OPTIMIZATION OF ULTRAFILTRATION AND DIAFILTRATION PROCESSES FOR ALBUMIN PRODUCTION

This paper presents a model of the combined ultrafiltration-diafiltrat ion process used by plasma fractionation centers to prepare human albu min by Cohn's ethanol precipitation technique. This process consists o f a predilution to lower the ethanol concentration C-a from 40 to 20%, a preconcentration phase to raise albumin concentration to similar to 80 g/l, a diafiltration to reduce ethanol concentration to 0.1 g/l an d a final concentration of albumin to 210 g/l. Laboratory scale experi ments were run with water-ethanol solutions of bovine albumin at vario us concentrations to determine, for each membrane rested, a correlatio n for the permeate flux as a function of C-a and C-p. The model was us ed to determine the effects of initial dilution and albumin concentrat ion at diafiltration on a normalized process time, which is defined as the time necessary to process 1 kg of albumin with 1 m(2) of membrane . Optimal initial ethanol concentrations were found to depend upon the membrane material (30% for polysulfone, 16% for cellulose acetate) an d the minimum process time was generally obtained when diafiltration w as carried out at the maximum albumin concentration.