Recent advances in photo-activated sulfate radical-advanced oxidation process (SR-AOP) for refractory organic pollutants removal in water

In recent decades, a growing number of refractory organic pollutants with serious health risks are frequently detected in aquatic environment. Sulfate radical (SO4 center dot-)-based advanced oxidation process (SR-AOP) under light irradiation (ultraviolet (UV) light, visible light or simulated solar light) is considered as a prospective method for refractory organic pollutants degradation. The satisfactory removal depends on the generation of active radicals SO4 center dot- as well as OH% from the activation of persulfate (PS) and peroxymonosulfate (PMS). In this paper, different methods of PS/PMS photo-activation, including catalyst-free, metal catalyst and metal-free catalyst activation, under different light sources as well as their activation mechanisms are reviewed comprehensively. The effects of key parameters are commendably assessed, such as PS/PMS concentration, catalyst dosage, initial contaminant concentration, pH, and coexisting organic or inorganic matters. This study will help to deeply understand the photo-activated SR-AOP for the refractory organic pollutants removal and present better perspectives for future researches.