Formulating Alcohol-Free Microemulsions Using Rhamnolipid Biosurfactant and Rhamnolipid Mixtures

This research focused on developing alcohol-free biosurfactant-based microemulsions. Rhamnolipid-based mixtures were found to have double the solubilization parameter as compared to sodium bis(2-ethyl) dihexyl sulfosuccinate/sodium dihexyl sulfosuccinate/sodium mono- and dimethyl naphthalene sulfonate at the same total molar concentration. For the first time, a phase diagram was developed for surfactant mixtures containing soy methyl ester ethoxylate, rhamnolipid and oleyl alcohol with limonene oil. This phase diagram can be used as a guideline for selecting a surfactant system and surfactant ratio to formulate microemulsions with a given oil. In addition, the alcohol-free biosurfactant-based microemulsions required reasonable salinity values for limonene, making it viable in a variety of applications.