Adsorption and electrokinetic properties in the system: Beta-cyclodextrin/alumina in the presence of ionic and non-ionic surfactants

Abstract

Abstract The influence of some ionic and non-ionic surfactants (CTAB, SDS, TX-100 and TX-405) on the adsorption of β-cyclodextrin (β-CD) at the surface of alumina using the spectrophotometric measurements was determined. The additional information concerning the process of oligosaccharide-surfactant complexation was obtained by the use of the surface tension measurements. The obtained results show that there is no competitive adsorption between the β-cyclodextrin and surfactants but the adsorption of the oligosaccharide-surfactant complexes takes place. β-CD creates the complexes characterized by 2:1 stoichiometry with CTAB and TX-100 whereas these with SDS and TX-405 have 1:1 stoichiometry. The structure of the adsorption layer in the oligosaccharide/surfactant/metal oxide system was determined using the thickness of adsorption layer, the zeta potential and the surface charge density measurements. The lack of information the worldwide literature concerning this subject in together with the ability of β-cyclodextrin possessing chelating properties toward surfactants to modify the alumina surface was the motivations of this study. The obtain results create new possibilities in the fields of functionalized materials especially such as adsorbents, catalysis and drug delivery systems.