ZIF-67/melamine derived hollow N-doped carbon/Co9S8 polyhedron to activate peroxymonosulfate for degradation of tetracycline

A N-doped carbon-wrapped Co 9 S 8 catalyst (N-C/Co 9 S 8 ) was prepared in this work by pyrolysis sulfurized-ZIF-67 and melamine mixture. The prepared catalyst was used to degrade tetracycline (TC) with peroxymonosulfate (PMS) as oxidant. The optimized catalyst could remove 96.8 % TC in 15 min with a rate constant of 0.196 min –1 . The degradation mechanism, intermediates, and possible pathway were discussed. It was found that pyridinic N, Co-N, Co species, S 2– , C-S-C, and C-SO x were active sites to activate PMS. The N-doped carbon (N-C) could facilitate electron transfer . The surface-bound ·OH, SO 4 •− , and ⋅O 2 − radicals, especially 1 O 2 and electron transfer mechanism contributed to TC degradation . The effects of solution pH, inorganic ions and humic acid on TC degradation were discussed. This study might prompt the development of other ZIF-67-derived sulfides for environmental remediation.