Heat-activated persulfate for the degradation of micropollutants in water: A comprehensive review and future perspectives

This work is a critical review of the most important studies that have dealt with heat-activated persulfate to degrade persistent micropollutants in the last six years. The effect of the different operating parameters is dis-cussed, wherein in all cases, the efficiency was favored at higher temperatures and oxidant concentrations. Particular emphasis was given to the effect of the aqueous matrix. Since heat activation is a homogeneous process based on the production of free radicals, in most of the studies presented, the removal of pollutants decreases as the complexity of the aqueous matrix increases except in cases where secondary oxidative species are produced that are selective with specific pollutants. It has also been observed that the change in toxicity usually follows the removal of the parent compound despite the formation of several by-products. Nowadays, combining different processes for the simultaneous activation of persulfate seems to be gaining ground. A hybrid process is an interesting strategy to reduce costs and increase efficiency, especially in real wastewater. In this light, the most interesting studies of hybrid systems for the destruction of micropollutants in recent years based on thermally activated persulfate are also summarized. Finally, some steps are proposed for future research towards the in-dustrial application, including the study of chemical mixtures, the integrated toxicity assessment, the exami-nation of simultaneous disinfection and decomposition of pollutants into real wastewater, the estimation of the required costs, and energy the combination of processes and their coupling with renewable sources, and the design of pilot plants and the scale-up of the hybrid processes.

Automated summary

This work provides a critical review of recent studies on the use of heat-activated persulfate to degrade persistent micropollutants. The influence of various operating parameters, such as temperature and oxidant concentrations, is discussed, with higher temperatures and oxidant concentrations generally improving efficiency. The effect of the aqueous matrix is particularly emphasized, as studies have shown that the removal of pollutants decreases with increased complexity of the aqueous matrix, unless specific oxidative species are produced. The study also highlights the growing interest in combining different processes for persulfate activation and summarizes recent research on hybrid systems for micropollutant destruction.