Further separation of KCl and NH4Cl by l-propanol-KCl-NH4Cl-water aqueous two-phase system

摘要

The solubility of KCl and NH4Cl in water, 1-propanol and 5%1-propanol were determined by static analytical method. Based on the conjunction of static analytical method and titration method, the phase diagrams for l-propanol-KCl-NH4Cl-water quaternary systems with different mass fraction of KCl and NH4Cl have been determined experimentally at 298.15 K. Furthermore, the binodal curve data were satisfactorily correlated using a three-parameter equation. In the liquid-liquid-solid area of the phase diagram, the selective partition of KCl and NH4Cl has been studied. The effects of several parameters on the yield and the purity of KCl or NH4Cl in the precipitation were also investigated, such as different mass fraction of KCl to NH4Cl, the concentration of 1-propanol and temperature. The experimental results showed that the increase in the mass fraction of KCl to NH4Cl favored both the yield and the purity of KCl in the precipitation, and the purity of KCl is more than 98%, 95% and 91% when KCl/NH4Cl (w/ w) = 3/l, 2/1 and 1/1, respectively. The purity of NH4Cl is much higher only when KCl/NH4Cl (w/ w) = 1/3 and the purity can be >98%. The results also showed that low temperature favored the yield and has insignificantly influence on the purity of KG. The increase in the concentration of 1-propanol favored the yield greatly, while the purity of the precipitation has a modest decrease.