The waste water, containing numerous kinds of pollutants that are discharged from various industries are contaminating the fresh water bodies posing a stern risk to the environment and living organisms Schwarzenbach, R. P.et al 2010. When compared to types of waste water pollutants, heavy metals are the most significant ones, as they are very toxic even at very low concentrations and are persistent in the environment which is causing a life threatening problem to aquatic flora, fauna and its environment Seiler, H. G. et al .1988, Yadanaparthi, S. K. R.et al,2009. Electroplating industry, tanneries, electronics manufacturing industry, coal-fired power plants and mining operation are key sources of heavy metal pollution in water. Thus before releasing these waste waters from industries into freshwater bodies they must be treated well to prevent the contamination by toxic metals. Wang, J. & Chen ,2009, Yin, P.,2010 . automobile batteries, fuels, printing processes, photographic materials, pigments, ceramic and glass industries release tremendous amounts of Lead (Pb(II)), a potentially toxic metal ion that is being discharged into fresh water bodies making it unsuitable for consumption. Li, Y.-H. et al 2002,. Pb(II) is highly toxic to human beings and biota even at trace concentrations. Exposure to high levels of Pb(II) shows adverse effects as it can damAg(I)e the central nervous system and brain and finally leads to death Sanders, T.2009. US Environmental Potential Ag(I)ency (US EPA) has set the maximum contaminant level of Pb(II) in drinking water i.e 15 ?g L?1 Agarawal, A.2005. Most of the world’s silver is recovered from scraps, such as photographic films, X-ray films, jewelry, electroplating, ink formulation, mirroring, porcelain, and metal alloy industries. Due to its unique nature of antibacterial and anti fungal properties, silver is used especially in washing machines, refrigerators, air conditioners, air purifiers, and vacuum cleaners. As a result of which industries produce wastewater contaminated with a significant amount of silver Atia, A. A ,2005, Lu, X.2010
precipitation, electrolysis, solvent extraction, use of ion-exchange resins, chelating Ag(I)ents etc are the currently available technologies for silver removal. These processes show satisfying results when the concentrations in effluents are fairly high, i.e., above 100 ppm, Murat A.,2006.
Silver levels of less than 0.000001 mg silver per cubic meter of air ( mg/m3), 0.2-2 parts silver per billion parts water (Pb(II) in surface waters, such as lakes and rivers, and 0.2-0.3 parts silver per million parts soil (ppm) in soils are found from naturally occurring sources, U.S. Public Health Service, 1990.
It is imperative to develop techniques for trapping heavy metals from water. F. Fu. 2012, Y. Li 2015, J. Feng 2013,Q. Zhang 2013, Y. Huang 2015 several techniques have been proposed to remove heavy metals from aqueous solutions including chemical precipitation, reverse osmosis, membrane filtration, coaggulation, extraction electrochemical treatment techniques, ion exchange, irradiation, and adsorption. V. K. Gupta 2009, V. K. Gupta 2006, A. Heidari 2009, M. Xu 2011, F. Fu and Q 2011 Adsorption technique is the most extensively used compared to other methods owing to its low cost superior properties, high efficiency, operation-easiness, and cost-effectiveness, which make it an attractive approach for water treatment. V. K. Gupta 2012, K. Zargoosh 2015, K. Kalantari 2014, V. Chandra 2010, D. Zamboulis 2011, L. Ma 2016
Recently, nano material sorbents have been extensively used as sorbents due to their higher adsorption properties than bulk materials as they possess higher surface areas and more surface active sites. X. Wang,2012, P. Z. Ray 2015
Nano sized metal oxides as one of the inorganic materials are used largely for heavy metal ion removal in wastewater treatment in recent decades as they have specific affinity and exhibits minimal environmental impact and low solubility with no secondary pollution. C. Gao 2008, J. Fabrega 2011
Inorganic and organic pollutants from wastewater can be cheaply and potentially removed by Titanium dioxide photo catalyst. transition metal ions are doped with the titanium dioxide to enhance photo activity and shift of the absorption spectrum to the visible region.
Titanium(IV) oxide (TiO2), an important n-type semiconductor with a direct band gap of 3.2 eV, has also received considerable attention mainly in environmental photo catalytic processes such as splitting of water into H2 and O2, removal of pollutants from air, water and solar cells L. Etgar 2012, Q. Xiang 2011, G. Wang 2011, J. Tang 2011, . S. Liu 2011.
In heavy metal removal the dopant ions can function as both hole and electron traps or they can mediate interfacial charge transfer. The extent of metal dispersion on the particle surface and chemical composition homogeneity of a single particle depends markedly on the doping methods and calcinations temperature, thus leading to different morphological and crystalline properties Zhang, R.,2004, Anpo, M et al.2000, . Instead of using high cost UV-illumination, the widely available solar radiation makes photo catalytic process more attractive and provides a powerful source for waste water pollutant elimination Romero, M.,1999.
Although titania catalysts have been extensively studied, the procedure of preparing photo catalytic metal-doped titania is still of great interest. Particle size of catalyst is considered one of the most important physical parameters in these reactions, because it can directly furnish the active sites for the reaction to occur C. H. Cho 2003, Y. Oguri 1988, J. L. Look 1992.
In the present study the author has made an attempt to synthesize Cu-Sn-TiO2 nano particles by adopting Sol-gel method. The versatility of sol-gel chemistry provides a means of controlling the shape, morphology and textural properties of the final materials Rao, C. N. R,2003
The prepared Cu2+ and Sn4+ co-doped TiO2 photo catalyst was characterized by several analytical techniques such as XRD, FTIR, FE-SEM, EDS, HR-TEM, BET and SAED.
The synthesized oxide has been used for adsorption studies of heavy metals such as Ag(I) (II) and Pb(II). Batch equilibrium experiments were performed for various concentrations of 0.1 mg/L to 10 mg/L to study the removal efficiency of heavy metal ions. The effect of different parameters such as contact time, initial concentration, pH and effect of coexisting substance on the adsorption process were investigated. The adsorption kinetics were tried for pseudo-first order kinetic model, pseudo-second order kinetic model & Elovich’s equation. Langmuir Frendlich, Temkin and D-R isotherms studies are also performed. Weber-Morris and Reichenberg Kinetic equations were employed to explain the diffusion process.