Photocatalytic Degradation Pathways of Emerging Organic Pollutants in Aquatic Systems

Abstract

Pharmaceuticals, synthetic dyes and endocrine-disrupting compounds are among the emerging organic pollutants (EOPs) that have emerged as a big environmental issue due to their persistence, potential to bioaccumulate, and lack of response to the traditional water treatment procedures. Photocatalysis has received a lot of concern as a superior oxidation technology that has the ability of efficiently decomposing these contaminants under mild conditions. This paper discusses degradation mechanisms of typical EOPs in aquatic environments through photocatalytic degradation mechanisms powered mainly by catalysts made of semiconductors. The combination of experimental data on kinetic studies, intermediation discovery, and mineralization studies findings focuses on the impact of catalyst constituency, surface topography, and band-gap architecture on the degree of degradation presented in the research. Special focus is made on the functions of hydroxyl radicals, superoxide species and photogenerated holes in causing molecular cleavage and sustaining consecutive oxidation reaction. It has also been described in the paper how EOPs are transformed by the common routes of study, including antibiotics, hormones, and industrial additives, and how the structural properties of aromatic rings, functional substituents, and groups containing nitrogen are used to control degradation. Also, the paper addresses the variables which regulate pathway selectivity such as pH, dissolved organic matter, light intensity, and co-existing ions. Although photocatalysis has proven to have a great potential of total mineralization, the development of by-products that are transient, poses a question about toxicity and environmental safety. Thus, the study compares the toxicity of major intermediates and determines the conditions that reduce the presence of the harmful residues to a minimum. In general, the results present a thorough overview of the process of photocatalytic degradation in aqueous conditions and have practical implications in enhancing the treatment systems to relying on the increased use of photocatalytic degradation as a means of overcoming the rising problem of emerging organic pollutants.