Synergism and foam stability in a binary mixture of tea saponin derived from Camellia oleifera Abel and Sodium Lauryl Ether Sulfate

Abstract

Sodium Lauryl Ether Sulfate, AES, is an anionic surfactant containing ethylene oxide groups, which is widely used in various cosmetic. In this work we investigate the synergism and foam stability in a binary mixture of tea saponin (TS) and AES to promote the development of new formulations and reduce the use of synthetic surfactants in commercial products. The effect of TS addition on interfacial behavior was investigated by interfacial tension (γ) and foam properties, and the interfacial activity was analyzed on different fluid/fluid interfaces at different environments. The results showed that the mixtures of TS with AES displayed synergism in critical micelle concentration (cmc), such as the interaction parameter and thermodynamic parameter. Low concentration of TS addition not only caused the decrease of γcmc, but also improved the stability of the foam. The stability of foams has been interpreted on the basis of bubble distribution size and contact angle. Further study revealed that the interfacial activity of the AES/TS mixture was stable at high temperatures, in the presence of mono (Na+) and divalent (Ca2+ and Mg2+) counterions, and at a pH of 3–11.