Chemical Degradation of Microplastics: Current Technologies, Mechanisms, Challenges, and Future Perspectives

Abstract

Plastic pollution and pervasive microplastic contamination across terrestrial- aquatic ecosystems have raised widespread environmental concerns. Nevertheless, conventional water treatment only physically separates microplastics instead of destroying polymer structures, merely transferring pollutants rather than eliminating them completely. Against this backdrop, advanced oxidation processes (AOPs)- based chemical degradation stands out as a promising strategy, for highly reactive radicals can directly cleave polymer backbones. This review first outlines chemical properties and degradation patterns of typical microplastics including PE, PP, PET, PS and PVC. Subsequently, it systematically compares core mechanisms, merits and drawbacks of representative AOP technologies: photocatalysis, Fenton-like oxidation, ozonation, electrochemical oxidation and persulfate-activated hybrid systems. Notably, particle fragmentation should not be confused with genuine mineralization, since surface cracking and weight loss cannot guarantee full conversion of plastic carbon into harmless CO₂ and H₂O. In addition, practical application faces major obstacles such as incomplete mineralization, high energy consumption, difficult catalyst recovery and toxic intermediate risks. More importantly, most laboratory tests use pristine microplastics, whose behaviors differ greatly from environmentally aged counterparts. Accordingly, renewable-energy-driven hybrid systems are highly recommended for future research. Ultimately, standardized evaluation criteria, reusable catalysts and toxicity assessments are essential to translate lab-scale achievements into real-world microplastic remediation.