фазовые равновесия

A brief review of computational methods for the liquid-liquid equilibrium has been carried out, and their capabilities and limitations have been shown. Complications of such computational models for the liquid–liquid–solid equilibrium lead to a decreased accuracy of calculations. In this case, it is advisable for researchers to make use of the approximation of experimental data on the liquid – liquid and liquid – liquid – solid equilibria.

Phase equilibria in the ternary system sodium nitrate – water – dipropylamine where the constituent binary liquid system is characterized by a trend to form a lower critical solution temperature (LCST) were studied using the visual-polythermal method in the range ?10.0–90.0° C. It was found that the introduction of sodium nitrate into the water – dipropylamine system led to a significant decrease in the mutual solubility of the components.

Phase equilibria in the water–butyric acid binary system in the range of ?10?0° C and in the sodium chloride–water–butyric acid ternary system in the range of 10.0?60.0° C were studied using the visual polythermal method. The phase diagram of the water–butyric acid binary system at ?9.5° C is characterized by eutectic equilibrium, the solid phases of which being ice and butyric acid crystals. The metastable delamination range was found on the ice crystallization field, bounded by a binodal curve with an upper critical solution temperature of ?3.7° C.

Visual polythermal method in the bynary system of water-2-(2-butoxyethoxy) ethanol in the range of –25?0° C the ice melting line is determined and the phase equilibria in the ternary system potassium nitrate–water–2-(2-butoxyethoxy) ethanol are studied in the range of 10.0–90.0° C. The ice melting line in the water–2-(2-butoxyethoxy) ethanol binary system is a flat, smooth line. This form of the melting line shows a hidden separation in liquid mixtures.

A comparative analysis of the results of our polythermal study of the ternary systems sodium (potassium, cesium) nitrate – water – triethylamine has been carried out to estimate the efficiency of the use of triethylamine in the extractive crystallization of alkali metal nitrates from water–salt solutions containing 43.0, 44.0, 45.0, 46.0, and 47.0 wt. % sodium nitrate in the range of 10.0–25.0°C, 20.0, 21.0, and 22.0 wt.% potassium nitrate and 18.0, 19.0, 20.0 and 21.0 wt. % cesium nitrate in the range of 20.0–25.0°C.

The phase diagram of the ?-alanine–water binary system was studied using the visual polythermal method and the method of time–temperature curves in а temperature range of -20–90°С. There is a eutectic equilibrium at -18.3°С in the system; the solid phases of this equilibrium are ice and individual ?-alanine. For the first time, the composition of the liquid phase of the eutectic state was determined.

The quaternary mutual system Li,K||F,MoO4 ,WO4 was partitioned into the simplexes and described the chemical interaction by conversion method and by method of ion balance. The prediction of the crystallizing phases conducted on the basis of the partition and of the equations for the reactions of conversion lines and for the method of ion balance.