TiO₂-based photocatalytic degradation of microplastics in water: Current status, challenges and future perspectives

Abstract

Microplastics are a growing environmental concern due to their persistence, widespread presence in water bodies and uncertain toxic effects on ecosystems and humans. TiO₂-based photocatalysis has emerged as a promising method for degrading microplastics, yet its application is still largely confined to controlled laboratory settings. This review highlights recent developments in the photocatalytic degradation of common plastics such as polyethylene, polypropylene, polystyrene, polyvinyl chloride and polyethylene terephthalate. The process involves generating reactive oxygen species, which initiate chain reactions that break down polymer chains into smaller byproducts. However, the lack of standardized protocols complicates the assessment of photocatalysis performance for microplastic degradation, especially in complex wastewater environments. Despite TiO₂’s advantages, including low cost and stability, its photocatalytic efficiency is often hindered by factors like low solar spectrum efficiency, mass transfer limitations, and charge recombination. These challenges result in low degradation rates and inconsistent outcomes. Further research is needed to improve photocatalyst design, reactor configurations and the standardization of degradation assessment techniques. Additionally, the potential formation of harmful byproducts raises concerns, requiring further investigation of their ecotoxicological impacts. When combined with other treatment methods, TiO₂ photocatalysis shows promise for addressing microplastic pollution and other emerging pollutants in water treatment.