Fabrication of electrospun fibers for exposure control to airborne and drinking water contaminants
Creators: name: Jensen, Madeline Grace
Publisher: name: University of Iowa
Year: 2025
Subjects: air filtration
drinking water treatment
electrospinning
N95 FFRs
PFAS
public abstract

description: Many public health challenges are connected to at least one of two exposure pathways: water and air. In these instances, filter materials—such as reverse osmosis membranes for water treatment, facemasks, or HEPA filters—are relied upon for exposure control. Electrospinning, a fabrication technique for nanofiber-based materials, has the potential to rapidly develop new, high-performance filter materials for specialized applications in public health protection in response to emerging threats. Two such public health challenges have recently emerged in which electrospinning could play a key role in developing effective solutions for exposure control: shortages of N95 Filtering Facepiece Respirator (N95 FFR) during the COVID-19 pandemic and the widespread contamination of drinking water supplies by per- and poly-fluoroalkyl substances or PFAS.
description: Under the context of these two public health challenges, this work collectively demonstrates the versatility of electrospinning while providing simple, practical electrospun filter materials to address prominent airborne and drinking water risks. The studies reported here focus on fabrication efforts emphasizing: (i) simplicity (for ease of rapid production); (ii) tunability (to adapt to emerging societal needs); and (iii) scalability (to facilitate translation from the laboratory to industrial scale fabrication).
description: First in this work, an unsupported, nonwoven layer of uncharged polystyrene (PS) microfibers was produced via electrospinning that achieves N95 performance standards [e.g., high filtration efficiencies (≥97.5%) and low pressure drops (≤15 mm H2O)] based on physical parameters (e.g., filter thickness) alone. The PS microfiber filter demonstrates durability in its maintenance of high filtration efficiencies and low pressure drops over six rounds of disinfection. Additionally, the PS microfibers can be modified readily through integration of silver nanoparticles (AgNPs) during electrospinning to enhance their antimicrobial activity (≥ 3-log removal at 25wt% AgNP integration).
description: Electrospinning was used next to develop polystyrene (PS) nanofibers with embedded biocidal agents that exhibit performance meeting or exceeding that of meltblown filtration layers currently used in N95 FFRs. Three antimicrobial agents—tetrabutylammonium bromide (TBAB; a quaternary ammonium surfactant) and two sizes of silver (Ag) nanoparticles (35 nm and 80 nm)— were integrated both individually and as mixtures (i.e., TBAB + 35 Ag) into PS nanofibers at 0.006-5 wt% loadings, and demonstrated high biocidal activity against E. coli (8-log removal). The 0.5 wt% antimicrobial PS materials were developed into thin supported layers (tens of microns thick), which achieved high particle filtration efficiencies (≥ 98%) and low pressure drops (≤ 12 mmH2O). Because of their tunable filtration performance, both the PS microfibers and these supported PS nanofiber layers represent feasible filter alternatives for use in N95 FFRs.
description: Finally, this study produced via electrospinning PAN nanofiber membranes functionalized with TBAB and nonfunctionalized multiwalled carbon nanotubes (CNTs) for the removal of PFAS contaminants from drinking water. These membranes exhibited relatively fast uptake of PFAS (both long-chain PFOA and PFOS, and short-chain PFBS and HFBA). The primary mechanism for PFAS sorption was determined to be anion exchange at the embedded quaternary amine sites provided by TBAB integration, while CNTs appeared to hinder PFAS uptake via electrostatic repulsion due to their negatively charged surface across environmentally relevant pH values. However, both membranes exhibited good adsorption capacities for PFAS (32 ± 5 mg PFOS/g and 28 ± 8 mg HFBA/g for TBAB/PAN; 22 ± 4 mg PFOS/g and 19 ± 6 mg HFBA/g for CNT/TBAB/PAN). Additionally, the synthesis of these membranes was translated from a single-needle, laboratory scale system to an industrial scale, needleless electrospinning system, resulting large-scale membranes that exhibited comparable PFAS removal to the bench-scale membranes.
description: Ultimately, novelty in this work is derived from the high-performance of the materials to meet the needs of emerging public health challenges, as well as the simple fabrication methodologies developed for robust fabrication at both laboratory bench-top and industrial scales.