Mn-assisted ball milling enhances catalytic property of carbonized soil and reuse as PMS activator: quantification of ROS with probe-based kinetics model and mechanism insights

Purpose This study provides a novel resource utilization strategy for the carbonized soil derived from lubricant-contaminated soil. Materials and methods In this study, the lubricant-contaminated soil was treated by pyrolysis and ball milling with manganese carbonate to obtain Mn-loaded carbonized soil (Mn@BCS), which was then reused to activate peroxymonosulfate (PMS) oxidation for degradation of aniline (AN) in wastewater. Results and discussion When the dosage of Mn@BCS and PMS was both 1 g/L, 100 mg/L of AN was almost completely removed within 6 h. Three reactive oxygen species (ROS), including \({\text{SO}}_{4}^{\bullet -}\) , •OH and \({}^{1}{\text{O}}_{2}\) , were detected and verified. The probe-based kinetics models were established with atrazine, nitrobenzene and metronidazole as probes to quantify the generation of ROS. The exposure of the \({\text{SO}}_{4}^{\bullet -}\) , \(\bullet \text{OH}\) and \({}^{1}{\text{O}}_{2}\) at 6 h was 5.32 × 10 –11 , 5.40 × 10 –12 , 2.52 × 10 –10 M s, which contributed 33.62%, 2.02% and 2.98% to AN degradation, respectively. The main active sites include Mn–O, oxygen containing groups and graphitized carbon. The Mn–O and oxygen containing groups can activate PMS to produce \({\text{SO}}_{4}^{\bullet -}\) and \({}^{1}{\text{O}}_{2}\) , respectively. The graphitized carbon promotes AN degradation by generation of \({\text{SO}}_{4}^{\bullet -}\) and accelerating direct electron transfer. Conclusions Ball milling with manganese carbonate significantly improves the activation performance of carbonized soil for PMS oxidation, and thus promote the resource utilization of post-remediation soil.