Abstract:
The results of an experimental study on the solubility of acetone in carbon dioxide are presented. The study was conducted along the critical isopleth with a critical concentration of the binary mixture components beyond the binodal curve using a dynamic measurement method. The pressure ranges in which the solubility exhibits regular behavior in one case and singular behavior in another have been identified. For the first time, in the asymptotic vicinity of the critical point as it is approached, the fact of an anomalous increase in solubility has been established. The prerequisites and conditions for the swelling of the component intended for extraction, which formed the basis for new concepts about the mechanism of supercritical fluid extractive separation as applied to type I-II phase behavior systems, are discussed. For the first time, an explanation of the concept of pseudosolubility is provided. According to this concept, the designated characteristic simultaneously combines, on one hand, the indicators of the target component's extraction into the extractant phase within the traditional understanding of solubility, and on the other hand, the possibility of transferring macroscopic volumes of the extractable component to the separator. This transfer is caused by its swelling in the extractor due to the dissolution of the supercritical fluid solvent into it. Experimental data on the pseudo-solubility of acetone in carbon dioxide at supercritical isobars are presented. At pressures near its critical value, the pseudosolubility significantly exceeds the values of the equilibrium solubility by multiple times.
Keywords:extraction, supercritical fluid state, type of phase behavior, regime of complete miscibility, solubility, pseudosolubility.
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