Photocatalytic degradation of polyethylene microplastics by copper-doped titanium dioxide nanoparticles

The rising prevalence of microplastics in aquatic environments poses significant environmental and ecological challenges. Although various methods have been tried to solve the issues of microplastics, most approaches are inefficient and energy-intensive, or involve surface-level removal rather than molecular degradation. This study explores the application of Cu-doped TiO₂ nanoparticles as efficient photocatalysts for the degradation of polyethylene microplastics under ultraviolet light irradiation. Cu-doping improves the light absorption efficiency and enhances the photocatalytic activity of TiO₂. Photocatalytic experiments using Cu-doped TiO₂ nanoparticles revealed a significant degradation of microplastics from tens of μm to a few μm, demonstrating superior performance compared to undoped TiO₂. The degradation of 96.7 % in the 48-h reaction was higher than that achieved by the pristine TiO₂ catalyst. According to reactive species-trapping experiments using scavengers, degradation reactions are mainly attributed to holes and reactive oxygen species, particularly hydroxy radical. Then the degradation mechanism staring from the generation of ^•OH in the valence band of the catalyst, was estimated. The unit species and terminal groups produced by the reaction process were consistent with those revealed by the infrared absorption spectra. These findings highlight the potential of photocatalytic reactions as valuable solutions for mitigating microplastic pollution.