Experimental Study of Removal of Rhodamine B by …Rhodamine B is an organic dye; it is one of the xanthenes’ basic compounds, which is widely used in the textile industry. Like

Energy Procedia 18 ( 2012 ) 1208 – 1219

1876-6102 © 2012 Published by Elsevier Ltd. Selection and/or peer review under responsibility of The TerraGreen Society.

doi: 10.1016/j.egypro.2012.05.136

Experimental study of removal of Rhodamine B by activated cereal by product

S. ARRIS*, I. BRAHMIA, and L. BOUSBAA

Laboratory of the engineering and the processes of environment (LIPE)Department of industrial chemistry, Faculty of engineering, University Mentouri Constantine, 25000, Algeria.

E-mail: [email protected]

Abstract

Dyes have been used in dyeing paper and pulp, textiles, plastics, leather, cosmetics and food industries.Colour stuff discharged from these industries poses certain hazards and environmental problems. In this work westudy the potential feasibility of treated and untreated cereal by-product for removal of Rhodamine B from aqueoussolution. The effect of various experimental parameters such as contact time and initial concentration wereinvestigated. The suitability of the Freundlich, langmuir, BET and Harkin Jura models to the equilibrium data wasinvestigated for Rhodamina B-CCBP system. The results showed that the equilibrium data are better fitted by thefreundlich model. And the adsorption kinetic of Rhodamine B, by CCBP, shows that the pseudo second-order modelbetter represents experiment results.© 2010 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of [name organizer]

Keywords: dyes, Rhodamine B, natural adsorbent, chemical activation, adsorption

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© 2012 Published by Elsevier Ltd. Selection and/or peer review under responsibility of The TerraGreen Society.Open access under CC BY-NC-ND license.

Open access under CC BY-NC-ND license.

Arris Sihem et al. / Energy Procedia 18 ( 2012 ) 1208 – 1219 1209

1. Introduction.Many industries discharge wastewaters containing hazardous substances such as phenols, dyes and

heavy metals. Dyes have long been used in dyeing, paper and pulp, textiles, plastics, leather, cosmeticsand food industries [1]. These colored compounds are not only aesthetically displeasing but alsoinhibiting sunlight penetration into the stream and affecting aquatic ecosystem [2]. Dyes usually havecomplex aromatic molecular structures which make them more stable and difficult to biodegrade [3]

Rhodamine B is an organic dye; it is one of the xanthenes’ basic compounds, which is widely used inthe textile industry. Like other rhodamines, Rodhmine B is used as a dye tracer in the water to determinethe volumes, flow rates and directions of flow and transport. Rhodamine B is generally toxic and solublein water. The chemical structure of rhodamine B is shown in Figure 1-1. The main characteristics ofrhodamine B are grouped in Table 1.

There are various conventional methods of removing dyes, including coagulation and flocculation [4],oxidation or ozonation [5] and membrane separation [6]. The adsorption technique is the most versatileand widely used. The most common adsorbent materials are: alumina silica [7], metal hydroxides [8] andactivated carbon [9]. As proved by many researchers [10], removal of dyes by activated carbon iseconomically favorable and technically easier.

The aim of this paper is to evaluate the capacity of retention of Rodhamine B by a low cost adsorbent(cereal by-product). The effect of different experimental parameters such as pH, time, and initialconcentration were investigated. In order to improve the capacity of retention, we conducted to achemical activation with tree acids: HNO3, H2SO4 and H3PO4.

2. Materials and methods

2.1. Adsorbents:Our adsorbent used is the cereal by-product, it was:

- Washed with distilled water.- Dried in an oven at 105 ° C.- Calcined in an electric furnace in the exclusion of air (HEARAEUS D-6450 Hanau) at differenttemperatures.- crushed and sieveed (Retsch-ANALYSENSIEB-HAANW) to select the smallest particle size of<0.1mm.

Our adsorbent used is the cereal by-product called: CBP before calcination, (Cereal By-Product)CCBP after calcinations (Calcined Cereal By-Product)ACBP after calcinations and chemical activation (Activated Cereal By-Product)

2.2. Solutions:The solution of rodhmine B was prepared by dissolving 0.1g of the dye in powder form, which has a

pink colour, in a volume of 100 ml of distilled water freshly prepared. The homogenization of the solutionis provided by agitation on a simple magnetic stirring plate. The solution thus prepared was kept in thedark.The pH of the solution is adjusted by the addition of HNO3 or NaOH after the desired value.

All filters collected were diluted in order to read their absorbance in the UV-visible spectrophotometer.

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2.3 Chemical activationTo improve the performance of our solid, we tried to activate it by three different acids; nitric acid

HNO3, sulfuric acid H2SO4, and phosphoric H3PO4. In the first time we examined the effect of the acid'snature. After, we study the effect of acid concentrations, to obtain the one that gives the best performance.

The experimental procedure consists in contacting a volume of acid with the CCBP (aftercarbonization), stirring for 1 hour. Then we proceed to a washing repeated until stabilization of theconductivity value of the washing solution. The final values of conductivity for each acid are present inthe following table.

Table 1: conductivity of washing solutions

Acid pHfinal conductivityfinal

Nitric acid 6.57 5Sulfuric acid 6.10 9Phosphoric acid 4.550 11

2.4 Determination of the pHz

Sorption phenomena are governed by multiple factors. The electrostatic forces have a majorimportance. These obviously depend on the electric charge of the adsorbent material and those of theadsorbate molecules. So, determining the point of zero charge (PZC) is essential. The determination ofthe PZC is performed by contacting 0.5 g of the three types of adsorbents (CBP, CCBP, and ACBP) with10 ml of distilled water previously degassed to remove CO2 free. The mixture is stirred for 48 h at 20°C.After we measured the pH of the solution, this value represents the point of zero charge isoelectric point,pHz.

Table 2: Values of the PZC

adsorbent CBP CCBP ACBPPZC 4.29 6.43 5.55

This method of determination has been used with satisfaction by Leony Leon and Radovic, andMoreno-Castilla and al.

2.5 Batch study

The experimental protocol can be summarized in these steps:- Mixing a quantity of 2 g of the adsorbent with 200 ml of the Rhodamine B solution at a concentration of50mg/L (Rhodamine in solution gives a pH 7.47).- Filtration of the sample with filter paper.- Analysis of the filtrate by UV.- Determination of the adsorption capacity using the following equation:

q= (C0-Ce)*V/m (1)

With: V: volume of the adsorbate (L).q: Adsorption capacity (mg/g).

Arris Sihem et al. / Energy Procedia 18 ( 2012 ) 1208 – 1219 1211

C0: initial concentration of the Rodhamine B solution (mg/L).m: mass of the adsorbent (g)

3. Results and discussion.

3.1 Effect of contact timeA series of experiments has been performed to optimize the adsorption time at initial concentration of

20 mg/L, by cereal by-product calcineted at 500°C (CCBP). The results obtained are shown in the tableand the figure below:

Table 3: Yield of removal of Rhodamine (%)

t (min) 5 10 15 30 60 90 120 180 240R (%) 14.12 17.53 15.76 24.88 23.61 26.65 24.5 33.49 25.89

Based on previous results we note that the yield of elimination of Rhodamine is relatively low. It isaround 25% after 60 minutes. About the process of retention, we notice a high rate in the first time: linearvariation. Then a low rate after 1 hour: apparition of a plateau indicating saturation. This is due the strongattractive forces between the dye molecules and the adsorbent.

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

0 25 50 75 100 125 150 175 200 225 250

t (min)

q(m

g/g)

Figure 1: Effect of the contacting timeConditions : C0=20mg/l, PH=7.47, V=600tr/min, r=10g/l, d <0.315 mm

The plot below shows that maximum capacity of retention equals to 0.53363119 mg/g whichcorresponded at 90 minutes of agitation, and the residual concentration in the liquid phase is equal to:14.6693681 mg/l.

1212 Arris Sihem et al. / Energy Procedia 18 ( 2012 ) 1208 – 1219

3.2 Kinetic study:In order to determine type of the kinetic retention, the results are modelled by three models: Lagergren,

pseudo second-order and diffusional model.

a) Kinetic model of pseudo first orderLagergren proposed a pseudo-first order kinetic, represented by the follow equation:

dqt/dt = k1*(qe-qt) (2)

Where: k1: Rate constant of pseudo first order kinetic (min-1); qt: capacity of adsorption at time t;qe: capacity of adsorption at equilibrium. The integration of last equation gives:

Log (qe-qt)=log qe-(k1/2.303)*t (3)

b) Kinetic model of pseudo second orderThe pseudo second order kinetic is represented by the following equation:

dqt/dt=k2 (qe-qt) 2 (4)

Where: k2: Rate constant of pseudo second order kinetic (g mg-1min-1);qt: capacity of adsorption at time t;qe: capacity of adsorption at equilibrium.The integration of last equation gives:

t/qt=(1/k2*q2e2 )+(1/qe2)*t (5)

c) Model of the intraparticle diffusion:

This model was proposed by Weber and Morris. Knowing that adsorption is a series of somesteps. This model tells us the limiting step, which controls the adsorption process.This model is represented by the following formula:

Qt= Kint t1/2 (6)

Where:Kint: Constant of the intraparticle diffusion (mg/g min1/2)

The graphic representation of qt as a function of t1/2 is given on the figure 4. In the figure we can see thatthe curve shows a multi linearity indicating the existence of three stages: The first concave, phenomenarelated to outreach, the second line, attributed to the phenomena of internal diffusion and a thirdcorresponding to equilibrium.

The linear form of the second section of the curve is presented in the following figure5:The results of three kinetic models are regrouped in the following tables:

Arris Sihem et al. / Energy Procedia 18 ( 2012 ) 1208 – 1219 1213

Table 4: Graphic representation of three kinetic models

Lagergren model

k1 : The constant speed for kinetics ofthe pseudo first order;qt : Capacity of adsorption at themoment tqe : The capacity of adsorption toequilibrium 0 5 0 1 0 0 1 5 0 2 0 0 2 5 0

-1 0

-8

-6

-4

-2

0

log(

qe-q

t)

t ( m in )

m o d é le la g r a n g ie n a p ro x im a t io n l in é a i r e

Figure 2. Kinetics of the pseudo first order of RhodamineB

Model of the pseudo second order

tee

qqKqtt

22

22

1.1

k2 : The constant speed for second-orderkineticsqt : Capacity of adsorption at themoment tqe : The capacity of adsorption toequilibrium

0 5 0 1 00 15 0 20 0 2 50

0

1 00

2 00

3 00

4 00

5 00

t/qt(m

in.g

/mg)

t(m in )

m o d é le d e p s e ud o 2 é m e o rd re ap ro x im a tio n lin é a ire

Figure 3. Kinetic of the pseudo second order of RhodamineB

Model of the diffuse layer qt = kint t1/2

kint : The constant of the diffusion willintra particle in (mg/g min1/2)

2 4 6 8 10 12 14 163,0

3,2

3,4

3,6

3,8

4,0

4,2

q t(mg/

g)

t1/2(min)

résultats expérimentale

Figure 4. Diffusional model of Rhodamine B

3 4 5 6 7 8 9 10

3,3

3,4

3,5

3,6

3,7

3,8

q t(mg/

g)

t1 /2(m in)

les résultats expérimentales approximation lineaire

Figure 5: The linear form of the second section of the intra particle diffusionmodel

1214 Arris Sihem et al. / Energy Procedia 18 ( 2012 ) 1208 – 1219

Table 5: Test results of three kinetic models

Model R Equilirium capacity Kinetic Constant

first order Qe(mg/g) K1

-0.178170.02636877

-0.01282771

second order Qe(mg/g) K2

0.999150.528764805

0.59503853

Intrapart diff Kint

0.99799 0.08665

Based on these results, we conclude that the phenomenon of retention of rhodamine B is betterrepresented by a pseudo second order kinetic (R = 0.9915) and is controlled by internal diffusion (R =0.99799)

3.3 Effect of calcinations temperatureIn order to know the ideal calcinations temperature for better performance retention, we calcined the

cereal by product at different temperatures: 300 ° C, 400 ° C, 500 ° C and 600 ° C.

The results obtained after testing decontamination are shown in the figures below:

0 50 100 150 200 250

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

Q(m

g/g)

t(min)

T300c T400c T500c T600c

Arris Sihem et al. / Energy Procedia 18 ( 2012 ) 1208 – 1219 1215

Figure 6: Effect of calcinations temperatureConditions: C0=20mg/l, PH= 7.47, V= 600 tr/min, 20.1°C, r= 10g/l

From this figure we can see that the performance of CCBP increases with the calcinationstemperature, 500 ° C is the optimal value. After this temperature the performance of CCBP decreases.This is due to enlargement of the adsorbent’s pores with increasing temperature but above 600 ° C thedestruction of active sites is highly probable. The adsorbent loses his resistance.

3.5 Effect of the chemical activationTo further improve the effectiveness of CCBP we tried to activate chemically with acids valence

different: monovalent acid (HNO3), bivalent acid (H2SO4), and trivalent acid (H3PO4). The resultsobtained are shown in the following figures:

0 50 100 150 200 250

1,21,41,61,82,02,22,42,62,83,03,23,43,63,84,04,2

Q(m

g/g)

t(min)

H3PO4 H2SO4 HNO3

Figure 7: Effect of the chemical activation of CCBPConditions: C0=50 mg/l, T=20°C, d<0.315mm, v=600tr/min, pH = 7.47

This figure shows a wide gap between the performance of CCBP activated with phosphoricacid and CCBP activated by the other two acids namely sulfuric acid and nitric acid, the concentration ofthat three acids is 0.1 M.

3.6 Effect of initial concentrationIn order to know the effect of the initial concentration of pollutants on the retention capacity

of the solid support (ACBP) and determine the isotherms, we considered the following values of theinitial concentration: 10, 20, 50, 80 and 100mg / l. In this test we have used the cereal by-product calcinedat 500 ° C and chemically activated with phosphoric acid 0.1M. The results are shown in the followingfigures 8 and 9.According these figures, we see that the adsorption capacity increases with increasing initialconcentration. This is due to the increased probability of contact between the solid particles and thepollutant.

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0 5 0 100 15 0 2 00 250

1

2

3

4

5

6

Q(m

g/g)

t (m in)

10mg /l 20mg /l 50mg /l 80mg /l 100m g/l

Figure 8: Effect of the initial concentration of Rhodamine B on adsorption

pH=4.13, t=240min, v=600tr/min, T=20°C, r=10g/l, d<0.315mm,

0 20 40 60 80 1000

1

2

3

4

5

6

Q(m

g de

rhod

amin

e/g)

C0(mg/l)

Figure 9: Influence of the initial concentration on the adsorption capacity

Arris Sihem et al. / Energy Procedia 18 ( 2012 ) 1208 – 1219 1217

3.7 Adsorption isotherm study:In general, the adsorption isotherm describes how adsorbates interact with adsorbents. An adsorption

isotherm is characterized by some constant values which express the surface properties and affinity of theadsorbent and can also be used to compare the adsorptive capacities of adsorbent for different pollutants.

The graphic representation of q (mg/g) as a function of Ce, gives the adsorption isotherm. Our resultsconcerning the retention of Rhodamine B by the CCBP are represented in the following: plot:

0 10 20 30 40 500

1

2

3

4

5

6

q e(mg/

g)

Ce(mg/l)

Figure 10: Adsorption isotherm of the rhodamine B

3.8 Adsorption isotherm modellingIn this section we will look for models that can accurately describe the nature of the retention of

Rhodamine B by the CCBP. For this we calibrated our experimental results on four models namely,Langmuir model, Freundlich model, model of Brunauer, Emmett and Teller (BET) and the Harkins-Juramodel.

1218 Arris Sihem et al. / Energy Procedia 18 ( 2012 ) 1208 – 1219

0,0 0,1 0,2 0,3 0,4 0,5 0,60,0

0,2

0,4

0,6

0,8

1,0

1,2

1,41/

q e(g/m

g)

1/Ce(l/mg)

les résultats expérimentales approximation linéaire

0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8-0,2

0,0

0,2

0,4

0,6

0,8

log

q e(g/l)

logCe(mg/l)

Figure11: Langmuir adsorption isotherm of Figure 12: Freundlich adsorption isotherm of

Rhodamine B Rhodamine B

0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

1/Q

2 e

logCe0,05 0,10 0,15 0,20 0,25 0,30 0,35 0,40 0,45 0,50

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40C

e/qe*

(C0-C

e)(g/

mg)

Ce/C0

résultats expérimentales approximation linéaire

Figure 13: Harkins-Jura adsorption isotherme. Figure14: Linearized BET adsorption isothermof Rhodamine B Rhodamine B

The results for the three isotherm models tested in this study are summarized in the following table:Table 5. Correlation factors for isotherm models

Isotherme model Langmuir Freundlich Harkins-JuraFacteur de corrélation 0.56 0.886 0.6615

Arris Sihem et al. / Energy Procedia 18 ( 2012 ) 1208 – 1219 1219

The results showed that the equilibrium data for the Rhodamine B_CCBP system fitted theFreundlich model best.

Conclusion

This study shows that the cereal by product, an abundant material in Algeria, can be usedeffectively and efficiently for the removal oh Rhodamine B from waste water. The adsorption ofrhodamine reached equilibrium in 60 minutes. The results indicate that adsorption capacity of sorbent wasconsiderably affected by initial rhodamine concentration. The adsorption of the rhodamine b by cereal byproduct was represented by a pseudo second order model.Equilibrium data were best described by the Freundlich model. The chemical activation has reallyincreased the capacity of retention of this natural material.

References

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