Nanochemicals and ef fl uent treatment in textile i

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Nanochemicals and Ef fl uent Treatment in Textile Industries 87
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8.3.2 TiO 2 Nanoparticles Nanomaterials of metal oxides such as TiO 2 in addition to CeO 2 have also been used as catalysts for quick and relatively higher degree of degradation of organic contaminants in ozonation processes (Nawrocki and Kasprzyk-Hordern 2010 ; Orge et al. 2011 ). Polychlorinated biphenyls (PCBs) which are highly toxic to the environment are majorly used in nylon industries and can enter the ef fl uent stream during discharge. Photocatalysts such as TiO 2 nanoparticles are used effectively for treating wastewater polluted by organic contaminants such as polychlorinated biphenyls (PCBs), benzenes and chlorinated alkanes (Kabra et al. 2004 ). Removal of total organic carbon from wastewater has been enhanced by the use of TiO 2 . Decomposition of organic compounds can be enhanced by noble metal doping into TiO 2 due to enhanced hydroxyl radical production and so forth. For example, the doping of Si into TiO 2 nanoparticles was proved to be effectual in improving its ef fi ciency due to the increase in surface area and crystallinity (Iwamoto et al. 2000 , 2005 ). TiO 2 nanocrystals modi fi ed with noble metal deposits and so forth were used for degrading methylene blue dye in the visible light range (Liu and Gao 2005 ; Wu et al. 2006 ). Nitrogen- and Fe(III)-doped TiO 2 nanoparticles are useful in degrading azo dyes and phenol, respectively, than commercially avail- able TiO 2 nanoparticles. TiO 2 nanotubes have been effectively used to degrade organic compounds and were found to be more ef fi cient than TiO 2 nanoparticles (Macak et al. 2007 ). 8.3.3 Zero-Valent Iron Azo dyes are among the pollutants of signi fi cant concern that are being let out by most of the textile industries. Nanocatalysts including semiconductors, zero-valent metals, and bimetallic nanoparticles have been used for the removal of several organic pollutants, namely PCBs, pesticides and azo dyes. The main property that enables them to be effective is their greater surface area and shape speci fi c prop- erties (Zhao et al. 2011 ). Other class of chlorinated organic compounds and PCBs have been transformed successfully using nanoscale zero-valent iron (nZVI) (Wang and Zhang 1997 ) and inorganic ions such as nitrate and perchlorate (Choe et al. 2000 ; Cao et al. 2005 ). The stabilized nZVI particles could also be an ef fi cacious way for in situ treatment of industrial ef fl uents such as the textile industry (Xu and Zhao 2007 ). The nZVI and bimetallic nZVI can be used as effective redox reagents for reducing a variety of organic pollutants released by textile industries such as PCBs and organic dyes owing to larger surface areas and higher reactivity (Schrick et al. 2002 ; Nurmi et al. 2005 ). 88 P. Senthil Kumar et al.
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8.4 Other Nanomaterials The nanocatalyst of Ag and amidoxime fi bres was used ef fi ciently for the degra- dation of organic dyes useful for treating ef fl uent from textile industries (Wu et al.
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  • N. Gokarneshan

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