二元及三元体系液液界面张力的理论研究

【作者】 李步强；

【导师】 傅举孚；

【作者基本信息】 北京化工大学 ， 化学工程， 1991， 博士

【摘要】 液液界面张力是一个重要的基础物性。 通过分子物性及互溶度数据对界面张力进行预测具有重要的实际意义，对界面区中的分子层数、浓度分布及分子取向进行研究具有重要的理论价值。 基于组成连续变化的界面区模型，考虑界面区内任何一点的Gibbs自由能分为取决于组成的主体贡献和起因子浓度梯度的表面贡献两部分，UNIQUAC方程及其参数分别用于这两种贡献中的有关参数的计算，推导出计算二元体系液液界面张力的方程。方程给出满意的结果。同时，给出界面区中的浓度分布及分子层数的计算结果。 基于准晶榴界面模型，提出用互溶度数据和UNIQUAC参数计算二元体系液液界面张力的简单方程。引入取向校正因子，由此给出不同分子在界面上取向的定性解释。 基于单分子层界面相模型，推导出借助二元体系界面张力由UNIQUAC方法推算三元体系界面张力的方程。就UNIQUAC方程对互溶度数据的关联效果对界面张力推算的影响进行了讨论。计算给出界面相组成的定性结果，通过计算结果指出Backes et al方法的理论缺陷。 基于厚度变化的界面相模型，结合推导得到的界面张力随界面相厚度变化的半经验关系，提出由二元体系界面张力及互溶度数据估算三元体系界面张力的简单方程 σ=σ₀（X／X₀）^C根据实际应用的精度要求，参数（C）可当作常数用以估算，作为可调参数用以关联，修正为两参数用于高精度关联。或者估算或者关联，其精度皆较以往方程高，使用也最简便。 采用Du Nouy环式界面张力仪，测定了在25℃下七个三元体系45个不同组成时的界面张力数据。更多还原

【Abstract】 Liquid—liquid interfacial tension is a basic property.It is of practical importance to predict the interface tension from, pure component properties and mutual solubility data, and of theoretical value to study the concentration profile in the interfacial region and the orientation of molecules at the interface.Based on a model of an interfacial region where the compositions vary continuously from one phase to another and assuming that any molecule in the interfacial region is associated with it a volume contribution depending on the composition and a surface contribution arising from the concentration gradient to Gibbs free energy, an equation for predicting the interfaciai tensions of binary systems has been developed. UNIQUAC equation and its parameters are employed respectively in the calculations of the two contributions. The concentration profile and the number of molecular layers in the interfacial region can be calculated.According to a quasi-lattice model, a simple equation for predicting the interfacial tensions of binary systems from UNIQUAC parameters and mutual solubility data has been obtained. An appropriate orientation factor is introduced and a discussion is given for the orientations of different molecules at the interface.With a model of an interface phase of a monolayer of molecules, a method for predicting the interfacial tensions of ternary systems by UNIQUAC method has been established. A detailed descussion is given for the dffect of the precision of correlating mutual solubility data by UNIQUAC equation on the prediction of interfacial tensions. The composition of interfacial phase obtained in calculation was used to analyse qualitatively the adsorption of solute at the interface. The theoretically defects of Backes et al method are shown by calculation results.From the model of interface phase and a semi-empirical equation derived to describe the variation of interfacial tension with the thickness of the interface phase, a simple equation has been developed to estimate the interfacial tensions of ternary systems. It can give better estimation of interfacial tensions of ternary systems.By using a Du Nouy ring tensiometer, the interfacial tensions have been measured for seven ternary systems at更多还原