Peroxymonosulfate- and Persulfate-Based Advanced Oxidation Processes for Soil Remediation: A Review.

The presence of organic pollutants in soil represents one of the main remediation challenges of the 21st century, and in this regard, peroxymonosulfate- (PMS) and persulfate (PS)-based advanced oxidation processes (AOPs) are among the most promising technologies for in situ contaminant removal. However, the complex and heterogeneous nature of soil strongly influences (positively or negatively) the efficacy of PMS/PS-AOPs, necessitating the development of better-targeted application strategies. This review provides a comprehensive overview of state-of-the-art applications, mechanistic pathways, operational limitations, and future perspectives of PMS/PS-based treatments for soil remediation. Self- and external activation methods of PMS and PS in soil, including thermal activation, microwave field stimulation, ultrasound cavitation, transition metal catalysis, alkaline activation, mechanochemical ball milling, and electrokinetic transport system, are evaluated. A survey of the recent literature reveals laboratory-scale tests to have excellent efficiency in removing various low-molecular-weight organic pollutants, allowing the research to focus toward more complex molecules. However, large-scale application remains constrained by local soil characteristics, high operational costs, and the adverse impacts of such treatments on the soil biotic community and fertility. The synergistic combination of multiple techniques is emerging as an effective strategy to bridge the efficiency gap between liquid and solid matrices. This approach could mitigate adverse environmental side effects and optimize low-invasiveness treatments for large-scale soil remediation.