Degree

Doctor of Philosophy (PhD)

Department

Engineering Science

Document Type

Dissertation

Abstract

Advances in synthetic materials have enabled remarkable progress in medicine, infrastructure, and food security. However, these same developments have introduced persistent environmental pollutants that pose significant challenges to natural systems. Among these emerging concerns are microplastics (MPs), per- and polyfluoroalkyl substances (PFAS), and altered sediment transport processes relevant to wetland restoration. Although these issues may span distinct environmental compartments, they are unified by interfacial and colloidal processes that govern particle behavior. Through three interconnected projects, this dissertation examines how surface chemistry and interparticle interactions control the environmental fate of MPs, PFAS, and sedimentary particles across atmospheric and aquatic systems. In aqueous media, hydrophobic interactions drive PFAS adsorption to microplastic surfaces, while sunlight-induced weathering modifies microplastic surface chemistry and promotes PFAS desorption in a chain-length-dependent manner. Extending these principles to the atmosphere, microplastic surface chemistry is shown to control the structure of surface-bound water, thereby influencing ice nucleation activity and associated atmospheric microphysical processes. In aquatic systems relevant to wetland restoration, variations in water salinity govern the aggregation, settling, and deposition of fluvial sediments. Using three-dimensional micro–computed tomography, salinity-driven aggregation behavior is directly linked to the internal structure of settled sediment deposits, with implications for sediment retention and land-building processes. Together, these experimental investigations highlight the role of colloidal and interfacial phenomena in controlling pollutant transport, atmospheric microphysical processes, and 7 sediment deposition. By connecting particle-scale interactions to environmental outcomes, this thesis can inform future efforts in remediation, restoration, and policy-making.

Date

3-13-2026

Committee Chair

Bhuvnesh Bharti

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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