Peroxymonosulfate assisted mechanochemical method for the degradation of phenanthrene in contaminated soils

In recent years, mechanochemical method has received attention in the field of degrading pollutants, especially for persistent organic pollutants. In this study, peroxymonosulfate (PMS) as a co-grinding reagent, coupled with contaminated soil were placed in a ball mill for mechanochemical reaction. Through investigating the influences of ball-milling parameters on the degradation efficiency, the reaction conditions were optimized. Under the optimal condition (mass ratio of soil to oxidant is 10:1, mass ratio of ball to material is 30:1, rotation speed of ball mill is 400 rpm), more than 98% phenanthrene (PHE) in contaminated soil could be degraded within 4 h. Meanwhile, the effects of soil organic matter content and soil type on the degradation efficiency were investigated. The results showed that the organic matter content was negatively correlated with the degradation efficiency. XPS analysis provided evidence for the breakage of the CC bond and confirmed that Fe in soil was an important factor in activating PMS. XRD further verified the destruction of PHE structure. GC-MS analysis was performed to identify the intermediates and possible pathways were proposed. Keywords: Mechanochemical method, PMS, PHE, Degradation, Soi