A Study on Simultaneous Photocatalytic Removal of Hexavalent Chromium and Pharmaceutical Contaminant from Aqueous Phase
Chromium (Cr) as Cr(+VI) is a well known environmental pollutant being highly toxic to most organisms including humans and are difficult to remove. Pharmaceuticals have also become a cause of environmental concern in recent years. Photocatalysis has emerg
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1 Introduction The pollution of environment due to Chromium (Cr) release is a cause of serious concern in developing countries. Among various sources, the wastewater from leather tanning and mordant dyeing are the major contributor towards Cr pollution, and the wastewater from leather tanning is single largest source of Cr release to the environment. 60–70 % of Cr used in the tanning process reacts with the hides and the remaining 30–40 % of Cr is discharged with the solid and liquid wastes (spent tanning solution in particular) (Patterson 1985; Zayed and Terry 2003). Cr released in the environment occurs either occur as Cr(+III) or Cr(+VI). Cr(+III) plays a vital role in development of living organism. Also, Cr(+III) is readily precipitated or adsorbed on a variety of inorganic and organic substrates at neutral or alkaline pH (Zayed and Terry 2003; Esmaeili et al. 2005). Alternately, Cr(+VI) is highly toxic to most organisms including humans and do not readily precipitate or become bound to components of soil. Toxicity kinetics of Cr(+VI) show higher rate of penetration into biological membranes as compared to Cr(+III). The ulcer formation and carcinogenic reactions are some well documented adversities due to Cr(+VI) in human. Thus, Cr(+VI) contaminate ground water aquifers and surface water sources. These Cr(+VI) contaminated water sources present hazard to living beings
S. Pipileima L. Menan Devi Department of Civil Engineering, National Institute of Technology, Agartala, Barjala, Jirania 799055, Tripura (West), India S. Ray (&) Department of Chemical Engineering, National Institute of Technology, Agartala, Barjala, Jirania 799055, Tripura (West), India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2017 R. Mohan B. et al. (eds.), Materials, Energy and Environment Engineering, DOI 10.1007/978-981-10-2675-1_16
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and health hazard to humans. Hence, is considered as a priority pollutant and the removal of Cr(+VI) is highly desirable to minimize the health hazard and adverse environmental effects (Esmaeili et al. 2005; Wittbrodt and Palmer 1995; Johnson et al. 1992). Several methods have been investigated for removing of Cr(+VI) from aqueous solutions, which include chemical precipitation, ion exchange, membrane processes, solvent extraction, adsorption, etc. (Kotas and Stasicka 2000; Madhavi et al. 2013; Barrera-Díaz et al. 2012). However, these treatment methods are essentially phase separation process and does not effect reduction of Cr(+VI) to less toxic of Cr (+III). The reduction of Cr(+VI) in the natural aqueous environment is an extremely slow process, lasting from several days to months water environment (Feng et al. 2012). Accelerated Cr(+VI) reduction has demonstrated in chemical reduction and electrochemical reduction. Like natural aquatic systems biological reduction of Cr (+VI) is also a slow process (Barrera-Díaz et al. 2012; Kato and Nagai 1991; Durai and Rajasimman 2011). The chemical process is expensive due to cost of reducing chemicals and not e
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