38] L Youji Z Xiaoming C Wei et al ldquoPhotodecolorization ofRhodamine B on tungsten-doped TiO2activated carbonunder visible-light irradiationrdquo Journal of Hazardous Mate-rials vol 227-228 pp 25ndash33 2012
[39] A Y Shan T I M Ghazi and S A Rashid ldquoImmobilisationof titanium dioxide onto supporting materials in heteroge-neous photocatalysis a reviewrdquo Applied Catalysis A Generalvol 389 no 1-2 pp 1ndash8 2010
8 Journal of Chemistry
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