Peter Katherine T, Vargo John D, Rupasinghe Thilini P, De Jesus Aribet, Tivanski Alexei V, Sander Edward A, Myung Nosang V, Cwiertny David M
Department of Civil and Environmental Engineering, University of Iowa , Iowa City, Iowa 52242, United States.
State Hygienic Laboratory, University of Iowa , Iowa City, Iowa 52242, United States.
ACS Appl Mater Interfaces. 2016 May 11;8(18):11431-40. doi: 10.1021/acsami.6b01253. Epub 2016 Apr 27.
We developed an electrospun carbon nanofiber-carbon nanotube (CNF-CNT) composite with optimal sorption capacity and material strength for point-of-use (POU) water treatment. Synthesis variables including integration of multiwalled carbon nanotubes (CNTs) and macroporosity (via sublimation of phthalic acid), relative humidity (20 and 40%), and stabilization temperature (250 and 280 °C) were used to control nanofiber diameter and surface area (from electron microscopy and BET isotherms, respectively), surface composition (from XPS), and strength (from AFM nanoindentation and tensile strength tests). Composites were then evaluated using kinetic, isotherm, and pH-edge sorption experiments with sulfamethoxazole (log Kow = 0.89) and atrazine (log Kow = 2.61), representative micropollutants chosen for their different polarities. Although CNFs alone were poor sorbents, integration of CNTs and macroporosity achieved uptake comparable to granular activated carbon. Through reactivity comparisons with CNT dispersions, we propose that increasing macroporosity exposes the embedded CNTs, thereby enabling their role as the primary sorbent in nanofiber composites. Because the highest capacity sorbents lacked sufficient strength, our optimal formulation (polyacrylonitrile 8 wt %, CNT 2 wt %, phthalic acid 2.4 wt %; 40% relative humidity; 280 °C stabilization) represents a compromise between strength and performance. This optimized sorbent was tested with a mixture of ten organic micropollutants at environmentally relevant concentrations in a gravity-fed, flow-through filtration system, where removal trends suggest that both hydrophobic and specific binding interactions contribute to micropollutant uptake. Collectively, this work highlights the promise of CNF-CNT filters (e.g., mechanical strength, ability to harness CNT sorption capacity), while also prioritizing areas for future research and development (e.g., improved removal of highly polar micropollutants, sensitivity to interfering cosolutes).
我们开发了一种用于现场（POU）水处理的具有最佳吸附容量和材料强度的电纺碳纳米纤维-碳纳米管（CNF-CNT）复合材料。合成变量包括多壁碳纳米管（CNT）的整合和大孔隙率（通过邻苯二甲酸升华）、相对湿度（20%和40%）以及稳定化温度（250℃和280℃），用于控制纳米纤维直径和表面积（分别通过电子显微镜和BET等温线）、表面组成（通过XPS）以及强度（通过AFM纳米压痕和拉伸强度测试）。然后使用动力学、等温线和pH边界吸附实验，以磺胺甲恶唑（log Kow = 0.89）和阿特拉津（log Kow = 2.61）对复合材料进行评估，这两种具有不同极性的代表性微污染物被选作实验对象。尽管单独的CNF是较差的吸附剂，但CNT和大孔隙率的整合实现了与颗粒活性炭相当的吸附量。通过与CNT分散体的反应性比较，我们提出增加大孔隙率会使嵌入的CNT暴露出来，从而使其能够在纳米纤维复合材料中作为主要吸附剂发挥作用。由于吸附容量最高的吸附剂缺乏足够的强度，我们的最佳配方（聚丙烯腈8 wt%，CNT 2 wt%，邻苯二甲酸2.4 wt%；相对湿度40%；280℃稳定化）代表了强度和性能之间的一种折衷。在重力供料的流通过滤系统中，使用环境相关浓度的十种有机微污染物混合物对这种优化后的吸附剂进行了测试，去除趋势表明疏水和特异性结合相互作用都有助于微污染物的吸附。总体而言，这项工作突出了CNF-CNT过滤器的前景（例如机械强度、利用CNT吸附容量的能力），同时也确定了未来研发的重点领域（例如改善对高极性微污染物的去除、对干扰性共溶质的敏感性）。
