Solid–Liquid Equilibrium for Binary and Ternary Phases of Saturated Fatty Acid–Urea–Alcohol in Urea Complexation

Abstract

Urea complexation is a fractionating process to separate poly unsaturated fatty acids from vegetable and animal oil, based on the capability of saturated fatty acids (SFAs) to form complexes with urea in the ethanolic solution, which generates a solid−liquid system. This research determined models which are suitable for the fatty acid, urea, and ethanol/methanol solid−liquid equilibrium. Furthermore, activity coefficients and interaction parameters between the substances involved were evaluated. Pure SFAs were used in this experiment instead of SFAs produced from vegetable oil saponification. Solid-liquid phase diagrams for binary and ternary saturated fatty acid−urea−ethanol were developed. These binary data were used to determine experimental activity coefficients and interaction parameters using thermodynamic models based on excess Gibbs free energy, such as Wohl, Wilson, Margules, and nonrandom two liquid models. The resulting interaction parameters gave a good fitting between experimental data and adjustable or predictive models.

Solid-Liquid Equilibrium Study of Binary System Saturated Fatty Acid in Short Chain Alcohols

“…The experimental data from this study showed a tendency for fatty acids to reach the highest solubility in 95% ethanol (w/w). Figure 4 compares the solubility data of fatty acids in 95% ethanol (w/w) from this study with the research conducted by Setyawardhani, et al [3]. This research studied wider range of fatty acid mole fractions to complete the data from previous research.…”

“…Alcohol is widely used for fatty acid extraction and separation through urea complexation. Previous research showed that urea was more soluble in water than alcohol, due to their polarities [3]. However, fatty acids mostly insoluble in water.…”

“…Saturated fatty acids have no double bonds, while unsaturated fatty acids have single, double bonds or more [2]. Polyunsaturated fatty acids (PUFAs) are essential neutraceuticals and should be consumed through foods [3]. PUFAs which are contained in vegetable and animal oils have great potential to support growth and normal function in the body system [4].…”

“…PUFAs which are contained in vegetable and animal oils have great potential to support growth and normal function in the body system [4]. Meanwhile, SFAs are utilized for nonconsumable needs, such as alternative fuels, the coating industry and many oleochemical raw materials [3].…”

“…The principle of urea complexation fractionation is separation based on the diameter of fatty acid molecules. Urea complexation is also considered an SFA adsorption phenomenon in urea crystals [3].…”