二水硫酸钙在硫酸铵溶液中的溶解度测定

采用电感耦合等离子体发射光谱法（ICP-AES）测定了二水硫酸钙在硫酸铵溶液中（298.15～348.15 K）的溶解度，利用E-DH方程对实验数据进行关联，总平均相对偏差为2.81%；并考察了E-UDH方程的理论预测值，与实验值对比，总平均相对偏差为4.13%。实验和理论研究结果表明：在同离子效应和盐效应协同影响下，二水硫酸钙在（NH₄）₂SO₄-H₂O体系中溶解度随硫酸铵浓度增加先降低后又增大，在298.15～348.15 K温区内，溶解度突变点硫酸铵浓度为0.07～0.08 mol·kg^-1；随溶液中硫酸铵浓度增加，温度对二水硫酸钙溶解度的影响更趋显著。研究结果对磷石膏矿化烟气CO₂的过程设计具有指导意义。

Solubility determination of calcium sulfate dihydrate in ammonium sulfate solution

The effect of the concentration (0-2.5 mol·kg^-1) of ammonium sulfate on the solubility of calcium sulfate dihydrate is measured in inductively coupled plasma-atomic emission spectrometry (ICP-AES) under the conditions of 298.15-348.15 K. The activity coefficient model of extended Debye-Hückel was applied to correlate the experimental data, and the averaged relative deviation were found at 2.81%. Meanwhile, the activity coefficient model of extended UNIQUAC-Debye-Hückel was applied to calculate the solubility of calcium sulfate dihydrate in ammonium sulfate solution, and the experimental data agreed well with the model prediction, with an averaged relative deviation of 4.13%. The theoretical and experimental results show that the solubility of calcium sulfate dihydrate can firstly decrease and then increase with the increasing of the concentration of ammonium sulfate under the conditions of 298.15-348.15 K. At the solubility mutation point the concentration of ammonium sulfate is 0.07-0.08 mol·kg^-1 under the synergetic effect of common-ion effect and salt effect. There are strong effects of temperature on the solubility of calcium sulfate dihydrate under higher ammonium sulfate concentrations (0.3-2.5 mol·kg^-1). The results provide better understanding and theoretical guidance for process design of CO₂ mineralization with phosphogypsum.