Macrocolloidal Transport in Membrane Filters in Slow Laminar Flows: Polarization Chromatography

Abstract

Particle transport in crossflow membrane filters is the result of complex interactions originating from module hydrodynamics, suspension chemistry and external forces. Experimental and theoretical investigations of particle transport in dilute suspensions were conducted in a laboratory model membrane filter to understand fundamental aspects of macrocolloidal transport. Particle residence time distributions (RTDs) were obtained experimentally under varying hydrodynamic conditions in the filter by making pulse inputs. Under conditions of laminar flow, particle transport can be divided into two regimes: convection dominated and diffusion dominated. Convective transport is described quantitatively by theories of particle mechanics as evidenced by correlations presented regarding the first passage time as well as the peak response. Diffusive transport is demonstrated by multiple peaks in the RTDs under existing experimental conditions. Understanding these transport processes can lead to a more rational design, selection and operation of membrane systems and pre-treatment options.