Photoaging effects on polyethylene microplastics: Structural changes and chlorpyrifos adsorption

Area of Science:

• Environmental Science
• Polymer Science
• Environmental Chemistry

Background:

• Microplastics (MP) are persistent environmental pollutants with increasing global concern.
• Weathering processes, like UV radiation, alter MP properties, affecting their interaction with environmental contaminants.
• Pesticide sorption by microplastics complicates environmental impact assessments and mitigation strategies.

Purpose of the Study:

• To investigate the impact of UVB-induced photoaging on polyethylene (PE) microplastics.
• To evaluate the sorption behavior of aged PE microplastics towards the pesticide chlorpyrifos (CP).

Main Methods:

• Polyethylene microplastics were subjected to varying durations of UVB radiation to simulate aging.
• Sorption experiments were conducted to quantify chlorpyrifos adsorption onto pristine and aged microplastics.
• Physicochemical properties, morphology, and crystallinity of microplastics were analyzed.
• Density Functional Theory (DFT) calculations were used to model interactions.

Main Results:

• UVB aging significantly altered the physicochemical and morphological properties of PE microplastics.
• Aged microplastics demonstrated a 17.9% increase in chlorpyrifos adsorption capacity compared to pristine PE.
• Enhanced adsorption is linked to increased oxygen-containing functional groups, surface roughness, and reduced crystallinity.
• DFT calculations confirmed altered electronic structures facilitating CP interaction.

Conclusions:

• Photoaged microplastics exhibit a greater affinity for adsorbing pesticides like chlorpyrifos.
• Surface modifications induced by UV weathering play a crucial role in enhanced contaminant sorption.
• Understanding microplastic aging is vital for assessing their environmental risks and developing effective remediation strategies.