Advances in Nanomaterial-based Water Treatment Approaches for Photocatalytic Degradation of Water Pollutants

Demand of pure drinking water is increasing day by day in line with both a growing population and global industrialization. Studies in the past few decades on the application of advanced oxidation processes (AOP) for the treatment of wastewater containing perilous organic pollutants, are promising when compared to conventional water treatment methods. In case of AOP, generation of powerful oxidant radicals ((OH)-O-., HOO.) is crucial for the purpose of degradation. Several processes for the in-situ generation of such highly reactive oxidants have been discussed. This Review highlights the literature reports on the degradation of various organic pollutants (dyes, pharmaceuticals, pesticides, herbicides, insecticides) by means of photocatalysis. A number of scientific investigations have been performed, which elucidate suitable properties (band gap energy, carrier transport, crystallinity etc.) for the deliberate design of efficient photocatalysts. The oxidation rates and degradation efficiency of photocatalysts are governed by some basic parameters, like organic pollutant concentration, photocatalyst concentration, pH, reaction temperature, light intensity, irradiation time, inorganic ions, oxidants, and these are also discussed. Titania and titania based materials have many attractive properties (nontoxicity, less costly, advanced optical properties, high stability) towards photo degradation process. Several studies have been reported investigating the intermediates produced during degradation process as well as the final degraded product, which might be toxic and/or hazardous to the human as well as to the environment. This review assimilates elaborate study on the mechanism of photocatalytic degradation of various organic pollutants.