摘要
目的:利用多巴胺改性构建一种简单制备荷正电复合纳滤膜,解决多巴胺类改性材料耐碱性差的问题。创新点:1.利用共沉积技术与交联反应成功制备了荷正电复合纳滤膜;相较于传统多巴胺改性膜,该复合膜的稳定性大大提高。2.经过测试表征,制备得到的纳滤膜的分离尺寸属于疏松纳滤膜范围,可用于相应尺度的分离领域。方法:1.通过多巴胺与聚乙烯亚胺共沉积,首先实现二者的表面沉积,随后通过交联剂交联制备复合膜(图1);2.对改性膜前后表面理化性质进行相应表征(表2和图3~6);3.通过测试通量和截留等性能及分析相关纳滤模型,表征该复合膜分离性能(图7和8,公式(5)和(7));4.通过长期分离测试及碱性溶液清洗,测试复合膜的稳定性和耐碱性。结论:1.成功制备了具有荷正电性的复合纳滤膜;2.通过通量和截留数据拟合分析得出该膜截留尺寸在1.5 nm和2 nm之间,属于疏松纳滤膜,可用于相应尺度分离;3.该复合膜具有良好的稳定性及耐碱性,应用范围更广。
Positively charged composite nanofiltration（NF） membranes with good stability were prepared by dopamine（DA） assisted poly（ethylene imine）（PEI） deposition on a polysulfone ultrafiltration（UF） substrate followed by a cross-linking step. Attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electronic microscopy, and atom force microscopy were employed to characterize the surface chemistry and morphology of the obtained composite membranes. The DA and PEI co-deposition conditions were optimized based on knowledge of the co-deposition mechanism. The effects of the cross-linker concentration, cross-linking time, and reaction temperature on the permeation and separation properties of the prepared composite membranes were investigated in detail. Under optimized conditions, the Mg Cl2 rejection and permeation flux of the composite membrane reached 80.4% and 19.6 L/（m^2·h）, respectively（the feed was 0.01 mol/L of Mg Cl2 solution under a test pressure of 0.4 MPa）. The rejection of various salts followed the order Mg Cl2≈Ca Cl2〉 Mg SO4〉Na Cl〉Na2SO4, suggesting the membranes were positively charged. The composite membranes showed good durability under alkaline aqueous conditions. This study provided new insights into the fabrication of mussel-inspired thin-film composite nanofiltration membranes.
基金
supported by the National Natural Science Foundation of China(Nos.51273176 and 51573159)
the Fundamental Research Funds for the Central Universities(No.2016QNA4032),China
关键词
多巴胺
共沉积
纳滤膜
耐碱性
Dopamine（DA）
Poly（ethylene imine）（PEI）
Co-deposition
Nanofiltration（NF） membranes
Cross-linking
