Amino acids and peptides are essential components for many industrial branches. Knowledge on the solubility behavior is required in purification processes, which often involve crystallization as main unit operation. Since the determination of experimental solubility data is expensive, thermodynamic modeling is meaningful towards reducing the experimental effort. Modeling is usually based on a solid-liquid equilibrium condition that requires the melting properties of the solids. For amino acids and peptides such data is now available, and three g^E models (Wilson, NRTL, UNIQUAC) were applied in this work to model solubility in water as well as in water + 2-propanol. The new melting properties were used as input data and binary parameters for each model were fitted to experimental solubility data of the amino acids and peptides in water. Modeling solubility in water + 2-propanol required additional parameters. Binary parameters between water and 2-propanol were fitted to vapor-liquid-equilibrium data, and binary parameters between amino acid and 2-propanol as well as between peptide and 2-propanol were fitted to solubility data in water + 2-propanol mixtures. In general, the g^E models allowed describing the solubility in water, while some inaccuracies were observed for the temperature dependence of the modeled solubility. Further, the decrease of solubility upon 2-propanol addition was modeled qualitatively correct using the g^E models. The Wilson model was less accurate than NRTL and UNIQUAC, where the latter yielded similar results. The results were finally compared to PC-SAFT, which shows a dramatically improved modeling accuracy while using less binary parameters.

氨基酸和肽是许多工业分支的重要组成部分。在纯化过程中需要了解溶解性行为，这通常涉及结晶作为主要单元操作。由于确定实验溶解度数据很昂贵，因此热力学建模对于减少实验工作很有意义。建模通常基于需要固体熔化特性的固液平衡条件。对于氨基酸和肽，此类数据现已可用，并且 3 g ^E在这项工作中应用了模型（Wilson、NRTL、UNIQUAC）来模拟在水中的溶解度以及在水 + 2-丙醇中的溶解度。新的熔解特性被用作输入数据，并且每个模型的二元参数被拟合到氨基酸和肽在水中的实验溶解度数据。模拟在水 + 2-丙醇中的溶解度需要额外的参数。水和 2-丙醇之间的二元参数拟合到汽液平衡数据，氨基酸和 2-丙醇之间以及肽和 2-丙醇之间的二元参数拟合到水 + 2-丙醇混合物中的溶解度数据。一般来说，g ^E模型允许描述在水中的溶解度，而对于模拟溶解度的温度依赖性，观察到一些不准确之处。此外，使用 g ^E模型对添加 2-丙醇后溶解度的降低进行了定性建模。Wilson 模型不如 NRTL 和 UNIQUAC 准确，后者产生了相似的结果。结果最终与 PC-SAFT 进行了比较，PC-SAFT 显示出显着提高的建模精度，同时使用更少的二进制参数。