Particle deposition during membrane filtration of colloids: transition between concentration polarization and cake formation
Particle deposition during membrane filtration of colloids: transition between concentration polarization and cake formation
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DOI：
10.1016/s0376-7388(96)00187-1
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发表时间：
1997-03
影响因子：
9.5
通讯作者：
V. Chen;A. Fane;S. S. Madaeni-S.;I. Wenten
中科院分区：
文献类型：
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作者：
V. Chen;A. Fane;S. S. Madaeni-S.;I. Wenten
通过对膜通量的施加和系统响应的观察，研究了硅溶胶膜过滤过程中浓差极化向滤饼形成的转变。已经测量了临界通量（Jcrit），低于该临界通量，跨膜压降ΔP对于增加和减少通量是稳定的。低于Jcrit的操作的通量-压力曲线显示出很小的（MF）或可忽略的（UF）滞后。在Jcrit以上，压力对于增加和减少通量有一段不稳定期，并且存在显著的滞后。看起来，一旦超过Jcritis，极化层中的胶体形成固结的饼结构，该饼结构缓慢地脱附并且降低了通量。从电子显微照片中获得了滤饼沉积的证据。去极化可以通过交叉流、洗涤和增加pH来增加。观察到通量缓慢增加到给定的高值可以导致比直接应用该通量显著更低的ΔP。这些差异归因于由于非常快速的通量增加导致的溶质的固结和聚集而在膜表面附近形成停滞的、高度浓缩的层。
The transition from concentration polarization to cake formation has been studied for the membrane filtration of colloidal silica by imposing flux and observing the system response. A critical flux (Jcrit) has been measured, below which transmembrane pressure drop, ΔP, is stable for increasing and decreasing flux. The flux–pressure profiles for operations below Jcritshow little (for MF) or negligible (for UF) hysteresis. Above Jcritthe pressure has a period of instability for increasing and decreasing flux, and there is significant hysteresis. It appears that once Jcritis exceeded, the colloids in the polarized layer form a consolidated cake structure that is slow to depolarize and which reduces the flux. Evidence for cake deposition was obtained from electron micrographs. The depolarization can be increased by crossflow, by washing, and increasing pH. It was observed that the slow incrementation of flux to a given high value can result in significantly lower ΔP than the direct application of that flux. These differences are ascribed to formation of a stagnant, highly concentrated layer near the membrane surface due to consolidation and aggregation of solute resulting from very rapid flux increases.