摘要
Filtration characteristics and membrane fouling in BSA/dextran binary suspension cross-flow microfiltration is studied. An increase in cross-flow velocity or transmembrane pressure leads to higher pseudo-steady filtration flux due to less membrane fouling or higher driving force. The fouled membrane pore size and fouled layer thickness under various conditions are estimated using a theoretical model based on the Hagen–Poiseuille law. The fouled membrane pore size decreases with increasing transmembrane pressure due to ever increasing fouling. The fouled layer thickness becomes thicker and invariant with operating conditions under a lower pressure drop through the fouled membrane. Molecular adsorption occurs on the pore walls until a specific wall shear stress is reached in the membrane pores. However, the fouled layer becomes thinner when the pressure drop exceeds a critical value. An increase in cross-flow velocity results in a larger fouled membrane pore size and a thicker fouled layer in such condition. The dextran molecular deformation under higher transmembrane pressure causes a thinner fouled layer and an ultimate equilibrium adsorption in the membrane pores. Furthermore, an increase in cross-flow velocity leads to higher BSA and dextran rejection due to the sweeping effect on the membrane surface. The BSA rejection increases with transmembrane pressure due to the reduction in membrane pore size, while the decrease in dextran rejection under higher transmembrane pressure is attributed to the molecular deformation. The “coil-stretched” deformation of dextran molecules can be indicated using the Deborah number. The fouled membrane pore size and dextran rejection decrease with increasing Deborah number and remain constant as the Deborah number exceeds a critical value. Taking the filtration flux and solute rejection into consideration, operating a cross-flow microfiltration system under lower cross-flow velocity and higher transmembrane pressure is more efficient from the selectivity and mean dextran mass flux view points.
摘要译文
过滤特性和膜污染BSA /葡聚糖二元悬架横流微滤进行了研究。在交叉流速度或跨膜压力的增加导致更高的伪稳态过滤通量由于较少膜污染或更高的驱动力。在各种条件下的污染膜孔径和结垢层厚度是使用基于所述哈根 - 泊肃叶定律的理论模型来估计。随着跨膜压力，由于不断增加的污垢污染的膜孔径减小。该结垢层厚度变为下通过污染膜更低的压降较厚和不随操作条件。分子吸附发生在孔壁上，直到一个特定的壁剪切应力达到在膜孔。然而，结垢层时的压力降超过临界值变得更薄。在交叉流速度导致较大的结垢膜孔径的增加和更厚的结垢层在这样的条件。较高的跨膜压力下的葡聚糖分子变形导致较薄结垢层和一个最终的平衡吸附在膜孔。此外，增加了在交叉流速度会导致更高的BSA和葡聚糖排斥由于在膜表面上的清扫效果。与跨膜压力的BSA的排斥增加由于在膜孔径的减少，而在高跨膜压力下葡聚糖排斥的减少归因于分子变形。葡聚糖分子的“线圈拉伸”变形可以使用德博拉数来指示。的污染膜孔径和葡聚糖排斥减少随德博拉数和保持的常量作为德博拉数量超过临界值。取滤通量和溶质排斥的考虑，在较低的交叉流速度和更高的跨膜压力下操作的横流微量过滤系统是从选择性更高效和平均葡聚糖质量通量观点。
Kuo-Jen Hwang; Pan-Yu Sz. Filtration characteristics and membrane fouling in cross-flow microfiltration of BSA/dextran binary suspension[J]. Journal of Membrane Science, 2010,347(1-2): 75–82