Abstract: Experiment and calculation of solubility are the foundation of research on solid-liquid equilibrium(SLE) thermodynamics, and provide the important parameters for optimization of industrial crystallization processes. In this study, the research object was 4-acetamidobenzoic acid. Under normal atmospheric pressure, the solubilities of 4-acetamidobenzoic acid in methanol+ethanol mixed solvents (ethanol mass fraction of 0, 20%, 40%, 60%, 80%, 100%, respectively) were measured with a dynamic method at temperatures ranging from 277.95K to 323.35K, and subsequently the thermodynamic phenomena of the dissolution process were analyzed. The experimental data were correlated with the modified Apelblat equation and Jouyban Acree model. The solubilities of calculated values were in good agreement with the experimental results. The average relative deviations of the modified Apelblat equation and Jouyban Acree model were 0.702%, 1.105%, respectively. The thermodynamic parameters of dissolution of 4-acetamidobenzoic acid were calculated, and the result showed that dissolution entropy and dissolution enthalpy were greater than zero. The dissolution process was endothermic, enthalpy change was the main contributor to dissolution process.

Key words: 4-acetamidobenzoic acid, mixture solvents, solubility association, thermodynamic analysis

摘要： 溶解度的实验和计算是固-液相平衡热力学研究的基础, 为工业结晶分离过程优化提供重要参数。本文以对乙酰氨基苯甲酸为目标溶质, 在标准压力下, 通过激光动态法在277.95~323.35K温度范围内, 测量其在甲 醇+乙醇混合溶剂中(乙醇质量分数0、20%、40%、60%、80%、100%)的溶解度, 分析了溶解过程中的热力学现象。实验数据用Modified Apelblat、修正的Jouyban-Acree两种热力学模型进行了关联计算。结果表明, 两种模型对对乙酰氨基苯甲酸的关联效果都很好, 其中Modified Apelblat、修正的Jouyban-Acree方程的计算值与实验值的平均相对偏差分别为0.702%和1.105%。通过热力学理论分析, 计算得到对乙酰氨基苯甲酸在混合溶液中溶解焓Δ_dH_m和溶解熵Δ_dS_m, 结果发现该溶解过程为放热过程, 焓变对溶解过程影响较大。

关键词: 对乙酰氨基苯甲酸, 混合溶剂, 关联模型, 热力学分析