Oxygen vacancy synergetic mediated generation of 1O2 to enhance metronidazole degradation over N, S co-modified ZIF derivative anchored Fe0/peroxydisulfate system

The surface passivation deactivation and limited supply of Fe 2+ on nano zero-valent iron (nZVI, Fe 0 ) restrict activation of persulfate. Herein, L-cysteine modified cobalt-based ZIF derivative anchored Fe 0 (Fe 0 @ZIF-CoNS2) containing luxuriant oxygen vacancy (O v ) defects and bimetals was fabricated. The sintered bulk ZIF-CoNS2 and chain-shaped Fe 0 were disaggregated into rough and dispersed nanospheres, meanwhile, the loading of Fe 0 increased the specific surface area of ZIF-CoNS2 by 11 times. The peroxydisulfate (PDS) consumption efficiency of 96.11 % and the metronidazole (MNZ) removal efficiency of 96 % were achieved by the catalytic action of 0.18 g/L Fe 0 @ZIF-CoNS2. Compared than the unmodified system, the leaching concentrations of Fe and Co ions were reduced by 7.33 mg/L and 4.44 mg/L, respectively. The regulation of L-cysteine elevated the relative ratio of O v from 0.46 to 6.26 and augmented the electron transfer ability of precursor. Fe, Co and O v were identified as the main active sites, where O v played an important role as a medium in inducing sustainable generation of Fe 2+ /Co 2+ and 1 O 2 . The modified system fulfills the degradation of MNZ through plentiful 1 O 2 and scant free radical. This research offers insights into the formation of O v and enhancement of nZVI reactivity during advanced oxidation processes.