Studies on Photocatalytic and antimicrobial activities of chitosan based semiconductor metal oxide nanocomposites

Abstract

Water pollution has been defined as the direct and indirect ways of wastes newlinebeing released into the water bodies thereby affecting the environmental clean-up and newlinethe quality of human life. The main source of environmental contamination is due to newlinethe dumping of industrial wastes. Industries like chemical processing, tannery, textile newlinefood and pharmaceutical industries commonly used numerous toxic substances such newlineas dyes, pigments and endocrine disrupters etc., which are more carcinogenic in nature newlineand also they are contaminate the water sources. Certain conventional methods are newlineavailable to treat these kinds of industrial wastes such as membrane separation, newlinecoagulation, flocculation, chemical physical processes etc., Moreover, these processes newlinecan produce secondary waste and further it should be treated again. Advanced newlineOxidation Process is considered to be better method for the in-situ generation of newlinereactive free radicals and it has a tendency to destruct the complete mineralisation of newlineorganic toxic molecules. AOP based heterogeneous photocatalysis have more newlineadvantages owing to utilize the nanomaterials such as TiO2, ZnO, CeO2 etc., When newlinesuch kinds of nanomaterials are illuminated with a certain wavelength of light, the newlineelectrons are excited from the valence band to the conduction band. The excited newlineelectrons are involved in the redox process and generate the super oxide anions (O2 newline-). newlineThe positive holes in the valence band react with the water molecules and produce newline OH radicals which are more powerful oxidising agents for the mineralisation of newlineorganic compounds. Moreover the pristine metal oxides limit their energy band gap newlinewith suitable wavelength in the region of the solar spectrum. Higher energy band gap newlineand fast recombination rate are the demerits in the case of pristine oxides. newline