三元体系KH_(2)PO_(4)-CO(NH_(2))_(2)-H_(2)O在283.15 K的固液相平衡测定与关联

Determination and Correlation of Solid-liquid Equilibrium of Ternary System KH_(2)PO_(4)-CO(NH_(2))_(2)-H_(2)O at 283.15 K

采用等温溶解平衡法研究了KH_(2)PO_(4)-CO(NH_(2))_(2)-H_(2)O在283.15 K下的固液相平衡,根据实验结果绘制了相应的稳定相图,采用湿渣法和X射线衍射法相结合的方法鉴定了平衡固相的组成与结构。结果表明,相图中有1个共饱和点,2条单变量曲线和3个结晶区。该体系为简单共饱和型,无复盐和加和物形成。采用Wilson方程和NRTL方程关联计算了三元系KH_(2)PO_(4)-CO(NH_(2))_(2)-H_(2)O的溶解度数据,计算值与实验值吻合度较好。其中Wilson方程计算值与实验值的相对平均方差(Relative Average Deviation,RAD)和均方根差(Root Mean Square Deviation,RMSD)分别为0.575%和0.159%;NRTL方程计算值与实验值的RAD和RMSD分别为1.58%和0.136%。

The solid-liquid phase equilibrium of KH_(2)PO_(4)-CO(NH_(2))_(2)-H_(2)O at 283. 15 K was studied by isothermal dissolution equilibrium method. The corresponding stable phase diagram was drawn according to the experimental results,and the composition and structure of the equilibrium solid phase were identified by wet slag method and X-ray diffraction method. The results show that there are a invariant point,two univariate curves and three crystalline regions in the phase diagram,and the system is a simple co-saturation type,no double salts or adducts were formed. Wilson equation and NRTL equation were used to calculate the solubility of ternary KH_(2)PO_(4)-CO(NH_(2))_(2)-H_(2)O,and the calculated values were in good agreement with the experimental values. The relative average deviation( RAD) and root mean square deviation( RMSD) of the calculated values of Wilson equation and experimental values are 0. 575% and 0. 159%,respectively;the RAD and RMSD of the calculated of NRTL equation and experimental values are 1. 58% and 0. 136%,respectively.