Chemical and Thermodynamic Properties of Pure and Multicomponent Sucrose Solutions

Abstract

To select an optimal mode of evaporation and crystallization, sugar producers need comprehensive databases of chemical and thermodynamic properties of sucrose solutions. This article introduces refined experimental estimates of the chemical and thermodynamic properties of pure and technical multicomponent sucrose solutions. The study involved a modernized ebulliometer with two circulation tubes that measured the true boiling points of concentrated and supersaturated homogeneous solutions, as well as heterogeneous crystallizing systems. The boiling points of pure and multicomponent sucrose solutions were observed for the following variables: 5–93% dry solids, 60–100% purity, 20–100 kPa. In this study, the sucrose solutions did not obey Raoult’s laws for ideal mixtures, while the Ramsay-Young’s equation and Dühring’s rule were approximate. The thermodynamic properties of these solutions fit in the Lewis theory of activity. The study yielded a new thermodynamic equation for the boiling point in pure and technical multicomponent sucrose solutions. The authors revealed the correlation between the constants of Ramsay-Young and Dühring and the concentration and supersaturation of sucrose solutions, as well as the change in the entropy of these solutions. The error of estimate was 2–3%. The supersaturation coefficient was measured by the ratio of the boiling points of the solution and water. The authors used differential and relative ebulliometric criteria to develop some practical methods for monitoring and controlling the process of isobaric evaporative crystallization. The new method can improve the commercial mass sucrose crystallization from boiling solutions.