基于LiCl调控界面聚合的聚酰胺薄层复合纳滤膜制备与性能研究

Tailoring Properties and Performance of Polyamide Composite Nanofiltration Membranes by LiCl-added Interfacial Polymerization

针对传统界面聚合反应可控性差、相应聚酰胺薄层复合膜结构和性能难以调控的问题,本研究以经典的哌嗪/均苯三甲酰氯在烷烃-水界面发生的聚合反应为研究对象,以氯化锂为哌嗪水溶液的添加剂,调控了反应生成聚酰胺分离层的结构,提升了聚酰胺薄层复合纳滤膜的分离性能.在氯化锂最适浓度为1.25 g·L^(-1)时,所制备聚酰胺分离层的调和酰胺键密度有所降低,孔径则由0.51 nm增大到0.59 nm,而其表面形貌、化学组成、表面亲水性及荷电性没有受到明显影响.薄层复合纳滤膜的水通量提升了17%,达到216 L·m^(-2)·h^(-1)·MPa^(-1),同时对Na_(2)SO_(4)的截留率维持在98.8%以上.此外,所制备的纳滤膜具有优异的耐压性、较宽的处理料液浓度范围以及较好的长期运行稳定性.

Polyamide composite nanofiltration membranes prepared by interfacial polymerization have been widely used in brackish water purification,wastewater treatment and solvent recovery.However,it remains a challenge to further enhance the membrane performances by optimizing their structure due to the rapid reaction rate and poor controllability of the conventional interfacial polymerization.In this work,we report a facile strategy to fabricate polyamide composite membranes with improved nanofiltration performance by using lithium chloride as an additive in interfacial polymerization to regulate the membrane structure.The synthesized polyamide layers show a reduced harmonic amide bond density and an increased pore size from 0.51 nm to 0.59 nm,while the morphology,chemical structure,surface charge,and surface hydrophilicity remain almost unchanged under the optimal addition of lithium chloride at 1.25 g·L^(-1).The resulting structure endows the polyamide composite membrane with a 17%enhanced water permeance,reaching up to 216 L·m^(-2)·h^(-1)·MPa^(-1),while maintaining a high rejection of Na_(2)SO_(4) above 98.8%.In addition,nanofiltration membranes prepared demonstrate excellent performance stability when operated under various applied pressures,across a wide concentration range of feed solution,and during a 120-h long-term filtration process,indicating the potential of our membranes in practical applications.