定标粒子理论在加盐萃取分离醋酸丙酯-丙醇-水中的应用

The Application of Scaled Particle Theory in Extraction with Salt Used for Separation of n-Propyl Acetate/1-Propanol/Water System

采用选择性溶剂化模型和定标粒子理论计算了七种盐类萃取剂在醋酸正丙酯-正丙醇-水三元体系中的标准摩尔溶剂化自由能,结合萃取分离实验进行验证,结果表明,随着盐的标准摩尔溶剂化自由能绝对值的增大,有机相中酯的质量分数呈线性增大,而有机相中水的质量分数则呈线性降低。静电相互作用力是影响加盐萃取效果的主要原因,盐与水(或醇)分子之间的静电自由能绝对值越大,盐对酯的萃取效果越好。采用标准摩尔溶剂化自由能的计算值可从理论上定性选择适宜的盐类作为萃取剂。

In chemical industry, the extraction with salt has been widely used in some separation processes; during them, according to the salt effect to choose the suitable salt is a difficult task. In the n-propyl acetate/1-propanol/water system and at 25℃, the ionic salvation free energies for extractant respectively consisting of three kinds of solvent with seven kinds of salt separately were calculated by means of selective salvation model and scaled particle theory. The calculated values were verified via extraction experiments, and the results indicate that with the increase of the calculated absolute values of the ionic salvation free energies of salt, the mass fraction of acetate in the organic phase increases linearly, while the mass fraction of water in the organic phase reduces linearly. The results also show that the electrostatic interaction forcer is the major factor influencing the effect of extraction with salt; when the absolute value of the electrostatic interaction free energy between the salt molecule and molecule of water or l-propanol is bigger, the extraction effect of salt for n-propyl acetate is better. Moreover, it shows that the method of ionic salvation free energies calculation could be used to abstractly qualitatively select the proper salt used for the extraction with salt.