Zwitterion polymer modified membranes have demonstrated fouling resistance in wide applications. The ubiquitous success in scientific progress, however, has not yet brought significant breakthrough in the application of such membranes in wastewater treatment. Limitation of zwitterion materials in membrane is seldomly discussed. In this paper, we aimed to bring an engineering view on the pros-and-cons of zwitterion modified microfiltration membrane in treating solutions containing humic acid (HA) and bovine serum albumin (BSA). A 3-[[3-(trimethoxysilane)-propyl] amino] propane-1-sulfonic acid (TMAPS) grafted zwitterionic PVDF membrane was selected as a model membrane. The membranes were prepared via a two-step “hydroxylation-grafting” method; surface modified PVDF membrane was transformed from hydrophobic to hydrophilic with significant improvement in pure water flux. An 87% increase was obtained in the stable flux for the grafted membrane when treating HA, but very similar flux pattern to the pristine one was found when treating BSA. The membrane resistance model showed that cake layer was the main fouling factor for both foulants. For HA, the cake layer blocking model predicted the membrane flux well; but for BSA, the intermediate blocking model fits best the experimental results. Zwitterion grafted surface failed to show improvement in the fouling resistance even at very low BSA feed concentration. Adsorption experiment indicated that the interaction of BSA to membrane is significantly stronger than HA and membranes independent from the surface characteristics. Present work clarified the limitation of zwitterion modified membranes in treating solutions containing HA-like and protein matters.

两性离子聚合物改性的膜已在广泛的应用中显示出抗污性。然而，科学进步的普遍成功尚未在将这种膜应用于废水处理中带来重大突破。很少讨论两性离子材料在膜中的限制。在本文中，我们旨在为两性离子修饰微滤膜在处理包含腐殖酸（HA）和牛血清白蛋白（BSA）的溶液中的利弊带来工程学观点。选择3-[[[3-（三甲氧基硅烷）-丙基]氨基]丙烷-1-磺酸（TMAPS）接枝的两性离子PVDF膜作为模型膜。膜通过两步“羟基化接枝”方法制备。表面改性的PVDF膜从疏水性转变为亲水性，纯净水通量得到显着改善。当处理HA时，嫁接膜的稳定通量增加了87％，但是当处理BSA时，发现与原始的通量模式非常相似。膜阻力模型表明，滤饼层是两种污垢的主要污垢因素。对于HA，滤饼层阻隔模型很好地预测了膜通量。但是对于BSA，中间阻塞模型最适合实验结果。即使在非常低的BSA进料浓度下，两性离子接枝的表面也没有表现出抗污性的改善。吸附实验表明，BSA与膜的相互作用明显强于HA和独立于表面特性的膜。