Dr. S. Shanthi and V. Padmavathi

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1 International Journal of Chemistry and Applications. ISSN Volume 4, Number 4 (212), pp International Research Publication House Zinc oxide catalysed photo degradation of crystal and aniline dyes from aqueous solutions of their binary mixture,using sun light and microwaves A comparative study of nano particles of ZnO with A.R. ZnO Dr. S. Shanthi and V. Padmavathi Associate professor, M.Phil Department of chemistry, The Standard Fireworks Rajaratnam College For Women, Sivakasi, Tamilnadu, India patmavathi.balaji@gmail.com). Abstract The co-precipitation technique has been used for the synthesis of nano particles of Zinc oxide.the sample obtained by the co-precipitation technique was characterized by PXRD,FTIR, and SEM instrumental techniques. The FT- IR analysis of the spectra show a broad band at 49cm -1 with shoulder shape, characteristic of Zn-O vibrations.the images obtained by SEM of the sample show plate like nano particles. The ZnO nano particle has been distributed well with in the range of ~1nm.From the XRD spectrum the size of ZnO nano particles were calculated to be 12.3nm.The photo catalytic degradation of crystal and aniline dyes from aqueous solutions of their binary mixture was carried out using synthesized nano particles of Zinc Oxide and A.R. Zinc Oxide with two sources of radiations namely sunlight and micro waves, and the reaction can proceed to almost complete degradation. Kinetic study was performed by carrying the degradation reaction at different temperatures to determine the rate constant of degradation and the activation parameters, Using this study, we propose the optimum conditions required for maximum degradation. Key words: ZnO nano particles,photodegradation,crystal,aniline

2 352 Dr. S. Shanthi and V. Padmavathi Introduction In the last twenty years cationic dyes are produced and consumed annually in large quantities in textile industry. The environmental concern of these potentially carcinogenic pollutants in contaminated waters has drawn the attention of many research workers 1-3. Several techniques ranging from physicochemical (coagulation, adsorption, membrane separation, advanced oxidation processes) to biological methods for dye removal are available. Biodegradation is an environmentally friendly and cost competitive alternative but the conventional aerobic treatments have been proved ineffective while highly toxic aromatic amines can be formed by reductive fission under anaerobic conditions 4-7.Photo degradation is degradation of a photodegradable molecule caused by the absorption of photons, particularly those wavelengths found in sunlight such as infrared radiation, visible light and ultra light. Wide band gap metal oxide semi conductors are attractive candidates for the photo degradation of dyes capable of acting as catalysts upon exposure to light radiation to degrade the harmful organic contaminants into harmless mineral acids. Nano particles of semiconductors such as titanium dioxide (TiO 2 ), zinc oxide (ZnO), iron oxide (Fe 2 O 3 ), and cadmium sulfide (CdS) have become popular as a photo catalyst for the degradation of organic pollutants in water and air 8-1. In the past two decades, zinc oxide has attracted much attention with respect to the degradation of various pollutants due to its high photosensitivity, stability and wide band gap. ZnO is known as an important semiconductor, which has been studied extensively in the past two years due to its fundamental and technological characteristics. The synthesis of nano particles of ZnO by is co-precipitation technique. Co-precipitation is the transfer of impurities (trace constituents) to a precipitate concurrently with the deposition of some primary substances (macroscopic constituent) from a solution, melt, or vapor containing several substance. So consider the comparative study of photo degradation of dyes by with A.R. ZnO. Synthesized nano particles of ZnO having high photo catalytic activity than that of A.R. ZnO, which can be proved by varying the parameters like initial dye concentration, catalyst loading,ph of the medium,temperature of the dye solution on the of crystal and aniline dyes. The thermodynamic parameters were calculated. 2.Experimental Preparation of Nano particles of Zinc Oxide by co-precipitation technique One hundred millilitres of 2M sodium hydroxide was dropped very slowly to increase the ph value in 1-11 range from the burette to the beaker containing one hundred millilitres of 1M Zinc chloride solution and 2 grams of starch. After the complete addition of NaOH, the mixture was kept at room temperature under constant stirring, using magnetic stirrer for a period of 2-3 hours. The co precipitated solid was separated from the initial solution by filtration. The precipitate was washed with deionised water to remove impurities. The resulting precipitate was white in colour. The drying of the precipitate was carried out with initial drying inside a desicator for 24hours. Finally the precipitate was obtained. The co precipitation reaction can be represented as follows

3 Zinc oxide catalysed photo degradation of crystal and aniline dyes 353 ZnCl 2(aq) + 2 ZnOH (aq) Zn(OH) NaCl (aq) Zn (OH) 2 ZnO + H 2 O The precipitate was irradiated with microwave in a microwave oven. The sample was irradiated at 3W for 1 hour. The resultant Zinc oxide sample was subjected to powder X- ray diffraction Scanning Electron Microscopy and Fourier Transform Infrared Studies to confirm the nanostructure. 3.Photocatalytic degradation Stock solution of dyes (2ppm of crystal and aniline )were suitably diluted to the required initial concentration of dye with DD water. Fifty ml of the dye solution of known intial concentration (C i )was taken in 1ml beaker. Required amount of photo catalyst was exactly weighed and then transferred into the dye solution with different concentration. The beakers were then exposed to any one of the energy source, namely direct sunlight, microwave irradiation for a fixed period of contact time. After bleaching, the OD of these solutions were measured using Spectrometer at 595nm and 395nm.Then the final or equilibrium concentrations (C e ) were obtained from the standard graph by interpolation techniques.in all the batch degradation of dye experiments the extent of removal of the dye in terms of the values of % removal of dye have been calculated using the following relationships Percentage removed = 1(C I -C e )/C I Where C I = Initial concentration of dyes (ppm) C e = Equilibrium concentration of dyes (ppm) To prove the authenticity of the kinetic experiments,we have recorded the UV- Visible spectra of the aqueous solution of the binary mixture of dyes before and after photodegradation experiments. 4.Result and Discussion 4.1 Characterization of synthesized nano particles of ZnO In our project work, nano particles of zinc oxide was synthesized by co-precipitation technique. The synthesized nano particles were subjected to powder XRD studies, FT-IR studies and Scanning Electron Microscopy (SEM). The FT-IR spectra of the synthesised nano particles of zinc oxide is shown in Figure 1. The X-ray diffraction pattern observed for synthesised nano particles of ZnO is shown in Figure 2. From this the size of the synthesized Zno nano particle was calculated.the sem images obtained for the sample is given in Fig3. The image obtained by SEM of the sample, shows that the ZnO nano particles has been distributed well with in the range of ~1 nm which is the favorable property to exhibit better photo catalytic activity. The recorded UV-Visible spectra of the aqueous solution of mixture of dyes for before and after degradation is given in Fig (4,5&6)From this UV-visible spectra we can understood the better photo catalytic activity of synthesized nano particles of ZnO than A.R.ZnO.

$354 Dr. S. Shanthi and V. Padmavathi Fig 1-2 FT-IR Spectra and X-ray diffraction pattern of the synthesised nano particles of ZnO Fig.3 SEM images of synthesised nano Fig.$ 5 UV Visible spectra for mixture of crystal Fig 6UV Visible spectra for mixture of crystal and aniline dyes after degradation and aniline dyes after degradation using synthesized nano particles of

5 UV Visible spectra for mixture of crystal Fig 6UV Visible spectra for mixture of crystal and aniline dyes after degradation and aniline dyes after degradation using synthesized nano particles of

4 354 Dr. S. Shanthi and V. Padmavathi Fig 1-2 FT-IR Spectra and X-ray diffraction pattern of the synthesised nano particles of ZnO Fig.3 SEM images of synthesised nano Fig. 4UV Visible spectra for mixture of crystal particles of ZnO and aniline dyes before degradation Fig.5 UV Visible spectra for mixture of crystal Fig 6UV Visible spectra for mixture of crystal and aniline dyes after degradation and aniline dyes after degradation using synthesized nano particles of ZnO by using AR.ZnO 4.2. EFFECT OF VARIATION OF INITIAL CONCENTRATION OF DYE 1 %REMOVAL OF DYES CONCENTRATION (ppm) %CRYSTAL VIOLET %ANILINE BLUE % REMOVAL OF DYES CONCENTRATION(ppm) % of CRYSTAL VIOLET % ANILINE BLUE Fig: 7Effect of initial dyes concentration on the Fig:8 Effect of initial dyes concentration on the Photo degradation efficiency of crystal Photo degradation efficiency of crystal and aniline by using synthesized nano ZnO and aniline by using AR.ZnO

5 Zinc oxide catalysed photo degradation of crystal and aniline dyes Effect of variation of dose % REMOVAL OF DYES DOSE mg / L 4 % crystal % aniline % REMOVAL OF DYES Figure.9Effect of variation of dose of photo catalyst on Figure.1Effect of variation of dose of photo the photo degradation of dyes, by solar radiation with catalyst on the photo degradation of dyes, synthesised nano particles of ZnO as photo catalyst by solar radiation with AR.ZnO DOSE mg / L % crystal % aniline 4.4.Effect of variation of ph % REMOVAL OF DYES %CRYSTAL VIOLET %ANILINE BLUE %REMOVAL OF DYES %CRYSTAL VIOLET %ANILINE BLUE p H of dyes Fig.11Effect of variation of ph of solution on the photo Fig.12Effect of variation of ph of solution on the degradation of dyes of their binary mixture, by micro photo degradation of dyes of their binary wave radiation with synthesized nano ZnO as photo catalyst mixture, by solar radiation with A.R. ZnO 1 p H of dyes 4.5. Effect of variation of contact time on the photo degradation of dyes %REMOVAL OF DYES %crystal %aniline %REMOVAL OF DYES %CRYSTAL VIOLET %ANILINE BLUE TIME(hrs) TIME(hrs) Figure.13Effect of variation of contact time on the Figure.14Effect of variation of contact time on the photo degradation of dye solutions of their photo degradation of dye solutions of their binary binary mixture by solar radiation with mixture by solar radiation with A.R. ZnO at 25 C synthesized nano particles of ZnO at 25 C

6 356 Dr. S. Shanthi and V. Padmavathi 5. Kinetic studies: logOD TIME(hrs) CRYSTAL VIOLET ANILINE BLUE 1 2 Figure15 Kinetic plot for the degradation of Figure:16 Kinetic plot for the degradation of mixture of dyes with synthesised mixture of dyes with A.R.ZnO at 25 c nano particles of ZnO at 25 c 2+logOD TIME(hrs) CRYSTAL VIOLET ANILINE BLUE Lnk /T crystal Figure :17Arrhenius plot for the degradation Figure :18 Arrhenius plot for the degradation of crystal using nano particles of ZnO of aniline using nano particleof ZnO as catalysts as catalysts. Table: Catalysts Temperature( c) Rate constants(k) Solar radiation Crystal Aniline synthesized nano particles of ZnO synthesized nano particlesofzno synthesized nano particles of ZnO A.R.ZnO A.R.ZnO A.R.ZnO Table.2 Thermodynamic parameters calculated for photo degradation using synthesized nano particles of ZnO Temperature Ea KJ/mol H kj S JK -1 G kj mol C C C Lnk /T Aniline

7 Zinc oxide catalysed photo degradation of crystal and aniline dyes 357 Table.3 Thermodynamic parameters calculated for photo degradation using A.R.ZnO Temperature Ea KJ/mol H kj S JK -1 G kj mol C C C Conclusion The co-precipitation technique is the best method for the synthesis of nano particles of Zinc oxide.the sample obtained by the co-precipitation technique was characterized by PXRD,FTIR, and SEM instrumental techniques. The photo catalytic degradation of crystal and aniline dyes from aqueous solutions of their binary mixture was carried out using synthesized nano particles of Zinc Oxide and A.R. Zinc Oxide with different sources, and the reaction can proceed to almost complete degradation. Kinetic study was performed by carrying the degradation reaction at different temperatures to determine the rate constant of degradation and the activation parameters. These results will be helpful in designing effluent treatment plants in industries. Using this study, we propose the optimum conditions required for maximum degradation. Optimum condition required for photo degradation using synthesized nano particles of ZnO. and A.R ZnO Radiation Initial concentration ph Dose mgl -1 Contact time % Removal of dye Crystal Aniline Solar days Micro wave (hrs) Radiation Initial concentration ph Dose mgl -1 Contact time % Removal Crystal Solar days Microwave (hrs) Aniline

8 358 Dr. S. Shanthi and V. Padmavathi References [1] Rauf, M.A., Salmon, S., Ashraf, 28, Journal of Hazardous Materials [2] Kumar,A., Paliwal,M., Ameta,R., Ameta S.C., 28, J of Iran, Che, Soc, 5(2), 346. [3] Sudarjanto,G., Keller-Lehmann,B., Keller,J.25, Journal of Water and Environment Technology, (1), 1. [4] Stasinakis, A.S., 28, Global Nest Journal, 1(3),376. [5] Saif,M., Rehman,Ur., Muhammad,A., Shafeed,A., Chughtai,M.A., Mehmood Ali A., Ahmed,F., 28. Research Journal of Environmental Sciences, 2(5), 31. [6] Radulescu,C., Hossu,A.M., Ionita, I., Moater E.I.Stihi, C., 27, Bulletin of the Transilvania University of Brasov, IV, 571, [7] Wenzhong Sh., Zhijie L., Hui W., Yihong L., Qingjie G., Yuanli Z., (28), Journal of Hazardous Materials, 152, [8] Young, J., Cynthia, S., Taein, O., (26), Materials Res.Bulletin, 41, [9] Liu,H Q., Yang, J X., Liang,J H., Huang, Y X., Tangz,C Y., (28), J. Am. Chem. Soc, 91, [1] Xu,F., Zhang,P., Navrotsky,A., Yuan, Z Y., Ren,T Z., Halasa, M., (27), Chem. Mater 19,

STUDIES ON THE PHOTO DEGRADATION OF MALACHITE GREEN DYE BY THE SYNTHESIZED ZnO NANO PARTICLES WITH DIFFERENT SOURCES OF ENERGY

IJRPC 214, 4(3), 571-576 Shanthi et al. ISSN: 22312781 INTERNATIONAL JOURNAL OF RESEARCH IN PHARMACY AND CHEMISTRY Available online at www.ijrpc.com Research Article STUDIES ON THE PHOTO DEGRADATION OF