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Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst

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Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst Powered By Docstoc
					      INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 2, No 1, 2011

                   © Copyright 2010 All rights reserved Integrated Publishing Association

Research article                                                                        ISSN 0976 – 4402

  Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using
                      ZnO and TiO2 as Photocatalyst
                              Joshi K.M.1, Shrivastava V.S.2
       1- Department of Chemistry, Gangamai College of Engineering, Nagaon, (India)
          2- Nanochemistry Research Laboratory, G.T.P. College, Nandurbar, (India)
                                  kmjoshi35@gmail.com


ABSTRACT

The objective of this study was to investigate the ability of semiconductors like TiO2 and
ZnO used to remove a hazardous Alizarin red-S a textile dye from aqueous solution. The
adsorption of the Alizarin red-S was selected as a reference molecule for the adsorption
studies. The experimental results show that TiO2 and ZnO can remove the Alizarin red-S
from wastewater. The factor affecting rate process involved in the removal of dye for initial
dye concentration, effect of various process parameters like initial dye concentration, contact
time, dose of catalyst and pH. The adsorption rate data were analyzed using the pseudo first
order of kinetics of Lagergren and Pseudo second order model to determine adsorption rate
constant. The optimum contact time was fixed at 120 minutes for both TiO2 and ZnO. The
well known Freundlich and Langmuir isotherm equation were applied for the equilibrium.
Beside the above the semiconducting materials have also been irradiated with Alizarin red-S
before and after studied for SEM, EDX and XRD.

Key words: Alizarin red-S, Photodegradation, SEM, EDX, XRD.

1. Introduction

Textile dye produces huge amount of polluted effluents that are normally discharged to
surface water bodies and ground water aquifers (Ruby Jain, 2003). This wastewater causes
damages to the ecological system of the receiving surface water capacity and certain a lot of
disturbance to the ground water resources. Most of the dyes used in the textiles industries are
stable to light and non biodegradable (Dave, 2010). In order to reduce the risk of
environmental pollution from such as wastewater, it is necessary to treat them before
discharging it into the environment (Muhammad, 2007). Today more than 10,000 dyes have
been incorporated in colour index (Jalajaa, 2007). In order to remove hazardous materials like
dyes, adsorption is a method which has gain considerable attention in the recent few years
adsorption is such a useful and simple technique (Saad, A2007). Physical and chemical
processes have been usually used to treat the wastewater. However these processes are costly
and can not be used effectively to treat the wide range of dye wastewater (Arami 2005 and
Kanan, 2001). Alizarin red-S is an anionic dye which are widely used in woven fabrics, wool,
cotton textiles (Parra, 2004 and Kannan ,2007).

In recent years a great efforts have been made using widely called advance oxidation
technologies (AOT) for treatment of these recalcitrant pollutant to more biodegradable
molecule or miniaturization. The AOT, materials with photocatalytic function could be used
(CPDS-ICDD 1996). The semiconductors like TiO2, ZnO CdS are effective with UV light,
easily available relatively inexpensive and chemically stable photocatslyst. Among the
various oxide semiconductor photocatalyst, TiO2 is an important photocatalyst due to its


Received on April 2011 Published on September 2011                                                    8
   Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst


strong oxidizing power, non toxicity and long term photostablility.TiO2 exists in three
different crystalline phases eg. Rutile, anatase and brookite (Rajeev Jain 2008). Zinc oxide is
n-type semiconductor with many attractive features. Zinc oxide with the wide band gap of
3.17 eV as compared to TiO2 (anatase) =3.2 eV is capable to generate hydroxyl radicals. ZnO
was also shown to absorb more UV light than any other powder.

The present study, ZnO and TiO2 have been used as an adsorbent for the removal of Alizarin
red-S dye from textile wastewater (Patil A.K 2008). The adsorption study was carried out
involving various parameters as initial concentration, adsorbent dosage, agitation time and
pH. The data has been tabulated and discussed (Meahkw V.2001).. In the view of the above,
it has been considered worthwhile to study the removal of Alizarin red-S a textile dye by
using ZnO and TiO2 as photocatalysts in aqueous solution.

2. Materials and Methods

2.1 Adsorbate

The Alizarin red-S dye was used in this experiment procured from BDH India
Ltd.(M.formula C14H18O7NaS, M. Wt.=240.21, C.I. No. 58005, λmax= 430nm) was used as
adsorbate.The stock solution was prepared by dissolving 0.1g/L of dye in water and made up
a stock solution in volumetric flask. By making 20, 40, 60 ppm solution. The concentration of
the dye solution was determined spectrophotometericaly. The structure of Alizarin red-S is
given in figure1.




                                Figure 1: Structure of Alizarin red-S

2.2 Adsorbent: TiO2 and ZnO

Nano sized semiconductors like ZnO and TiO2 are one of the most basic functional materials.
Many studies have conformed that the anatase TiO2 is superior photocatalytic material for air
purification, water disinfection, hazardous water remediation and water purification. The
bleaching of Alizarin red-S was carried out in presence of semiconductor TiO2 and ZnO, the
rate of photobleaching is high. Among the generally used semiconductors,TiO2 is up to now
the most efficient one, become it shows the highest quantum yield

2.3. Experimental Procedure

The photocatalytic degradation of Alizarin red-S for both initial concentration and irradiation
sample was determined by UV-Visible Spectrophotometer,(SYSTRONICS Model-2203) The
calibration curve was obtained at λmax=430 nm . The reaction mixture was irradiated with
light source UV lamp (PHILIPS-400Watt) at a distance 30cm from the reaction vessel.
Double distilled water was used through out the experiment. Kinetics of adsorption was
determined by analyzing adsorptive uptake of dye from aqueous solution at different time
intervals 15 minutes. In each experiment an accurately weighted amount of ZnO and TiO2
was taken in flask in 100 ml dye solution by adjusting pH of the Alizarin red-S dye solution

                                       Joshi K.M, Shrivastava V.S.                                         9
                   International Journal of Environmental Sciences Volume 2 No.1, 2011
   Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst


was adjusted a pH in between 3 to10 with addition of requisite volume of NaOH and HCl (
E.Merck India).

In each experiment an accurately weighted amount of TiO2 and ZnO in the flask of dye
solution and the flasks were placed under UV lamp with continuously shaken by magnetic
stirrer, after certain period (15 Minutes Interval). The adsorbent was separated from the
solution by centrifugation. The absorbance of the supernant solution was estimated to
determine the dye concentration, and values of the % of dye removal was found to be
maximum at pH 8 therefore pH was finalized at 8 for further experiment. Kinetics of
adsorption was determined by analyzing adsorptive uptake of dye from aqueous solution at
different time interval.

3. Result and Discussion

3.1 Effect of pH

The pH of is one of the most important factor controlling the adsorption of dye on to the
adsorbent. The removal of Alizarin red-S dye was maximum at pH 8.0 was reported 84.4%
and it is increases from 6 to 8 from 69.4 to 84..4% and decreases from pH 8 to 14 There is
very slight difference in the percentage removal at 6 to 8 (Figure.2). Therefore the pH was
fixed at 8.0 for the further experiment (Senthilkumar S.2006).


                             90


                             80


                             70


                             60


                             50


                             40


                             30


                             20
                                                          Acid Blue 29

                              10


                              0
                                   0   2   4     6   pH   8    10    12   14




                         Figure 2: Effect of pH on degradation of Alizarin red S

3.2 Effect of adsorbent dose

The photocatalyst dose was studied with 100 ml solution of Alizarin red-S and the
concentration 20, 40 and 60 ppm with varying adsorption dose with 0.2 g/l to 0.6 g/l at pH 8
which is shown in figure 3. The percentage removal of Alizarin red-S increase with the
adsorbent dose increases. Due to the increase in photocatalyst dosage the percentage of dye
removal is also increases.




                                       Joshi K.M, Shrivastava V.S.                                         10
                   International Journal of Environmental Sciences Volume 2 No.1, 2011
   Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst




                                                             100
                                                              90
                                                                 80
                                                                 70




                                          % of removal
                                                                 60                                                              60 ppm
                                                                 50                                                              40ppm
                                                                 40                                                              20 ppm
                                                                 30
                                                                 20
                                                                 10
                                                                  0
                                                                      0                    5                     10
                                                                           A d s o r b e n t Do s e g m /L it




                Figure 3: Effect of contact time on adsorption of Alizarin red-S with ZnO

3.3 Effect of contact time

The effect of contact time on the amount of Alizarin red S adsorbed was investigated using
20, 40, 60 ppm initial concentration with 0.5g/l of TiO2 and ZnO, respectively. It was
observed that the adsorption percentage was found to be maximum at 120 minutes increases.
As concentration of Alizarin red S increases the percentage dye decreases from 92.9 to
78.5 % (Figure 4-5)


                                    100
                                         80
                          % of Removal




                                         60                                                                                     60ppm
                                                                                                                                40 ppm

                                         40                                                                                     20 ppm



                                         20
                                         0
                                                         0                50        100           150           200            250
                                                                                      Tim e (m in)



                    Figure 4: Effect of contact time of Alizarin red-S red with TiO2

                                           100

                                                90

                                                80

                                                70

                                                60                                                                    20 ppm
                                                50
                                                                                                                      40 ppm
                                                40
                                                                                                                      60 ppm
                                                30

                                                20

                                                 10

                                                         0
                                                             0                 50               100             150             200
                                                                                               Time




          Figure 5: Effect of contact time on adsorption of Alizarin red-S with ZnO
                                       Joshi K.M, Shrivastava V.S.                                                                        11
                   International Journal of Environmental Sciences Volume 2 No.1, 2011
   Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst




3.4 Effect of photocatalyst

Initial concentration of the dye Alizarin red-S was changed in order to determine proper dye
adsorption keeping the contact time 15 minutes for both adsorbent TiO2 and ZnO at fixed
dose 0.2 mg/lit at pH 8 for Alizarin red-S. The amount of the adsorbate increased with an
increasing the dye concentration However, the % removal rate decreases with an increase in
the dye concentration. It is also noted that the rate of the removal of the dye is as faster at the
lower concentration and decreases with an increase in the concentration. It is found that with
decreasing concentration of the dye from 1 x 10-5 to 6x10-5 .The percentage removal
decreases from 84.6 to 32.5 in Alizarin red-S. The adsorption of the dye was found to
decreases constantly with increasing the concentration of adsorbate for Alizarin red-S at 7
x10-5 is constant indicating a minimum adsorption (Figure 6).

                                                         12




                                                         10




                                                         8
                            amount of adsosrbed x10-5m




                                                         6



                                                                                                                                               60 ppm
                                                                                                                                               40 ppm
                                                         4
                                                                                                                                               20 ppm




                                                         2




                                                         0
                                                              0   0.00001   0.00002   0.00003   0.00004   0.00005    0.00006   0.00007   0.00008   0.00009   0.0001
                                                                                                  Initial dye concentration




                  Figure 6: Effect of Photocatalyst dose on Alizarin red-S
3.5 Adsorption isotherm

In order to optimize the design of an adsorption system to remove the day, it is important to
establish the most appropriate correlations for the equilibrium data for each system. Two
isotherm models have been tested in the present study which are Langmuir and Freundlich
model. The applicability of the isotherm equation is compared by judging the correlation
coefficient R2 (Fytianos K.2000).

Several mathematical models can be used to describe experimental data of adsorption
isotherms. In this work the equilibrium data for Alizarin Red-S on TiO2 and ZnO were
modeled with Langmuir and Freundlich models. The details of the lineareized Langmuir
isotherm are given in the table-1. The value of the Langmuir constant obtained in this study
are presented in table1 The Coefficient of correlation for Alizarin Red-S with TiO2 0.2
gm/lit-1 obtained from Langmuir expression (R2= 0.9996) and ZnO coefficient of correlation
respectively obtained from Freundlich expression (R2= (0.9999) indicates that Langmuir
expression provided better fit for the experimental data of Alizarin red-S on TiO2 with CAC
than Freundlich expression for Alizarin Red-S.

                                       Joshi K.M, Shrivastava V.S.                                                                                                    12
                   International Journal of Environmental Sciences Volume 2 No.1, 2011
   Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst


3.5.1 Langmuir isotherm

Langmuir theory was based on the assumption that adsorption was a type of chemical
combination or process and the adsorption layer was unimolecular. The theory can be
represented by the following equation.

                                             Ce/qe=1/bQ0+Ce/q0                    ………………                             (1)

Where qe is the amount of dye Alizarin Red-S adsorbed per unit mass of adsorbent (mg/g-1)
and Ce is the equilibrium concentration of Alizarin red-S Qo and b are Langmuir constant
related to the capacity and energy of adsorption respectively. The linear plot of Ce/qe v/s Ce
show that the adsorption obeys Langmuir isotherm model for all adsorption (figure 7).

                                       2.5


                                        2

                                                                                    20ppm AZR- ZnO
                                       1.5
                           log ce/qe




                                                                                    40 ppm AZR-ZnO
                                                                                    60 ppm AZR-ZnO
                                                                                    20 ppm AZR-TiO2
                                        1                                           60 ppm AZR-TiO2
                                                                                    60 ppm AZR-TiO2


                                       0.5


                                        0
                                         1.15        1.2       1.25     1.3       1.35
                                                             log ce


                   Figure 7: Freundlich adsorption isotherm of Alizarin red-S

The values of Qo and b were determined for all adsorbent from the intercept and slope of the
linear plot of Ce/qe v/s Ce (Table 1). The good fit for the experimental data and the
correlation coefficients R2 higher than 0.9996 indicates the applicability of Langmuir
isotherm model.

The essential characteristics of the Langmuir isotherm can be expressed in terms of
dimensionless constant separation factor RL which is given by the following equation.

                                                       1
                                             RL = --------------                  ……………….                          (2)
                                                   (1+Ka Co)

                             Table 1: Langmuir and Freundlich Constant

  Adsorbent     Adsorbent              Conc.         Tim        Langmuir Constant                     Freundlich Constant
                g/L.                   Of Dye        e
                                       Alizarin
                                       in ppm        in         Qo            b          r2           Kf     1/n         r2
                                                     Min
                                                        30      4.286    6.259     0.9786        1.1023      0.967       0.9849
                                                        60      7.527    1.761     0.9889        1.3395      1.653       0.9876
                          2                     20      90      8.145    0.192     0.9745        9.6072      1.618       0.9923
                                                      120      12.522     4.09     0.9687        16.031      0.979       0.9876

                                       Joshi K.M, Shrivastava V.S.                                                            13
                   International Journal of Environmental Sciences Volume 2 No.1, 2011
   Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst


                                           150     20.175   2.419    0.9774    22.205    1.408     0.9281
                                            30      9.912    3.82    0.9821    32.411     0.58     0.9806
                                            60     13.125   0.642    0.9651    46.298    1.098     0.9912
        ZnO               4          40     90     22.415   0.566    0.9759     1.445    0.733     0.9945
                                           120     24.879   2.352    0.8997     3.047    1.458     0.9981
                                           150     29.284   3.754    0.9853     4.879    0.451     0.9948
                                            30     4.7589   2.833    0.9458     5.682    0.205     0.9878
                                            60     9.2458   1.045    0.9876     7.448    0.569     0.9956
                          6          60     90     15.689   2.348    0.9519     2.852    0.923     0.9995
                                           120     18.559   3.078    0.9325     3.761    0.948     0.9799
                                           150     22.879   4.038    0.9158     6.154    0.795     0.9971
                                            30      4.286   3.784    0.9477      0.96    0.923     0.9923
                                            60      6.527   6.995    0.9987     1.213    0.251     0.9996
                          2          20     90      8.545    1.76    0.9474      0.97    0.602     0.9876
                                           120     10.522   0.192    0.9821     1.962    0.617     0.9674
                                           150     18.175   0.382    0.9889     2.403    0.854     0.9923
                                            30      7.912    4.09    0.9759     2.252    1.021     0.9876
                                            60     14.125   0.602    0.9451     1.722    0.953     0.9281
        TiO2              4          40     90     20.415   0.643    0.9759      0.91    1.722     0.9948
                                           120     24.879   0.568    0.8997     1.363     0.91     0.9878
                                           150     28.284   0.642    0.8353     0.954    1.363     0.9956
                                            30      2.758   0.566    0.7458     0.617    1.458     0.9995
                                            60      7.245   2.352    0.9876     0.256    0.845     0.9876
                          6          60     90     11.689   3.754    0.9875     0.602     0.92     0.9674
                                           120     15.559   1.546    0.9954     0.985    0.987     0.9923
                                           150     20.879   6.458    0.9368     2.603    1.023     0.9876

Where Co (mg/lit-1) is the initial concentration .The values of separation factor is RL,
Indicating the nature of adsorption. The adsorption process in between 0 to 1 indicates the
adsorption isotherm is favorable (Haghseresht, 1998).

                                RL values            Adsorption
                                RL>1                 Unfavorable
                                RL=1                 Linear
                                0<RL<1               Favorable
                                RL=0                 Irreversible

RL indicates the nature of the adsorption isotherm it is given below. The RL Values for the
adsorption of Alizarin Red-S was observed to in the range 0 to 1 indicating that the
adsorption process is favorable for type of TiO2 and ZnO, respectively.

3.5.2     Freundlich Isotherm

The Freundlich adsorption isotherm model stipulated that the ration of solute adsorbed to the
solute concentration is a function of the solution.

                         Log qe= log Kf +1/(n log Ce)          …………………….                         (3)

Where log Kf is a measure of adsorption capacity and n is the adsorption intensity.



                                       Joshi K.M, Shrivastava V.S.                                         14
                   International Journal of Environmental Sciences Volume 2 No.1, 2011
   Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst


The slope 1/n which should have values in the range of 0 to1 for favorable adsorption
(Armagan 2004). The value for 1/n below one indicates a normal Freundlich isotherm while
1/n A graph of Log qe vs log Ce shown in figure 8. Where the values of Kf and 1/n are
determined from the intercept and slope of the linear regressions.

                                  1                                                                                6 0 p p m A Z R - T iO 2


                                0 .9                                                                               4 0 p p m A Z R - T iO 2

                                                                                                                   2 0 p p m A Z R - T iO 2
                                0 .8

                                                                                                                   6 0 p p m A Z R -Z n O
                                0 .7

                                                                                                                   40 ppm     A Z R -Z n O
                                0 .6

                                                                                                                   20 ppm     A Z R -Z n O
                        ce/qe

                                0 .5


                                0 .4


                                0 .3


                                0 .2


                                0 .1


                                  0
                                        7               9     11        13   c15
                                                                              e        17         19   21




Figure 8: Langmuir adsorption isotherm of Alizarin red-S by using TiO2 and ZnO with CAC


The coefficient of correlation was high (R2=0.9997 and 0.9999 for Alizarin Red-S with
TiO2 and ZnO respectively) showing the good linearity. The values of Kf and 1/n are
determined from the intercept and slope of the linear regretions (Table-1) indicating that the
dye is favorable adsorption on the magnitude of Freundlich constant

3.5.3   Adsorption kinetics

For the evaluating the adsorption kinetics of Alizarin Red-S on TiO2 and ZnO were treated
with Lagergren first order model express as

                                                            Log (qe-qt)=log qe-(k1/2.303)t                           …………………….(4)

The first order rate constant k1 is obtained form the slope of the plot log( qe-qt ) versus time,
The coefficient of correlation for the first order kinetic model was not high for all adsorbents
and concentration figure 9. The estimated values of qe calculated from the equation different
from the experimental values (Table-2) shows that the model is not appropriate to describe
the adsorption process.

                                                                                                        20 ppm AZR-TiO2

                                                 2. 5
                                                                                                        40 ppm AZR-TiO2
                                                2.25
                                                                                                        60 ppm AZR-TiO2
                                                   2

                                                1.75                                                    20 ppm AZR-ZnO
                                   log(qe-qt)




                                                 1. 5
                                                                                                        40 ppm AZR-ZnO
                                                1.25

                                                   1                                                    60 ppm AZR-ZnO
                                                0.75

                                                 0. 5

                                                0.25

                                                   0
                                                        0          50         100           150        200

                                                                              t i me




                     Figure 9: Lagergren first order plot of Alizarin red-S

                                       Joshi K.M, Shrivastava V.S.                                                                            15
                   International Journal of Environmental Sciences Volume 2 No.1, 2011
   Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst


Adsorption kinetics were explained by the pseudo second order model

                                          t/qt=1/k2*qe2+t/qe           ……………………….. (5)

Where K2 is the second order rate constant (mg-1min-1). The value of K2 is different initial
dye concentration for all adsorbents were calculated from the slope of the respective linear
plot of t/qt Vs t (Figure.10).

                                                                                20 ppm AZR-ZnO
                                    4.5                                         40 ppmAZR-ZnO
                                                                                60 ppmAZR-ZnO
                                     4                                          20 ppmAZR-Ti O2
                                                                                40 ppmAZR-Ti O2
                                    3.5                                         60 ppm AZR-Ti O2

                                     3

                                    2.5
                             t/qt




                                     2

                                    1.5
                                     1

                                    0.5
                                     0
                                          0   25 50 75 10 12 15 17 20 22
                                                       0 5 0 5 0 5
                                                        tim e



             Figure 10: Pseudo Second order of Alizarin red-S on TiO2 and ZnO


 Table 2: Comparison of adsorption rate constant, calculated and experimental qe values for
 different initial concentration and adsorbent dose for Pseudo First order and Pseudo Second
                                         order reaction.

                                                         Pseudo First order                        Pseudo Second order
Adsorbents                    Dye             qe
                              conc.           expt.
              Adsorbent        in             mg./gm
                              mg/L
               g/L                                     qe cal.    K1       r2            qe cal        K2       r2       h

                         2           20        26.58    32.45    1.183   0.9836          28.47       0.7546   0.9946   0.6589
                         4           40        53.16    62.36    2.239   0.9784          56.25       0.5126   0.9966   1.2656
  ZnO                    6           60        78.43    85.32    2.874   0.9892          78.45       0.2498   0.9998   2.6758
                         2           20       101.46    98.78    1.568   0.9883         100.97       0.4858   0.9997   0.7843
                         4           40       205.17   197.45    0.987   0.9722         206.45       0.3356   0.9987   1.4589
   TiO2                  6           60       289.28   304.25    1.422   0.9872         286.75       0.1689   0.9998   2.7893

The correlation coefficients were 0.9946-0.9998, suggest a strong relationship between the
parameters and also explain that the process follows the pseudo Second order kinetics figure
11. This shows that the adsorption process of Alizarin Red-S with TiO2 and ZnO is psuedo
second order kinetics.

3.5.4   Characterization of semiconductors

                                         Joshi K.M, Shrivastava V.S.                                                         16
                     International Journal of Environmental Sciences Volume 2 No.1, 2011
   Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst


A scanning electron microscope (SEM) Phillips XL-30 has been a primary tool for
characterizing the surface morphology of the adsorbent. SEM is widely used to study the
morphological features and surface characteristics, as well as its useful to determine particle
shape, porosity and appropriate size distribution of the adsorbent materials (Alyson 2007).
The SEM images for TiO2 and ZnO semiconductors before adsorption and after 120 minutes
after adsorption process. The TiO2 and ZnO were analyzed by SEM is shown in Figure.10
the present study SEM photographs of TiO2 and ZnO reveals surface texture and porosity
(Holde Puchtler1968). After dye adsorption a significant change is observed in the structure
of the adsorbent (Figure.11 i and ii), It is clear that TiO2 has rough surface with
heterogeneous porous and cavities (B.H. Hammeed 2008) this indicates that there is good
possibility for Alizarin red-S to be trapped and adsorbed in to the surface (N. Barka2009)

                   Before Treatment                                  After treatment




                        a                                           b
             Figure 11: (i) SEM images of ZnO after and before irradiation of dye

                   Before Treatment                                  After treatment




                        c                                           d
            Figure 11: (ii) SEM images of TiO2 after and before irradiation of dye

Energy dispersive X-ray spectroscopy Energy Dispersive X-ray Spectroscopy (EDX or EDS)
is a chemical microanalysis technique used in conjunction with SEM. EDX analysis was used
to characterize the elemental composition of the TiO2 films. A typical EDX pattern of the
coated TiO2 is shown in figure 12. The elemental composition of the film was found to be
55% Ti, 39% Si, and 6% O where the presence of TiO2 on the film was confirmed.
                                       Joshi K.M, Shrivastava V.S.                                         17
                   International Journal of Environmental Sciences Volume 2 No.1, 2011
 Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst




                            Figure 12: EDX Spectrum of TiO2 powder

The surface roughness and morphologies of TiO2 and ZnO were evaluated by X ray
diffraction (XRD) pattern-obtained on a Philips Holland Xpert MPD model using Cu Kα
radiation at a scanning rate (Valderrama2008).The XRD pattern of the TiO2 and ZnO
powdered are shown in figure 13-16. The XRD pattern of TiO2 and ZnO consist of few
smaller peaks at the position 2θ=36.92°, 38.71°, 68.79°, and 82.69° of TiO2and
66.34°,72.71°,81.54°,92.76°of ZnO respectively with the large peak centered at the
approximately at 2θ =25.25°and 25.28°of TiO2 Before and after treatment, and for ZnO
2θ=36.31°, 36.36° before and after treatment. Corresponding refraction of the TiO2 and ZnO
lattice growing in hexagonal phase with the axis perpendicular to the substrate surface (Chin
Mei Ling 2004 and Donia 2002)




                                                                       
            Figure 13: XRD diagram of TiO2 semiconductor before irradiation




             
                 Figure 14: XRD diagram of TiO2 semiconductor after irradiation

                                        Joshi K.M, Shrivastava V.S.                                      18
                    International Journal of Environmental Sciences Volume 2 No.1, 2011
     Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst


This confirms the formation of TiO2 and ZnO semiconductor. However the peak at 2θ=3.52°
and 2θ=2.48° corresponding to (110) and (111) were also found to be present with respective
lower intensities. The relative intensities of the different peak shows that TiO2 and ZnO
semiconductor film have grown with a strongly preferential oriented along the axis also we
obtained XRD spectra for TiO2 and ZnO(Nicolas Kelar2004).

                                   Dnm = (Kλ / βcos θ)

         K = 0.90 but in most cases it is close to 1, Hence the grain size
                Calculation it is taken as one and λ is the wavelength of X ray
         β = full width at half of the peak max. in radiations
         θ = Bragg’s angle
         λ = 1.54° A

4.    Conclusion

The present study has revealed that the TiO2 and ZnO with commercial activated carbon can
be effectively used as a photocatalytic material for the or the removal of Alizarin red-S dye.
Adsorption was influenced by various parameters such as initial pH initial dye concentration
and dose of adsorbent. It was observed that ZnO is more effective dye for removal of Congo
red while TiO2 is less suitable to remove Congo red therefore ZnO is used to remove the
Congo red and TiO2 is used for removal of Alizarin red-S Removal efficiency increased with
decreasing the dye concentration and increasing dose of adsorbent. The study of the influence
of pH of the experimental dye solution on the adsorption potential have reveals the pH 4
appears to the most favorable for removal of Alizarin red-S.

The experimental adsorption data have been fitted reasonably well to Langmuir and
Freundlich adsorption isotherm. The applicability of Lagergren model suggested the
formation of monomolecular layer of the dye on the surface of the adsorbent. It was shown
that the adsorption of Alizarin red-S fitted by Pseudo second order model.

References

      1. Ruby Jain, Sharma S, Manoj S.V, Bansal S.Pand Gupta K.S., (2003), “Application
         of Titanium dioxide semiconductor photocatalysis in the photomineralization of dyes
         in textile industry”, Indian Journal of Environmental protection 23(1), pp 63-68.

      2. Dave R.S. and Patel A.R., (2010), “Photochemical and photocatalytic of
         cypermethrin under UV radiation”, Der pharma chemica, 2(1) pp 152-158.

      3. Muhammad Javed Iqbal, Muhd Naem Ashiq, (2007), “Thermodynamic adsorption of
         dyes from aqueous media on activated charcoal”, Journal of Research Science
         Pakistan, 18 (2) pp 91-99.

      4. Jalajaa.D., Manjuladevi M., Saravanan S.V.(2007), “Removal of acid dye from
         textile wastewater by adsorption using Activated carbon prepared from pomegranate
         rind”., Pollution Research., 28(2), pp 287-290.




                                         Joshi K.M, Shrivastava V.S.                                         19
                     International Journal of Environmental Sciences Volume 2 No.1, 2011
Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst


 5. Saad S.A, Daud S. Kasim F.H. Saleh M.N., (2007), “Metylene blue removal from
    Simulated      wastewater by adsorption using treated oil palm fruit bunch”,
    International Conference of Sustainable Materials,3,pp 293-296

 6. Arami, M, Limaee. N.Y. Mahmoodi. N.M. Tabrizi. N.S., (2005), “Removal of dyes
    from colourd textile wastewater by adsorbent: equilibrium and kinetic studies.
    Journal of Colloid and interface Science, 288, pp 371-376.

 7. Kanan N., Sundaram M.M.,(2001) “Kinetics and mechanism of removal of
    methylene blue by adsorption on various carbons a comparative study”, Dyes and
    pigment., 51, pp 25-40.

 8. Parra, S., Sarria V., Maloto S., Periner P., and pulgarin C.,(2004) “Photocatalytic
    Degradation of Attrzine using suspended and supported TiO2. Journal of Applied
    Catalyssis.B: Environmental ., 51, pp 107-116.

 9. Kannan N. and Nagnathan G.G.(2007), “Photocatalytic degradation of Saferanine
    dye on semiconductor by UV radiation” International Journal of Environmental
    Protection, 27 , pp 1103- 1108

 10. CPDS-ICDD reference Oattern database, (1996), International center for Diffraction
     data Philips Analytical X ray . Almelo, Release, 4, pp 46-48.

 11. Rajeev Jain and shalini Shirkarwar, (2008),“Removal of hazardous dye Congo red
     removal from waste material., Journal of hazardous materials., 152, pp 942-948.

 12. Patil A.K and Shrivastava V.S, (2008), “Adsorption of Congo Red from aqueous
     solution using   Banana plant waste material”, Asian Journal of Chemical and
     Environmental Science, 1(4), pp 20- 26.

 13. Meahkw V., Markovska M., Mincheva and A.E. Rodrigues A.E., (2001).
     “Adsorption of Basic dyes in activated carbon and natural zeolite”. Water research,
     35, pp 3357- 3366

 14. Senthilkumar S., Kalaamani P., Porkodi K., Varadarajan P.R. and Subburaam C.V.,
     (2006), “Adsorption of dissolved reactive red dye from aqueous      phase on to
     activated carbon prepared from agricultural waste, Biosource. Technology, 97, pp
     1618-1625

 15. Fytianos K., Voudras E. and Kokkalis E.,(2000), “Sorption desorption, behavior of
     2,4 dichlorophenol by marine sediments” , Chemosphere, 40, pp 735- 741.

 16. Haghseresht and G. Lu,(1998), “Adsorption characteristics of Phenolic compound on
     to coal reject derived adsorbent”, Energy fuels, 12, pp1100-1107.

 17. Armagan B. Ozdemir O. M. Turan, (2004), Colour removal of reactive dyes from
     water clinoptilolite, Journal of Environmental Science Health A, 39(5), pp1251-1261.

 18. Alyson V. Whitney, Francesca Casadio and Richsrd P. Van Duyne.(2007),
     “Identification and Characterization of Artist’s Red dye and their mixtures by
     surface- Enhanceed Raman spectroscopy, Applied spectroscopy, 61, pp 994-1000.


                                    Joshi K.M, Shrivastava V.S.                                         20
                International Journal of Environmental Sciences Volume 2 No.1, 2011
Degradation of Alizarine Red-S (A Textiles Dye) by Photocatalysis using ZnO and TiO2 as Photocatalyst


 19. Holde Puchtler, Susan N. Melon and mery S. Terry,(1968), The History and
     mechanism of Alizarin Red S stain for calcium, The Journal of
     Histochemistry.,17(2), pp110-124

 20. B.H. Hammeed , M.I. EI-Khaiary, (2008), Removal of basic dye from aqueous
     medium using a Novel agricultural waste material:Pumkin seed hull, Journal of
     Hazardous Materials, 155, pp 601-609.

 21. N. Barka, Ali Assabbane, Abederrahaman Nounah, Larbi Laanab,(2009), Removal
     of textile dyes from aqueous solution by natural phosphate as          new
     adsorbent,Desilanation 235, pp 264- 275

 22. Valderrama, J.L.Cortina, A.Fsrran,X. Gamisans, Fx de las Heras, (2008), “Kinetic
     study of acid red dye removal by activated carbon and hyper cross linked
     polymeric sorbent macronet hyper sol MN-200 and MN-300”, Polymers News, 68,
     pp 718- 731.

 23. Chin Mei Ling, Abdul Rahman Mohd, Subhash Bhatia,(2004), “Performance of
     photocatalytic reactors using immobilized TiO2 film for the degradation of phenol
     and methylene blue dye present in water stream”, Chemosphere,57, pp 547–554.

 24. Donia Beydoun, Rose Amal, (2002), “Implication of heat treatment on the properties
     of maghetic iron oxide- titanium dioxide as photocatalyst”, Material Sciece and
     Engineering , 94, pp 71-78

 25. Nicolas Kelar, Velerie Keller, Francois Gavin, Marc J Ledoux,(2004), “A new TiO2-
     β SiC material for use of photocatalyst” , Material Letters, 58, pp 970-974




                                    Joshi K.M, Shrivastava V.S.                                         21
                International Journal of Environmental Sciences Volume 2 No.1, 2011

				
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