Date of Award

Spring 2022

Track

Chemistry

Degree Type

Thesis

Degree Name

Master of Science in Chemical Sciences (MSCB)

Department

Chemistry

Committee Chair

Dr. Marina Koether

Committee Member

Dr. Amy Gruss

Committee Member

Dr. Daniel Ferreira

Abstract

Two weathering methods of pristine microplastics have been studied and compared to determine the best combination for the desired weathering results, chemical versus irradiation. The chemical weathering was studied using various temperatures, pH values and contact time. Irradiation studies were done at varying contact times. Weathered microplastics, as opposed to pristine, more accurately indicate how microplastics can serve as vectors for other pollutants in the environment. Evidence of weathering is found in Optical Contact Angle Analysis (OCA) and Fourier-Transform Infrared Spectroscopy (FTIR) analysis; the results of which show an increase in hydrophilicity and a growing carbonyl peak around 1770 cm-1 respectively. In the chemical oxidation method, temperature and contact time are major factors in the successful weathering of microplastics, while pH did not appear to have any influence over weathering. In the irradiation oxidation method, the most important factor for successful weathering was the contact time.

Additionally, to further test the vector capability of weathered microplastics as well as the impacts of the weathering method used; the microplastics were put through an adsorption/desorption protocol with the heavy metal lead (Pb). The ICP-OES was used to quantify the adsorption/desorption of lead on the weathered microplastics. Polyethylene microbeads weathered via chemical weathering successfully adsorbed and desorbed the heavy metal lead, and the irradiated samples successfully adsorbed lead. Further study is needed to confirm the desorption capabilities of irradiated microbeads. Polyester, specifically polyethylene terephthalate, fabric swatches successfully adsorbed and desorbed lead after chemical weathering, suggesting that microplastics from clothing could also be vectors in the environment.

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