荷正电聚四氟乙烯复合纳滤膜的制备及表征

以聚四氟乙烯(PTFE)平板膜为基膜,对其进行亲水改性后,以支化聚乙烯亚胺(PEI)和均苯三甲酰氯(TMC)为主要单体,通过界面聚合制备了荷正电聚四氟乙烯复合纳滤膜。采用红外光谱、扫描电子显微镜、原子力显微镜和固体表面Zata电位分析仪研究了复合纳滤膜的表面化学结构、微观形貌和荷电特性,结果表明,在亲水PTFE基膜表面形成了致密的多层结构,复合纳滤膜在pH为中性的条件下呈现荷正电。通过优化制备条件,复合纳滤膜对MgCl_2溶液的截留率达到95.7%,水通量为13.47 L/(m~2·h)(测试液浓度1000 mg/L,操作压力0.4 MPa)。此外,测试复合纳滤膜对不同盐溶液的截留率大小顺序为MgCl_2(95.7%)MgSO_4(90.7%)Na_2SO_4(77.5%)NaCl(58.1%),对聚乙二醇(PEG)的截留相对分子质量为402。研究表明制备的复合纳滤膜在硬水软化领域具有潜在的应用价值。

Synthesis and Characterization of Positively Charged Polytetrafluoroethylene Composite Nanofiltration Membrane

A positively charged composite nanofiltration (NF) membrane was formed by interfacial polymerization with polyethylenimine (PEI) and trimesoyl chloride (TMC) on a hydrophilic polytetrafluoroethylene (PTFE) substrate.Surface chemical structure,surface morphology and charge of the prepared composite membrane were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FT-IR),scanning electron microscopy (SEM),atomic force microscopy (AFM) and Zeta potential analyzer.The results indicate that a dense multistructure is formed on the hydrophilic PTFE substrate.The prepared composite nanofiltration membrane is positively charged at a neutral pH.After preparation parameters were optimized,the prepared composite nanofiltration membrane presents the rejection of 95.7％ and permeate flux of 13.47 L/(m2·h) (MgCl2).In addition,rejection values of different solutes are the following order,MgCl2 (95.7％) ＞ MgSO4 (90.7％) ＞ Na2SO4 (77.5％) ＞ NaCl (58.1％).The molecular weight cut off (MWCO) of PEG is 402.It suggests that the prepared composite nanofiltration membrane may be potential in the field of water softening.