Dynamic crossflow ultrafiltration of colloids: a deposition probability cake filtration approach

A description of the dynamic, time-dependent ultrafiltration of charged colloids has been developed by combining an adhesion model for crossflow filtration of non-interacting particles with a Wigner-Seitz cell model for frontal filtration of charged colloidal dispersions. The adhesion model helps provide a criterion for the deposition of particles in a filter cake on the membrane surface, The Wigner Seitz cell model provides a quantitative description of the hydraulic resistance of the resulting filter cake. Two means of evaluating the deposition probability of charged colloidal particles have been considered - a cell based approach and an adjustable parameter approach, which was subsequently combined with multiple linear regression. The latter combined approach gave excellent agreement with experimental filtration flux-time data for silica colloids as a function of applied pressure. particle concentration. ionic strength and pH. Overall. this is a relatively simple yet Useful means of correlating the time-dependent performance of such a membrane process over a wide range of operating conditions. (C) 2001 Elsevier Science B.V. All rights reserved.