Amorphous Co3O4 nanoparticles-decorated biochar as an efficient activator of peroxymonosulfate for the removal of sulfamethazine in aqueous solution

In this study, amorphous Co 3 O 4 nanoparticles-decorated biochar was synthesized and employed to activate peroxymonosulfate (PMS) for sulfamethazine (SMT) degradation in aqueous solution. Hydrochar of corn straw obtained from hydrothermal carbonization was impregnated in CoCl 2 solution for anchoring cobalt nanoparticles onto biochar surface before pyrolysis. Application conditions of as-prepared cobalt-loaded biochar (Co-BC) involving dosage, pyrolysis temperature, cobalt loading, solution pH and groundwater components were examined; and the stability of the catalyst was investigated by examining its performance in recycling experiments (3 rounds) and the variation of catalytic mechanism in recycling experiment was investigated. 100% SMT was removed under the optimum condition within 60 min: 1.0 mmol/L CoCl 2 aqueous solution, 800 °C of pyrolysis temperature, 400 mg/L Co-BC, 0.06 mM PMS, solution pH 8. The results turned out that the amorphous Co 3 O 4 nanoparticles were favorable for the activation of PMS. BC not only played as a support for dispersion of Co 3 O 4 nanoparticles but also acted as an electron shuttle between Co 3 O 4 and PMS/SMT molecules. During the recycling use, the key free radicals changed from ▪OH and SO 4 ▪- to SO 4 ▪- and only low degree of cobalt ions leaching was monitored. Additionally, the mixed groundwater components exerted trivial influence on the reaction system.