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 50 to 340 nm). The 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 of these ENMs, which was well described by a one compartment, first-order kinetic model. Typical times to reach 90% equilibrium (t_90%) were ≤7 days under mixing conditions for all the 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 (K_ENM–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 K_ENM–W ∼1.5–6.2), but also fast uptake. For these optimized ENMs, the rates of uptake into PAN and PMMA were limited by aqueous phase diffusion to the nanofiber surface, and the rate-determining 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 the 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. Furthermore, fast uptake for a suite of structurally diverse hydrophilic and moderately hydrophobic compounds was obtained for PAN and PS, with t_90% ranging from 0.01 to 4 days with mixing and K_ENM–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.

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新兴的研究者系列：聚合物电纺纳米纤维毡作为有机化合物的平衡-被动取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50到340 nm）的ENM。最初使用亲水性（苯胺和硝基苯）和疏水性（选定的PCB同类物和二恶英）化合物模型研究了ENM性能，通常揭示了所有这些ENM中化学物质的快速吸收，这通过一个区室的一阶动力学模型可以很好地描述。 。达到90％平衡的典型时间（t _90％对于所有ENM，在混合条件下）≤7天，而在静态（即不混合）条件下，性能最佳的材料在<0.5天之内。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。亲水性和疏水性分析物的平均分配系数（K _{ENM – W}，L kg ^-1）分别平均为2和4.7 log个单位。PAN，PMMA和PS被优先考虑进行其他研究，因为它们不仅展示了同时摄取整个模型套件的最大能力（log  K _ENM–W〜1.5–6.2），但吸收速度也很快。对于这些优化的ENM，通过水相扩散到纳米纤维表面来限制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在加标土壤和淡水沉积物中孔隙水浓度测量中的性能。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，可以快速摄取一系列结构多样的亲水性和中度疏水性化合物，t _90％范围从0.01到4天，混合范围和K _ENM–W值范围从1.3到3.2 log单位。我们的发现表明，有希望开发和使用ENM作为平衡被动采样器，用于土壤/沉积物和水系统中的一系列有机污染物。