Nanostructured photocatalysts for degradation of environmental pollutants

Abstract

Water is the most essential life form on earth and a prerequisite for human survival. Due to manifold anthropogenic and industrial activities, voluminous discharge of diverse organic and inorganic pollutants has blown up into the water bodies. Organic pollutants, in particular, have a major contribution to the degradation of water quality on a vast scale. There is an exigent need for the abatement of these organic contaminants from water and wastewater. There are many conventional techniques of wastewater treatment including sedimentation, filtration, adsorption, reverse osmosis, ion exchange, coagulation and flocculation, and Fenton process. Photocatalysis is a highly efficient technique for the degradation of organic contaminants from water and wastewater. Several semiconducting materials have been used as photocatalysts, including ZnO, WO3, TiO2, Fe2O3, and ZnS, for the photocatalytic decomposition of multifarious organic pollutants. These semiconducting materials are highly beneficial for their application in the photocatalytic treatment of wastewater due to their favorable properties. They have favorable electronic structure, excellent charge transfer properties, a long lifetime in the excited state, high stability, low cost, and strong capability to absorb light. However, due to the wide gap, their application is limited to ultraviolet region with only 5% of the total spectrum of available solar light. So, modified metal oxide-based photocatalysts have been employed for the effective utilization of a wide visible spectrum of light. To modify and enhance the efficacy of these catalysts, various methodologies such as nano-structuring, metal doping, and genesis of nanocomposites have been engineered. These modified nanostructured photocatalysts provide an effective treatment potential to degrade organic water pollutants. This chapter outlines the potential and efficacy of metal oxide and modified metal oxide-based photocatalysts for the treatment of contaminants from water and wastewater.