Susanto Heru, Ulbricht Mathias
Lehrstuhl für Technische Chemie II, Universität Duisburg-Essen, 45117 Essen, Germany.
Langmuir. 2007 Jul 3;23(14):7818-30. doi: 10.1021/la700579x. Epub 2007 Jun 5.
Highly fouling-resistant ultrafiltration (UF) membranes were synthesized by heterogeneous photograft copolymerization of two water-soluble monomers, poly(ethylene glycol) methacrylate (PEGMA) and N,N-dimethyl-N-(2-methacryloyloxyethyl-N-(3-sulfopropyl)ammonium betaine (SPE), with and without cross-linker monomer N,N'-methylene bisacrylamide (MBAA), onto a polyethersulfone (PES) UF membrane. The characteristics, the stability, and the UF separation performance of the resulting composite membranes were evaluated in detail. The membranes were characterized with respect to membrane chemistry (by ATR-IR spectroscopy and elemental analysis), surface wettability (by contact angle), surface charge (by zeta potential), surface morphology (by scanning electron microscopy), and pure water permeability and rejection of macromolecular test substances (including the "cutoff" value). The surface chemistry and wettability of the composite membranes did not change after incubating in sodium hypochlorite solution (typically used for cleaning UF membranes) for a period of 8 days. Changes in water permeability after static contact with solutions of a model protein (myoglobin) were used as a measure of fouling resistance, and the results suggest that PEGMA- and SPE-based composite membranes at a sufficient degree of graft modification showed much higher adsorptive fouling resistance than unmodified PES membranes of similar or larger nominal cutoff. This was confirmed in UF experiments with myoglobin solutions. Similar results, namely, a very much improved fouling resistance due to the grafted thin polymer hydrogel layer, were also obtained in the UF evaluation using humic acid as another strong foulant. In some cases, the addition of the cross-linker during modification could improve both permeate flux and solute rejection during UF. Overall, composite membranes prepared with an "old generation" nonfouling material, PEGMA, showed better performance than composite membranes prepared with a "new generation" one, the zwitterionic SPE.
通过将两种水溶性单体聚乙二醇甲基丙烯酸酯（PEGMA）和N，N - 二甲基 - N -（2 - 甲基丙烯酰氧基乙基） - N -（3 - 磺丙基）甜菜碱（SPE），在有和没有交联剂单体N，N'-亚甲基双丙烯酰胺（MBAA）的情况下，非均相光接枝共聚到聚醚砜（PES）超滤膜上，合成了高抗污染超滤（UF）膜。详细评估了所得复合膜的特性、稳定性和超滤分离性能。通过膜化学（衰减全反射红外光谱和元素分析）、表面润湿性（接触角）、表面电荷（zeta电位）、表面形态（扫描电子显微镜）以及纯水渗透率和对大分子测试物质的截留率（包括“截留分子量”值）对膜进行了表征。在次氯酸钠溶液（通常用于清洗超滤膜）中孵育8天后，复合膜的表面化学和润湿性没有变化。与模型蛋白（肌红蛋白）溶液静态接触后水渗透率的变化用作抗污染性能的指标，结果表明，在足够的接枝改性程度下，基于PEGMA和SPE的复合膜比具有相似或更大标称截留分子量的未改性PES膜表现出更高的吸附抗污染性能。这在肌红蛋白溶液的超滤实验中得到了证实。在使用腐殖酸作为另一种强污垢物质的超滤评估中，也获得了类似的结果，即由于接枝的薄聚合物水凝胶层，抗污染性能得到了极大改善。在某些情况下，改性过程中添加交联剂可以提高超滤过程中的渗透通量和溶质截留率。总体而言，用“旧一代”抗污染材料PEGMA制备的复合膜比用“新一代”两性离子SPE制备的复合膜表现出更好的性能。
