Phase equilibria and phase diagrams of the ternary system (NaNO3 + RbNO3 + H2O) at 298.15 and 338.15 K: Experimental and application

The phase equilibria of the ternary system at 298.15 and 338.15 K were investigated by the isothermal dissolution equilibrium and wet-reside solid phase (Schreinemarkers rule) methods. The solubilities and the physicochemical properties containing density and refractive index were obtained experimentally. Then, the phase diagrams and the diagrams of physicochemical properties against the composition in the ternary system at two temperatures were proposed. The phase diagrams of this system at two temperatures contain two invariant points, three solubility curves, and three crystallized regions corresponding to NaNO 3 , RbNO 3 and double salt NaRb 2 (NO 3 ) 3 . According to the phase diagrams at 298.15 and 338.15 K, a novel separation process of RbNO 3 from the mixture solution of NaNO 3 was established for the first time, and the separation rate of RbNO 3 in the mixed solution reached 43.75% in a single yield. This work provides an efficient and reliable RbNO 3 green recovery method from the eluent solution of NaNO 3 efficiently.