Removal Mechanism of Carbendazim in Water by Ozone and Remediation of Carbendazim Pollution in Soil

Abstract

Carbendazim, a commonly used fungicide, was identified as a contributor to soil degradation. Despite the extensive use of carbendazim, the degradation mechanisms and the removal process of carbendazim in the soil environment were not yet fully understood. A deeper understanding of the degradation pathways of carbendazim was considered essential for developing effective strategies to mitigate long-term environmental impacts. The degradation of carbendazim using ozone in water and soil environments was investigated with the simulation experiments of ozone exposure in water and soil, and the degradation pathways and removal efficiency of carbendazim in water were also explored under different conditions in the study. The results showed that ozone-induced degradation proceeded in three stages: rapid removal, slow removal, and equilibrium. In water, ozone directly reacted with carbendazim, generating hydroxyl radicals (˙OH), which oxidized carbendazim into intermediates, including 2-aminobenzimidazole, 2-hydroxybenzimidazole, 2-benzimidazolone, and o-phenylenediamine. The intermediates eventually degraded into nontoxic byproducts such as carbon dioxide and water. In soil, ozone treatment enhanced the removal of carbendazim by catalyzing the production of active substances, including hydroxyl radicals (˙OH) and hydrogen peroxide (H₂O₂). Increasing the aeration frequency to four times daily significantly improved the efficiency of carbendazim removal, reaching the peak removal rate of 70.4% after 21 days of ozone exposure in the soil. The findings of this study clarified the theoretical mechanisms of ozone treatment for carbendazim remediation, highlighted the critical role of hydroxyl radicals (˙OH) in the degradation process, and established a scientific foundation for developing remediation strategies targeting carbendazim-induced soil contamination.