A Study On Phase Equilibrium Of KCL And NH₄CL Aqueous Solution By The Separation Of Extraction Technology

Based on the two methods of water-1-propanol-KCl-NH4 Cl aqueous two-phase system(ATPSs) and reactive extraction with tributylamine for the separation of KCl and NH4 Cl from aqueous salt solution, this work investigate the variation of the equilibrium under different proportions of inorganic salts for the separation, including ATPSs(water +1-propanol + KCl + NH4Cl) and(water + 1-butanol + KCl + NH4Cl), and further analyze the influence of extractant and extracted complex on quaternary systems(water + 1-butanol+ TBA?HCl + KCl) in reactive extraction and(water + 1-butanol + TBA + NH4Cl) in the recovery of extractant.Binodal curves of studied ATPSs were fitted by three-parameter equation at different salt(KCl and NH4Cl) mass-fraction rations(0/1, 1/3, 1/1, 3/1 and 1/0). Tie-lines data of four related ternary systems(salt mass-fraction ratios 0/1 and 1/0) were successfully described by Othmer-Tobias and Hand equations, while the tie-lines data and saturated equilibrium data of quaternary systems(salt mass-fraction ratios 1/3, 1/1, 3/1) were correlated using the modified Eisen-Joffe equation. The result shows that liquid-liquid regions increase with the increasing of KCl/NH4 Cl ratios, and the partition coefficient and selectivity of aliphatic alcohol also increased, which reach to the maximum at 303.15 K.Binodal curves of quaternary systems(water + 1-butanol + TBA?HCl + KCl) in reactive extraction and(water + 1-butanol + TBA + NH4Cl) in the recovery of extractant can be fitted by three-parameter equation. Tie-lines data can also be successfully described by Othmer-Tobias and Hand equations. The difference between this two quaternary systems and related ternary systems(water + 1-butanol + KCl) and(water + 1-butanol +NH4Cl) is that the existence of TBA ? HCl will increase liquid-liquid two-phase region,while TBA will decrease the area.To obtain the phase equilibrium experimental data accurately and rapidly, this work constructed the model of multi-output support vector regression based on genetic algorithm(GA-MSVR) on the basis of electrolyte solution theory, statistical mechanics and support vector machine(SVM). The model has good generalization ability, and it can successfully predict the composition of organic aqueous solution containing electrolyte and the mean error is <0.3% when they reach phase equilibrium.