Cobalt-based sea urchin-shaped hollow microspheres promotes PMS activation for ultrafast removal of PAHs

Addressing the secondary contamination associated with advanced oxidation processes based on sulfate radicals (SR-AOPs) is the primary challenge in developing efficient cobalt-based catalysts. In this study, a simple two-step hydrothermal procedure was used to successfully prepare hollow sea urchin-like Co3O4@CuO/CuMoO4 (CCM) polymetallic composite catalysts to rapid activate peroxymonosufalte (PMS) for phenanthrene (PHE) degradation with less amount of catalyst and PMS. Mo doping effectively enhanced the redox cycle between Co-Cu bimetals and could achieve 100% degradation of PHE within 10 min with a higher kinetic-rate constant (k= 0.402 min(-1)), it was 3.2 times higher than that of Co3O4@CuO (CoCu). Quenching experiments, XPS, and EPR confirmed that the incorporation of Mo facilitated CoOH+ formation and altered the production of reactive oxygen species, the oxidative degradation of PHE changed from a non-radical (O-1(2)) dominated to a combination of multiple reactive oxygen species (SO4 center dot-, center dot OH, and O-1(2)). The toxicity of the intermediates was evaluated using T.E.S.T. and lettuce germination experiments to verify the superior mineralization capacity of the CCM/PMS system for PHE degradation. Also, the efficiency and stability of the catalysts in actual wastewater treatment provided significant value for the practical application of SR-AOPs.