聚哌嗪酰胺原生荷正电纳滤膜的制备与性能研究

Fabrication and performance of poly(piperazine-amide)nanofiltration membrane with innate positive charge

纳滤膜表面的荷电性是影响纳滤分离性能的最主要因素之一,传统聚哌嗪酰胺纳滤膜表面均带负电,因此对钙镁等二价阳离子的截留率较低.本文通过在界面聚合制膜过程中添加表面活性剂并改变有机溶剂类型,以降低单体的跨界面阻力并增强单体跨界面驱动力,从而促进哌嗪单体向有机相的扩散.利用红外光谱、XPS、SEM、AFM、Zeta电位仪等对复合膜的物化及结构特性进行了表征,结果表明,分离层聚酰胺材料中含有过量的氨基,形成了原生荷正电的聚哌嗪酰胺纳滤膜.错流测试表明,该纳滤膜对不同盐溶液的截留率顺序表现为CaCl_(2)>NaCl>Na_(2)SO_(4),其中CaCl_(2)截留率达到95.3%,通量118.4 L/(m^(2)·h·MPa).

The charge on the surface of nanofiltration membrane is one of the most important factors that affect the separation performance of nanofiltration membrane.The traditional polypiperazine amide nanofiltration membrane has negative charge on the surface,thus show a relatively low rejection toward divalent cations salts such as calcium salt and magnesium salts.In this paper,a positively charged poly(piperazine amide)nanofiltration membrane was prepared by reducing the interfacial resistance of monomer and enhancing the interfacial driving force of monomer,promoting the diffusion of piperazine monomer to the oil phase and leaving an excess of Amino groups after the interfacial polymerization.The chemical properties,surface morphology,structure and chargeability of the composite membranes were characterized by infrared spectroscopy,XPS,SEM,AFM,Zeta potential meter and other instruments,and the membrane properties were evaluated by cross-flow test.The results showed that the nanofiltration membrane showed excellent retention characteristics of positively charged membrane,and the retention sequence of different salt solutions was CaCl_(2)>NaCl>Na_(2)SO_(4),in which CaCl_(2)retained 95.3%,flux 118.4 L/(m^(2)·h·MPa).