This research attempted to leverage the unique properties of poly (allylamine hydrochloride) (PAH)/poly (acrylic acid) (PAA) bilayer coatings to enhance antifouling and antimicrobial properties of a commercially available ultrafiltration (UF) membrane as well as the removal of PFOA and PFOS—the two CECs that most frequently represent the class of PFAS. The effects of selected water matrix components (humic acids [HA] and cations) on PFOA and PFOS removals were also investigated when using the functionalized membrane. PAH/PAA films were first deposited on the membrane using a fluidic layer by layer (LbL) technique and then crosslinked, followed by embedding of the silver phosphate nanoparticles (AgPNPs) within the PE coatings. Microprofile measurements using a solid contact Ag micro-(ion-selective electrode) ISE as well as post-filtration an inductively coupled plasma (ICP) analysis demonstrated that AgPNP were effectively immobilized within the crosslinked PAH/PAA bilayers. The PAH/PAA functionalization imparted enhancements in membrane properties including surface charge and hydrophilicity and rendered a smoother membrane surface. Upon stable and uniform deposition of PAH/PAA "bilayer" (BL) coatings, the permeate flux was governed by both PAH/PAA-derived hydrophilicity and surface/pore coverage. Membrane porosity and MWCO were reduced by approximately 9% and 38%, respectively. It was observed that an optimum number of bilayers must be applied to ensure that the resulting permeability is not offset by the hindrance from the deposition of bilayers. Furthermore, membrane functionalization rendered antimicrobial property as indicated by less attachment of bacteria that would have initiated the formation of biofilms leading to biofouling. When compared to the unmodified membrane, PFOA and PFOS removals while using the modified UF membrane increased from 20 to 50% and from 22 to 52%, respectively. The approximately 30% higher removal of both PFOA and PFOS may be attributed to the size exclusion mechanism. While the presence of only HA did not influence the removal of PFOA and PFOS significantly, the coexistence of HA and cations in water resulted in significant increase in the rejection of both the PFASs. This can be attributed to the enhanced size exclusion of the complexes that PFOS and PFOA may form with HA and cations in the source water.
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Sadmani, A H M Anwar
Doctor of Philosophy (Ph.D.)
College of Engineering and Computer Science
Civil, Environmental, and Construction Engineering
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Olimattel, Kunal, "The Effect of Polyelectrolyte Modification of Ultrafiltration Membranes on Fouling Resistance and Rejection of Contaminants of Emerging Concern" (2021). Electronic Theses and Dissertations, 2020-. 1149.