KH2PO4-KCl-H2O、NH4H2PO4-NH4Cl-H2O三元体系283.15 K相平衡研究

Phase equilibrium of KH2PO4-KCl-H2O and NH4H2PO4-NH4Cl-H2O ternary system at 283.15 K

采用等温溶解平衡法研究了三元体系KH2PO4-KCl-H2O、NH4H2PO4-NH4Cl-H2O在283.15 K时的相平衡,并用湿渣法与X射线衍射相结合的方法鉴定了平衡固相的组成与结构。结果表明,三元体系KH2PO4-KCl-H2O和NH4H2PO4-NH4Cl-H2O为简单共饱和型,无固溶体或加合物形成,每个相图包含1个不变点、2条单变量曲线和3个结晶区。运用Pitzer电解质溶液理论计算了简单三元体系KH2PO4-KCl-H2O、NH4H2PO4-NH4Cl-H2O的饱和溶解度数据,结果表明,KH2PO4-KCl-H2O体系的相对平均偏差为0.046,均方根偏差为0.29,NH4H2PO4-NH4Cl-H2O体系的相对平均偏差为0.044,均方根偏差为0.31,溶解度理论计算结果与实验值基本一致。

The phase equilibrium of KH2PO4-KCl-H2O and NH4H2PO4-NH4Cl-H2O at 283.15 K was determined by using isothermal dissolution equilibrium method.The composition and structure of equilibrium solid phase were identified by analysis of wet slag and X-ray diffraction.Results showed that the ternary systems KH2PO4-KCl-H2O and NH4H2PO4-NH4Cl-H2O were simple cosaturated,and no solid solution or adduct was formed.Each phase diagram contained one invariant point,two univariate curves and three crystallization regions.The saturated solubility data of simple ternary systems KH2PO4-KCl-H2O and NH4H2PO4-NH4Cl-H2O were calculated by Pitzer electrolyte solution theory.Results showed that the relative average deviation and the root mean square error of KH2PO4-KCl-H2O system were 0.046 and 0.29 respectively,and the relative average deviation and the root mean square error of NH4H2PO4-NH4Cl-H2O system were 0.044 and 0.31 respectively.The calculated value agreed with the experimental value well.