Enhanced electron transfer-based nonradical activation of peroxymonosulfate by CoNx sites anchored on carbon nitride nanotubes for the removal of organic pollutants

Abstract

The nonradical pathway selectively oxidizes pollutants with less interference from environmental factors, which can effectively improve the environmental suitability of peroxymonosulfate (PMS) activation. Herein, a Co-doped nanotubular carbon nitride catalyst (Co-CNNT) based on CoNx sites was constructed for stable and efficient PMS activation with a better specific surface area, number of CoNx sites, and electron transfer capability than Co-doped lamellar carbon nitride catalyst (Co-CN). Co-CNNT improved PMS utilization efficiency (∼50%) and enhanced the contribution of the electron transfer pathway to tetracycline (TET) degradation. The enhanced ability of Co-CNNT to adsorb PMS leads to Co-CNNT–PMS* generated by PMS at the CoNx site, which raises the Co-CNNT surface potential and allows PMS to be activated in a manner that captured electrons. Thus, the Co-CNNT/PMS system could effectively destroy electron-rich or low-potential pollutants within 24 min. The stronger environmental adaptability allows it to maintain catalytic activity in complex aqueous matrices, achieving effective oxidation of diluted tetracycline-based pharmaceutical wastewater. This paper reveals the effects of carbon nitride morphology control strategies on the properties of CoNx active sites and PMS activation mechanisms, providing new insights into the induction of nonradical PMS activation pathways.