新型PEI/PAA复合正渗透膜的制备及性能表征

采用聚乙烯亚胺(PEI)和聚丙烯酸(PAA)分别作为聚阴阳电解质,间苯二胺(MPD)与均苯三甲酰氯(TMC)分别为水相和油相单体,依次采用层层自组装(LBL)和界面聚合的方法对聚丙烯腈(PAN)基膜进行改性,探究层层自组装和界面聚合条件对膜性能的影响,并制备新型复合正渗透膜.得出最佳制备条件为:PAA与PEI的沉积时间为10 min,浓度为1 g·L~(-1),pH分别为9和3,支撑盐浓度为1.5 mol·L~(-1),MPD浓度为20 g·L~(-1),水相沉积时间为2 min,TMC浓度为1 g·L~(-1),界面聚合反应时间为60 s,聚电解质层数为2层,在此条件下制得的复合正渗透膜性能优良.以去离子水作为原液,1 mol·L~(-1) NaCl作为汲取液,水通量最高可达26.12 L·m~(-2)·h~(-1),反向盐通量为13.08 g·m~(-2)·h~(-1),与基膜相比,复合膜的亲水性能明显提高,抗污染性能提高,为正渗透膜的制备提供了新的方法和思路.

Preparation and characterization of novel PEI/PAA composite forward osmosis membrane

A novel forward osmosis membrane was fabricated through layer-by-layer (LBL) assembly technology and then interfacial polymerization (IP) method with polyacrylonitrile (PAN) as substrate material in this study. The influences of LBL and IP conditions on the properties of membranes were investigated in detail. Polyethyleneimine (PEI) and polyacrylic acid (PAA) were used as the cationic and anionic polyelectrolytes. M-phenylenediamine (MPD) and 1,3,5-benzenetricarbonyl trichloride (TMC) were used as monomers in water and oil phase, respectively. The optimum preparation conditions were obtained as follows. The deposition time and concentration of PAA and PEI were all 10 min and 1 g·L^-1. The pH for PAA and PEI were 9 and 3, respectively. The concentration of sodium chloride was 1.5 mol·L^-1. 20 g·L^-1 MPD aqueous solution was firstly deposited on membrane for 2 min and then followed by interfacial polymerization of 1 g·L^-1 TMC for 60 s. The optimum polyelectrolyte layer was 2 layers. In this condition, the water flux of 26.12 L·m^-2·h^-1 and the reverse salt flux of 13.08 g·m^-2·h^-1 were achieved by the composite forward osmosis membrane with deionized water as the raw solution and 1 mol·L^-1 NaCl as the draw solution. Compared with the base film, the hydrophilic property and anti-fouling property of composite membrane were obviously improved, which provided a new approach for the preparation of forward osmosis membrane.