A Study On Phase Equilibria In Quinary System Na⁺,K⁺//Br^-，SO₄^2-，B₄O₇^2--H₂O At348K

Phase equilibria of reciprocal quinary system Na⁺，K⁺//B^r-，SO₄^2-，B₄O₇^2--H₂Oat348K and phase equilibria of quaternary system KCl-K₂B₄O₇-K₂SO₄-H₂O at348Kwere determinded by isothermal solution quilibrium. Subsystems of the reciprocalquinary system which included four quaternary systems, NaBr-Na₂SO₄-Na2B4O7-H₂O,KBr-K₂SO₄-K₂B₄O₇-H₂O, Na⁺, K⁺//B^r-, SO₄^2--H₂O and Na⁺, K+//SO₄^2-, B₄O₇^2--H₂O,were also studied by isothermal solution equilibrium methed. The solubilities anddensities of system listed at348K were mensurated. Based on the experimental data,the equilibria phase diagram, corresponding water conten diagram, corresponding Na⁺content diagam and density-composition diagram of the quinary system（saturatedwith Na2B4O7） were plotted. The phase diagrams, corresponding water contentdiagrams and corresponding Na⁺content diagrams of the quaternary systems werealso finished.The experimental results indicate that the quaternary system NaBr-Na₂SO₄-Na2B4O7-H₂O at348K was of simple eutectic type and no double salt and solidsolution was found. In the phase diagram, the quaternary system has three univariantcurvers, one invariant point, three fields of crystallization （NaBr，Na2B4O7·5H₂O andNa₂SO₄）. The experimental results of the quaternary system show NaBr had thesalting-out effect on Na2B4O7·5H₂O and Na₂SO₄.The quaternary system KBr-K₂SO₄-K₂B₄O₇-H₂O at348K was of simple eutectictype and no double salt and solid solution was found. In the phase diagram, thequaternary system has three univariant curvers, one invariant point, three fields ofcrystallization （KBr, K₂SO₄ans K₂B₄O₇·4H₂O）. The experimental results of thequaternary system show KBr had the salting-out effect on K₂SO₄and K₂B₄O₇·4H₂O.In the quaternary system Na⁺，K⁺//B^r-，SO₄^2--H₂O at348K, the double salt Na₂SO₄·3K₂SO₄forms. In the phase diagram, the quaternary system has threeinvariant points, seven univariant curves, five fields of crystallization （NaBr，KBr，Na₂SO₄·3K₂SO₄，Na₂SO₄，K₂SO₄）. The experimental results of the quaternary systemshow bromide had the salting-out effect on sulfate.In the quaternary system Na⁺，K+//SO₄^2-，B₄O₇^2--H₂O at348K, the double saltNa₂SO₄·3K₂SO₄forms. In the phase diagram, the quaternary system has threeinvariant points, seven univariant curves, five fields of crystallization （Na₂SO₄，K₂SO₄，Na₂SO₄·3K₂SO₄，Na2B4O7·5H₂O，K₂B₄O₇·4H₂O）.In the reciprocal quinary system Na⁺，K⁺//B^r-，SO₄^2-，B₄O₇^2--H₂O at348K, thedouble salt Na₂SO₄·3K₂SO₄forms. In stable equilibrium phase diagram, the quinarysystem has four invariant points, nine univariant curves, six fields of crystallization（NaBr，KBr，Na₂SO₄，K₂SO₄，Na₂SO₄·3K₂SO₄，K₂B₄O₇·4H₂O）. The experimentalresults of the quinary system show bromide had the salting-out effect on sulfate andborate.The quaternary system KCl-K₂B₄O₇-K₂SO₄-H₂O at348K was of simple eutectictype and no double salt and solid solution was found. In the phase diagram, thequaternary system has three univariant curvers, one invariant point, three fields ofcrystallization （KCl, K₂B₄O₇·4H₂O and K₂SO₄）. The experimental results of thequaternary system show that KCl had the salting-out effect on K₂SO₄andK₂B₄O₇·4H₂O.