Free-radical and surface electron transfer dominated bisphenol A degradation in system of ozone and peroxydisulfate co-activated by CoFe2O4-biochar

We developed a composite material of CoFe2O4-biochar (CoFe2O4@BC) with high performance of peroxydisulfate activation and catalytic ozonation for pollutant degradation in one system. Through single-factor experiments and dynamic fitting calculations, the optimal process (that is, CoFe2O4@BC-peroxydisulfate/ozonation) was used to degrade bisphenol A in water. The system revealed higher catalytic efficiencies for bisphenol A (100 mg·L−1) degradation with the removal ratio of 95.8% and TOC removal ratio of 63.4% within 8.0 min. The reaction kinetic in the CoFe2O4@BC-peroxydisulfate/ozonation process was approximately four-fold higher than that in the peroxydisulfate/ozonation process and eight-fold higher than that without any catalyst in the bare peroxydisulfate process. CoFe2O4@BC, peroxydisulfate, and ozonation showed synergism with one another. A thorough discussion was conducted to explicate the peroxydisulfate activation and catalytic ozonation mechanism via radical quenching experiments, oxygen functional group, and electrochemical analysis. Bisphenol A elimination was determined by the combined effects of free-radical dominated pathway and synergistic electron transfer.