Environ Sci Technol. 2015 Jun 2;49(11):6574-80. doi: 10.1021/es505830h. Epub 2015 May 12.
To determine further the enhancement and mitigation mechanisms of protein fouling, filtration experiments were carried out with polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes and bovine serum albumin (BSA) over a range of ionic strengths. The interaction forces, the adsorption behavior of BSA on the membrane surface, and the structure of the BSA adsorbed layers at corresponding ionic strengths were investigated. Results indicate that when the ionic strength increased from 0 to 1 mM, there was a decrease in the PVDF-BSA and BSA-BSA electrostatic repulsion forces, resulting in a higher deposition rate of BSA onto the membrane surface, and the formation of a denser BSA layer; consequently, membrane fouling was enhanced. However, at ionic strengths of 10 and 100 mM, membrane fouling and the BSA removal rate decreased significantly. This was mainly due to the increased hydration repulsion forces, which caused a decrease in the PVDF-BSA and BSA-BSA interaction forces accompanied by a decreased hydrodynamic radius and increased diffusion coefficient of BSA. Consequently, BSA passed more easily through the membrane and into permeate. There was less accumulation of BSA on the membrane surface. A more nonrigid and open structure BSA layer was formed on the membrane surface.
为了进一步确定蛋白质污染的增强和缓解机制，在一系列离子强度下，用聚偏二氟乙烯（PVDF）超滤（UF）膜和牛血清白蛋白（BSA）进行了过滤实验。研究了相互作用力、BSA 在膜表面上的吸附行为以及相应离子强度下 BSA 吸附层的结构。结果表明，当离子强度从 0 增加到 1 mM 时，PVDF-BSA 和 BSA-BSA 静电斥力减小，导致 BSA 更高速率地沉积在膜表面上，形成更致密的 BSA 层，从而增强了膜污染。然而，在离子强度为 10 和 100 mM 时，膜污染和 BSA 去除率显著降低。这主要是由于水合排斥力的增加，导致 PVDF-BSA 和 BSA-BSA 相互作用力减小，同时 BSA 的水动力半径减小，扩散系数增大。因此，BSA 更易通过膜进入渗透物，在膜表面的积累减少，形成更具非刚性和开放性的 BSA 层。
