树状聚合物PAMAM制备高脱盐纳滤膜

High salt rejection nanofiltration membrane prepared by poly(amidoamine)(PAMAM) dendrimer

通过发散法合成了以N-(2-胺乙基)哌嗪为核的端胺基树状聚合物聚酰胺胺(PAMAM),并以此为水相单体与均苯三甲酰氯发生界面聚合反应制备了高脱盐率纳滤膜。采用傅里叶转换红外光谱(FTIR-ATR)、X射线光电子能谱(XPS)等手段研究膜表面化学组成的变化,扫描电镜(SEM),原子力显微镜(AFM)观察膜的结构与形貌,接触角测定仪评价膜的亲水性。结果表明,使用高代数PAMAM、增大PAM-AM浓度、延长反应时间均促使膜的致密度增加,脱盐率增大。使用浓度为4.46×10-3 mol/L第二代PAM-AM溶液为反应物制备的纳滤膜对Na2SO4、MgCl2、MgSO4的脱除率分别达到93.0%,92.3%和91.4%。值得注意的是,PAMAM浓度的增加导致酰氯基由过量到相对不足,最终所制备的纳滤膜对NaCl、Na2SO4、MgCl2和MgSO4等4种盐的脱盐顺序也发生相应变化,主要体现在MgCl2的脱除率由低于Na2SO4和MgSO4变化到高于这两种盐最后三者的脱除率趋于近似相等,均>90%。

N-（2-aminoethyl）-piperazine cored amine-terminated poly（amido-amine）（PAMAM） dendrimer was synthesized by divergent procedure.A series nanofiltration（NF） membranes with high salts rejection were prepared with PAMAM and trimesoyl chloride（TMC） via in situ interfacial polymerization.Fourier transform infrared spectroscopy in attenuated total reflection mode（FTIR-ATR）,X-ray photoelectron spectroscopy（XPS）,scanning electron microscopy（SEM） and atomic force microscopy（AFM） were applied to characterize the NF membranes.Water contact angle was also employed to evaluate the hydrophilicity of the resulting membranes.The results indicated that membrane became more compact by using higher generation PAMAM,increasing the PAMAM concentration or prolonging reaction time which lead to higher salt rejection.The salt rejection coefficient of Na2SO4,MgCl2,MgSO4 reached 93.0%,92.3% and 91.4%,respectively for the membrane prepared by NG2 dendrimer（4.46×10-3mol/L）.It should be noted that the increase of PAMAM concentration resulted in the amount of acyl chloride group changed from excess to relatively less than amino group which greatly affected the salt rejection order of NaCl,Na2SO4,MgCl2 and MgSO4.The MgCl2 rejection changed from lower to higher than and then nearly equal to that of Na2SO4 and MgSO4,all of them finally reached more than 90%.