Vitamin B12 derived CoCNx composite confined in SBA-15 as highly effective catalyst to activate peroxymonosulfate for naproxen degradation

Abstract

Vitamin B12 confined in the pores of SBA-15 was converted into Co and N co-doped carbon composite (denoted as CoCNx), which was confined in the pores of SBA-15 (CoCNx@SBA-15) after pyrolysis. For comparison, CoCNx catalyst supported on SBA-15 (denoted as CoCNx/SBA-15) was prepared by the impregnation method using VB12 as CoCNx precursor followed by pyrolysis. The catalysts were fully characterized and naproxen (NPX) degradation by catalytic activation of peroxymonosulfate (PMS) on the catalysts was investigated. The characterization results showed that in contrast to CoCNx/SBA-15, CoCNx of CoCNx@SBA-15 was successfully confined in the pores of SBA-15. For catalytic PMS activation for NPX degradation, CoCNx@SBA-15 exhibited a much higher catalytic activity than CoCNx/SBA-15 and CoCNx as well as commonly used carbon-based and Co-based catalysts. Additionally, Co leaching from CoCNx@SBA-15 was substantially suppressed as compared with CoCNx/SBA-15. Accordingly, the removal of either Co or CNx from CoCNx@SBA-15 led to substantially decreased catalytic activity and a considerable synergistic effect was identified between active Co and CNx species for catalytic PMS activation. The reuse of CoCNx@SBA-15 in catalytic PMS activation showed a gradual catalyst deactivation, whereas the activity of the used catalyst could be effectively restored by calcination in N2 atmosphere.