Liquid–liquid equilibrium data for binary systems containing o-dichlorobenzene and nitrobenzene

Abstract

The liquid–liquid equilibrium (LLE) data of four binary systems (o-dichlorobenzene(1) + 1,2-ethanediol(2)), (o-dichlorobenzene(1) + 1,2-propanediol(2)), (nitrobenzene(1) + 1,2-ethanediol(2)) and (nitrobenzene(1) + 1,2-propanediol(2)) under atmospheric pressure and at temperatures 290–400 K were determined in this study. The results indicated the mutual solubility between all the binary systems increased with temperatures. The NRTL and UNIQUAC models were applied to correlate the liquid–liquid equilibrium data. In addition, the data were correlated well by the UNIFAC (Do) group contribution method, in which 1,2-ethanediol was treated as a single DOH group (methodI) or two CH₂OH groups (method II), and 1,2-propanediol was divided into groups (CH₃, CH₂OH, CHOH). The new group interaction parameters for (ACCl–DOH, ACNO₂–DOH, ACCl–CH₂OH, ACNO₂–CH₂OH, ACH–CH₂OH) were obtained by the experimental LLE data regression. Moreover, all the new interaction parameters except the group ACNO₂–DOH were proved reliable, among which the parameters for ACCl–DOH were proved by estimating the binary system (chlorobenzene + 1,2-ethanediol) LLE data from literature and the parameters for (ACCl–CH₂OH, ACNO₂–CH₂OH, ACH–CH₂OH) were proved by estimating the LLE data of the (o-dichlorobenzene(1) + 1,2-ethanediol(2)) and (nitrobenzene(1) + 1,2-ethanediol(2)) binary systems in this work.

Introduction

Glycols especially 1,2-ethanediol and 1,2-propanediol have been widely used as solvents for separating aliphatic hydrocarbons from aromatics by extractive distillation [1], [2], [3], [4], [5], [6], [7], [8]. The knowledge of liquid–liquid and vapor–liquid equilibrium of the glycols with aromatics is desirable for the extractive process [9]. However, existing studies on mutual solubilities between binary glycols/aromatics systems are limited. Only the liquid–liquid equilibrium (LLE) data of 1,2-ethanediol/benzene [9], [11], 1,2-ethanediol/toluene [4], [10], [11], 1,2-ethanediol/xylene [11] systems and 1,2-propanediol/benzene [9], [12], 1,2-propanediol/toluene and 1,2-propanediol/xylene [11] systems have been reported. As important members of aromatic, o-dichlorobenzene is used for medicine, pesticide, organic synthesis widely and nitrobenzene is a significant organic intermediate. Nevertheless, the LLE data for the four binary systems of (o-dichlorobenzene/1,2-ethanediol, o-dichlorobenzene/1,2-propanediol, nitrobenzene/1,2-ethanediol, nitrobenzene/1,2-propanediol) have not been found in the existing literatures.

The present work has focused on the LLE data of the four binary systems between temperatures 290 K and 400 K at atmospheric pressure. The experimental data were correlated by the NRTL [13] and UNIQUAC [14] models with the function of temperature dependent parameters. All the calculated results by the models agreed well with the experimental data. Moreover, the UNIFAC (Do) [15] group contribution method was used to correlate and estimate the LLE data. 1,2-ethanediol was treated as a single DOH group (method I) or two CH₂OH groups (method II). 1,2-propanediol was divided into groups (CH₃, CH₂OH, CHOH). The new group interaction parameters for (ACCl–DOH, ACNO₂–DOH) were obtained by regressing the experimental LLE data of binary systems (o-dichlorobenzene(1) + 1,2-ethanediol(2)) and (nitrobenzene(1) + 1,2-ethanediol(2)). The parameters for ACCl–DOH were checked reliable by estimating LLE data of the (chlorobenzene + 1,2-ethanediol) binary system in the literature [16]. The new parameters for (ACCl–CH₂OH, ACNO₂–CH₂OH, ACH–CH₂OH) were obtained by regressing the binary systems (o-dichlorobenzene(1) + 1,2-propanediol(2)) and (nitrobenzene(1) + 1,2-propanediol(2)). The parameters were verified reliable by estimating LLE data of the (o-dichlorobenzene(1) + 1,2-ethanediol(2)) and (nitrobenzene(1) + 1,2-ethanediol(2)) binary systems, in which 1,2-ethanediol was divided by method II in our study.