Boosting organic pollutant degradation through synergistic photocatalysis and peroxymonosulfate activation by bismuth oxybromide

Abstract

Integrating semiconductor photocatalysis with peroxymonosulfate (PMS) activation has proven to be a highly effective solution for eliminating refractory organic pollutants from water. Herein, a synergistic system that couples bismuth oxybromide (BiOBr), obtained via a hydrothermal process, with PMS under visible light (Vis) is developed. The results show that the BiOBr/PMS/Vis system exhibits obviously enhanced removal efficiency for tetracycline hydrochloride compared to its individual components, along with moderate reusability. Subsequently, the applicability of the system was assessed by determining the influence of inorganic anions, degradation performance in different water matrices, and effectiveness against different pollutants. Notably, the addition of typical inorganic anions, particularly chlorine and carbonate ions, is found to promote the removal efficiency. Moreover, the system performs more effectively in lake water and tap water than in ultrapure water. When applied to various contaminants, including Rhodamine B, methylene blue, methyl orange, and levofloxacin, the system achieves high removal efficiency for most compounds. Mechanistic investigations reveal that PMS simultaneously functions as an electron acceptor to facilitate charge separation and participates in a surface redox cycle. During the reaction process, superoxide radicals and photogenerated holes appear to be the dominant reactive species, while hydroxyl radicals and singlet oxygen play a secondary role. This work provides insights into the cooperative behaviour of photocatalysis and PMS activation and highlights the potential of the BiOBr/PMS/Vis system as an efficient candidate for organic wastewater remediation.