Prof. Dhiraj Sud Dean Academic Department of Chemistry, Sant Longowal Institute of Engineering and Technology, (Deemed to be University), Longowal 148106,
Post on 03-Jan-2016
222 Views
Preview:
Transcript
SYNTHESIZED DOPED TIO2 PHOTOCATALYSTS FOR MINERALIZATION OF QUINALPHOS
FROM AQUEOUS STREAMS
Prof. Dhiraj SudDean Academic
Department of Chemistry, Sant Longowal Institute of Engineering and Technology, (Deemed to be University), Longowal 148106, India
E-mail address: suddhiraj@yahoo.com
An influx of anthropogenic substances in environmental matrix is an issue of National & Global concerns
Nature does not have any mechanism to deal
Emergence of Recalcitrant, Xenobiotic chemicals - resistant towards Biological degradation, Bioaccumulation tendency
Xenobiotic Chemicals commonly present in Wastewater streams are: Dyes , Phenols ,Pesticides Detergents and Surfactants Agrochemicals Pharmaceutical Compounds(ug /l to ng/l) >>>>>>>>>>>>
Synthesized Doped TiO2 Photocatalysts ……………
Organophosphate pesticides are of great significance in pest control as compared to other types. These cover the 70% of the total pesticides used.
Commonly used Pesticides
Commonly used Pesticides
organophosphate pesticides
pyrethoid miscellaneous compounds urea
anilides
Organochlorine Pesticides
carbamates
Pesticides are the synthetic compounds or mixtures intended for preventing, destroying or controlling pest including vectors of human or animal disease, unwanted species of plants and animals causing harm during or otherwise interfering with the production, storage, processing and transportation or marketing of food, agricultural commodities.
Synthesized Doped TiO2 Photocatalysts ……………
Pesticide???
SunDegradation
Persistence
Desorption/
Leaching Ground water
Adsorption
Micro-organism
s
Hydrolysis
FATE AND BEHAVIOUR OF PESTICIDE IN ENVIRONMENT
Synthesized Doped TiO2 Photocatalysts ……………
5
Mainly used for control a variety of sucking, chewing
and boring insects and spider mites on vegetables, fruits, cotton, groundnut,
cereals and rice.
The EPA classifies Quinalphos as a class II toxicity - moderate
toxic.
Solubility in water- 20mg/l
Acute oral LD50 for rats- 14 to 37 mg/kg
Mode of Action- By inhibiting acetylcholinesterase
PSO
OOH5C2
H5C2
N
N
QUINALPHOS (Organophosphate Pesticide)
Synthesized Doped TiO2 Photocatalysts ……………
235 255 275 295 315 335 355 375 3950
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
QP
Soil C
Soil D
Soil A
Soil B
Wavelength
Absorb
ance
Soil %age adsorption (QP)
A 43.4
B 44.o3
C 47.9
D 62.8
Paramjeet Kaur and Dhiraj Sud, Clean – Soil, Air, Water 2011, 39 (12), 1060–1067
ADSORPTION OF QUINALPHOS ON VARIOUS SOILS
Synthesized Doped TiO2 Photocatalysts ……………
7
Mainly used for control a variety of sucking, chewing
and boring insects and spider mites on vegetables, fruits, cotton, groundnut,
cereals and rice.
The EPA classifies Quinalphos as a class II toxicity - moderate
toxic.
Solubility in water- 20mg/l
Acute oral LD50 for rats- 14 to 37 mg/kg
Mode of Action- By inhibiting acetylcholinesterase
PSO
OOH5C2
H5C2
N
N
QUINALPHOS (Organophosphate Pesticide)
Synthesized Doped TiO2 Photocatalysts ……………
PERSISTENCE IN WATER AFTER 10 DAYS
PERSISTENCE IN WATER AFTER 105 DAYS
0 5 10 15 20 250
5
10
15
20
25
30
35
40
45
Retention time
Inte
nsit
y
0 2 4 6 8 10 12 14 16 180
5
10
15
20
25
30
35
After 105 days
Retention Time
Inte
nsit
y
After 10 days
Synthesized Doped TiO2 Photocatalysts ……………
9
Conventional methods for Waste water
treatment
Advanced
Oxidation
Systems
Heterogeneous(UV,Catalyst and oxidant)
Homogeneous
(UV,Ozone or H2O2)
Emerging trendAdvanced oxidation
processes (AOP’s) as potential destructive technology
Titanium dioxide (TiO 2) is
found to be most efficient catalyst
• Organic Pollutant + O2 → CO2+ H2O + mineral acid
• Oxidation of pollutant in ppb range
•Capable of destroying the organics without harmful byproducts.
Potential to utilize sunlight instead of artificial light as a UV source
Adsorption Filtration Aeration
Aerobic Anaerob
ic
Ion exchange Membrane
sepn Precipitation
Synthesized Doped TiO2 Photocatalysts ……………
PHOTOCATALYTIC MECHANISM
TiO2 + hυ → e- TiO2 (CB) + h + TiO2 (VB)
O2 +e- (CB) → O▪ -
2
O▪ -2 + H2O →▪ OH + OH-
h+ (VB) + OH- → ▪ OH ▪ OH + C6H5ClO → Intermediate → CO2 +
H2O
Synthesized Doped TiO2 Photocatalysts ……………
NANOSIZED SEMICONDUCTOR PARTICLES
Nanosized semiconductor particles exhibit unique size and shape dependent photophysical (Optical, Electronic, Catalytic and magnetic and photocatalytic properties) distinct from their bulk counterparts .
They can possess enhanced photo redox chemistries and reduction reactions that might not otherwise occur using bulk materials .
Higher catalytic activities Smaller a semiconductor particle becomes, the more the
number of atoms located at the surface and the surface area to volume ratio increase - enhance available surface active sites and interfacial charge-carrier transfer
Inner sphere absorption mechanism
Synthesized Doped TiO2 Photocatalysts ……………
Photocatalyst
Extension of excitationwavelength using Photosensitizers
Band-gap tuning
promoting forward reaction andreactant absorbance by providing adequate quality and quantity of active sites
Extending charge-carrier
recombination times
Doping
Sensitization
Synthesized Doped TiO2 Photocatalysts ……………
NON-METAL ION DOPING METAL ION DOPINGSubstitutional doping of nitrogen into the TiO2 lattice causes a significant shift of the absorption edge in the visible region because the N 2p states con-tribute to the band-gap narrowing by mixing with the O 2p states.
Metal ion traps the holes
and electrons and prevents recombination of e– h+ pairs. This helps maintain electro neutrality while degrading organic compounds.
R. Asahi, T. Morikawa, T. Ohwaki, K. Aoki, Y. Taga, Science, 293 (2001) 269-271.
Synthesized Doped TiO2 Photocatalysts ……………
Dopant + Ethanol TTIP + Ethanol
Ppts. With NH3
Ultrasonicated
Calc
inat
ed
Filtered
Different temperatures 350, 450, 550 and 750°C
Prepararation Method
Synthesized Doped TiO2 Photocatalysts ……………
Non-metal doped
Photocatalyst
N-doped TiO2
S-doped TiO2
Mn-N-doped TiO2
Metal co doped Photocatalyst
Synthesized Doped TiO2 Photocatalysts ……………
XRD analysis of N-doped TiO2
Position [°2Theta] (Copper (Cu))
10 20 30 40 50 60 70
Counts
0
200
400
0
1000
2000
0
500
1000
0
200
400
600
800
NS4-550
F-RB-750
450
350
N-doped TiO2 calcinated at different temperature
S. no.
Calcination treatment (°C)
Lattice parameters
d-spacing (A°)
Crystalline phase
a b
1. Pure TiO2
3.776
9.486 3.54 Anatase
2. 350 3.765
9.454 3.5067
Anatase
3. 450 3.765
9.454 3.5072
Anatase
4. 550 3.765
9.454 3.5066
Anatase
5. 750 3.765
9.454 3.5073
Rutile+ Anatase
Crystal phase, interplanar distance and d- spacing value of pure TiO2 and N-doped TiO2 calcinated at
different temperatures
S.No
Pos. [°2Th.]350°C
Pos. [°2Th.]
450°C
Pos. [°2Th.]550°C
hkl Rel. Int. [%]
1 25.37
25.38 25.40 101 100.00
2 37.89
37.93 37.76 004 16.70
3 48.33
48.23 48.01 200 18.78
4 54.11
54.21 54.03 105 13.70
5 62.82
62.77 62.85 204 10.10
6 75.38
75.26 75.33 215 5.47
S.No
Pos. [°2Th.]750°C
hkl
Rel. Int. [%]
1 25.35 101
100.00
2 27.49 110
22.12
3 37.86 101
18.56
4 38.64 210
4.78
5 48.13 200
23.60
6 54.39 105
9.85
7 55.12 220
12.77
8 62.75 310
9.00
9 70.38 202
3.98
Anatase phase at 350°, 450°, 550°C
Rutile phase
at 750°C
Phase transformati
on
2θ, hkl and relative intensity of peaks appeared in XRD
SEM Results of N-doped TiO2S.No. Sonicatio
n time (min)
yield (mg)
1. 10 1815.66
2. 20 2042.38
3. 40 2586.15
4. 60 1906.33
Surface morphology at different calcination temperatures Optimization of Sonication conditions
UV-Vis Spectra
FT-IR Raman Crystallite size
Band gap
576 nm
1019 cm-1 143, 397, 519 and 638 cm-1
10.13 2.10
Spectroscopic studies of N-doped TiO2
RC SAIF PU, Chandigarh
Spectrum Name: Nidhi SLIET-13.sp Description: S-4
Date Created: fri mar 01 12:35:05 2013 India Standard Time (GMT+5:30)
4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 450.0
42.543
44
45
46
47
48
49
50
51
52
53
54
55
55.8
cm-1
%T
3365
2925
1628
1019
763
465
anatase is predominant phase
structure
TEM OF N-doped TiO2 calcinated at 450°C
XRD Results of S-doped TiO2
S-doped TiO2 calcinated at different temperatures
Sample
S/TiO2
(molar ratio)
EDS (wt %)
Phase composition at 750 ˚C
S-750 1:0.1 .43%
11.9 (A) + 88.1 (R)
S-750 1:0.5 .57%
58.2 (A) + 41.8 (R)
S-750 1:1 .76%
89.5 (A) + 10.5 (R)
1:0.1 1:0.5 1:1
Sample Phase composition
Axial distance(edge lengths)
Axial angles Volume of the cell Lattice strain
S-550 Anatase a= b= 3.7760c= 9.4860
α = β = γ = 90° 135.25 0.0039
Phase composition, lattice parameter, cell volume and lattice strain of S-550 Nidhi Sharotri and Dhiraj Sud, New Journal of Chemistry,
2015,39, 2217- 2223
SEM Results of S-doped TiO2
S-doped TiO2 calcinated at different temperatures
S-doped TiO2 synthesized at different molar ratio’s
Nidhi Sharotri and Dhiraj Sud, New Journal of Chemistry, 2015,39, 2217- 2223
TEM of S-doped TiO2 calcinated at 350, 450, 550 and 750ºC
Calcinated at 350°C
Calcinated at 450°C
Calcinated at 550°C
Calcinated at 750°C
Nidhi Sharotri and Dhiraj Sud, New Journal of Chemistry, 2015,39, 2217- 2223
UV-Vis Spectra
FT-IR Raman Crystallite size
Band gap
500 nm
1400.63 cm-1 (S=O stretching ),1142.61 cm-1 (S-O stretching ) 1051.62 cm-1 (Ti-S stretching vibration)
197, 397, 512 and 637 cm-1
10.13 2.47 eV
Spectroscopic studies of S-doped TiO2
RC SAIF PU, Chandigarh
Nidhi SLIET-28.sp - 2/18/2014 - S-3
4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0
45.0
48
50
52
54
56
58
60
62
64
66
68
70
72
75.0
cm-1
%T
3368,52
2342,56
1627,58
1400,63
1142,611051,62
668,48
200 400 600 800 1000 1200
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.55
Abso
rban
ce
Wavelength (nm)
S-550 S-350 S-750 S-450
200 400 600 800
10000
20000
30000
40000
50000
60000
70000
80000
Inte
nsity
(a.u
.)Raman shift (cm-1)
(143)
(197)
(397) (512)(637)
Nidhi Sharotri and Dhiraj Sud, New Journal of Chemistry, 2015,39, 2217- 2223
XRD data of Mn- N co-doped TiO2
Position [°2Theta] (Copper (Cu))
30 40 50 60 70
Counts
0
1000
0
500
0
200
400
0
200
400
600
24
23
22
21
S.No 2θ350°C
2θ450°C
2θ550°C
2θ750°C
Rel. Int. [%]
1 25.15 25.41 27.55 27.55 77.38
2 28.96 27.59 31.14 28.97 27.36
3 31.05 28.95 32.42 31.11 10.90
4 32.42 31.08 36.14 32.40 51.41
5 36.13 32.41 38.16 36.19 100.00
6 37.23 36.17 41.83 36.56 10.18
7 38.13 38.10 44.44 38.06 12.56
8 44.49 39.28 50.01 39.32 4.67
9 50.95 41.45 50.87 41.36 16.46
10 53.94 44.51 55.13 44.16 5.33
11 54.97 48.06 58.61 44.53 13.60
12 56.11 49.95 59.96 49.93 3.35
13 58.55 50.84 64.63 50.78 12.07
Sample Phase composition Axial distance (edge length)
Axial angles Volume of the cell
Lattice strain
Crystallite size (nm)
Mn-N - 350 Anatase + Wurtzite a= b= 3.7760, c= 9.4860
α = β = γ = 90°
135.25 .0031 66.9
Mn-N - 450 Anatase + Wurtzite a= b= 3.7760, c= 9.4860
α = β = γ = 90°
135.25 0.0022 38.3
Mn-N - 550 Anatase + Rutile + Wurtzite a= b= 3.7760, c= 9.4860
α = β = γ = 90°
135.25 0.0027 33.4
Mn-N - 750 Rutile + Wurtzite a= 3.765, b= 9.454 α = β = γ = 90°
135.25 0.0018 53.1
Mn-N-doped TiO2 calcinated at different temperatures 2θ, hkl and relative intensity of peaks appeared in XRD
TEM of Mn-N co-doped TiO2 calcinated at 350, 450, 550 and 750ºC
Calcinated at 350°C
Calcinated at 450°C
Calcinated at 550°C
Calcinated at 750°C
UV-Vis Spectra
FT-IR EPR Crystallite size
Band gap
700 nm 1466.62, 1149.62 and 1086.62 cm-1 (N-H mode)550 and 620 cm-1 ( Mn-O-Ti and O-Ti-O resp.)
280- 350mT (Mn2+)125-175mT ( Mn4+ )
33.43 2.4 eV
Spectroscopic studies of S-doped TiO2
RC SAIF PU, Chandigarh
Nidhi SLIET-26.sp - 2/18/2014 - S-1
4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0
40.0
42
44
46
48
50
52
54
56
58
60
62
64
66
67.8
cm-1
%T
3369,52
2922,56
2852,58
1729,62
1629,59
1466,62 1149,621086,62
629,42
530,47
416,63
nm.190.00 400.00 600.00 800.00 1000.00 1100.00
Abs
.
3.000
2.000
1.000
0.000
2
1
2
1
2
1
2
1
0 50 100 150 200 250 300 350 400 450-200
-100
0
100
200
300
Inten
sity (
a.u.)
Magnetic field (mT)
Photocatalytic degradation of Quinalphos
Percentage Degradation/Degradation Efficiency % Degradation = {(C0 –C) /C0} x100
HPLC
RESPONSE PARAMETERS
Photocatalytic Chamber Jacketed Wall Reactor UV Lamp (30 W Philips,
05 Nos.) Millipore 0.45 µm Filter Magnetic Bead Magnetic Stirrer Lab Jack
100 ml of sample solution of various
concentrations
Fixed amount of Photo catalyst
UV light
At different time interval aliquot was taken with the help of syringe
Aqueous suspension was
magnetically stirred and
aerated
Absorption spectra were recorded at
λmax
Rate of degradation was studied in terms of change
in absorption spectra.
Filtered (Millipore syringe filter of 0.45 µm)
Photocatalytic Degradation Experiment
Experimental setup for photocatalytic process
TIME DEPENDANT UV-VIS SPECTRA OF QUINALPHOS (OPTIMAL CONDITION-: N-550– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)
EFFECT OF VARIOUS WAVELENGTH REGION (490 NM, 565 NM AND 660 NM) ON THE PERCENTAGE DEGRADATION OF QP (OPTIMAL CONDITION-: N-550– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L
220 240 260 280 300 320 340 360 380 400
0.0
0.2
0.4
0.6
0.8
1.0
% d
egra
datio
n
Wavelength (nm)
0 min 30 min 60 min 90 min 240 min
60 90 1500
20
40
60
80
100
79.870
57.7
660 nm565 nm490 nm
Time (min)
% d
eg
rad
ati
on
Synthesized Doped TiO2 Photocatalysts ……………
Photocatalytic activity of NT-450
COMPARISON OF DEGRADATION EFFICIENCY OF DEGUSSA P25 AND N-DOPED TIO2 (OPTIMAL CONDITION-: N-550– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)
EFFECT OF VARIATION IN pH (2-10) FOR DEGRADATION OF QP
0 20 40 60 80 100 120 140 1600
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
% d
egra
datio
n
Time (min)
Degussa P25 N-doped TiO2
2 4 6 8 10
0
10
20
30
40
50
60
70
80
50.7 53.3
68.1
79.8
64.6
pH
% d
egra
dati
on
Synthesized Doped TiO2 Photocatalysts ……………
Photocatalytic activity of NT-450
TIME DEPENDANT UV-VIS SPECTRA OF QUINALPHOS (OPTIMAL CONDITION-: S-550– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)
% REMOVAL EFFICIENCY AT DIFFERENT WAVELENGTHS % REMOVAL EFFICIENCY AT DIFFERENT WAVELENGTHS (OPTIMAL CONDITION-: S-550– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)
220 240 260 280 300 320 340 360 380 4000.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Abso
rban
ce
Wavelength (nm)
0 min 30 min 60 min 120 min 180 min 240 min
0 20 40 60 80 100 120 140 160 180 2000
10
20
30
40
50
60
70
80
90
490 nm 565 nm 660 nm
Per
cent
age
degr
adat
ion
Time (min)
Synthesized Doped TiO2 Photocatalysts ……………
Photocatalytic activity of S-doped TiO2
COMPARATIVE DEGRADATION EFFICIENCY OF S-DOPED TIO2, TIO2 (MERCK) AND DEGUSSA P25 FOR DEGRADATION OF QP (OPTIMAL CONDITION-: CATALYST DOSE– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)
EFFECT OF VARIATION IN pH (2-10) FOR DEGRADATION OF QP
S-550TiO2 (Merck)
TiO2 (Degussa)
0
10
20
30
40
50
60
70
80
9086.7
50.1
37.7
Catalyst
% d
egra
dat
ion
2 4 6 8 100
102030405060708090
100
60.669.6
86.475.9
63.1
pH
% d
eg
rad
ati
on
Synthesized Doped TiO2 Photocatalysts ……………
EFFECT OF CALCINATION TEMPERATURE ON THE PERCENTAGE DEGRADATION OF QP (OPTIMAL CONDITION-: CATALYST DOSE– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)
EFFECT OF VARIATION OF WAVELENGTH ON THE PERCENTAGE DEGRADATION OF QP (OPTIMAL CONDITION-: CATALYST DOSE– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L)
250 300 350 400 450 500 550 600 650 700 750 80060
75
90
% d
egra
datio
n
Effect of calcination
Quinalphos
480 500 520 540 560 580 600 620 640 660 680
65
70
75
80
85
90
Quinalphos
% d
egra
datio
n
Effect of wavelength (nm)
Synthesized Doped TiO2 Photocatalysts ……………
Photocatalytic activity of Mn-N-doped TiO2
TIME DEPENDANT UV-VIS SPECTRA OF QUINALPHOS QP (OPTIMAL CONDITION-: CATALYST DOSE– 50mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)
KINETIC ANALYSIS OF QUINALPHOS UNDER CONDITION(MN-N-550–50 mg, PESTICIDE INITIAL CONCENTRATION – 20 mg/L, RED LIGHT)
220 240 260 280 300 320 340 360 380 4000.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Abs
orba
nce
Wavelength (nm)
0 min 30 min 60 min 120 min 180 min 240 min
0 50 100 150 200 2501.5
1.6
1.7
1.8
1.9
2.0
2.1
lnC
0/C
Time (min)
Synthesized Doped TiO2 Photocatalysts ……………
HPLC CHROMATOGRAPH OF QP AT 0 MIN AND 8 HR
N-DOPED
Mn-N-CO-DOPED
Synthesized Doped TiO2 Photocatalysts ……………
Proposed mechanism of Photocatalysis
Synthesized Doped TiO2 Photocatalysts ……………
Conclusions
Ultrasonication process , an ecofriendly technique can be applied effectively for synthesis of nanophotocatalysts in lesser span of time.
The particle size of the synthesized photocatalysts catalysts varies from 10- 100 nm.
Anion doped, cation doping and double doping resulted in excellent visible light activity of TiO2.
Mn2+ codoped N-TiO2 shows higher activity probably due to early phase transformation.
Photocatalytic degradation of the synthesized catalysts resulted in almost complete mineralization of quinalphos after 8 hr without the formation of intermediates.
The synthesized visible light responsive photocatlysts offers an opportunity to make this technique commercially viable using solar light.
Synthesized Doped TiO2 Photocatalysts ……………
SLIET, Longowal Panjab University, Chandigarh AIIMS, New Delhi IIT, Ropar
Acknowledgement
Thanks!
top related