Solubility of Small-Chain Fatty Acids In Supercritical Carbon Dioxide

Currently, lipids derived from biomass are being considered as a promising renewable feedstock to synthesize a wide range of fuels and chemicals. Animals, plants, and microorganisms are biomass sources potentially rich in lipids. In fact, biodiesel, a renewable alternative to petroleum diesel, is produced primarily from soybean lipids. Individual lipid components must be considered as a source of chemicals. For example, many lipid sources contain unsaturated fatty acids, which can be oxidized to form a variety of products such as diacids and epoxides. These chemicals are valuable intermediates for the formulation of pharmaceuticals, herbicides, detergents, plasticizers, lubricants, paints, and other useful products. The use of supercritical fluids, such as carbon dioxide, in processing lipid components is being heavily researched; however, experimental solubility data primarily exists for lipids composed of higher molecular weight fatty acids such as oleic acid. In this research, the solubility of small-chain fatty acids in supercritical carbon dioxide has been determined at (313.15, 323.15, and 333.15) K over a pressure range of (10 to 30) MPa. The compounds considered include heptanoic, octanoic, nonanoic, and decanoic acids. The experimental apparatus was of a flow-type, dynamic design, and the solubility was obtained with the aid of GC analysis.