Calcium oxide was used as photocatalyst for the degradation of indigo carmine dye solution in the visible, long UV, and short UV radiation. We have investigated the effectiveness of degradation of indigo carmine dye solution at pH 9 and 12 using calcium oxide with the particle size of 30–36?nm by varying the concentration, dose of adsorbent, and duration. It has been found that the degradation of indigo carmine dye is effective at pH = 9, when 0.12?g of calcium oxide was used. The nature of interaction between calcium oxide and indigo carmine dye was discussed. 1. Introduction The water bodies are continuously polluted due to the unscientific methods adopted by the chemical, textile, paper, and pulp industries, and so forth, during the discharge of toxic and hazardous chemicals [1–5]. Complexity of the dye molecules does not favour the natural process of degradation and also during certain instances incomplete degradation or transformation may generate carcinogenic byproducts [6–9]. Therefore, physical, chemical, and biological methods have been developed for the treatment of dye effluents from industries [10]. Precipitation, coagulation, floatation, and oxidizing agents have been used for the treatment of different types of dyes. Major disadvantages of chemical methods are that they require expensive chemicals and the products generated after dye treatment are also polluting in nature [11, 12]. Biological methods to degrade dyes include enzymes and microorganisms and are found to be effective but the difficulty is to scale up the process [13]. Membrane-filtration processes, electrodialysis, and adsorption involve physical processes which are cheaper compared to biological methods but the maintenance of membranes is expensive [14–16]. Electrochemical process, electrokinetic coagulation, irradiation with light, and photochemical oxidation have been employed for the removal of dye effluents [17]. Major limitations of the above methods are the operating cost, generation of byproducts, and the process of regeneration of the starting compounds which are difficult or tedious [10]. Therefore, degradation of dyes into its smaller fragments of less toxic organic compounds is one of the major challenges faced by scientists, technologists, and researchers across the world. Development of catalysts which can interact with sunlight and degrade the toxic dyes into its low molecular weight colourless and nontoxic fragments which can be discharged into the water bodies without affecting their physicochemical properties is the major objective. Photocatalytic degradation
References
[1]
R. M. Christie, Environmental Aspects of Textile Dyeing, Wood Head, Boca Raton, Fla, USA, 2007.
[2]
B. R. Babu, A. K. Parande, S. Raghu, and T. Prem Kumar, “Cotton textile processing: waste generation and effluent treatment,” Journal of Cotton Science, vol. 11, no. 3, pp. 141–153, 2007.
[3]
J. S. Bae and H. S. Freeman, “Aquatic toxicity evaluation of new direct dyes to the Daphnia magna,” Dyes and Pigments, vol. 3, pp. 81–85, 2007.
[4]
R. Helmer and I. Hespanhol, Water Pollution Control—A Guide to the Use of Water Quality Management Principles, E & FN Spon, London, UK, 1997.
[5]
F. I. Hai, K. Yamamoto, and K. Fukushi, “Hybrid treatment systems for dye wastewater,” Critical Reviews in Environmental Science and Technology, vol. 37, no. 4, pp. 315–377, 2007.
[6]
M. N. Chong, B. Jin, C. W. K. Chow, and C. Saint, “Recent developments in photocatalytic water treatment technology: a review,” Water Research, vol. 44, no. 10, pp. 2997–3027, 2010.
[7]
J. A. Byrne, P. A. Fernandez-Iba?ez, P. S. M. Dunlop, D. M. A. Alrousan, and J. W. J. Hamilton, “Photocatalytic enhancement for solar disinfection of water: a review,” International Journal of Photoenergy, vol. 2011, Article ID 798051, 12 pages, 2011.
[8]
M. R. Hoffmann, S. T. Martin, W. Choi, and D. W. Bahnemann, “Environmental applications of semiconductor photocatalysis,” Chemical Reviews, vol. 95, no. 1, pp. 69–96, 1995.
[9]
K. Pirkanniemi and M. Sillanp??, “Heterogeneous water phase catalysis as an environmental application: a review,” Chemosphere, vol. 48, no. 10, pp. 1047–1060, 2002.
[10]
Y. M. Slokar and A. Majcen le Marechal, “Methods of decoloration of textile wastewaters,” Dyes and Pigments, vol. 37, no. 4, pp. 335–356, 1998.
[11]
A. Al-Kdasi, A. Dris, K. Saed, and K. C. T. Guan, “Photoluminescence and photocatalysis of the flower-like nano-ZnO photocatalysts prepared by a facile hydrothermal method with or without ultrasonic assistance,” Global Nest: The International Journal, vol. 6, pp. 222–230, 2004.
[12]
I. D. Mall, S. N. Upadhyay, and Y. C. Sharma, “A review on economical treatment of wastewaters and effluents by adsorption,” International Journal of Environmental Studies, vol. 51, no. 2, pp. 77–124, 1996.
[13]
A. Khalid, M. Arshad, and D. E. Crowley, “Accelerated decolorization of structurally different azo dyes by newly isolated bacterial strains,” Applied Microbiology and Biotechnology, vol. 78, no. 2, pp. 361–369, 2008.
[14]
G. Crini, “Non-conventional low-cost adsorbents for dye removal: a review,” Bioresource Technology, vol. 97, no. 9, pp. 1061–1085, 2006.
[15]
A. Da?browski, “Adsorption—from theory to practice,” Advances in Colloid and Interface Science, vol. 93, no. 1–3, pp. 135–224, 2001.
[16]
R. Wanchanthuek and W. Nunrung, “The adsorption study of Methylene Blue onto MgO from various preparation methods,” Journal of Environmental Science and Technology, vol. 4, no. 5, pp. 534–542, 2011.
[17]
M. C. Gutiérrez and M. Crespi, “A review of electrochemical treatments for colour elimination,” Coloration Technology, vol. 115, no. 11, pp. 342–345, 1999.
[18]
Y. Lai, M. Meng, Y. Yu, X. Wang, and T. Ding, “Photoluminescence and photocatalysis of the flower-like nano-ZnO photocatalysts prepared by a facile hydrothermal method with or without ultrasonic assistance,” Applied Catalysis B: Environmental, vol. 105, no. 3-4, pp. 335–345, 2011.
[19]
E. A. Konstantinova, A. I. Kokorin, S. Sakthivel, H. Kisch, and K. Lips, “Carbon-doped titanium dioxide: visible light photocatalysis and EPR investigation,” Chimia, vol. 61, no. 12, pp. 810–814, 2007.
[20]
W. Cun, Z. Jincai, W. Xinming et al., “Preparation, characterization and photocatalytic activity of nano-sized ZnO/SnO2 coupled photocatalysts,” Applied Catalysis B: Environmental, vol. 39, no. 3, pp. 269–279, 2002.
[21]
L. Song and S. Zhang, “A simple mechanical mixing method for preparation of visible-light-sensitive NiO-CaO composite photocatalysts with high photocatalytic activity,” Journal of Hazardous Materials, vol. 174, no. 1–3, pp. 563–566, 2010.
[22]
L. Song, S. Zhang, B. Chen, and D. Sun, “Highly active NiO-CaO photocatalyst for degrading organic contaminants under visible-light irradiation,” Catalysis Communications, vol. 10, no. 5, pp. 421–423, 2009.
[23]
J. Luan, W. Zhao, J. Feng et al., “Structural, photophysical and photocatalytic properties of novel Bi2AlVO7,” Journal of Hazardous Materials, vol. 164, no. 2-3, pp. 781–789, 2009.
[24]
J. Luan, M. Li, K. Ma, Y. Li, and Z. Zou, “Photocatalytic activity of novel Y2InSbO7 and Y2GdSbO7 nanocatalysts for degradation of environmental pollutant rhodamine B under visible light irradiation,” Chemical Engineering Journal, vol. 167, no. 1, pp. 162–171, 2011.
[25]
J. Luan, Z. Zheng, H. Cai, X. Wu, G. Luan, and Z. Zou, “Structural characterization and photocatalytic properties of novel Bi2YVO8,” Materials Research Bulletin, vol. 43, no. 12, pp. 3332–3344, 2008.
[26]
J. Luan, H. Cai, X. Hao et al., “Structural characterization and photocatalytic properties of novel Bi2FeVO7,” Research on Chemical Intermediates, vol. 33, no. 6, pp. 487–500, 2007.
[27]
T. Kornprobst and J. Plank, “Photodegradation of rhodamine B in presence of CaO and NiO-CaO catalysts,” International Journal of Photoenergy, vol. 2012, Article ID 398230, 6 pages, 2012.