Complexation between lignosulfonates and cationic surfactants and its influence on emulsion and foam stability

The association between sodium lignosulfonates and cationic as well as noni onic surfactants (quaternary ammonium bromides, cetylpyridinium chloride (C PC)) has been investigated by means of surface tension measurements, with a dditional information from measurements of viscosities and electrophoretic mobilities. A strong interaction is revealed between the lignosulfonate (LS ) and micelles of the cationic surfactant, whereas no interaction is found in the case of a polyethyleneoxide-based nonionic surfactant. This is in ag reement with the general behavior of polyelectrolyte-surfactant systems. LS as emulsifier in oil/water emulsions (o/w) gives rapid creaming into a hig hly concentrated emulsion, which is stable towards coalescence. The additio n of cationic surfactant enhances the stability towards creaming. LS is a p oor foaming agent, but the addition of cationic surfactant greatly improves the foam stability. (C) 1999 Elsevier Science B.V. All rights reserved.