Adsorption of surfactants and polymers at the solid-liquid interface

Surfactants, polymers and their mixtures are widely used in several important industrial processes such as dispersion-flocculation, flotation, dewatering, paints and pigments and oil recovery. Many types of surfactants (anionic, cationic or non-ionic) and polymers (charged and otherwise) are used individually or in combination to achieve desired surface modifications. The adsorption of these molecules at the solid-liquid interface depends on several factors such as the nature of the substrate, solvent, adsorbate species, the presence of secondary competing-cooperative species, temperature and even mode of mixing. The nature of the adsorbed layer determines the surface modification achieved and this in turn depends on the adsorption mechanisms and the conditions prevailing during and after adsorption. Several spectroscopic techniques such as fluorescence, electron spin resonance and Raman spectroscopy have been employed to investigate the structure of various adsorbed layers and to obtain correlations with observed changes in the dispersion properties. In this paper, we review our previous work on adsorption of various ionic and non-ionic surfactants, polymers and their mixtures and mechanisms involved, in aqueous and non-aqueous media. (C) 1997 Published by Elsevier Science B.V.