Fabrication of CoFe2O4/BC composite for efficient degradation of organic pollutants via percarbonate activation: Performance, mechanistic insight, and toxicity assessment

Abstract

Advanced oxidation using sodium percarbonate (SPC) is an economical and environmentally friendly method for removing pollutants and treating water bodies. In this study, CoFe₂O₄ spinel (CF) was loaded onto biochar (BC), as a carrier, to construct a heterogeneous composite catalyst (CoFe₂O₄/BC). Due to the synergistic interaction between BC and CoFe₂O₄, CoFe₂O₄/BC (CFB) effectively and stably activated SPC for removing pollutants from aqueous media. The optimized catalyst (CF/BC = 2:1) CFB-2:1 achieved efficient removal of tetracycline hydrochloride (TC) within 30 min (6.05 and 2.34 times that of BC and pristine CoFe₂O₄, respectively). The CFB-2:1/SPC system exhibited excellent catalytic performance with variation of the environmental conditions (pH, inorganic anions, humic acids, and water matrices) and good reusability. Quenching experiments and electron paramagnetic resonance (EPR) demonstrated that the degradation of TC in the reaction system involved multiple reactive oxygen species (CO₃^•−, ¹O₂, O₂^•−, and •OH), among which CO₃^•− and O₂^•− played important roles. The potential pathways of TC degradation in the system were elucidated via density functional theory (DFT), while the ecological toxicity of the intermediate products was calculated using the T.E.S.T. (Toxicity Estimation Software Tool) method. This work offers novel perspectives on the design of bimetallic catalysts for SPC activation and highlights the potential applicability of this system in remediating of polluted aquatic environments.