Solubility, Phase Equilibria, and Critical Phenomena in the Ternary KBr + H₂O + C₅H₅N System from T = 283.15 to 363.15 K

Abstract

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.

Phase Equilibria, Solubility, and Extractive Salt Crystallization in the Ternary Potassium Bromide + Water + Triethylamine System from T = 273.15 to 333.15 K

“…The critical tie line KS transforms, as temperature increases, into a triangle scriptl 1 + scriptl 2 + normalS of monotectic state with adjoining fields of the delamination field scriptl 1 + scriptl 2 with the critical point K and saturated solutions scriptl 1 + normalS and scriptl 2 + normalS (e.g., the phase diagram at 278.15 K in Figure c). This set of phase states characteristic of isothermal phase diagrams of such three-component systems with salting-out of mixtures of the components of the incoming binary homogeneous system , is observed in the temperature range 274.25–291.45 K (Figure c,d). At the same time, with an increase in temperature, the fields of monotectics and delamination expand.…”

“…The ratio of the TEA concentrations in the equilibrium organic and water phases of the monotectics at each selected temperature is its distribution coefficients . The compositions of liquid phases of monotectics were calculated by the graphical method at different temperatures from the phase diagrams. , These compositions in mass fractions and distribution coefficients K d of TEA depending on the temperature are given in Table (in mole fractions in Table S7 in the Supporting Information). K d grows with increasing temperature, namely, salting-out of TEA from its aqueous solutions under the influence of potassium bromide enhances.…”

“…All the reagents used in this work were purified and dried. Deionized water of high purity (specific electrical resistance 18.0 MΩ × cm at 298.15 K) was obtained using a “Spectrum OSMOS” water treatment system . A TEA sample (analytical grade, Vekton, Russian Federation) was dried over KOH within 72 h, and the filtrate was then distilled on a fir reflux device exchanger (50 cm height), and the fraction characterized by a boiling point from 363.05 to 363.45 K was isolated.…”

“…The purified TEA was stored over 4 Å molecular sieves. KBr (chemical grade, Reakhim Corp., Russian Federation) was prepared and stored as previously described . The absence of moisture was monitored by thermogravimetry.…”

“…Phase behaviors of various mixtures of the three-component system KBr + H 2 O + TEA were studied by the visual polythermal method within a range of 273.15–333.15 K. The compositions of the liquid–liquid equilibrium (LLE) critical points were defined by the method of phase volume ratio . The experimental procedure was delineated in detail previously. , Now, it is presented in the Supporting Information (the experimental procedure).…”