Progress and problems of water treatment based on UV/persulfate oxidation process for degradation of emerging contaminants: A review

The emerging contaminants (ECs) in the water environment are complicated, diverse and difficult to be degraded, which seriously threaten human health and ecological environment, and is an urgent problem to be solved. Ultraviolet (UV) combined with persulfate (PS) advanced oxidation process (AOPs) showed good degradation performance for ECs, and has been attracted the attention of researchers all the time. In this review, the research progress of various homogeneous and heterogeneous UV/PS AOPs were summarized (including UV/ PS/metal ions, UV/PS/ozone, UV/PS/ultrasonic, UV/PS/metal-based materials, UV/PS/carbon-based loaded materials, UV/PS/photocatalytic materials). The degradation pathways and the contribution of active species in various oxidation systems were analyzed. The influence of different factors (pH value, water matrix, etc.) on the removal of ECs by various UV/PS AOPs was analyzed. In addition, this review puts forward some suggestions and positive prospects for future research direction focusing on existing defects and the limitations of engineering applications. For example, the optimization of light source reactor, the development of environmentally friendly and efficient new catalysts, and the optimization of process parameters, etc., to continuously promote the practical engineering application of UV/PS AOPs.