Adsorption behaviour of polyvinyl pyrrolidone on oxide surfaces

Adsorption of polyvinyl pyrrolidone (PVP) onto the oxide surfaces, namely, kaolinite, titanium dioxide, iron oxide and alumina has been studied by electrokinetics and measurement of adsorption density. The mechanism of adsorption is suggested to be as the acid-base interaction between the substrate surface and polymer segments. The presence of surface hydroxyl groups. with the tendency to lose protons acting as Bronsted acid sites in the crystal lattice of these metal oxides, can interact with the binding sites of PVP segments considered as Lewis base in aqueous solution. Electrokinetic and adsorption studies of individual oxide system has been carried out to comprehend the mechanism of interaction and qualitative investigation were sketched out incorporating the Stern-Graham and Langmuir adsorption isotherm equations. (C) 2000 Elsevier Science B.V. All rights reserved.