Mass Transfer Characteristics of Hollow Fiber Ultrafiltration of Soy Protein Systems

Mass transfer characteristics and the applicability of theoretical transport models in ultrafilitration were evaluated in a pilot‐scale hollow fiber system processing soybean water extracts. Permeate flux was found to increase linearly with transmembrane pressure and then reach an asymptotic value. Substantial deviations from the pure water permeation line and marked hysteresis effects were also observed, indicative of concentration polarization and additional hydrodynamic resistance at the membrane surface. Pressure‐independence occurred at lower pressures with lower Reynolds Numbers (Re) and higher Schmidt Numbers (Sc). Flow rate and temperature significantly affected flux in the totally polarized region. The exponent in the flux‐Reα relationship varied from 0.6 at 20°C to 0.32 at 50°C. Theoretical laminar flow mass transfer models were found to predict Sherwood Numbers (Sh) and flux lower than experimental values. The correlation that fit the data best was Sh = 0.181 (Re).47 (Sc).33