Degradation of sulfamethoxazole using peroxymonosulfate activated by cobalt embedded into N, O co-doped carbon nanotubes

In this study, cobalt embedded into oxygen and nitrogen co-doped CNTs (Co@N-O-CNTs) was prepared by pyrolysis and used to activate peroxymonosulfate (PMS) for degradation of sulfamethoxazole. The experimental results showed that the content of oxygen precursor had important influence on the catalytic activity of Co@N-O-CNTs. When the content of oxygen precursor was 2 g, Co@N-O-CNTs exhibited better catalytic activity than previously reported Co@N-CNTs. Bulk and surface-bound radicals resulted in sulfamethoxazole (SMX) degradation, in which SMX degradation rate reached 0.247 min(-1) with the mineralization of 35.6%. The possible pathway of SMX degradation was proposed based on the identified degradation products. Characterization results indicated that nitrogen, oxygen and cobalt in the structure of Co@N-O-CNTs-2 were active sites for PMS activation. Theoretical calculation suggested that nitrogen and oxygen co-doping created more active sites to activate PMS compared with single nitrogen doping. During the six cycling experiments, Co@N-O-CNTs-2 exhibited good catalytic and structural stability. The influencing factors, including temperature, pH, PMS concentration, chloridion, bicarbonate and humic acids were investigated. This study could provide a way to boost active sites of nitrogen doped carbonaceous materials to effectively activate PMS for degradation of emerging organic pollutants.

Automated summary

In this study, cobalt embedded into oxygen and nitrogen co-doped CNTs was prepared by pyrolysis for activating peroxymonosulfate (PMS) to degrade sulfamethoxazole. The presence of oxygen precursor significantly influenced the catalytic activity of Co@N-O-CNTs. Experimental results indicated that nitrogen, oxygen, and cobalt in the Co@N-O-CNTs structure served as active sites for PMS activation.