单体配比对PI/PP耐溶剂复合纳滤膜结构与性能的影响

Effect of monomer ratio on structure and properties of PI/PP solvent resistant nanofiltration membrane

为提高纳滤膜的分离透过和耐溶剂性能,以间苯二胺(MPD)为水相单体,均苯四甲酰氯(BTC)与均苯三甲酰氯(TMC)为有机相单体,通过界面聚合法及后续的亚胺化制备了聚酰亚胺/聚丙烯(PI/PP)耐溶剂复合纳滤膜;采用傅里叶变换衰减全反射红外光谱(ATR-FTIR)、扫描电子显微镜(SEM)等手段研究了复合膜表面组成、结构及性能,考察了水相与有机相单体浓度配比及有机相中TMC与BTC质量浓度比对膜结构及性能的影响。实验表明:当水相单体质量浓度为1.14g/L、水相单体与有机相单体摩尔浓度比为1.15∶1、有机相单体TMC与BTC质量浓度比为6∶4时,所制备的膜性能最优;在0.5 MPa的过膜压差下,膜通量为52.6 L/(m^2·h),对PEG-400的截留率为93.8%;在甲醇等8种常见有机溶剂中浸泡8 d后发现,复合膜的拉伸强度、水通量及截留率变化不大,说明实验制备的复合纳滤膜具有良好的耐溶剂性能。

In order to improve the solvent resistance of nanofiltration,m-phenylene diamine(MPD)is utilized as the monomer of aqueous phase,1,2,4,5-benzene tetracarbonyl chloride(BTC)and trimesoyl chloride(TMC)are utilized as the monomers of organic phase,then polyimide/polypropylene(PI/PP)composite nanofiltration membrane was prepared by interfacial polymerization and subsequent imidization on the PP support membrane.Using attenuated total reflection Fourier transformed infrared spectroscopy(ATR-FTIR),scanning electron microscope(SEM)to observe the composition,structure and performance of composite membrane.The effects of aqueous phase and organic phase monomer concentration ratio and the quality concentration ratio of TMC to BTC on membrane structure and properties were investigated.Experimental results show that when the aqueous phase concentration is 1.14 g/L,the mole concentration ratio of aqueous phase monomer to organic phase monomer is 1.15∶1,and organic phase monomer mass concentration ratio of TMC to BTC is 6∶4,the performance of the composite membrane is optimal.The flux of the resulted membrane is 52.6 L/(m^2·h),and rejection of PEG400 is 93.8%under 0.5 MPa pressure.After immersed in eight kinds of common solvent,such as methanel,ethanel,etc,for 8 days,the tensile strength,flux and regection have little change,which explains that the resulted membrane showed excellent solvent resistance.