Department of Chemical and Environmental Engineering , Yale University , New Haven , Connecticut 06520-8286 , United States.
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering , Shandong University , Qingdao 266237 , China.
Environ Sci Technol. 2018 Jul 3;52(13):7279-7288. doi: 10.1021/acs.est.8b01040. Epub 2018 Jun 12.
We demonstrate the fabrication of a loose, negatively charged nanofiltration (NF) membrane with tailored selectivity for the removal of perfluoroalkyl substances with reduced scaling potential. A selective polyamide layer was fabricated on top of a poly(ether sulfone) support via interfacial polymerization of trimesoyl chloride and a mixture of piperazine and bipiperidine. Incorporating high molecular weight bipiperidine during the interfacial polymerization enables the formation of a loose, nanoporous selective layer structure. The fabricated NF membrane possessed a negative surface charge and had a pore diameter of ∼1.2 nm, much larger than a widely used commercial NF membrane (i.e., NF270 with pore diameter of ∼0.8 nm). We evaluated the performance of the fabricated NF membrane for the rejection of different salts (i.e., NaCl, CaCl, and NaSO) and perfluorooctanoic acid (PFOA). The fabricated NF membrane exhibited a high retention of PFOA (∼90%) while allowing high passage of scale-forming cations (i.e., calcium). We further performed gypsum scaling experiments to demonstrate lower scaling potential of the fabricated loose porous NF membrane compared to NF membranes having a dense selective layer under solution conditions simulating high water recovery. Our results demonstrate that properly designed NF membranes are a critical component of a high recovery NF system, which provide an efficient and sustainable solution for remediation of groundwater contaminated with perfluoroalkyl substances.
我们展示了一种具有定制选择性的疏松负电荷纳滤（NF）膜的制备，该膜可用于去除具有低结垢潜力的全氟烷基物质。通过均苯三甲酰氯与哌嗪和双哌啶混合物的界面聚合，在聚醚砜支撑体上制备了选择性聚酰胺层。在界面聚合过程中加入高分子量的双哌啶可形成疏松的纳米多孔选择性层结构。所制备的 NF 膜具有负表面电荷，孔径约为 1.2nm，远大于常用的商业 NF 膜（即孔径约为 0.8nm 的 NF270）。我们评估了所制备的 NF 膜对不同盐（即 NaCl、CaCl 和 NaSO）和全氟辛酸（PFOA）的截留性能。所制备的 NF 膜对 PFOA 的截留率很高（约 90%），同时允许形成结垢阳离子（即钙）的高透过率。我们进一步进行了石膏结垢实验，以证明在模拟高水回收率的溶液条件下，与具有致密选择性层的 NF 膜相比，所制备的疏松多孔 NF 膜具有更低的结垢潜力。我们的结果表明，适当设计的 NF 膜是高回收率 NF 系统的关键组成部分，可为受全氟烷基物质污染的地下水修复提供高效和可持续的解决方案。
