ZIF-8-derived single-atom Cu and N co-coordinated porous carbon as bifunctional material for SMX removal

Single-atom Cu and N co-coordinated porous carbon (Cu-N-C) was synthesized by hydrothermal-calcination using zinc zeolite imidazole frameworks (ZIF-8) as the precursor. The catalyst showed excellent adsorption and catalytic ability due to the ideally-dispersed single atomic copper sites and the unique nitrogen-doped porous carbon. The complete removal of sulfamethoxazole (SMX, 18 mg/L) could be achieved within 40 min of pre-adsorption and 25 min of oxidative degradation in the present of peroxymonosulfate (PMS). The adsorption capacity of Cu-N-C (0.2 g/L) was evaluated to be 58.69 mg/g. The apparent degradation rate constant (k) of SMX on Cu-N-C was 0.155 min-1, which was 14.1 times faster than that on N-C (0.011 min-1). From the activation mechanism, it was found that CuN units acted as the main active sites in Cu-N-C for PMS activation. EPR analysis and quenching experiments verified that the reactive oxygen species (ROSs) of SO4·- and 1O2 were involved in the decomposition and mineralization of SMX. This work provides a new perspective for the development of Fenton-like single-atom catalysts.