Phase behavior and solubility of components of the binary butyric acid – polyethylene glycol-1500 system

Abstract

A critical review of the literature on the methods of concentration and extraction of biobutyric acid from fermentation solutions has been carried out. The best results of these processes are achieved by combining extraction with salting. It is proposed to use polyethylene glycols with diff erent molecular weights as non-fl ammable and environmentally friendly extractants. The purpose of the study was to identify the phase behavior of mixtures of components, study solubility and construct a phase diagram of the previously unexplored double system butyric acid – PEG-1500 in the range −10.0–50.0°C. The transition temperatures of phase states in mixtures of components of the dual system butyric acid (BA) – polyethylene glycol-1500 (PEG-1500) in the temperature range −10–50°C have been found by the visual-polythermal method. The phase diagram above the eutectic line shows a large crystallization fi eld of PEG-1500, while the crystallization fi eld of BA has very small dimensions. It has been established for the fi rst time that eutectic equilibrium is carried out in the system at −6.6°C, the solid phases of which are crystals of BA and PEG-1500, the composition of the liquid phase of eutectic (3.20 wt.% BA) has been determined. A method for concentrating BA and separating the components of the investigated system based on the crystallization of PEG-1500 during cooling of mixtures is proposed.

Keywords

• solubility
• phase diagram
• eutectic
• butyric acid
• peg-1500