Solubilization of selected free fatty acids in palm oil by biodegradable ethoxylated surfactants.

The solubilization of three major components, viz., palmitic, oleic, and linoleic acids, in palm oil by ethoxylated surfactants was investigated. The results were analyzed in terms of the molecular properties of surfactants and free fatty acids (FFAs). It was found that the solubilities of these FFAs in various micellar solutions depend not only on their octanol-water partition coefficients (Kow), but also on their physicochemical properties. The study on the solubilization kinetics was conducted by choosing palmitic acid as a model solubilizate and Tergitol 15-S-7 as the model surfactant. A first-order film diffusion model, which accounts for the direct uptake of organic molecules at a solid surface into surfactant micelles, was adopted to analyze the effect of surfactant on dissolution of palmitic acid. It was observed that the presence of surfactant reduced the mass-transfer coefficient. Instead, the overall mass-transfer rate was enhanced because of the much higher driving force from the increased solubilization capacity.