Novel activated carbon-supported multi-metal oxides for peroxydisulfate activation and efficient organic pollutant degradation: insights into operations, transformation mechanism, and DFT study

Abstract

Bisphenol A (BPA), a widely used endocrine-disrupting compound, poses significant environmental and health risks due to its persistence and resistance to conventional water treatment methods. Overcoming the limitations of existing catalytic systems, such as low selectivity, poor stability, and vulnerability to matrix interferences, remains a major challenge in wastewater treatment. Herein, we present a novel magnetic composite catalyst, activated carbon-coated multimetallic oxides (ACMOs), for peroxydisulfate (PS) activation, which enables efficient BPA degradation through radical and non-radical-mediated pathways. ACMO catalysts were established by immobilizing spinel cobalt ferrite (CoFe₂O₄) and magnetite (Fe₃O₄) nanoparticles onto AC. The complete degradation and more than 70% mineralization of BPA were achieved in the ACMO/PS system within 90 minutes under optimized conditions with outstanding catalytic performance of this system. Complementary quenching tests revealed that reactive oxygen species (ROS), including SO₄˙⁻, HO˙, O₂˙⁻, and ¹O₂, were primarily responsible for BPA degradation through dual ring-cleavage pathways, as confirmed by DFT and LC-MS studies. Subsequently, the study confirmed the excellent reusability of the catalyst over five cycles, with minimal loss of efficiency and negligible metal leaching. The ACMO also exhibits good catalytic reactivity toward activation of other chemical oxidants (hydrogen peroxide (HP), peroxymonosulfate (PMS), peracetic acid (PAA), and periodate (PI)). Overall, the ACMO/PS system offers a novel, promising, practical, and environmentally friendly method for BPA degradation, even in complex water matrices. These findings offer a sustainable strategy for future development of practical applications.