Heteroaggregation Behaviors of Nanoplastics and Hematite with Natural Organic Matter

Presenter

Marko Stephen Cerne

Group Members

Karen Marian Maradiaga Mendoza, Sophie Jinying MacRae, Xiupei Zhou

Campus

UMass Amherst

Sponsor

Baoshan Xing, Stockbridge School of Agriculture, UMass Amherst

Schedule

Session 1, 10:30 AM - 11:15 AM [Schedule by Time][Poster Grid for Time/Location]

Location

Poster Board A31, Campus Center Auditorium, Row 2 (A21-A40) [Poster Location Map]

Abstract

From the peaks of Mount Everest to the bottom of the Mariana Trench, plastics have accumulated in almost every corner of the Earth. Among them, nanoplastics (NPs) are an increasingly pervasive plastic debris ranging in size from 1 nm to less than 100 nm (or 1 µm). The environmental fate of NPs is primarily determined by their colloidal stability which is dependent on homoaggregation (interactions between nanoplastics) and heteroaggregation (the interaction between nanoplastics and naturally occurring substances including minerals or natural organic matter (NOM)). Further knowledge of how NPs behave in the environment is crucial to assessing the exact risks they pose.

As a model, we studied the impact of NOM on the heteroaggregation between polystyrene (nPS), a ubiquitous plastic, and iron oxide (nFe₂O₃). As a baseline for understanding nPS interactions, individual homoaggregation rates and surface charges were determined for nPS and nFe₂O₃ suspensions. The point of zero charge was utilized to standardize the experiment. Humic acid (HA), a representative of NOM, was then added at different concentrations to the nPS-nFe₂O₃ suspensions.

Both homoaggregation of nPS and heteroaggregation of nPS and nFe2O3 decreased with higher HA concentrations, suggesting that HA inhibits aggregation. The NOM’s impact on heteroaggregation is attributed to charge reversal on the positive surface charge of nFe₂O₃ as negative HA molecules surround it. With disrupted heteroaggregation, NPs are more likely to remain dispersed in the environment. Higher dispersion implies increased mobility of NPs and consequently greater potential to affect more ecosystems as well as higher bioavailability to organisms. 

Keywords

Nanoplastics, Heteroaggregation, Contaminant Pollutants, Polystyrene, Natural Organic Matter

Research Area

Environmental Science and Sustainability

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