Dramatic enhancement of mineralization capability for ozone/peroxymonosulfate process by single atom Co/CMK-3 catalyst

Single Co atoms dispersed on CMK-3 was synthesized and employed as efficient catalyst to degrade APAP in O3/PMS process. The results of morphology and structure characterization indicated that the as prepared catalyst possessed uniform array of mesoporous channel structure with a long-range. Co atoms were single atomic dispersed in CMK-3 skeleton with the form of CoN4 coordination. The BET surface area and average pore diameter of 3.6% SA Co/CMK-3 were measured as 956 m2/g and 3.6 nm, respectively. For APAP degradation by 3.6% SA Co/CMK-3 + PMS/O3 process, TOC removal efficiency reached to 60% and 78.9% in initial 1 min and 15 min, respectively. The influence of initial pH was investigated and demonstrated that APAP could be efficiently mineralized in a wide pH range. In addition, high mineralization rates were also achieved for other refractory organics (nitrobenzene and sulfamethoxazole). Radical quenching experiments and ESR indicated that SO4•− , •OH and 1O2 were all responsible for APAP degradation. DFT simulations elucidated that single Co atoms and N-heteroatoms on 3.6% SA Co/CMK-3 served as dual reaction sites for PMS and O3 decomposition, which enhanced the ROS generation and APAP mineralization.