关键词: 乙二醇, 硫酸钾, 相平衡, 物理性质, 固溶体

Abstract:

An experimental study on phase equilibria in the system (K⁺, NH₄⁺//Cl^-, SO₄^2--H₂O) and (K⁺, NH₄⁺//Cl^-, SO₄^2--(CH₂OH)₂-H₂O) is done by the method of isothermal solution saturation. In these systems, the initial mass fraction of ethylene glycol is 30% in the salt-free binary solvent water + ethylene glycol. The solubilities, densities, viscosities, and refractive indices of saturated solutions have been measured for the two systems. On the basis of the experimental data, corresponding phase diagrams and diagrams of physical properties versus composition were plotted. All the physical properties of both systems change regularly with concentration change of the liquid phase. The phase diagram of (K⁺, NH₄⁺//Cl^-, SO₄^2--H₂O) consists of one invariant point, four univariant curves, and four solid phase crystallization regions at 333.15 K. The phase diagram of (K⁺, NH₄⁺//Cl^-, SO₄^2--(CH₂OH)₂-H₂O) is similar to the previous one, which contains one invariant point, four univariant curves, and four solid phase crystallization regions at 333.15 K. Comparisons of the stable phase diagrams for (K⁺, NH₄⁺//Cl^-, SO₄^2--H₂O) and (K⁺, NH₄⁺//Cl^-, SO₄^2--(CH₂OH)₂-H₂O) at 333.15 K are shown that they all have four solid solutions[respectively (K, NH₄)Cl, (NH₄, K)Cl, (K, NH₄)₂SO₄ and (NH₄, K)₂SO₄)]. These changes between phase diagrams at different solvents will be very useful for extracting the salts. According to this work, the measured data and phase equilibrium diagrams can be used for a new technology to design and optimize the production of K₂SO₄, from mother liquor of calcium carbonate whiskers prepared by FGD gypsum. At the same time, it can provide fundamental data support for chemical industry development.

Key words: ethylene glycol, K₂SO₄, phase equilibria, physical properties, solid solutions