Advanced oxidation process as a promising approach for microplastic degradation.

Area of Science:

• Environmental Science
• Chemical Engineering
• Materials Science

Background:

• Microplastics (MPs) are persistent environmental contaminants challenging conventional treatment methods due to their size and stability.
• Advanced oxidation processes (AOPs) offer a promising degradation-based strategy for chemically transforming MPs via reactive oxygen species (ROS).

Purpose of the Study:

• To critically synthesize and mechanistically review recent advances in AOPs for microplastic degradation.
• To systematically compare various AOPs based on radical generation, degradation mechanisms, efficiency, and operational constraints.

Main Methods:

• Review of photocatalysis, Fenton/photo-Fenton, electrochemical oxidation, persulfate, ozone, and plasma-assisted AOPs.
• Comparative analysis of polymer-specific degradation, efficiency, and influencing factors (polymer type, crystallinity, aging).

Main Results:

• Degradation performance is highly dependent on microplastic characteristics and process conditions; no single AOP is universally effective.
• Integrated and hybrid AOPs (e.g., photo-Fenton, photo-electro-Fenton, persulfate-assisted) demonstrate superior performance through synergistic radical production.
• Key challenges include high energy demand, catalyst sustainability, scalability, and the potential formation of risky secondary transformation products.

Conclusions:

• A comparative and mechanistic framework is provided to advance understanding of AOPs for microplastic remediation.
• Rational design of efficient, scalable, and environmentally sound AOP-based technologies requires addressing identified challenges.