Emerging investigator series: development and application of polymeric electrospun nanofiber mats as equilibrium-passive sampler media for organic compounds

Abstract

We fabricated a suite of polymeric electrospun nanofiber mats (ENMs) and investigated their performance as next-generation passive sampler media for environmental monitoring of organic compounds. Electrospinning of common polymers [e.g., polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and polystyrene (PS), among others] yielded ENMs with reproducible control of nanofiber diameters (from 70 to 340 nm). ENM performance was investigated initially with model hydrophilic (aniline and nitrobenzene) and hydrophobic (selected PCB congeners and dioxin) compounds, generally revealing fast chemical uptake into all ENMs that was well described by a one compartment, first-order kinetic model. Typical times to reach 90% of equilibrium (t90%) were ≤ 7 days under mixing conditions for all ENMs, and < 0.5 days for the best performing materials under static (i.e., no mixing) conditions. Collectively, these short equilibrium timescales suggest that ENMs may be used in the field as an equilibrium-passive sampler, at least for our model compounds. Equilibrium partitioning coefficients (KENM-W, L kg−1) averaged 2 and 4.7 log units for the hydrophilic and hydrophobic analytes, respectively. PAN, PMMA and PS were prioritized for additional studies because they exhibited not only the greatest capacity for simultaneous uptake of the entire model suite (log KENM-W ~ 1.5 – 6.2), but also fast uptake. For these optimized ENMs, rates uptake into PAN and PMMA were limited by aqueous phase diffusion to the nanofiber surface, and the rate-determine step for PS was analyte specific. Sorption isotherms also revealed that the environmental application of these optimized ENMs would occur within the linear uptake regime. We examined ENM performance for the measurement of pore water concentrations from spiked soil and freshwater sediments. Soil and sediment studies not only yielded reproducible pore water concentrations and comparable values to other passive sampler materials, but also provided practical insights into ENM stability and fouling in such systems. Further, fast uptake for a suite of structurally diverse hydrophilic and moderately hydrophobic compounds were obtained for PAN and PS, with t90% ranging from 0.01 to 4 days with mixing and KENM-W values ranging from 1.3 to 3.2 log units. Our findings show promise for the development and use of ENMs as equilibrium-passive samplers for a range of organic pollutants across soil/sediment and water systems.

Comparisons of a Novel Air Sampling Filter Material, Wash Buffers and Extraction Methods in the Detection and Quantification of Influenza Virus

“…Filters made of PS nanofibers were fabricated via electrospinning, according to the equipment and methodologies described elsewhere. 31 As detailed in this earlier work, PS filters consisted of nonwoven nanofibers with average diameters of 140 (± 30) nm, a specific surface area (measured by N 2 -BET) of 28 (± 4) m 2 /g, and a water contact angle of 109 ± 9.9, indicative of a hydrophobic surface, as expected.…”

Nanofiber-enabled multi-target passive sampling device for legacy and emerging organic contaminants

“…Specifically, for a matrix of five different polymers and 19 organic pollutants ranging from hydrophilic to hydrophobic, we quantified equilibrium partition coefficients between ENMs and water (or KENM-W values) of 1.1-and 4.7-log units, and observed rapid uptake with time to reach 90% equilibrium (t90%) of < 7 days with mixing. 125 For optimally performing materials [e.g., polyacrylonitrile (PAN) and polystyrene (PS)], we observed very fast chemical uptake, with t90% values < 1 day even under a static (i.e., no-mixing)…”

“…Carbon nanotubes (CNTs) and metal or metal oxide nanoparticles are two types of common commercial products used for this purpose. [124][125][126] For example, CNTs are noted for their extreme mechanical strength, and their integration into polymers produces a stronger polymer composite material that is likely more robust during environmental applications. [126][127][128][129] In addition to structural benefits, integration of other nanomaterials may also impart other beneficial properties related to the physical and chemical nature of the fabricated composites.…”

“…Please note that all of the content in Chapter 2 has been published in Environmental Science Processes & Impacts. 125 The contents of each research chapter are briefly summarized below. Chapter 4 demonstrates that the addition of cationic and anionic surfactants into the electrospinning precursor sol-gel can be used to enhance organic pollutant sorption on ENMs.…”

“…ENMs were synthesized using a customized electrospinning apparatus, which has been described in Chapter 2, as well as in the related published work. 125 For production of ENM-CNT composites, we modified our standard polymer ENM fabrication procedures to accommodate precursor solutions of homogenous suspensions of CNTs and polymer precursors.…”