298K时(NH_4)_2S_2O_3-(NH_4)_2SO_4-H_2O三元体系相平衡研究

通过改良合成复体法对(NH4)2S2O3-(NH4)2SO4-H2O三元体系在298 K下的溶液相平衡进行研究。利用X-射线粉末衍射法(XRD)表征平衡固相组成。结果证实:该方法能很好地用于(NH4)2S2O3-(NH4)2SO4-H2O三元体系平衡固相组成的分析。依据水、硫酸铵及硫代硫酸铵组成的饱和溶液各组分的质量分数绘制了(NH4)2S2O3-(NH4)2SO4-H2O在298 K下的三元体系相图。依据三元体系相图,结果显示:硫代硫酸铵的结晶区远远大于硫酸铵的结晶区,同时在该温度下,硫代硫酸铵、硫酸铵及水形成简单三元体系,体系中没有水合物形成。

Solid-liquid phase equilibrium for ternary (NH4)2S2O3-(NH4)2SO4-H2O system at 298 K

The phase equilibrium for ternary(NH4)2S2O3-(NH4)2SO4-H2O system was investigated at 298 K by improved method of compound synthesis.The solid phase composition of equilibrium was characterized by X-ray powder diffraction(XRD) method.The result indicates that this method can be well applied to the analysis of solid phase composition of(NH4)2S2O3-(NH4)2SO4-H2O system.The isothermal phase diagrams of the system were constructed on the basis of the mass fractions of water,ammonium sulfate and ammonium thiosulfate saturated solution at 298 K.From the phase diagram,the crystallization region of ammonium thiosulfate is far larger than that of ammonium sulfate.At 298 K,ammonium thiosulfate,ammonium sulfate and water form a simple ternary system,and no hydrate is produced in the system.