UV-AGING OF POLYETHYLENE TYPE MICROPLASTICS AND ITS EFFECT ON SORPTION OF ORGANIC CONTAMINANTS

Date

2024-9-2

Author

Türkeli, Ülkü Dide

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Microplastics (MPs), plastic particles smaller than 5 mm, pose a significant environmental risk due to their ubiquitous presence and ability to retain organic contaminants (OCs) on their surfaces, which impart toxicity in organisms. Environmental aging alters the surface properties of MPs, influencing their interactions with OCs. This thesis investigates the sorption of Malachite Green (MG) and Perchloroethylene (PCE) on pristine and UV-aged polyethylene (PE) MPs, specifically high-density PE (HDPE) and low-density PE (LDPE). UV-aging in laboratory conditions simulated environmental exposure, leading to the formation of new functional groups like carbonyl and changes in surface morphology, melting temperature, and crystallinity. Kinetic studies showed faster equilibrium for MG and PCE with pristine LDPE compared to HDPE. Comparative equilibrium studies indicated that UV-aging significantly enhanced MG sorption (log KPEw =1.18 L/kg for pristine vs. 2.20 L/kg for UV-aged LDPE), whereas PCE sorption remained unchanged (log KPEw=2.72 L/kg for pristine vs. 2.78 L/kg for UV-aged LDPE). Enhanced MG sorption was attributed to increased hydrophilic interactions of UV-aged LDPE, contrasting with hydrophobic interactions of pristine LDPE. MG sorption was also influenced by pH, solution matrix, and particle size, while PCE sorption was unaffected. Diffusion into the polymer, i.e., partitioning and chemisorption are discussed as possible sorption mechanisms. The coexistence of MPs and OCs in the environment may facilitate the transport of chemicals through MPs, contributing to bioaccumulation and intensifying their impact on the food web. This highlights the necessity for further research into the potential impacts of MP-OC pollution.

Subject Keywords

Microplastics, Organic Contaminants, Aging, Malachite Green, PCE.

URI

https://hdl.handle.net/11511/111482

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Graduate School of Natural and Applied Sciences, Thesis