Co,Zn-MOF derived Co@C-NCNTs for boosting non-radical oxidation of norfloxacin by peroxymonosulfate

Norfloxacin (NX), as one of the most widely used antibiotics, is becoming a potential pollutant in water. Here, the cobalt-decorated nitrogen-rich carbon material containing abundant carbon nanotubes (Co@C-NCNTs) was synthesized by pyrolysis of the Co,Zn bimetal organic frameworks (Co,Zn-MOF). The introduction of Zn led to the formation of abundant CNTs with high aspect ratio and high N-doping in the carbon metrix. The obtained Co@C-NCNTs catalyst was applied to boost non-radical catalysis of peroxymonosulfate for NX degradation with high efficiency. The release of cobalt was greatly inhibited by Co-N interaction and carbon layer protection. The CNTs amount in Co@C-NCNTs and its catalytic activity were tunable with the Zn/Co ratio. At the optimal Zn/Co ratio, the derived Co@C-NCNTs delivered 92% removal of NX in 30 min, significantly higher than the single Co-MOF based catalyst. Free radical quenching experiments and electron paramagnetic resonance demonstrated the singlet 1O2-dominated degradation process of NX accompanied by the •OH and SO4− effect. The electrochemical characterization verified that the electron transfer in the PMS system is greatly enhanced due to the presence of Co@C-NCNTs.