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.