INTERFACIAL STATE CHANGE OF CELLULOSE TRIACETATE MEMBRANE BY ADSORPTION OF POLYELECTROLYTE

Lysozyme, albumin, and PAS-H (poly diallyl dimethyl ammonium chloride) , which are positively and negatively charged proteins, and cationic p olysulfones, respectively, were adsorbed by a cellulose triacetate (CT A) membrane to investigate their effects on ionic transport through th e membrane. The interface states between the membrane and the adsorpti on layer are discussed based on the measurements of contact angle and membrane potential and atomic force microscopy (AFM). The contact angl e shows that the membrane changed from hydrophobic to hydrophilic due to adsorption of the above substances. AFM imaged the aggregates on th e surface and showed that lysozyme, in particular, penetrates the memb rane pores, making them shallower and decreasing their porosity. The r esults of membrane potential measurements shelved that lysozyme and al bumin did not change the membrane charge state, but PAS-H changed it f rom negative to positive. The permeability coefficients of KCI and K2H PO4 varied significantly with the adsorption of each polyelectrolyte. In particular; the permeability coefficient of phosphate through the l ysozyme-adsorbed membrane increased to twice that of the nonadsorbed, membrane. Such polyelectrolyte adsorption on the membrane surface can be used for the modification of commercial artificial kidney phosphate extraction. (C) 1997 Academic Press.