Colloid–membrane interaction effects on flux decline during cross-flow ultrafiltration of colloidal silica on semi-ceramic membranes
Colloid–membrane interaction effects on flux decline during cross-flow ultrafiltration of colloidal silica on semi-ceramic membranes
复制标题
半陶瓷膜上胶体二氧化硅错流超滤过程中胶体-膜相互作用对通量下降的影响
DOI：
10.1039/b315220k
复制
发表时间：
2004
影响因子：
3.3
通讯作者：
R. Leysen
中科院分区：
文献类型：
--
作者：
P. Meeren;H. Saveyn;S. B. Kassa;W. Doyen;R. Leysen
为了研究胶体-胶体以及胶体-膜相互作用对膜过程中发生的通量下降的影响，在不同的电解质浓度以及不同的pH值下进行过滤试验。胶态二氧化硅颗粒的表面性质通过电泳光散射测定，而超滤膜的表面电荷特性来自流动电位测量。从通量与跨膜压力的曲线，它是推导出，高和低的盐浓度都是优选的，以优化渗透通量提供的颗粒和膜具有相似的电荷特性。在低盐浓度下，这种行为是由于胶体-胶体以及胶体-膜排斥相互作用，这大大降低了浓差极化。在高盐浓度下，胶体分散体的絮凝产生大的多孔絮体。由于后者的影响，浓度极化层变得高度可渗透。另一方面，在pH条件下观察到严重的通量下降，其中胶体颗粒和超滤膜带相反的电荷，产生吸引力的静电相互作用。
结果表明，超滤膜的性能受到其与饲料中的胶体颗粒的相互作用的强烈影响。如果排斥相互作用占优势，则获得最佳条件，这可以通过适当调节进料来实现。
In order to investigate colloid–colloid, as well as colloid–membrane interaction effects on the flux decline occurring during membrane processes, filtration tests were performed at different electrolyte concentrations, as well as at different pH values. The surface properties of the colloidal silica particles were determined by electrophoretic light scattering, whereas the surface charge characteristics of the ultrafiltration membranes were derived from streaming potential measurements. From the flux versus transmembrane pressure curves, it was derived that both high and low salt concentrations were preferable to optimise the permeate flux provided that both particles and membrane had similar charge characteristics. At low salt concentration, this behaviour was due to colloid–colloid as well as colloid–membrane repulsive interactions, which largely reduced concentration polarisation. At high salt concentrations, flocculation of the colloidal dispersions gave raise to large, porous flocs. As a consequence of the latter effect, the concentration–polarisation layer became highly permeable. On the other hand, a severe flux decline was observed at pH conditions where the colloidal particles and the ultrafiltration membrane were oppositely charged, giving rise to attractive electrostatic interactions.
The results indicate that the performance of ultrafiltration membranes is strongly affected by its interaction with the colloidal particles in the feed. Optimum conditions are obtained if repulsive interactions prevail, which may be accomplished by proper conditioning of the feed.