Study On The Equilibria In Quinary And Its Partial Sub-systems Li⁺,K⁺//Cl^-,SO₄^2-,B₄O₇^2--H₂O At 273 K

In this paper,the phase equilibria of the reciprocal quinary system Li⁺,K⁺//Cl^–,SO₄^2–,B₄O₇^2––H₂O and its partial sub-systems at 273 K were studied.The stable phase equilibria of ternary systems Li₂SO₄–Li₂B₄O₇–H₂O,K₂B₄O₇-K₂SO₄-H₂O and LiCl–Li₂B₄O₇–H₂O,and reciprocal quaternary system Li⁺,K⁺//Cl^–,B₄O₇^2––H₂O,and quinary system Li⁺,K⁺//Cl^–,SO₄^2–,B₄O₇^2––H₂O were studied by isothermal solution equilibrium method.Meanwhile,the metastable phase equilibria of the ternary sub-system Li₂SO₄–Li₂B₄O₇–H₂O and quaternary system Li⁺,K⁺//Cl^-,B₄O₇^2-–H₂O were studied by isothermal evaporation crystallization method.For the solubilities and densities of equilibrium liquid phase in different systems were determined in turn.Based on the experimental data and the corresponding equilibrium solid phase,the phase diagrams and density versus composition diagrams of the ternary systems were plotted,respectively.The corresponding water content diagrams for the quaternary and quinary systems were dipicted.The solid components of saturated salt were identified by X-ray powder diffraction,and the corresponding XRD patterns were obtained.Both the stable and metastable phase equilibria of Li₂SO₄–Li₂B₄O₇–H₂O belong to simple co-saturation type.There exist solubility curve of the hydrate salt in the systems,and no double salt or solid solution.Both the stable and metastable phase diagrams consist of one invariant point,two univariant solubility curves,and divided into two solid phase crystalline regions corresponding to Li2B4O7·3H2O and Li₂SO₄·H₂O.Comparing the two phase diagrams of stable and metastable,the equilibrium solid phases of the phase diagram are?Li₂B₄O₇·3H₂O+Li₂SO₄·H₂O?and?LiBO₂·8H₂O+Li₂SO₄·H₂O?.The stable phase equilibria of ternary system K₂B₄O₇-K₂SO₄-H₂O belong to simple co-saturation type.The solubility curves of the hydrate salts are found in the phase diagram.And there are no double salt or solid solution formed in saturated solution.Stable phase diagrams are constituted by one invariant point and two univariant solubility curves,as well as two solid phase crystalline regions corresponding to K₂B₄O₇·4H₂O and K₂SO₄.The stable phase equilibria of ternary system LiCl–Li₂B₄O₇–H₂O belong to simple co-saturation type.The solubility curves of the hydrate salts are participated in the system,and without double salt or solid solution formed.Stable phase diagrams are composed of one invariant point,two univariant solubility curves,and two solid phase crystalline regions corresponding to LiCl·2H₂O and Li₂B₄O₇·3H₂O.Both the stable and metastable reciprocal quaternary system Li⁺,K⁺//Cl^-,B₄O₇^2-–H₂O belong to simple co-saturation type.The solubility curves of the hydrate salts are existed in the systems,and no double salt or solid solution.Both the stable and metastable phase diagrams are constituted by two invariant points,five univariant solubility curves,and four solid phase crystalline regions.Stable phase diagrams are composed of four solid phase crystalline regions corresponding to KCl,K₂B₄O₇·4H₂O,Li₂B₄O₇·3H₂O and LiCl·2H₂O.However,equilibrium solid phase has been changed under the state of metastable compared with the stable equilibrium.the solid phase crystalline region of Li₂B₄O₇·3H₂O will exist in the crystalline form of LiBO₂·8H₂O,while the other solid phase crystalline in the system will not change.The stable phase equilibrium of reciprocal quaternary system Li⁺,K⁺//Cl^–,SO₄^2–,B₄O₇^2––H₂O belongs to complex type.The double salt KLiSO₄ was found in the stable phase equilibrium of reciprocal quinary system Li⁺,K⁺//Cl^–,SO₄^2–,B₄O₇^2––H₂O?saturated with Li₂B₄O₇·3H₂O?,There are four invariant points,nine univariant solubility curves,and six solid phase crystalline regions of KLiSO₄,LiCl·2H₂O,K₂B₄O₇·4H₂O,K₂SO₄,Li₂SO₄·H₂O and KCl.