Rapid and Sustainable Decontamination of Antibiotics Using a Bifunctional Catalyst

The oxidation of antibiotics in wastewaters into less or nontoxic products is very challenging because of their strong chemical resistance. Herein, the conversion of peroxymonosulfate (PMS) into highly oxidative species was boosted by the use of an innovative bifunctional catalyst based on Co-doped carbon spheres (ZIF67@RF) obtained from the calcination of resorcinol-formaldehyde resins and ZIF67. The calcination of the catalyst composite led to the transfer of RF resin into a highly porous material, which improves the sorption ability toward antibiotics. On top of that, heat treatment is behind the conversion of pyridinic N into pyrrolic N and graphitic N in the ZIF67@RF platform. These groups exhibit important activity toward in situ generation of 1O2 oxidative species. The ZIF67@RF-800+PMS system showed the best performance toward the oxidation of ciprofloxacin, with an oxidation rate of up to 97% at a concentration of 10 mg/L within 2 h and a kinetic constant of 0.2006 min-1. It was found that the increase of solution pH led to lower ciprofloxacin oxidation because of the conversion of center dot OH and SO4 center dot- into nonactive HSO5 - and SO5 2- species. EPR experiments proved that multiple reactive species including center dot OH, SO4 center dot-, and 1O2 contributed synergistically to the degradation of ciprofloxacin, while 1O2 played the most crucial role. In addition to the efficiency, the catalyst showed excellent stability as confirmed by cycling tests without a notable reduction in the efficiency. Overall, this work provides a simple approach to design highly porous Co-doped carbon spheres for fast PMS activation toward the advanced oxidation of antibiotics at large scale.