Water Solubilization in Mixed Nonionic Surfactants Microemulsions

The systems investigated were water/sucrose laurate/ethoxylated mono-di-glyceride/oleic phase. The oleic phase used first was the pure oils R (+)-limonene, isopropylmyristate, and caprylic-capric triglyceride; these oils were then mixed with ethanol at different mixing ratios (w/w). The total area of the one phase microemulsion region is dependent on the mixing ratios (w/w) of the mixed surfactants and that of the ethanol/oil. The largest microemulsion phase area formed with a surfactants mixing ratio (w/w) equals unity. For the systems where the oleic phase was a mixture of oil and ethanol, the total area of the monophasic microemulsion increases with the increase in the ethanol/oil mixing ratio (w/w). The Gibbs free energy of solubilization was estimated. It increases as the mixing ratio (w/w) of ethoxylated mono-di-glyceride/sucrose laurate increases and with the increase in the ethanol/oil mixing ratio (w/w). The Gibbs free energy of solubilization decreases with the increase in the water content in the water-in-oil microemulsions. The values of the Gibbs free energy of solubilization are higher for oil-in-water microemulsions compared to those of the water-in-oil microemulsions.