Acceleration of photodegradation of microplastics in aquatic environments through laser pretreatment

The presence of microplastics (MPs) in the environment poses significant challenges due to their structural stability and resistance to degradation. While photocatalytic degradation is recognized as an environmentally sustainable approach, its direct application to MPs is hindered by inefficiencies and slow degradation rates. This study introduces a "Fe/LIP-UV/H2O2" system for efficient degradation of polyethylene microplastics (PE MPs), focusing on the mechanism by which laser-induced plasma (LIP) pretreatment enhances subsequent photodegradation via its instantaneous high-temperature and shock wave effects. The morphological characteristics, elemental composition, chemical bonds, particle size changes, transformation products, and mass loss of the PE MPs were analyzed. The results show that LIP pretreatment severely compromised the surface integrity of the PE MPs, leading to a significant reduction in particle size and generating numerous micron-sized lamellar fragments. Concurrently, iron and iron oxide nanoparticles were found to adsorb onto the surface, facilitating a collaborative interaction between the Fenton reaction and photodegradation in the subsequent treatment phase. After an 18-hour UV/H2O2 treatment, the particle size of the pre-treated PE MPs was further reduced to approximately 60 nm. This research offers a novel strategy for the effective removal of persistent microplastics from the environment.