Phase Equilibria in Triacylglycerols – Ethanol – Oleic Acid – Athyl Oleate Quasi-Quaternary System

<p>In order to use waste vegetable oils to produce biodiesel a possibility of reagents (sunflower oil and ethanol) mixture homogenization under the simultaneous effect of two cosolvents (oleic acid and ethyl oleate) was investigated. The possibility of action of oleic acid and ethyl oleate as cosolvents was analyzed with GSP model. For qualitative assessment of the intermolecular interaction parameter ξ was used. This parameter is a measure <br />of the ratio between cross-association (solvation) energy A–B and self-association (association) energies A–A and B–B. It was shown that most important role at intermolecular interactions of oleic acid and ethyl oleate with triglycerides belonged to dispersion forces. Predominant contribution of hydrogen bonds in the interaction of oleic acid and ethyl oleate with ethanol was shown. The prediction of improving the effect of the cosolvents with temperature increasing was done, and it was confirmed by experimental results.<br />The effect of oleic acid and ethyl oleate as cosolvents for homogenization of mixtures of sunflower oil and ethanol was investigated experimentally by studying the phase equilibria in the quasi-quaternary system triacylglycerols (sunflower oil) –ethanol –oleic acid –ethyl oleate at 30, 40, 50, 60 and 70 °C. The results of the experiments are presented in the form of phase diagrams of quasi-ternary boundary systems: triacylglycerols –oleic acid –ethanol and triacylglycerols –ethyl oleate –ethanol, and the phase <br />diagrams of composition tetrahedron sections with five different ratios of components oleic acid: ethyl oleate. Generalization of the research results is presented in the form of polythermal phase diagram for the system triacylglycerols –ethanol –oleic acid –ethyl oleate. Solubility polytherms (from 30 to 70 °C) for the system triacylglycerols –ethanol –mixed cosolvent with different ratios of oleic acid and ethyl oleate were plotted.</p>

Solubility and critical phenomena in reactive liquid–liquid systems

The goal of this work is to consider solubility phenomena in reactive fluid mixtures with liquid-phase splitting. One of the main tasks is to analyze peculiarities of liquid–liquid (LL) systems with equilibrium and nonequilibrium chemical reaction. The special aim is to consider the critical states in these systems. The reactive liquid–liquid equilibrium (LLE) is treated on the base of phase rule. The topology of diagrams of reactive LLE is discussed for some types of binary and ternary systems. Examples are presented of a possible transformation of phase diagrams caused by the shifting of chemical equilibrium and by changes in the shape of the binodal. The transformations resulting in the reactive critical phase formation are considered. Quaternary mixtures are also discussed with the use of experimental data on the solubility in the system with n-propyl acetate synthesis reaction. The mutual crossing of the chemical equilibrium surface and binodal in the composition tetrahedron leads to the origin of the area of simultaneous chemical and LLE with two critical points (reactive critical phases). The shape of the curve of simultaneous chemical and phase equilibrium is also presented in the square of transformed composition variables.