Heterogeneous degradation of refractory pollutants by peroxymonosulfate activated by CoOx-doped ordered mesoporous carbon

CoOx-doped ordered mesoporous carbon (Co-OMC) was synthesized and employed as an efficient activator of peroxymonosulfate (PMS) for the degradation of refractory pollutants. Co-OMC possessed high BET specific surface area (723 m2/g) and uniform pore size distribution (∼4 nm) because of its ordered mesoporous structure. 20 mg/L phenol could be completely degraded with the addition of 0.1 g/L Co-OMC and 1 mM PMS in 60 min. In addition, the catalytic activity of Co-OMC for PMS activation was much higher than some efficient catalysts such as Co3O4, CoFe2O4 and OMC. Besides, Co-OMC showed remarkable efficiency for the destruction of seven representative pollutants. Results indicated that the catalytic activity of Co-OMC increased with the calcination temperature increasing, which may be caused by the higher defect degree at higher calcination temperature. In addition, various practical parameters such as PMS concentration, initial pH, anion, nature organic matter and reaction temperature were systematically investigated using phenol as the target pollutant. The electron-spin resonance and radical quenching experiments results demonstrated that reactive oxygen species (ROS), such as SO4−, OH, O2− and 1O2, were involved in the degradation of phenol, and their generation strongly depended on the solution pH. Based on these results, a catalytic mechanism for PMS activation was proposed: O2− and 1O2 were responsible for the degradation of phenol when initial pH was 6, but the role of SO4− and OH was limited; while SO4− and OH were the major reactive species when initial pH was 11.0.