RES/PIP混合聚酰胺纳滤膜的制备

Preparation of RES/PIP mixtures polyamide composite nanofiltration membranes

以聚砜超滤膜为基膜,间苯二酚(RES)与哌嗪(PIP)混合作为水相溶液,均苯三甲酰氯(TMC)为有机相溶液,采用界面聚合法制备复合纳滤膜。探索了混合水相质量比RES/PIP、TMC浓度、界面聚合时间、热处理温度及热处理时间等界面聚合条件对复合膜分离性能的影响,考察了最佳条件所得复合膜对不同种类无机盐的分离性能,并使用原子力显微镜(AFM)对基膜及所得复合膜表面形貌进行了表征。结果表明最佳聚合条件为:RES质量分数0.5%,PIP质量分数1.5%,TMC质量分数0.15%,水相浸渍时间3 min,界面聚合反应时间60 s,热处理温度80℃,热处理时间3 min;在0.6 MPa下,所得复合膜对4种无机盐的截留顺序依次为Na_2SO_4>MgSO_4≥MgCl_2>NaCl,这表明静电排斥作用在纳滤膜分离过程中占主导地位;此外,由基膜和所得复合膜的表面形貌对比结果可得,通过界面聚合反应会在基膜表面形成一层粗糙度较大的聚酰胺功能层。

Polyamide composite nanofiltration membranes were fabricated through interfacial polymerization.The membranes were prepared on polysulfone（ PSF） ultrafiltration membrane supports,with a mixture of 1,3-resorcinol（ RES） and piperazine（ PIP） as the aqueous monomer and trimesoyl chloride（ TMC） as the organic monomer. The effects of interfacial polymerization conditions,that is,factors such as the RES / PIP mass ratio,TMC concentration,reaction time,curing temperature,and curing time,on the performance of the composite membranes were analyzed. The composite membrane separation properties for different salt solutions were systematically investigated,and the surface morphologies of the substrate and composite membranes were examined via atomic force microscopy（ AFM）. According to the results,the optimum polymerization conditions were as follows： RES and PIP concentrations of 0. 5% and 1. 5%,respectively,TMC concentration of 0. 15%,soaking time in aqueous phase of 3 min,reaction time of 60 s,curing temperature of 80 ℃,and curing time of 3 min.The salt rejection order was Na_2SO_4 MgSO_4≥MgCl_2 NaCl when tested under a pressure of 0. 6 MPa. This sequence revealed that electrostatic repulsion forces played a dominant role in the process of nanofiltration membrane separation. Moreover,by comparing the surface images of the substrate with the composite membrane,it could be seen that a polyamide active layer was formed on the substrate through interfacial polymerization.