Use of Strontium Chromate as Photocatalyst for Degradation of Azure-A

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Research Available Online at www.ijcrr.in International Journal of Contemporary Research and Review ISSN 0976 4852 CrossRef DOI: https://doi.org/10.

1 Research Available Online at International Journal of Contemporary Research and Review ISSN CrossRef DOI: March, 2018 Volume 09 Issue 03 Section: Chemistry Use of Strontium Chromate as Photocatalyst for Degradation of Azure-A Monika Jangid a*, Rakshit Ameta b, Suresh C. Ameta b, and Ajay Sharma c a Research Scholar, PAHER University, Udaipur (Raj.) India b Department of Chemistry, PAHER University, Udaipur (Raj.) India c P.G. Department of Chemistry, Govt. Science College, Sirohi (Raj.) India * id: monikajangid24@gmail.com Received ; Accepted Abstract: The photocatalytic activity of strontium chromate (SrCrO 4 ) is for the photo dye. The progress of photodegradation reaction was monitored by measuring the absorbance of the reaction mixture at definite time intervals. The effect of various parameters such as ph, the concentration of dye, amount of semiconductor and light intensity were varied to achieve the optimum rate of photodegradation. It was observed that strontium chromate has the highest catalytic activity in basic medium. A tentative mechanism for the reaction has been proposed. Key words: Photocatalytic degradation, Strontium Chromate, azure-a dye. 1. Introduction Water pollution is one of the major problems faced by the humans. Industrialization, urbanization, increase in human population are responsible for water pollution. Effluents from various industries like textile, pulp, paper, dyeing and printing industries contain pollutants such as acids, detergent, soaps, chemicals, pesticides, dye etc, which are the major sources of water pollution. Dyes are all around us, they make out our world beautiful but they also bring pollution and therefore, attention has to be focused on possible solutions of environmental problems caused by dye industries. The manufacturing and the processing of dye involve the handling and the production of many organic compounds that are toxic and hazardous to human health. Various methods such as flocculation, coagulation, osmosis, ozonation, biological treatment etc., have been used for removing colour from waste water. Every method of wastewater treatment has its own limitation. In this context, photocatalysis has been considered as an emerging technology for the treatment of wastewater, as the photocatalysts are able to degrade the undesirable organics dissolved in water completely. The photocatalytic process can mineralize the hazardous organic chemicalsto carbon dioxide, water and simple ions. Various studies have focused on treatment of industrial wastewater using different treatment methods; however, most of these treatments have intricacy in realistic uses by Chong et al. 1 International Journal of Contemporary Research and Review, Vol. 9, Issue. 02, Page no: CH doi: Page 20181

Photocatalytic oxidation processes, which involves the generation of highly reactive hydroxyl radical have emerged as a promising water and wastewater treatment technology for the degradation or

2 Photocatalytic oxidation processes, which involves the generation of highly reactive hydroxyl radical have emerged as a promising water and wastewater treatment technology for the degradation or mineralization of a wide range of organic contaminants 2-3. Chen et al. 4 reported that SrTiO 3 as an effective photocatalyst for NO degradation under UV light irradiation. Bhati et al. 5 studied the photocatalytic degradation of fast green using CeCrO 3 as photocatalyst. In recent years, AOPs are promising methods for the treatment of wastewaters containing organic pollutants and involve two stages, first is the formation of strong oxidants and second is the reaction of these oxidants with organic contaminants in water. The efficiency of the AOP is maximized by the use of an appropriate catalyst and/or ultraviolet light. 6-8 Asai et al. 9 suggested visible light responsive rhodium and antimonycodoped SrTiO 3 photocatalyst loaded with an IrO 2 cocatalyst for solar water splitting. Chen et al. 10 reported the theoretical investigation of the metal doped SrTiO 3 photocatalysts for water splitting. Synthesis of highly active rhodium doped SrTiO 3 powders in Z-scheme systems for visible light driven photocatalytic overall water splitting was done by Kato et al. 11 Composite Sr 2 TiO 4 /SrTiO 3 (La,Cr) heterojunction based photocatalyst for hydrogen production under visible light irradiation byjia et al. 12 Very little work has been carried out on SrCrO 4 as photocatalyst. Therefore, in the present work SrCrO 4 has been used as photocatalyst for the. Paliwal et al. 13 reported the theoretical investigation of the enhancing photocatalytic activity of bismuth ferrite by doping with cobalt and its use for degradation of evans blue. Determination of keratin degradation by fungi using keratin azure was done by Scott et al. 14 Ameta et al. 15 reported the theoretical investigation of the photocatalytic mineralization of azure-a using Li 2 CuMo 2 O 8 nanoparticles. Preparation of ultralong SrCrO 4 nanowires by a surfactant free solvothermal reaction was synthesised by Huh et al. 16 Bhardwaj et al. 17 suggested use of a new nano sized photocatalyst BaO 3 TiO.SrO 3 TiO for degradation of azure-b an eco-friendly process. Photocatalytic on carbon doped zinc oxide was done by Benjamin et al. 18 Benjamin et al. 19 studied use of barium chromate in photocatalytic degradation of eosin yellow. Ameta et al. 20 reported the theoretical investigation of the photocatalytic degradation of azure-b in aqueous solution by calcium oxide rameshwar. 2. Experimental: Figure 1: Structure of Azure-A Synthesis of strontium chromate: Strontium chromate were synthesized by precipitation in a wet chemical process with watersoluble strontium chloride and sodium chromate and characterized by SEM-EDS techniques g of strontium chloride and g of sodium chromate taken in separate beaker, distilled water was added. When strontium chloride and sodium chromate react with together it gives precipitation of deep lemon yellow colour strontium chromate. Then it was filtered, washed with water many time and dried at 80 C. Photocatalytic process: The photocatalytic activity of the catalyst was evaluated by measuring the rate of degradation of azure-a dye. A stock solution of dye (1.0 x 10 3 M) was prepared by dissolving ( g) of dye in 100 ml of doubly distilled water. ph of the dye solution was measured by a digital ph meter (Systronics model 335), and the desired ph of the solution was adjusted by the addition of standard 0.1 N sulphuric acid and 0.1 N sodium hydroxide solutions. The reaction mixture containing 0.10 g photocatalyst was exposed to a 200 W tungsten lamp, and about 3 ml aliquot was taken out every 10 min. Absorbance (A) was measured at λ max =630 nm. A water filter was used to cut off thermal radiations. The intensity of light was varied by changing the distance between the light source and reaction mixture, and it was measured by Suryamapi (CEL model SM 201). The absorbance of the solution at various time intervals was measured with the help of autocalorimeter (Systronics model LT-114). It was observed that the absorbance of the solution decreases with increasing the time of exposure, which indicates that the concentration of Azure-A dye decreases with increasing time. The calculation of degradation efficiency (φ) was made by the relation: doi: Page 20182

3 ψ =100 A- A 0 A 0 (1) Here, A 0 is initial absorbance, and A is absorbance after degradation of dye at time t. A plot of 1 + log A versus time was linear following pseudo-first Table 1: Typical runs for photocatalytic order kinetics. Typical runs are given in Table 1 and graphically presented in Figure 2. The rate constant was calculated by using the expression: k = slop (2) Time (min) SrCrO 4 with 2-propanol SrCrO 4 without 2-propanol Abs 1+log A Abs 1+log A K Sec SrCrO 4 : ph=8.0, concentration [Azure-A] = M, Semiconductor=0.10 g, Light intensity=50.0 mwcm 2, Rate constant= Sec -1 (SrCrO 4, with 2-propanol) and (SrCrO 4, without 2-propanol) Figure 2: Typical runs for photocatalytic degradation of Azure-A 3. Results and discussion: Effect of parameters: (i) ph variation: The effect of variation of ph range strontium chromate, respectively. All other parameters were kept to be identical. The results are given in Table 2 and Figure 3. It was observed that with an increase in ph, the rate of reaction increases. After attaining the maximum value at ph 8.0 for strontium chromate, respectively, the rate decreases with a further increase in ph. In this case, the presence of scavenger i.e. 2-propanol does not affect the rate of reaction adversely and hence, it may be concluded that OH radical does not participate in the degradation. It was interesting to observe that strontium chromate was active in basic range ( ). Table 2: Effect of ph on photocatalytic ph Rate constant, (k) (10-4 sec 1 ) doi: Page 20183

4 SrCrO 4 : concentration [Azure-A]= M, Semiconductor=0.10 g, Light intensity=60.0 mwcm SrCrO 4 : ph=8.0, Semiconductor=0.10 g, Light intensity=60.0 mwcm 2 Figure 3: Effect of ph on photocatalytic SrCrO 4 : Concentration [Azure-A]= M, Semiconductor=0.10 g, Light intensity=60.0 mwcm 2 (ii) Concentration variation: The effect of variation of concentration of azure-a on its degradation rate has been observed in the range from to M for strontium chromate keeping all other parameters to be the same. The results are given in Table 3 and Figure 4. It has been observed that the rate of degradation increases with increasing concentration of dye up to M for strontium chromate. Further increase in concentration beyond this limit results in a decrease in degradation rate. This may be explained on the basis that on increasing the concentration of dye, the reaction rate increases as more molecules of dyes were available but a further increase in concentration results appearing an internal filter effect which does not permit sufficient amount of light to reach the surface of the photocatalyst thus, decreasing the rate of photocatalytic occurs. Table 3: Effect of dye concentration on photocatalytic [Azure-A] 10 5 M Rate constant (k) 10 4 (sec -1 ) Figure 4: Effect of dye concentration on photocatalytic SrCrO 4 : ph=8.0, Semiconductor=0.10 g, Light intensity=60.0 mwcm 2 (iii) Amount variation: The effect of variation of the amount of catalyst on the rate of dye degradation has been studied in the range from 0.02 to 0.20 g in 50 ml and the results are reported in Table 4 and Figure 5. It has been observed that with an increase in the amount of catalyst, the rate of degradation increases to a certain amount of catalyst i.e g, for strontium chromate. Beyond this point, the rate of reaction becomes virtually constant. This behaviour may be explained by the fact that with an increase the amount of catalyst, the exposed surface area of catalyst will increase. doi: Page 20184

5 Hence, the rise in the rate of reaction has been observed, but with further increase in the amount of catalyst beyond a limit, the only thickness of the layer (and not the exposed surface area) will increase at the bottom of the reaction vessel, which was completely covered by the catalyst. Table 4: Effect of amount of catalyst on photocatalytic Photocatalyst g in (50 Rate constant(k) (10-4 ml) sec 1 ) M, Light intensity=60.0 mwcm 2 increasing light intensity, the rate of reaction increases and maximum rates were found at 50.0mW cm 2 for strontium chromate, respectively. It may be explained on the basis that as the light intensity was increased, the number of photons striking per unit area also increases, resulting in higher rate of degradation. Further increase in the light intensity may start some thermal side reactions. Table 5: Effect of light intensity on photocatalytic Light intensity Rate constant (k) (mw cm -2 ) 10 4 (sec -1 ) M, Semiconductor=0.10 g Figure 5: Effect of amount on photocatalytic M, Light intensity=60.0 mwcm 2 (iii) Light intensity variation: The effect of light intensity on the rate of dye degradation was also studied by varying the intensity of light from 20.0 to 70.0 mwcm 2. The observations are presented in Table 5 and Figure 6. The data indicate that with Figure 5: Effect of light intensity on photocatalytic M, Semiconductor=0.10 g Mechanism: On the basis of the experimental observations, a tentative mechanism has been proposed for the in the presence of strontium chromate. Azure-A absorbs radiations of suitable doi: Page 20185

6 wavelength and transforms to singlet then triplet excited state (intersystem crossing, ISC). The semiconductor also absorbs light to excite an electron from its valence band (VB) to its conduction band (CB), which will be abstracted by dissolved oxygen to generate O 2 (in basic media, SrCrO 4 ). These radicals can oxidize the dye to its leuco form ultimately degrading to products. 1EB 0 1EB 1 (3) 1EB 1 3EB 1 (4) SrCrO 4 SrCrO 4 (h+ (VB)+e (CB)) (5) O 2 (dissolved oxygen) + e (CB) O 2 (6) In acidic medium- O 2 + H + HO 2 (7) 3EB 1 + HO 2 Leuco EB (8) Leuco EB Products (9) In basic medium- 3EB 1 + O 2 Leuco EB (10) Leuco EB Products (11) Carrying out the reaction in the presence of OH radical scavenger, 2-propanol, the reaction rates were unaffected. This unambiguously shows that there was no involvement of OH radicals in the reactions as an active oxidizing species. 4. Conclusion: The feasibility of photocatalytic degradation of azure a dye was tested using synthesized SrCrO 4 semiconductor as photocatalyst. The experimental results indicated that degradation efficiency of azure-a was affected by ph, concentration of dye, amount of semiconductor and light intensity. It was observed that photocatalytic treatment increased the biodegradability of dye containing polluted water. In the present work, a quaternary semiconductor strontium chromate was successfully used as a photocatalyst for. It may be explored for removal of a variety of industrial effluents in future. Reference: 1. M. N. Chong, B. Jin, C. W. K. Chow, and C. Saint. Recent developments in photocatalytic water treatment technology: a review. Water Res., 44(10), , N. P. Ndasi, M. Augustin, and T. J. Bosco. Biodecolourisation of textile dyes by local microbial consortia isolated from dye polluted soils in ngaoundere. Int. J. Environ. Sci., 1(7), , C. S. Turchi, and D. F. Ollis. Photocatalytic degradation of organic water contaminants: mechanisms involving hydroxyl radical attack. J. Catal., 122(1), , L. Chen, S. Zhang, L. Wang, and D. Xue. Preparation and photocatalytic properties of strontium titanate powder via sol-gel process. J. Cryts. Growth., 311(3), 746, I. Bhati, P.B. Punjabi, and S.C. Ameta. Photocatalytic degradation of fast green using nano sized CeCrO 3. Maced. J. Chem. Chem. Eng., 29(2), 195, O. Legrini, E. Oliveros, and A. M. Braun. Photochemical processes for water treatment. Chem. Rev., 93(2), , C. V. Sonntag. Advanced oxidation processes: mechanistic aspects. Water Sci. Technol., 58(5), , A. Matilainen, and M. Sillanpaa. Removal of natural organic matter from drinking water by advanced oxidation processes. Chemosphere, 80(4), , R Asai, H Nemoto, Q Jia, K Saito, A Iwase, and A Kudo. A visible light responsive rhodium and antimony-codoped SrTiO 3 powdered photocatalyst loaded with an IrO 2 cocatalyst for solar water splitting. Chem. Commun. 50, , H. C. Chen, C. W. Huang, J. C. S. Wu, and S. T. Lin. Theoretical Investigation of the Metal-Doped SrTiO 3 Photocatalysts for Water Splitting. J. Phys. Chem. C, 116, , H. Kato, Y. Sasaki, N. Shirakura, and A. Kudo. Synthesis of highly active rhodiumdoped SrTiO 3 powders in Z-scheme systems for visible-light-driven photocatalytic overall water splitting. J. Mater. Chem. A 1, , Y. Jia, S. Shen, D. Wang, X. Wang, J. Shi, F. Zhang, H. Han, and C. Li. Composite Sr 2 TiO 4 /SrTiO 3 (La,Cr) heterojunction based photocatalyst for hydrogen production doi: Page 20186

7 under visible light irradiation. J. Mater. Chem. A1, , A. Paliwal, R. Ameta, and S. C. Ameta. Enhancing photocatalytic activity of bismuth ferrite by doping with cobalt and its use for degradation of evan s blue. Eur. Chem. Bull., 6(3), , J. A. Scott, and W. A. Untereiner. Determination of keratin degradation by fungi using keratin azure. Med Mycol, 42 (3), , S. C. Ameta, M. Joshi, P. Kumawat, and R Ameta. Photocatalytic mineralization of azure a using Li 2 CuMo 2 O 8 nanoparticles. Int. J. Res. Chem. Environ., 5(4), , Y. D. Huh, and S. H. Lee. Preparation of ultralong SrCrO 4 nanowires by a surfactant free solvothermal reaction. Bull. Korean Chem. Soc., 34(6), , S. Bhardwaj, S. Nihalani, and A. Vijay. Use of a new nano sized photocatalyst BaO 3 TiO.SrO 3 TiO for degradation of azure b: an eco-friendly process. Scholars Research Library, 5 (6), , S. Benjamin, P. Rao, And P. Tak. Photocatalytic on carbon doped zinc oxide. Sci. Revs. Chem. Commun., 6(2), 19-26, S. Benjamin, S. Gupta, D. Soni, and R. Ameta, Use of barium chromate in photocatalytic degradation of eosin yellow. Chemical Science Transactions, 4(3), , S. C. Ameta and P. Jhalora. Photocatalytic degradation of azure-b in aqueous solution by calcium oxide rameshwar. J. Curr. Chem. Pharm. Sc., 4(1), 22-29, doi: Page 20187

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