The interfacial properties of biosurfactant mixtures

There is growing global demand to transition to more sustainable surfactant technologies. Towards this vision, bio-based surfactants and biosurfactants are being explored as alternatives to traditional petrochemical surfactants. However, the transition towards these technologies is expected to be gradual, therefore there is a critical need to formulate new biosurfactants in combination with traditional surfactant classes such as alkoxylates, sulfates and amine-oxides to achieve a balance of performance, cost, and sustainability. To this end, we report a study of the impact of sophorolipid biosurfactants on the cloud point of alcohol ethoxylates, and on the surface tension and foaming of alkyl sulfate/amine-oxide mixtures. We make the surprising finding that high-acid sophorolipids can act as highly efficient hydrotropes and increase the cloud point of alcohol ethoxylates. In sulfate/amine-oxide mixtures, models of experimental data suggest that both high-acid and high-lactone sophorolipids can replace 40–50% of the primary surfactants without significant changes to the surface tension or foaming performance. These findings will enable the next-generation of high performing sustainable cleaning formulations to be realized.