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.

中文翻译：

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新兴的研究者系列：高分子电纺纳米纤维毡作为有机化合物的平衡无源采样器介质的开发和应用

我们制造了一套聚合物电纺纳米纤维毡（ENM），并研究了它们作为用于有机化合物环境监测的下一代无源采样器介质的性能。普通聚合物的电纺[例如，聚丙烯腈（PAN），聚甲基丙烯酸甲酯（PMMA）和聚苯乙烯（PS）等]产生了可重复控制纳米纤维直径（从70到340 nm）的ENM。最初使用亲水性（苯胺和硝基苯）模型和疏水性（选定的PCB同类物和二恶英）模型化合物研究了ENM性能，通常揭示了对所有ENM的快速化学吸收，这是一个一室一阶动力学模型很好地描述的。在所有ENM的混合条件下，达到平衡的90％（t90％）的典型时间≤7天，且<0。在静态（即不混合）条件下，性能最好的材料需要5天。总的来说，这些较短的平衡时标表明，至少在我们的模型化合物中，ENM可以在现场用作平衡被动采样器。亲水和疏水分析物的平均分配系数（KENM-W，L kg-1）分别为2和4.7 log个单位。PAN，PMMA和PS被优先考虑用于其他研究，因为它们不仅具有最大的同时摄取整个模型套件的能力（对数KENM-W〜1.5 – 6.2），而且还具有快速摄取的能力。对于这些优化的ENM，由于水相扩散到纳米纤维表面而限制了PAN和PMMA的吸收速率，而PS的速率确定步骤是分析物特异性的。吸附等温线还表明，这些优化的ENM在环境中的应用将发生在线性吸收范围内。我们检查了ENM性能，用于测量加标土壤和淡水沉积物中的孔隙水浓度。对土壤和沉积物的研究不仅产生了可重现的孔隙水浓度和与其他被动采样器材料相当的值，而且还提供了有关此类系统中ENM稳定性和结垢的实用见解。此外，对于PAN和PS，获得了一组结构多样的亲水性和中度疏水性化合物的快速吸收，t90％为0.01至4天，混合时的KENM-W值为1.3至3.2 log个单位。