Author ORCID Identifier
Date Available
3-21-2025
Year of Publication
2023
Document Type
Doctoral Dissertation
Degree Name
Doctor of Philosophy (PhD)
College
Engineering
Department/School/Program
Chemical and Materials Engineering
Advisor
Dr. J. Zach Hilt
Co-Director of Graduate Studies
Dr. Thomas D. Dziubla
Abstract
Decades of use of per- and polyfluoroalkyl substances (PFAS) in a multitude of consumer and industry-based products have led to a devastating amount of soil and water contamination. Although these chemicals and compounds possess advantageous qualities – such as that of PFAS in the role of fire-fighting foams that have no doubt saved countless lives and homes, we must take responsibility for the anthropogenic hazards that threaten our global health. This entails being able to cost-effectively remediate problems created in the past from overuse of toxic substances that could negatively impact our future, and in this case, the future of clean water availability. The chemical and thermal stability of PFAS have proved them to be an especially daunting challenge from an environmental remediation standpoint. Presently, the only full-scale water treatment separates via sorption and uses non-selective materials such as activated carbon (AC) or mineral media which are extremely difficult and/or costly to regenerate. Research focused on selective adsorption is becoming a more practical route for capture and removal from contaminated water systems. The work presented here investigates the development and effectiveness of polymer-based sorbents that have affinity toward PFAS through incorporation of various monomers that possess cationic and/or fluorinated functionalities. In some instances, composite systems were created with the inclusion iron oxide nanoparticles during the synthesis process. Although the main route of PFAS sorption occurs via ionic and hydrophobic interactions, several approaches were explored: (1) Thermoresponsive hydrogel expansion and contraction to drive contaminant into gel for sorption on functionalized sites; (2) Magnetic polymer composites allow for contaminant binding via sorption to cationic sites of quaternary amine functionalized polymers and removal via magnetic decantation; (3) Linear, non-crosslinked systems drive contaminant binding through flocculation with functionalized thermoresponsive polymers.
The affinity of the synthesized materials for PFAS was evaluated at equilibrium conditions using a liquid chromatography coupled to mass spectrometer detection (LCMS) for quantification purposes, and the data was used to determine removal efficiency in both spiked and real-world environmental samples. Binding studies were conducted by subjecting 2.5 mg/mL of each sorbent to 500 ppb of aqueous PFAS for up to 24 h at room temperature for crosslinked systems and 1 h at 50 ºC for linear systems. Cationic crosslinked polymers showed high affinity for PFOA (>80%) and PFOS (>90%) across a range of aqueous pH (4 – 10). Linear polymers that included both cationic and fluorinated monomers showed improved flocculation and contaminant removal as compared to those systems with isolated functionality. Furthermore, upon exposure of the magnetic composites to an alternating magnetic field (AMF) for a period of 30 minutes, release of bound PFAS is realized in minor amounts depending on regeneration solvent selection. Overall, we have provided strong evidence that the materials presented here have a promising application as sorbents for PFAS contaminants in polluted water sources providing high binding affinities, a low-cost regeneration technique and are capable of withstanding use under environmental conditions offering a cost-effective alternative to current remediation approaches.
Digital Object Identifier (DOI)
https://doi.org/10.13023/etd.2023.040
Funding Information
This research was supported by the National Institute of Environmental Health Sciences within the National Institute of Health, grant P42ES007380 from 2017 to 2023.
Recommended Citation
Frazar, E. Molly, "DEVELOPMENT OF POLYMERIC SORBENTS AS REUSABLE FILTRATION SYSTEMS FOR REMEDIATION OF PFAS CONTAMINATED WATER" (2023). Theses and Dissertations--Chemical and Materials Engineering. 149.
https://uknowledge.uky.edu/cme_etds/149
Included in
Environmental Engineering Commons, Polymer and Organic Materials Commons, Polymer Science Commons
