戊酮-2与脂肪醇系列溶液的超额焓模型

A Model for Excess Enthalpies of Solutions Formed by Pentan-2-one and n-Alkan-1-ol (from Propanol to Octanol)

超额焓是现代科学研究和工程设计的重要基础数据,目前尚难以准确地预测.作者曾指出,溶液的性质取决于组成溶液的所有分子间的有机联系和相互制约,这种协同作用不是同种分子间或异种分子间个体相互作用的简单叠加,而是表现出一种整体的复杂的协同性行为.与纯液体相比,溶液的组成和性质之所以特殊,在于分子交互组成特殊的群聚体,在于分子间作用力特殊的协同作用.据此,构成超额焓的三系数模型.在此基础上,用Wiener指数定量表征模型关键参数,建立了戊酮-2与C3～C8脂肪醇组成的系列溶液超额焓的双参数模型,用实验数据进行了检验.结果表明,新模型计算值接近作者提出的三参数模型计算值,稍优于刘国杰提出的三参数模型计算值.

Excess enthalpies are important basic data used in modern chemical engineering design, scientific research, molecular thermodynamics and solution theory research. The experimental measurement, correlation, reckon and theoretical research about them are very active. For simple solutions with minute molecules, excess enthalpies can be predicted by means of computer simulation, perturbation theory and state equations. However, for most non_ideal solutions, they are valuable in engineering practice, since there are few reliable theoretical predicting models. Some modified UNIFAC models have been widely researched in recent years, but the predicting results are not satisfactory when they are used in associated solution system, especially for the ketone-alcohol systems in which there are associations between the same molecules and cross associations between different molecules. Empirical or semi_empirical correlation models are still better in accuracy. At present Redlich_Kister equation and SSF equation are widely used. But both of them are multinomials with undetermined parameters. The number of parameters needs to be determined by means of empirical trials. The equation with three parameters proposed by Liu Guojie has a fixed form, but besides three undetermined parameters, the molar volume of the solution needs to be known. A molecular thermodynamics model with three parameters that does not have this demand is proposed by the present author, but the three undetermined parameters a, b, g in the model need to be determined with experimental data by means of gradual approach search, and some times the unseemingly initial values of g may cause bad results. In this paper, the Wiener index is used to express the key parameter g quantificationally, so a two-parameter model for excess enthalpies of solutions formed by pentan-2-one and n-alkan-1-ol (from propanol to octanol) is proposed. Tested by experimental data, the results indicats that the calculation values of the new model are near to the calculation values of the three parameters model the present author proposed, and slightly better than the three parameters model proposed by Liu Guojie.