Facile synthesis of CoFe2O4@BC activated peroxymonosulfate for p-nitrochlorobenzene degradation: Matrix effect and toxicity evaluation

Abstract

p-Nitrochlorobenzene (p-NCB) is widely used in industry and poses a potential threat to the public health due to its persistence, carcinogenicity and mutagenicity. Herein, magnetic catalyst CoFe₂O₄@Biochar (CoFe₂O₄@BC) was synthesized by a facile sol-gel method, efficiently activating peroxymonosulfate (PMS) to degrade p-NCB. The synergistic effect of Fe and Co in well-dispersed CoFe₂O₄ and the electron transfer promote the production of reactive oxygen species (ROS) (OH, SO₄^- and O₂^-), efficiently removing p-NCB enriched by CoFe₂O₄@BC. Under optimum conditions, the CoFe₂O₄@BC/PMS system could remove 89% of p-NCB from water, and the degradation efficiency could reach 80% in soil. Toxic chlorinated intermediates appeared during the degradation process and thus efficient dechlorination process can lower the toxicity of the reaction solution, which was also proved by the oxygen uptake inhibition experiment as well as zebrafish toxicity experiments. Furthermore, p-NCB degradation efficiency could be inhibited by Cl^-, HCO₃^-, HPO₄^2- and humic acid (HA) through quenching effect or occupation of CoFe₂O₄@BC surface active sites while HPO₄^2- could also improve the efficiency by directly activating PMS. The CoFe₂O₄@BC/PMS system can be efficiently applied in the remediation of p-NCB pollution in water and soil.

Keywords: Biochar; CoFe(2)O(4); Environmental matrix; P-Nitrochlorobenzene; Peroxymonosulfate; Toxicity.