Ultrafiltration of charge-stabilized dispersions at low salinity.

We present a comprehensive study of cross-flow ultrafiltration (UF) of charge-stabilized suspensions, under low-salinity conditions of electrostatically strongly repelling colloidal particles. The axially varying permeate flux, near-membrane concentration-polarization (CP) layer and osmotic pressure profiles are calculated using a macroscopic diffusion-advection boundary layer method, and are compared with filtration experiments on aqueous suspensions of charge-stabilized silica particles. The theoretical description based on the one-component macroion fluid model (OCM) accounts for the strong influence of surface-released counterions on the renormalized colloid charge and suspension osmotic compressibility, and for the influence of the colloidal hydrodynamic interactions and electric double layer repulsion on the concentration-dependent suspension viscosity η, and collective diffusion coefficient Dc.

Temperature-modulated water filtration using microgel-functionalized hollow-fiber membranes.

In the present work, we investigate the potential of aqueous polymer microgels in membrane technology, especially for filtration applications. The poly(N-vinylcaprolactam)-based microgels exhibit thermoresponsive behavior and were employed to coat hollow-fiber membranes used for micro- and ultrafiltration. We discuss the preparation of microgel-modified membranes (by "inside-out" as well as "outside-in" filtration in dead-end mode).