Le Tin, Jamshidi Elnaz, Beidaghi Majid, Esfahani Milad Rabbani
Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, Alabama 35487, United States.
Department of Mechanical Engineering, Auburn University, Auburn, Alabama 36849, United States.
ACS Appl Mater Interfaces. 2022 Jun 8;14(22):25397-25408. doi: 10.1021/acsami.2c03796. Epub 2022 May 24.
Due to adverse health effects and the broad sources of per- and polyfluoroakyl substances (PFAS), PFAS removal is a critical research area in water purification. We demonstrate the functionalization of thin-film composite (TFC) hollow fiber nanofiltration (HFN) membranes by MXene nanosheets during the interfacial polymerization (IP) process for enhanced removal of perfluorooctane sulfonic acid (PFOS) from water. A MXene-polyamide (PA) selective layer was fabricated on top of a polysulfone (PSF) hollow fiber support via IP of trimesoyl chloride (TMC) and a mixture of piperazine (PIP) and MXene nanosheets to form MXene-PA thin-film nanocomposite (TFN) membranes. Incorporating MXene nanosheets during the IP process tuned the morphology and negative surface charge of the selective layer, resulting in enhanced PFOS rejection from 72% (bare TFC) to more than 96% (0.025 wt % MXene TFN), while the water permeability was also increased from 13.19 (bare TFC) to 29.26 LMH/bar (0.025 wt % MXene TFN). Our results demonstrate that both electrostatic interaction and size exclusion are the main factors governing the PFOS rejection, and both are determined by PA selective layer structural and chemical properties. The lamella structure and interlayer of MXene nanosheets inside the PA layer provided different transport mechanisms for water, ions, and PFAS molecules, resulting in enhanced water permeability and PFAS rejection due to traveling through the membrane by both diffusions through the PA layer and the MXene intralayer channels. MXene nanosheets showed very promising capability as a 2D additive for tuning the structural and chemical properties of the PA layer at the permeability-rejection tradeoff.
由于全氟和多氟烷基物质（PFAS）对健康有不利影响且来源广泛，PFAS去除是水净化领域的一个关键研究方向。我们展示了在界面聚合（IP）过程中通过MXene纳米片对薄膜复合（TFC）中空纤维纳滤（HFN）膜进行功能化处理，以增强从水中去除全氟辛烷磺酸（PFOS）的能力。通过均苯三甲酰氯（TMC）与哌嗪（PIP）和MXene纳米片的混合物进行IP，在聚砜（PSF）中空纤维支撑体顶部制备了MXene-聚酰胺（PA）选择性层，从而形成MXene-PA薄膜纳米复合（TFN）膜。在IP过程中加入MXene纳米片可调节选择性层的形态和表面负电荷，使PFOS截留率从72%（裸TFC膜）提高到96%以上（0.025 wt% MXene TFN膜），同时水通量也从13.19（裸TFC膜）增加到29.26 LMH/bar（0.025 wt% MXene TFN膜）。我们的结果表明，静电相互作用和尺寸排阻都是决定PFOS截留率的主要因素，而这两者均由PA选择性层的结构和化学性质决定。PA层内MXene纳米片的层状结构和层间为水、离子和PFAS分子提供了不同的传输机制，由于通过PA层的扩散和MXene层内通道的扩散，使得水通量增加且PFAS截留率提高。MXene纳米片作为一种二维添加剂，在渗透率-截留率权衡方面，对于调节PA层的结构和化学性质具有非常可观的能力。
