Photo-induced degradation of toxic recalcitrant compounds from surface water: Insights into advanced nanomaterials, hybrid photocatalytic systems, and real applications
Lokesh Kumar, Bramha Gupta, Mihir Kumar Purkait
Abstract
The rapid increase in toxic recalcitrant organic compounds (ROCs) from various industrial, residential, and agricultural sources poses a significant public health concern and threatens environmental preservation. The presence of these toxic ROCs weakens the effectiveness of conventional water and wastewater treatment systems. As a result, numerous physicochemical and biological treatment processes have been explored, each demonstrating varying removal efficiencies depending on experimental conditions. Given the limitations of existing treatment methods, research has increasingly focused on advanced oxidation processes, particularly photocatalysis. Photocatalysis is a prominent treatment technique due to its low sludge production, non-toxic nature, reusable characteristics, and ability to harness visible light. This review comprehensively examines the ecotoxicological effects of ROCs, existing biological and physicochemical treatment methods, advancements in photocatalyst synthesis, the transition from conventional to advanced photocatalysts, and hybrid treatment systems. In the context of photocatalytic removal of ROCs, the review also addresses several influencing parameters, including initial pollutant concentration, solution pH, light intensity, catalyst dose, and catalyst type. Global case studies focusing on the mechanisms of photocatalytic degradation of ROCs are highlighted. The documented photocatalysts for removing ROCs from water and wastewater have shown promising results. Moreover, integrating photocatalysis with advanced physicochemical and biological processes has effectively removed various dissolved (e.g., ROCs) and suspended impurities, showcasing its practical applications. Thus, this study could serve as a valuable resource for researchers and engineers working on the treatment of various micropollutants, such as ROCs, in real wastewater.