Peroxymonosulfate activation on carbon nano-onions modified graphitic carbon nitride via light-tuning radical and nonradical pathways

Carbon-based catalyst has unique advantages as peroxymonosulfate (PMS) activator due to its unique structure and metal-free characteristics. Herein, the carbon nano-onions modified graphitic carbon nitride (CN-CNO) were prepared via the facile ultrasonic-assisted method in different proportions. With the aid of visible-light, the CN-CNO catalyst possessed a much better PMS activation capacity for norfloxacin (NOR) degradation than conventional C3N4. The incorporation of CNO with g-C3N4 provided an effective interface afforded by the π-π stacking interaction, which significantly enhanced photogenerated-electron mobility as evidenced by electron microscopy and electrochemical studies. Radical quenching experiments and EPR illustrated that the outstanding oxidative performance of CN-CNO/PMS system originated from the h+, O2•-, SO4•-, •OH and 1O2 under visible-light irradiation. In addition, in the absence of light, CN-CNO/PMS system exhibited nonradical degradation for NOR through the possible surface-bound complexes mediated electron transfer pathway, confirmed by radical scavenging, substrate specificity test and ATR-FTIR spectra. According to the NOR degradation path analysis, complete intermediates were detected under visible light. This study supplies new insight into the fabrication and application of carbon-based catalysts for efficient antibiotic pollution elimination in aquatic environments.