Photocatalytic Degradation of Microplastics Using Visible Light Activated Semiconductors

Abstract

Microplastics represent a pervasive pollutant in aquatic ecosystems, resistant to natural degradation and prone to bioaccumulation. Addressing this challenge, we synthesize zinc doped bismuth oxyhalide (BiOBr?.?Cl?.?:Zn) nanoplates exhibiting a narrowed bandgap (2.1?eV) and high surface area to volume ratio. Under simulated solar irradiation, the catalyst achieves 86?% mineralization of polypropylene microbeads (<500?µm) within 12?h, as quantified by total organic carbon analysis. Mechanistic studies reveal synergistic generation of •O?? and h? radicals, with electron paramagnetic resonance confirming radicals’ dominance in polymer chain scission. A fluidized bed photoreactor, scaled to 5?L, maintains >75?% efficiency over ten cycles without significant photocorrosion. Toxicity assays on Daphnia magna show an 80?% reduction in acute toxicity after treatment. Comparative analysis versus TiO? benchmarks highlights superior visible light utilization and reduced energy demand. The findings offer a pragmatic route toward remediation of plastic laden effluents using sunlight driven chemistry.

Keywords: Microplastic degradation, Photocatalysis, Visible light semiconductors, Bismuth oxyhalide, Environmental remediation