Synergistic effect and performance characterization of an efficient environmental-friendly Camellia oleifera saponins based foamed cleaning agents

Foamed cleaning agents mainly consist of synthetic surfactants. However, the widespread use of petroleum-based surfactants not only consumes non-renewable resources but also causes harm to the environment. It is necessary to develop surfactants with higher biodegradability and lower toxicity to obtain a recipe for an environment friendly foamed cleaning agent. Camellia oleifera saponins (TS) was prepared and mixed with a zwitterionic surfactant (dodecyl dimethyl sulfopropyl betaine, SB12-3). The equilibrium surface tension of single surfactants and their binary mixtures in the air/water system was measured using Wilhelmy method. The interaction and thermodynamic parameters of different mixtures were calculated via the regular solution model. The parameters showed that the mixtures displayed a synergistic effect, and the optimum molar ratio of TS/SB12-3 was determined to be 5/95. The mixture had the shortest wetting time (13 s), the smallest contact angle (32.4°), and the lowest surface tension (32.2 mN/m). Furthermore, the addition of TS significantly improved the emulsifying and foam properties. Cleaning experiments were completed by applying foamed surfactant solutions with different liquid fractions (ε) prepared by the double syringe technique on oil-contaminated glass substrates. The foamed surfactant solutions of the mixture were cleaner than those of TS or SB12-3 at all ε. The maximum oil area removal efficiency of the mixture was 94.9% at ε = 15%. The mixture exhibits a better cleaning efficiency than that of single surfactants. This study provides a new way for the utilization of Camellia oleifera cake.