A new strategy integrating peroxymonosulfate oxidation and soil amendments in contaminated soil: Bensulfuron methyl degradation, soil quality improvement and maize growth promotion

Bensulfuron methyl (BSM) residues have caused serious yield reductions of sensitive crops. Chemical oxidation is an effective remediation technology, while it affects soil quality and subsequent agricultural activity, necessitating approriate improvement measures. So Fe₂O₃-Mn₃O₄ with excellent bimetallic synergistic effect was synthesized to activate peroxymonosulfate (PMS) for BSM degradation. The catalytic activity and influencing factors were systematically predetermined in water in view of soil remediation. Results showed Fe₂O₃-Mn₃O₄/PMS oxidized 99.3 % BSM within 60 min with the help of multi-reactive species and electron transfer. Meanwhile, Fe₂O₃-Mn₃O₄/PMS treatment exhibited technical feasibility in soil that 97.6 % BSM was degraded in 5 days under the low usages of Fe₂O₃-Mn₃O₄ (0.8 %) and PMS (0.15 %). Although Fe₂O₃-Mn₃O₄/PMS decreased BSM phytotoxicity and improved maize growth, a few gaps existed between the remediated group and uncontaminated group, including biomass, length, available potassium, organic matters, pH, redox potential (Eh) and sulfate content. The introductions of biochar and chitosan in remediated soils promoted growth, increased organic matters content, improved soil resistance to acidification and decreased Eh, alleviating the negative effects of Fe₂O₃-Mn₃O₄/PMS. Overall, the study provided new insights into the combination of Fe₂O₃-Mn₃O₄/PMS and biochar and chitosan in BSM-contaminated soil, achieving BSM degradation and improvements of soil quality and plant growth.