Influence of Common Surfactant Binary Composite System on Foamability

Anionic surfactant-sodium dodecyl benzene sulfonate (SDBS), sodium lauryl sulfate (SLS), sodium N-lauroyl sarcosinate (NLSS), sodium dodecyl sulfonate (SDS), zwitterionic surfactant-cocoamide propylene betaine (CAB), and non-ionic surfactant-fatty alcohol polyoxyethylene ether (AEO), Tween 20 (T20) had been used for combination experiment in binary surfactant systems. Foamability which defined by the ratio of foam volume and initial liquid volume had been characterized as well as the relevant surface activity parameters such as interaction parameter(β^m), the mole fraction in micelle and surface, and the Gibbs free energy(\Delta G_\rmm^0). Further exploration was performed to evaluate the effect of the interaction of the binary surfactant mixture on the foamability. The results showed that during the combination process of anionic and zwitterionic surfactants, coagulation occurred when the molar concentration ratio closing to 1∶1. When the surfactant with linear hydrophobic group and the nonionic surface with larger hydrophilic group were mixed, competitive adsorption occurred, which weakened the foamability of the surfactant. Synergistic effects could be produced when anionic surfactants with similar structures were compounded. The mixture of sodium dodecylbenzene sulfonate (SDBS) and sodium lauroyl sarcosinate (NLSS) has the best foaming performance when the molar concentration ratio was 7∶3, which had the best foam quality(Q=14.0). The interaction parameter was β^m=−9.83 (x_\rmSDBS^\rmm =0.4) calculated by the theory of synergy, which had a strong synergistic effect. The Gibbs free energy is ΔG_m ⁰=−13.60 kJ/mol, proving that the formation of micelles was a spontaneous process.