Peroxymonosulfate-assisted photocatalysis with g-C3N4/BiOCOOH nanocomposites for the synergistic removal of organic pollutants

Photocatalysis is an efficacious technology for pollutants degradation; however, there remains ample room for the improvement of its degradation efficiency. Herein, a system involving a g-C3N4/BiOCOOH photocatalyst coupled with peroxymonosulfate (PMS) was developed, using Malachite green (MG), Rhodamine B (RhB), ciprofloxacin hydrochloride (CIP), and levofloxacin hydrochloride (LVF) as target pollutants. The prepared g-C3N4/ BiOCOOH nanocomposites were systematically characterized. In contrast to pure g-C3N4 or BiOCOOH, the photocatalytic activities of the nanocomposites were enhanced due to the formation of g-C3N4/BiOCOOH heterojunctions, extensive specific surface areas, and more efficient charge separation. The degradation of RhB, MG, CIP, and LVF was further improved in this g-C3N4/BiOCOOH/PMS system due to the synergistic effects between the photocatalysts and PMS (the degradation of MG in the photocatalyst/PMS system was four fold that of a single photocatalyst system). An exploration of these synergetic mechanisms indicated that center dot O2- and O-1(2) were the most significant reactive oxygen species in the single photocatalysis system, whereas in the photocatalyst/PMS system, additional O-1(2) was generated due to the addition of PMS, and became the dominant species. This research suggests that the combination of photocatalysts and PMS is a feasible strategy for improving the pollutant removal activities of photocatalysts, which have strong potential for myriad applications in environmental remediation.