Graphene Oxide–Supported Cobalt Phthalocyanine as Heterogeneous Catalyst to Activate Peroxymonosulfate for Efficient Degradation of Norfloxacin Antibiotics

Abstract

Developing highly potent and environmentally friendly catalysts to activate peroxymonosulfate (PMS) to generate reactive species has received considerable and increasing attention in the field of antibiotics elimination. In the present work, cobalt phthalocyanine (CoPc) supported by graphene oxide (GO) was prepared and used as a heterogeneous catalyst to activate PMS to generate hydroxyl and sulfate radicals for effective degradation of norfloxacin (NOR) in water. In this study, the CoPc/GO/PMS system had the advantages of the excellent performance of sulfate radicals generation and the reduction of cobalt leaching by the catalytic effect of GO delocalizing π electrons. The optimum conditions for NOR degradation were 2.0% by weight CoPc/GO, catalyst dosage of 0.1 g/L, pH of 7, and PMS addition of 0.4 g/L. The analysis of intermediates indicated that the piperazinyl ring and fluorine atom of NOR were attacked by OH• and SO4•− originating from CoPc activation in the CoPc/GO/PMS system. However, anions such as Cl−, NO3−, and CO32− in a natural water environment could inhibit the generation of reactive radicals, greatly affecting the removal of NOR. Meanwhile, the degradation mechanisms of NOR, including intermediate products, degradation pathways, and active species, were analyzed via liquid chromatography-mass spectrometer (LC-MS). It is believed that this work will promote the development of advanced oxidation technology based on PMS activation and the application of a heterogeneous catalyst in water treatment.