The superoxide radicals' production via persulfate activated with CuFe₂O₄@Biochar composites to promote the redox pairs cycling for efficient degradation of o-nitrochlorobenzene in soil

CuFe₂O₄ nanoparticles are decorated on biochar (BC) by modified sol-gel method to form the CuFe₂O₄@BC catalyst for persulfate (PS) activation in a wide pH range. The application of CuFe₂O₄@BC for o-nitrochlorobenzene degradation in soil was explored in this study. The mechanism of heterogeneous PS activation was comprehensively investigated. The synergistic effects between CuFe₂O₄ and BC could enhance catalytic activity and stability, including well dispersed CuFe₂O₄ species, efficient electron transfer and abundant oxygen functional groups. The superoxide radicals (O₂^-) produced from CuFe₂O₄ and BC could mediate Cu(I)/Cu(II) and Fe(II)/Fe(III) redox pairs on CuFe₂O₄@BC surface to activate PS, and then generating •OH and SO₄^- continuously. Moreover, the reaction intermediates are identified as well to elucidate the possible degradation pathways. These findings help to achieve more comprehensive understanding of the heterogeneous activation process of PS by CuFe₂O₄@BC catalyst.