Activation of Persulfate for the Degradation of Ethyl-parathion in Soil: Combined Effects of Microwave with Biochar

Abstract

Sulfate radical (SO4−•), formed by persulfate (PS) activation during advanced oxidation process, can be used for the remediation of organic contaminated soil. However, the role of biochar and microwave (MW) in the activation of PS are not fully understood, especially the corresponding mechanism. Herein, biochar combined with MW were used to activate PS for the remediation of ethyl-parathion (PTH)-polluted soil. The dynamic evolutions of PTH under different conditions, such as biochar content, types, and reaction temperature, and the degradation mechanisms of PTH were also systematically investigated. Significant enhancement performance on PTH removal was observed after adding BC, which was increased from 75.35–88.78% within 80 min. Meanwhile, activating temperature and the PFRs in biochar exhibited remarkable abilities to activate PS for PTH removal. Furthermore, chemical probe tests coupled with quenching experiments confirmed that biochar combined with MW system contributed to the decomposition of PS into active species, such as SO4−•, •OH and O2−•, which could oxidize PTH into oxidative products, including paraoxon, p-nitrophenol, and hydroquinone. The results of this study provided valuable insights into the synergistic effects of biochar and MW in the PS activation, which is helpful for the potential application of biochar materials combined with MW-activated PS in the remediation of pesticide-polluted soils.