Emerging pollutants and their removal using visible-light responsive photocatalysis – a comprehensive review

Abstract

Emerging pollutants (EP) are the group of contaminants newly detected in aquatic environments around the globe. Conventional water purification systems are less efficient in removing these pollutants; therefore, innovative, and eco-friendly technologies are needed. Recently, semiconductor-supported photocatalysis has attracted attention in environmental remediation for removing EP's owing to their unique characteristics of low-cost, higher thermal and mechanical stability, and excellent pollutant removal efficiency. The charge separation and effective light absorption, particularly in the visible region, are two essential characteristics in photocatalyst which are hard to achieve. Several approaches have been adopted to enhance the charge separation and light-absorption ability in the visible range, including elemental-doping, morphology-engineering, and composite photocatalyst formation. This review concisely discusses the several recently discovered EP's, their fate and transport properties, as well as recent progress in the design and development of visible light-responsive photocatalysts for degradation of EP's. Furthermore, synthesis methods, key features such as optical properties, energy-bandgap structure, crystallinity, and surface features are emphasized in this review. The influencing process parameters, reusability, and stability of photocatalyst are also outlined. Finally, the summary and future perspectives for designing a sustainable photocatalysis system are presented.