Contact angles and external protein adsorption onto UF membranes

Both receding and advancing contact angles of pure water and BSA solutions against the active layers of several retentive ultrafiltration membranes ar e studied here. In particular, three membranes from desalination systems, w hose active layers are made of aromatic polyamides: G5, G20 and G50 have be en chosen. It has been shown that these membranes are hydrophilic with equal advancing contact angles against pure water while the receding ones decrease with in creasing pore radii. Finally, both the contact angles against the BSA solutions are studied at d ifferent pH and concentrations. It is shown that the stationary advancing c ontact angles correspond to the early adsorption steps while receding ones correspond to the final adsorption level. When analyzed within this frame, the results obtained can easily be explained in terms of the qualitatively known molecule-molecule and molecule-membrane surface interactions. (C) 199 9 Elsevier Science B.V. All rights reserved.