Cost-Effective Abatement of Tetrabromobisphenol A from Contaminated Water by a Visible-Light-Driven Photochemical System

Micro-pollutants in water and wastewater pose significant risks to aquatic ecosystems due to their toxic and persistent nature. However, micro-pollutant abatement using conventional advanced oxidation processes requires high energy and chemical consumption. Therefore, a visible-light-driven photochemical system mediated by AgCl/AgBr composites (Vis-AgCl/AgBr system) was proposed to degrade tetrabromobisphenol A (TBBPA), a model micro-pollutant. The AgCl/AgBr composites, which were fabricated using a simple precipitation method, had a heterojunction structure (an interface formed between AgCl and AgBr). The AgCl/AgBr composites exhibited a narrow bandgap of 2.26 eV, which resulted in high catalytic activity under visible light. The Vis-AgCl/AgBr system efficiently degraded TBBPA in simulated and real water. The TBBPA degradation efficiency of the Vis-AgCl/AgBr system reached 99% within 30 min, which was 0.94–5.9 times higher than that by AgCl or AgBr alone. This efficient TBBPA degradation was attributable to reactive species produced in the Vis-AgCl/AgBr system, including photoelectrons (e−), holes (h+), hydroxyl radicals (•OH), and superoxide radicals (•O2−). Reduction by e− and oxidation by h+, •OH, and •O2− caused the destruction of TBBPA and the formation of bromide (Br−) and debrominated organic products. Debromination was anticipated to reduce the toxicity and persistency of TBBPA and increase its biodegradability. The findings of this study provide a cost-effective solution to the abatement of refractory emerging micro-pollutants in water and wastewater when sunlight can be used as a light source.