抗污染纳滤膜的制备及性能研究

Preparation and Performance of Anti-Fouling Nanofiltration Membrane

以哌嗪为水相单体,海藻酸钠为其亲水性表面活性剂,以含有均苯三甲酰氯的Isopar G为油相,聚砜超滤膜为底膜,通过界面聚合反应制备一种网络结构的抗污染纳滤膜。利用扫描电子显微镜,原子力显微镜和红外光谱仪等检测方法对纳滤复合膜进行了性能和结构方面的表征。结果表明:在0.75 MPa、3.785 L/min、25℃恒温条件下这种水相中添加海藻酸钠的纳滤膜对硫酸镁截留率为98.9%、水通量为94 L/(m^(2)·h)。而氯化钠的截留率为51.4%,水通量97 L/(m^(2)·h)。在进行抗污染实验时,经过18 h的运行,此纳滤膜的截留率降低幅度很小,水通量降低了35%,但是经过碱洗后,膜片的水通量恢复明显,可达86.2%,说明本纳滤膜具有一定的抗污染性能,而且由于海藻酸钠是一种多糖,将其应用于纳滤膜领域无毒,因此此方法有很好的前景。

In this experiment, piperazine was used as water phase monomer, sodium alginate as its hydrophilic surfactant, and Isopar-G as oil phase which contained trimesoyl chloride. An anti-fouling nanofiltration membrane with a network structure was prepared on the polysulfone ultrafiltration membrane by interfacial polymerization. The properties and structure of nanofiltration composite membranes were characterized by scanning electron microscopy, atomic force microscopy, and infrared spectroscopy. The results showed that the rejection rate of magnesium sulfate was 98.9% and the water flux was 94 L/(m^(2)·h) under the conditions of 0.75 MPa, 3.785 L/min, and 25 ℃. The rejection rate of sodium chloride was 51.4% and the water flux was 97 L/(m^(2)·h) under the same conditions. In the anti-fouling test, the rejection rate of the nanofiltration membrane slightly decreased after 18 h operation, and the water flux decreased by 35%. However, the water flux of the membrane recovered obviously up to 86.2% after alkali washing,indicating that the nanofiltration membrane has a certain anti-fouling performance. Because sodium alginate is a kind of polysaccharide, it is non-toxic when it is used in the field of nanofiltration membrane, so this method has a good prospect.