ULTRAFILTRATION OF ALBUMIN ETHANOL SOLUTIONS ON MINERAL MEMBRANES

This paper investigates the ultrafiltration of albumin-ethanol solutio ns on ZrO2 mineral membranes for the preparation of human albumin from plasma. The classical process consists of a preconcentration phase of a 20% ethanol-albumin 7.5 g/L solution to raise albumin concentration to 80 g/L, then a diafiltration to reduce ethanol concentration to le ss than 0.3 g/L, and a final concentration to adjust albumin concentra tion to its final value of 210 g/L. The potential advantages of minera l membranes relative to the polysulfone membranes presently used are a longer membrane life and higher permeate fluxes in the presence of et hanol. In addition, they lend themselves to the use of back flushing o r pulsatile flows for reducing membrane fouling. Using 2.7 mm i.d. Car bosep membranes with a 10 kd cut-off and velocities of 7 m/s, permeate fluxes of 40 L/h.m2 at 4-degrees-C were obtained with 50 g/L albumin, 20% ethanol solutions representative of the preconcentration phase, w hile 45 to 50 L/h.m2 were obtained at albumin concentrations of 100 g/ L without ethanol at 8-degrees-C, representative of the final concentr ation phase. These fluxes compare favorably with fluxes obtained previ ously in our laboratory with polysulfone membranes which were respecti vely of 22 and 40 L/h.m2 for the same solutions. This study confirms t he expectation of a smaller reduction in the presence of ethanol of th e permeate flux for the mineral membranes while albumin concentration in the permeate remained generally under 0.4 g/L irrespective of reten tate concentration. The superposition of pressure and flow pulsations on the filter inlet by a piston-in-cylinder system decreases concentra tion polarization and increases permeate flux by 50 to 60% as compared with steady flows under the same conditions.