Author ORCID Identifier
Date Available
2-20-2025
Year of Publication
2024
Degree Name
Doctor of Philosophy (PhD)
Document Type
Doctoral Dissertation
College
Engineering
Department/School/Program
Chemical and Materials Engineering
First Advisor
Dr. Dibakar Bhattacharyya
Abstract
The environmental remediation of water and air sources is a challenging field, due to widespread contamination, pollutant variety, and efficiency of existing treatment options. Remediation of certain pollutants, such as per- and polyfluorinated chemicals (PFAS), polychlorinated biphenyls (PCBs), volatile organic compounds (VOCs), and viral aerosols, has shown promise via adsorptive, degradative, or filtration-based processes, each with their respective advantages and limitations. Membrane technology is one option that has exhibited considerable pollutant removal from environmental sources via reverse osmosis (RO) filtration, but is limited by low permeabilities and lack of pollutant detoxification. With the support of NIEHS and NSF, the functionalization of microfiltration (MF) membrane systems with high water/air permeabilities was investigated to increase remediation efficiency, decrease operation cost, and create a flexible platform that could adapt to different pollutant environments. Depending on the intended pollutant, membranes were functionalized with stimuli-responsive polymers, biological components, and catalytic nanoparticles to incorporate adsorptive and/or degradative properties.
For enhancing the remediation of perfluorooctanoic acid (PFOA), adsorptive capabilities were incorporated in flat-sheet polyvinylidene fluoride (PVDF) membranes via functionalization with poly-N-isopropylacrylamide (PNIPAm), a temperature-responsive polymer that can exhibit both hydrophilic and hydrophobic properties below and above its lower critical solution temperature (LCST) of 32°C, respectively. Over 5 cycles of convective flow, PNIPAm-functionalized PVDF membranes showed stable PFOA adsorption of ~1800 μg/m2 of membrane above the LCST (hydrophobic expression) with 50-60% desorption of PFOA below the LCST (hydrophilic expression), displaying the temperature swing adsorption/desorption capabilities of the membrane/polymer matrix.
Membrane systems with bimetallic nanoparticle catalysts, which are limited by low mass transfer between the pollutant and catalyst active site, benefited from the incorporation of stimuli-responsive polymer hydrogels as well. The addition of PNIPAm into a Fe/Pd-functionalized membrane matrix allowed for increased interaction between the pollutant, such as PCB-1, and catalyst site above the LCST, resulting in first-order kSA values of 0.28 and 1.36 L/m2/g at 25 ºC and 45 ºC, respectively. This functionalization was additionally applied to highly-scalable hollow fiber membranes, which yielded a 30% and 420% increase in kSA above 32 °C for the dye methyl orange and the VOC trichloroethylene, respectively. As a cost-effective option for increasing degradation rates, precise heating of the catalytic membrane domain was also studied via the palladium nanoparticle’s plasmonic properties.
This work extended to viral aerosols by utilizing enzyme-functionalized membranes for the denaturation of SARS-CoV-2 spike glycoproteins. PVDF membranes provided a protection factor of 540 ± 380 for coronavirus-sized particle, above the Occupational Safety and Health Administration’s standard of 10 for N95 masks. SARS-CoV-2 spike glycoprotein on the surface of virus-sized particles was denatured in 30 s by subtilisin enzyme-functionalized membranes with 0.02-0.2% water content on the membrane surface. For the environmental remediation of both water and air, stimuli-responsive functionalized membranes exhibit a promising field for high-efficiency capture and detoxification of harmful pollutants.
Digital Object Identifier (DOI)
https://doi.org/10.13023/etd.2024.26
Funding Information
This research was supported by the National Institute of Environmental Health Sciences-Superfund Research Program grant (P42ES007380) in 2020-2024, the National Science Foundation Graduate Research Fellowship Program in 2022-2024, and the National Science Foundation Grants for Rapid Response Research (2030217) in 2020-2021.
Recommended Citation
Mills, Rollie George, "FUNCTIONALIZED MICROFILTRATION MEMBRANES FOR AEROSOL CAPTURE TO CHLORO-ORGANIC DEGRADATION" (2024). Theses and Dissertations--Chemical and Materials Engineering. 160.
https://uknowledge.uky.edu/cme_etds/160
Included in
Biochemical and Biomolecular Engineering Commons, Catalysis and Reaction Engineering Commons, Membrane Science Commons, Polymer Science Commons
