Ren Yuling, Qi Pengfei, Han Yujie, Wan Yinhua, Lin Jiuyang, Xie Ming, Chen Xiangrong, Feng Shichao, Luo Jianquan
State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, PR China.
School of Environment, Henan Normal University, Xinxiang 453007, PR China.
Environ Sci Technol. 2025 Jan 21;59(2):1434-1447. doi: 10.1021/acs.est.4c10120. Epub 2025 Jan 7.
The efficient removal of organic contaminants from high-salinity wastewater is crucial for resource recovery and achieving zero discharge. Nanofiltration (NF) membranes are effective in separating organic compounds and monovalent salts, but they typically exhibit an excessive rejection of divalent salts. Modifying the charge characteristics of NF membranes can improve salt permeation; however, the role of charge spatial distribution in governing salt transport behavior is not fully understood. In this study, we developed a mix-charged NF membrane with a horizontal charge distribution by employing interfacial polymerization combined with a polyester template etching and solvent-induced polyamine intercalation strategy. The ratio of positive to negative charge domains in the membrane can be precisely controlled by adjusting the aqueous monomer ratio and polyamine modifier type. X-ray photoelectron spectroscopy (XPS) depth profiling and separation layer thickness analysis confirmed the complete penetration of polyamines into the separation layer, providing direct evidence of the formation of horizontally distributed charge domains. This unique charge distribution results in a high charge density and a near-electroneutral surface, which facilitates the permeation of the divalent salts. The size-dependent "plug-in" modification and covalent cross-linking further reduce pore size, enhancing rejection of small organic molecules. Additionally, the membrane demonstrated exceptional antifouling performance against both negatively and positively charged pollutants, attributed to its unique charge distribution and smooth surface. Molecular dynamics (MD) simulations further revealed that weak electrostatic interactions and a tightly bound hydration layer contribute to the membrane's superior antifouling properties. This work provides valuable insights into the design of NF membranes with tailored microstructures and charge distributions for improved water treatment performance.
从高盐度废水中有效去除有机污染物对于资源回收和实现零排放至关重要。纳滤（NF）膜在分离有机化合物和单价盐方面有效，但通常对二价盐表现出过高的截留率。改变纳滤膜的电荷特性可以改善盐分渗透；然而，电荷空间分布在控制盐分传输行为中的作用尚未完全理解。在本研究中，我们通过采用界面聚合结合聚酯模板蚀刻和溶剂诱导的多胺插层策略，开发了一种具有水平电荷分布的混合电荷纳滤膜。通过调节水相单体比例和多胺改性剂类型，可以精确控制膜中正负电荷域的比例。X射线光电子能谱（XPS）深度剖析和分离层厚度分析证实多胺完全渗透到分离层中，为水平分布电荷域的形成提供了直接证据。这种独特的电荷分布导致高电荷密度和近电中性表面，有利于二价盐的渗透。尺寸依赖性的“插入”改性和共价交联进一步减小孔径，增强对小有机分子的截留率。此外，该膜对带负电和带正电的污染物均表现出优异的抗污染性能，这归因于其独特的电荷分布和平滑表面。分子动力学（MD）模拟进一步表明，弱静电相互作用和紧密结合的水化层有助于膜的优异抗污染性能。这项工作为设计具有定制微观结构和电荷分布以改善水处理性能的纳滤膜提供了有价值的见解。
