Adsorption and surface properties of vladipor cellulose acetate and polysulfonamide membranes

Surface and adsorption characteristics of porous cellulose acetate (UAM) and polysulfonamide (UPM) membranes with pore diameters from 0.015 to 0.1 mu m are compared. The specific surface areas of UPM membranes are 130 and 150 cm(2)/cm(2), whereas those of UAM membranes vary from 80 to 360 cm(2)/cm(2) of the membrane area. The density of negative charges on the pore surface is 5 x 10(-8) and about 20 x 10(-8) C/cm(2) for UAM and UPM membranes, respectively. The adsorption of basic and acidic substances, proteins (cytochrome C and ovalbumin) and dyes (rhodamine 6G and Acid Orange), from aqueous solutions is studied. Far stronger hydrophobic interactions are observed for the UPM than for UAM membranes. The adsorption of basic substances is markedly higher than that of acidic substances because of acidic properties of the membrane surface. The distribution constants for the adsorption of Acid Orange and cytochrome C on the UPM membrane with a pore diameter of 0.1 mu m are 50- and 100-fold higher than for the UAM membrane of the same pore diameter and specific surface area.