Biochar-Supported Fe2O3/CoFe2O4 Nanocomposite as an Efficient Peroxymonosulfate Activator for the Remediation of PAH-Contaminated Soil

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in soils, and their inherent toxicity and persistence pose serious threats to terrestrial animals and plants. This study reports the synthesis of a biochar-supported Fe2O3/CoFe2O4 nanocomposite (Fe2O3/CoFe2O4@BC) as a peroxymonosulfate (PMS) activator for the degradation of PAHs in contaminated soil. The one-step prepared Fe2O3/CoFe2O4@BC exhibits abundant nanoporous structures, with a specific surface area of 158.34 m2 g−1 and average pore size of 2.84 nm. Compared with pristine biochar (BC), Fe2O3/CoFe2O4@BC shows superior catalytic performance in activating PMS for the efficient degradation of seven kinds of 3–4 ring PAHs in soil. Based on electron paramagnetic resonance (EPR) analysis, electrochemical analysis and scavenger quenching experiments, the catalytic mechanism was elucidated, revealing that •OH, SO4•−, and electron transfer were primarily responsible for the degradation of phenanthrene (PHE) in soil. The presence of coexisting soil constituents, including Cl−, HCO3−, NO3− and humic acid (HA), was found to inhibit PHE degradation. Furthermore, plant growth experiments revealed that the Fe2O3/CoFe2O4@BC/PMS system effectively alleviated the ecotoxicity of PHE-contaminated soil. This work thus provides a promising nanocatalyst for PMS-mediated remediation of soil contaminated with refractory organic pollutants and offers a feasible strategy for the in situ chemical remediation of PAH-polluted soil.