Heterogeneous activation of peroxymonosulfate over monodispersed Co3O4/activated carbon for efficient degradation of gaseous toluene

Gas-phase VOCs decomposition generally produces intermediates and causes secondary air pollution. To avoid this issue, we proposed a novel method for a typical gaseous VOC (toluene) degradation via catalytic activation of peroxymonosulfate (PMS) in the liquid phase. Herein, activated carbon supported monodispersed Co 3 O 4 nanoparticles (Co 3 O 4 /AC) were prepared via a facile deposition method. It is highly efficient in PMS activation for toluene degradation due to the presence of Co-OH + species and well dispersed Co 3 O 4 on Co 3 O 4 /AC. A toluene removal efficiency of nearly 90% was maintained during the reaction, and few gaseous intermediates were discharged. Sulfate radical (SO 4 − ) and hydroxyl radical (HO ) derived from PMS activation played different roles during toluene oxidation and mineralization. Electron spin resonance (EPR) suggested that the generation of plentiful SO 4 − resulted in the superior toluene degradation, and the presence of HO can improve carbon mineralization. Radical quenching tests further confirmed that SO 4 − played a dominant role for toluene degradation, whereas the absence of HO inhibited the carbon mineralization. The toluene degradation pathway in the Co 3 O 4 /AC-PMS system was proposed based on the intermediates identified by GC–MS.