In this study, efficient remediation of p-chloroaniline (PCA)-contaminated soil by activated persulfate (PS) using nanosized zero-valent iron/biochar (B-nZVI/BC) through the ball milling method was conducted. Under the conditions of 4.8 g kg-1 B-nZVI/BC and 42.0 mmol L-1 PS with pH 7.49, the concentration of PCA in soil was dramatically decreased from 3.64 mg kg-1 to 1.33 mg kg-1, which was much lower than the remediation target value of 1.96 mg kg-1. Further increasing B-nZVI/BC dosage and PS concentration to 14.4 g kg-1 and 126.0 mmol L-1, the concentration of PCA was as low as 0.15 mg kg-1, corresponding to a degradation efficiency of 95.9%. Electron paramagnetic resonance (EPR) signals indicated SO4•-, •OH, and O2•- radicals were generated and accounted for PCA degradation with the effect of low-valence iron and through the electron transfer process of the sp2 hybridized carbon structure of biochar. 1-chlorobutane and glycine were formed and subsequently decomposed into butanol, butyric acid, ethylene glycol, and glycolic acid, and the degradation pathway of PCA in the B-nZVI/BC-PS system was proposed accordingly. The findings provide a significant implication for cost-effective and environmentally friendly remediation of PCA-contaminated soil using a facile ball milling preparation of B-nZVI/BC and PS.
Keywords: ball milling; p-chloroaniline; persulfate; soil remediation; zero valent iron/biochar.