Synergistic action of TiO2 particles and surfactants on the foamability and stabilization of aqueous foams

Abstract

Small particles can be activated via a synergistic effect with surfactants and adsorbed to the air–water interface to generate and stabilize foams, which has been applied extensively to develop new materials and techniques. Here, we studied the synergistic effects of TiO₂ particles with ionic surfactant SDS (sodium dodecyl sulfate), ionic AOT (sodium di-2-ethylhexylsulfosuccinate), and cationic CTAB (cetyltrimethylammonium bromide) in aqueous solution, and their impacts on the foamability and foam stability were assessed by measuring the foam volume and observing the number of particles adsorbed onto the foam surface. The results showed the interactions of TiO₂ particles with SDS and CTAB surfactants were synergistic in both foamability and foam stability. The degree of synergy of the CTAB–TiO₂ mixed system was stronger than that of the SDS–TiO₂ mixed system as a whole. However, the interaction of TiO₂ with AOT (a double carbochain anionic surfactant) in the TiO₂–AOT mixed system was generally not synergistic. Unexpectedly, a maximum synergistic effect among these mixed systems occurred in the TiO₂–AOT system at an AOT concentration of approximately 5 mM. This study provides further understanding for the mechanism of foaming and stability of foam modulated by surfactant and colloidal particles and provides a useful reference for future applications.