Formic acid promotes chemical remediation of carbon tetrachloride contaminated soil during thermal activated persulfate processing via reductive radicals

Carbon tetrachloride (CT, CCl₄) is one typical persistent organochlorine pollutant, which is refractory to be degraded in environment due to its strong chemical inertness. In this study, organic acids were introduced into the thermal activated persulfate (PS) system, which would react with oxidative radicals to generate reductive radicals, promoting the rapid degradation of CT. The results showed that formic acid (FA) enhanced the degradation rate by 3.38 times compared to the PS system alone, and the reductive degradation dominated in this process. Electron paramagnetic resonance (EPR) spectra, quenching experiments, and probe trapping confirmed that carbon dioxide radicals (CO 2 •- ) was the primary reactive specie responsible for CT degradation. This system can achieve great effect on a variety of soils with different properties. Furthermore, the microbial community analysis of soil revealed that the thermal/PS/FA system caused less disruption on soil microbiome and promoted faster microbial recovery than thermal/PS systems. This study proposes a green and efficient technology for remediating CT-contaminated soils. The thermal/PS/FA system mitigates adverse effects on soil microbial communities and accelerates ecosystem recovery, underscoring its potential as a sustainable technology for environmental pollution treatment.