Analysis of different possibilities for determining tie lines in liquid-liquid equilibria

Abstract

Due to the global trend of increasing environmental pollution, green solvents are being implemented in various branches of the chemical industry to, which would replace standard industrial solvents with harmful characteristics. In order to examine the possibilities of using green solvents, the possibility of appropriate replacement and process design, it is necessary to determine thermodynamic data such as liquid-liquid equilibria, i.e. tie lines in liquid- liquid extraction (LLE), and the corresponding binodal curve. Solubility of components are of great importance for the separation processes (especially for extraction) applied in the chemical industry. Tie lines are a very important thermodynamic data, which are mostly determined by chromatographic analysis depending on the nature of the components in the mixture. Tie lines are mostly determined by chromatographic analysis. Chromatographic analysis is one of the methods that not every laboratory can afford, due to the high cost of the apparatus and high operational costs. In this paper some of the alternative methods for determining tie lines in liquid-liquid equilibria are presented. On the example of the ternary system water+dimethyl adipate+2-propanol, the determination of tie lines via the refractive index and the density of the mixture are shown. These analytical methods are often used in various branches of industry. Based on the obtained results, a mutual comparison of the results obtained through these three methods is performed.