Abstract
Petroleum contamination poses a serious threat to soil ecosystems and microbial communities. Persulfate (PS)-based advanced oxidation has shown promising remediation potential; however, conventional nanoscale zero-valent iron (nZVI) suffers from surface passivation, aggregation, and limited stability in complex soil systems. To address these challenges, a biochar-supported sulfidated nanoscale zero-valent iron composite (S-nZVI@BC) was synthesized via liquid-phase reduction to enhance PS activation efficiency and improve remediation performance in crude oil-contaminated soil. Material characterization confirmed the successful loading of sulfidated nZVI onto biochar with good dispersion. At a biochar loading rate of 25%, S/Fe molar ratio of 1:10, and activated carbon particle size of 0.83 mm, the S-nZVI@BC/PS system achieved the best crude oil degradation effect. Moreover, a maximum degradation efficiency of 90.14% was achieved by employing PS and S-nZVI@BC dosages of 2 and 10%, respectively, at a water-soil ratio of 1:1. SO(4) (-)∙ and ∙OH are the primary species responsible for crude oil degradation, and the contribution of SO(4) (-)∙ was greater than that of ∙OH. After the reaction, significant reductions were observed in saturated hydrocarbons, aromatic hydrocarbons, resins, and asphaltenes. Meanwhile, The soil remediated by S-nZVI@BC/PS altered the microbial community structure and increased the relative abundance of petroleum degradation-related microorganisms. The germination rate of Elymus dahuricus increased markedly, approaching that of uncontaminated soil. These findings highlight the potential of the S-nZVI@BC/PS system as an efficient and sustainable strategy for the remediation of crude oil-contaminated soils.