An overview of advanced oxidation processes using copper-based catalytic degradation of organic pollutants in water

Organic pollutants are harmful to the environment due to their bio-accumulative and long-persistent nature, causing adverse effects on plants, animals, and humans. Their rapid spread beyond target applications in the ecosystem could be responsible for various fatal diseases and eco imbalances. Conventional techniques for removing these pollutants are ineffective because of their high solubility in water and nonbiodegradability. In contemporary times, we have witnessed a notable surge in interest in advanced oxidation processes (AOPs) for water treatment processes. This heightened attention is attributed to their exceptional degradation efficiency for recalcitrant organic pollutants. This review, therefore, focuses on copper-based homogeneous and heterogeneous catalysts for AOPs that offer both cost-effectiveness and high performance. Emphasis is placed on the use of copper-based catalysts in photocatalysis, Fenton-like process (including photo-Fenton (Fe2+/UV/H2O2)), persulfates activation, and ultrasonic irradiation. The catalytic performance, mechanism, and pathway for the abatement of the target pollutants by the copper-based catalysts in each AOP are described in detail. The reusability, stability, and factors affecting the AOPs are briefly highlighted. We further provide perspectives on the key opportunities and challenges associated with copper-based catalysts in AOPs, recommending further exploration for enhanced applications in future studies.