Studies on UV Visible Light Responsive Metal Oxide Nano Composites as Photocatalyst

Abstract

An extensive literature survey (Chapter I) on water pollution suggested that dyes and inorganic pollutants are responsible for the contaminating the water body. Finding right kind of photocatalyst that can adsorbs or degrade the pollutant is a challenge. As the literature review shows though enormous work has been done in photocatalysis still lot of research is being conducted in order to find right kind of catalyst. Single catalyst can t remove every kind of dyes and pollutants present in the waste water. Though UV light can also initiate the photocatalysis process still Visible light driven photocatalysis is desirable to expand applicability under solar irradiation. As discussed in the literature review tuning the band gap by controlling size and shape, non-metal doping, making composite with other systems can enhance the efficiency of the photocatalytic systems. Chapter II focuses on the preparation of nanocrytalline cerium oxide by template free microwave-assisted hydrothermal route using relatively inexpensive precursors. Systematic characterization of the synthesized powder by different physicochemical methods and evaluation of its photocatalytic efficiency towards two commonly used structurally different organic dyes namely Eriochrome Black T (EBT) and Alizarin Red S (ARS) were also studied. Batch adsorption studies without light irradiation showed significant adsorption of both the dyes on CeO2 nanoparticles with monolayer adsorption capacity (Qo) values 44.1 and 57.8 mg gand#8722;1 for ARS and EBT, respectively. Under visible light irradiation, the overall decolourisation (adsorption/photo-degradation) of both the dyes increased substantially and the optimum amount of CeO2 required for complete decolourisation of ARS (100 mg Land#8722;1) was 0.80 g Land#8722;1 while relatively lesser dose of catalyst (0.60 g Land#8722;1) was required for the same concentration of EBT. Suitable mechanisms were proposed for the decolourisation of dyes under visible light based on GC MS/LC MS data of the degraded products/intermediates.