Publication Date

2026

College

College of Sciences & Mathematics

Department

Chemistry and Physics, Department of

Student Level

Undergraduate

Faculty Mentor

Dr. Maria Danielle Garrett

Presentation Type

Talk/Oral

Summary

Pharmaceutical contaminants such as acetaminophen (APAP) are showing a rising presence in aquatic environments, where their interactions with microplastics (MPs) can potentially modulate natural degradation mechanisms. Concurrent presence of the two substances has been shown to potentiate increase their individual harmful effects. This study investigates whether oxidative aging and humic-acid surface modification of PET microplastics influence APAP adsorption.

In this study, UV-aging was reproduced using an iron (II)-activated potassium persulfate (Fe(II)-KPS) oxidation system. Aqueous dissolved organic matter (DOM) is simulated using multi-hour exposure to humic acid. The MPs are then removed from the solution to examine adsorption mechanisms. While most studies examine the simultaneous presence of DOM and pharmaceuticals in solution, this work specifically investigates the impact of pre-adsorbed humic acid on subsequent APAP interactions.

Quantitative analysis of PET oxidation was confirmed using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to determine any differences in carbonyl indices on the PET surfaces (p = 0.04, n = 16). Adsorption was observed using ultraviolet-visible spectroscopy (UV-Vis) at 243 nm. No statistically significant decrease in APAP concentration was observed for the Fe(II)-KPS-treated PET compared to non-aged (virgin) PET, indicating minimal adsorption under the tested conditions. These results indicate that Fe(II)-KPS alone is not sufficient to produce meaningful adsorption under the tested conditions. Ongoing work is evaluating whether humic-acid-coated microplastics exhibit enhanced adsorption behavior under environmentally realistic conditions.

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