Carbon-doped Co3O4-MgO catalyzed peroxymonosulfate activation via an enhanced Co(III)/Co(II) cycle for rapid chloramphenicol degradation

Advanced oxidation processes based on heterogeneous peroxymonosulfate activation (PMS) have been a feasible strategy for removing organic pollutants. In this study, the waste filter membranes in the laboratory were used as a carbon material, which combines with cobalt and magnesium to obtain the carbon-doped cobalt-magnesium binary oxides (C/Co3O4–MgO) after calcination to activate PMS for chloramphenicol (CAP) degradation. The results revealed that the degradation efficiency of CAP in the C/Co3O4–MgO/PMS system reached 98% within 15 min, much higher than those in C/Co3O4/PMS (62%) and Co3O4–MgO/PMS (68%) systems. The excellent catalytic performance of the C/Co3O4–MgO material was attributable to a good synergistic interaction between C, Co, and Mg. Electron paramagnetic resonance test and quenching experiments confirmed that •OH, SO4•−, and 1O2 were reactive oxygen species involved in CAP degradation. The intermediates of CAP degradation were analyzed via a high-performance liquid chromatography–high-resolution mass spectrometry method, and the possible degradation pathways of CAP were proposed. C/Co3O4–MgO exhibited good stability and reusability. The concentration of leached Co ions was lower than 0.53 mg L−1, and over 95% of CAP was still decomposed in the fifth cycle. Furthermore, the degradation of rhodamine B, sulfamethazine, and phenacetin via PMS activation by C/Co3O4–MgO was investigated. These three pollutants are almost completely degraded within 10 min. Therefore, C/Co3O4–MgO is an excellent heterogeneous catalyst used for activating PMS to degrade organic pollutants.