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Adsorption of beta-lactoglobulin to strong anion exchange membranes was investigated using three different contacting modes (batch adsorption, radial and tangential flow), and by equilibrium adsorption isotherm, as a function of temperature. The maximum binding capacity (qmax) was: (1) higher at lower temperature for the isotherm where qmax = 1.08 mg/cm2 at 10 °C versus qmax = 0.82 mg/cm2 at 50 °C, (2) independent of temperature for batch adsorption where the average qmax = 0.82 mg/cm2, (3) higher at lower temperature for radial flow where qmax = 0.87 mg/cm2 at 15 °C versus qmax = 0.38 mg/cm2 at 50 °C. For tangential flow at 10 °C, qmax = 0.65 mg/cm2. Differences in qmax between the three contacting modes were minor compared to the differences in the mass transfer coefficients that were tenfold higher for tangential flow than for batch adsorption. This was attributed to convective flow in the membrane pores closest to the flow channel, and diffusive mass transfer in the membrane pores farthest from the flow channel. The present work is the first report of mass transfer coefficients in tangential flow adsorbers, and the first report on the effect of temperature on the binding capacity of beta-lactoglobulin to adsorptive membranes. |
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