The solubility of components, phase equilibria, and critical phenomena in the potassium bromide + water + pyridine system were investigated from T = 283.15 to 363.15 K by the visual polythermal method. KBr delaminates water–pyridine solutions above 323.75 K. The formation temperature of the critical tie line of the monotectic state (323.75 K) and the compositions of the solutions corresponding to the critical solubility points of liquid–liquid equilibrium at three temperatures were determined. The distribution coefficients K d of pyridine between the organic and aqueous phases of the monotectic state at 328.15, 343.15, and 363.15 K were calculated. The salting-out effect of KBr relative to pyridine from solutions is shown to be enhanced with an increase in the temperature. A comparative analysis of the results of our polythermal study of the salting-out action of potassium salts (iodide, bromide, nitrate, and chloride) on the binary water + pyridine system was done. It has been found that a decrease in the crystallographic radius of the salt anion in the KI–KBr–KNO3–KCl series leads to a decreased formation temperature of the critical tie line of the monotectic state of the ternary salt + water + pyridine systems and an enhanced salting-out effect of pyridine from aqueous solutions.

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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 dependences of the yield of these salts on the amount of triethylamine added and temperature have been found. It has been established that the maximum yield of sodium nitrate (79.4%) is observed for the aqueous solution with 47 wt.% salt upon the introduction of 90 wt.% triethylamine at 25.0° C. The maximum yield in the systems potassium (cesium) nitrate – water – triethylamine was 68.9% (22 wt. % potassium nitrate solution) and 66.2% (21 wt. % cesium nitrate solution) at 20.0° C and 90 wt. % amine content.

Phase equilibria, critical phenomena, and the solubility of components in the system potassium bromide + water + triethylamine (TEA) were studied in the range 273.15− 333.15 K by the visual polythermal method. The constituent twocomponent system H 2 O + TEA is characterized by delamination with lower critical solution temperature. The temperature of formation of the critical tie line of the monotectic state (274.25 K) and the compositions of the critical points of the liquid−liquid equilibrium at two temperatures were established. The phase diagrams of the ternary system at eight temperatures were plotted. The distribution coefficients of TEA between the organic and aqueous phases of the monotectic state at 13 temperatures were evaluated. The effect of salting-out of KBr in relation to TEA from its aqueous solutions enhances with temperature. Salt yield was evaluated by extractive crystallization at 11 temperatures and several TEA concentrations. It was found that the yield of potassium bromide crystals increases with increasing concentration of TEA in the three-component mixtures. The maximum yield of potassium bromide (73.7%) from an aqueous salt solution containing 38 wt % KBr took place at 15 °C upon the introduction of 90 wt % TEA. To find optimal conditions for extractive salt crystallization, a new approach is proposed based on analysis of the phase diagram of the ternary system salt + water + antisolvent within a certain temperature range.

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