Quantitative flux analysis of gas - Liquid two-phase ultrafiltration

The gas-liquid two-phase upward-flow ultrafiltration in a hollow-fiber membrane module with dextran aqueous solution as tested solution is studied in this work. The permeate fluxes are measured under various feed concentrations, superficial liquid velocities, superficial gas velocities, and transmembrane pressures. The flux increases with the increase in liquid velocity, gas velocity, and the transmembrane pressure, and decreases with the increase in the feed concentration. The flux enhancement by gas slugs is particularly significant when the ultrafiltration system is operated at a lower liquid velocity. The resistance-in-series model combined with the modified gel polarization model is applied to obtain the mass transfer coefficient of the gas-liquid two-phase ultrafiltration, and the dimensional analysis technique is used to find the correlation equation of the mass transfer coefficient. Furthermore, the flux equation for gas-sparging ultrafiltration is proposed. The predicted fluxes agree well with the experimental data.