A theoretical and experimental study of the crossflow microfiltration process of silica particles in an aqueous suspension

This work presents a theoretical and experimental analysis of a crossflow microfiltration process of silica particles in suspension. The silica suspensions were 0.001 M of NaCl with a pH of 6 (to maintain a constant ionic force within the medium to produce a stable silica particle suspension) for three different concentrations of silica particles: 100, 300, and 500 mg L⁻¹. The membrane used in the crossflow microfiltration experiments was a commercial polymeric membrane, microporous, asymmetric with a nominal pore diameter of 0.2 µm, manufactured by OSMONICS (Minnetonka, MN). The experiments were performed in a bench scale crossflow microfiltration system with a flat rectangular membrane cell. The permeate flux was obtained as a function of the transmembrane pressure, the crossflow velocities, and the silica particles concentration. The mathematical model describing the process takes into account the variation of the physical properties of the suspension (dynamic viscosity and mass diffusivity) with the silica concentration. The experimental data are used to predict the maximum silica concentration at the membrane surface as a function of the operating conditions.