PROPERTIES OF MICROFILTRATION MEMBRANES - ADSORPTION OF BOVINE SERUM-ALBUMIN AT POLYVINYLIDENE FLUORIDE MEMBRANES

The adsorption of bovine serum albumin at polyvinylidene fluoride microfiltration membranes has been studied as a function of protein concentration, pH, electrolyte type, and flow rate through the membrane. Adsorption is initially rapid. Equilibrium is achieved after a period of 30 min to 3 h. Adsorption isotherms indicate two different adsorption sites, one of high affinity and the other of lower affinity for the protein. The numbers of such sites and the appropriate binding constants have been determined. The saturation coverage of the membranes by the protein occurs at substantially less than a monolayer. The variation of the amount of protein adsorbed with pH and electrolyte strength indicates that both electrostatic and short range forces need to be considered. The data show that the role of calcium ions is different from the role of sodium ions, possibly due to calcium bridging between carboxyl groups of the protein and the membrane surface. © 1991.