Study on the influence of surfactants on the adsorption and electrokinetic properties of the system: Cationic starch/alumina

The aim of this paper was to investigate the influence of some surfactants of different chemical character (SDS, CTAB, TX-100 or their equimolar mixtures) on the adsorption and electrokinetic properties of the cationic starch (CS)/alumina system. The obtained results show that CS creates multilayer complexes with SDS, TX-100 and their mixture, but does not interact with CTAB. The reason for that is connected with chemical character of the polyelectrolyte and the above-mentioned surface active agents. Formation of complexes was confirmed by the surface tension measurements and by the measurements of surfactants adsorption at the alumina surface in the presence and absence of CS. The crucial information about both the electrokinetic properties of the system and the structure of the adsorption layer was obtained from the surface charge density and zeta potential measurements. The obtained data showed the specific structure of the adsorption layer polymer/surfactant/metal oxide. According to the results the polymer is directly bonded to the surface whereas the surfactants are present in the upper parts of the electrical double layer. (C) 2015 Elsevier B.V. All rights reserved.