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

Abstract

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, 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.

Study on High-Efficiency Photocatalytic Degradation of Oxytetracycline Based on a Spiral Microchannel Reactor

“…A number of studies had shown that the photocatalytic rate would decrease when the catalyst dosage exceeded a certain amount , because at higher catalyst dosages, light scattering, catalyst particle agglomeration, and turbidity of the solution would increase, which led to a decrease in the light passing through the suspension and the surface area of the catalyst that absorbed light . The optimal dosage depended on the geometry, the working conditions of the photoreactor, and the type of UV lamp (power, wavelength, etc.)…”

Carbon Nanostructures Decorated with Titania: Morphological Control and Applications

“…The photoactivity of titania has been widely applied for environmental remediation; for instance, through the generation of graphene-bearing membranes for water purification [186,206]. The mechanisms of titania-photocatalyzed dye degradation proceed through the generation of reactive oxygen species (ROS) that trigger the photooxidation of organic molecules [207]. This phenomenon can be applied to a variety of different pollutants.…”

The application of photoelectrocatalysis in the degradation of rhodamine B in aqueous solutions: a review

“…Examples of such organic pollutants include pesticides originating from agricultural activities, pharmaceuticals and personal care products emanating from pharmaceutical industries, hospitals and households, and organic dyes originating from textile industries. 4 The textile sector remains a robust sector responsible for more than 800 tons of synthetic dyes yearly. 5 Unfortunately, more than 10% of this dyestuff ends up in the environment as constituents of untreated or improperly treated effluents.…”