Ofloxacin degradation in peroxymonosulfate system by Co/Fe bimetal-doped carbon nitride with pyridine nitrogen regulation

Abstract

A bimetallic cobalt-iron supported graphite carbon nitride (CoFe/NC) was prepared via simple calcination method and used as a persulfate (PMS) activator for the removal of ofloxacin (OFL). The catalytic activity was regulated by pyrolysis temperature and nitrogen species in this activator. The characterization results proved that the material has the characteristics of ultra-low metal load and highly dispersed atoms. The OFL degradation efficiency of PMS activated by activators prepared at different pyrolysis temperatures (500 ℃/700 ℃/900 ℃) was compared. The results showed that the activator CoFe/NC-900 obtained by pyrolysis at 900 ℃ has the best removal efficiency (86%). Metal-pyridine N-site binding, hydroxyl group and electron transfer are the main mechanisms of OFL degradation in the CoFe/NC-900/PMS system. The reactive species responsible for the degradation of OFL were SO4• and •OH. Pollutant intermediates generated during pollutant disposal were detected by HPLC-MS and possible degradation pathways were proposed. Furthermore, the CoFe/NC-900 has good activation properties in different water bodies, and still achieves high performance after five cycles of utilization. This work will benefit the development of environmental friendly catalysts with low metal content and provide new strategies for environmental remediation.