Mechanisms of Concentration Polarization and Cake Formation in Crossflow Membrane Filtration of Aqueous Colloidal Particles

0114527 Elimelech本研究的目的是提供一个全面的微观层次的理解热力学和微观流体动力学的浓差极化和滤饼形成的错流膜过滤。 一个主要的重点将放在识别的过渡点，从无序的类液体相的浓度极化层的有序固体状的饼层。研究将涉及以下任务：1）预测胶体分散体的平衡结构，2）评估渗透压、沉降系数和扩散系数，3）预测错流膜过滤条件下胶体体系中的液-固转变点，4）预测浓差极化和/或滤饼形成的程度以及所得的渗透通量下降行为，5）选择用于验证理论的模型实验系统和6）在各种背景电解质浓度、颗粒浓度、pH、交叉流速和操作压力下使用模型胶体分散体对上述理论方法进行实验验证。该研究为定量分析胶体分散液错流膜过滤过程中渗透通量下降行为提供了理论依据。 这些结果将变得越来越重要，因为膜工艺，特别是纳滤和超滤，对于处理天然和废水沃茨变得更加可行，因为这些技术提供了一种全面的方法来满足多种溶解和胶体污染物的多个水质目标。***

0114527 Elimelech The objective of this research is to provide a comprehensive microscopic-level understanding of the thermodynamics and micro-hydrodynamics of concentration polarization and cake formation in crossflow membrane filtration. A major emphasis will be placed on the identification of the transition point from a disordered liquid-like phase in the concentration polarization layer to an ordered solid-like cake layer. The research will involve the following tasks: 1) Prediction of the equilibrium structure of a colloidal dispersion, 2) Evaluation of the osmotic pressure, sedimentation coefficient and diffusion coefficient, 3) Prediction of the liquid-solid transition point in colloidal systems under crossflow membrane filtration conditions, 4) Prediction of the extent of concentration polarization and/or cake formation and the resulting permeate flux decline behavior, 5) Selection of a model experimental system for validation of the theory and 6) Experimental validation of the above theoretical approach using model colloidal dispersions at various background electrolyte concentrations, particle concentrations, pH, crossflow velocities and operating pressures. This research is expected to lead to a sound theoretical basis for quantification of permeate flux decline behavior in crossflow membrane filtration of colloidal dispersions. These results will become increasingly important as membrane processes, particularly nanofiltration and ultrafiltration, become more viable for treatment of natural and waste waters because these technologies offer a comprehensive approach to meeting multiple water quality objectives for a myriad of dissolved and colloidal contaminants. ***