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

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 H2O + 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 degrees 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.