Experimental and correlated liquid-liquid equilibrium data for water + 1,6-hexanediol + 1-pentanol/3-methyl-1-butanol/2-methyl-2-butanol at different temperatures

https://doi.org/10.1016/j.jct.2020.106341Get rights and content

Highlights

  • Solubility and LLE data for three ternary systems were measured.

  • Distribution coefficients and separation factors were calculated.

  • 1-Pentanol and 3-methyl-1-butanol are better solvent than 2-methyl-2-butanol.

  • Experimental data were correlated by NRTL and UNIQUAC models.

Abstract

Liquid-liquid equilibria (LLE) data for ternary systems of water + 1,6-hexanediol + 1-pentanol/ 3-methyl-1-butanol/ 2-methyl-2-butanol were measured at (293.15, 303.15, 313.15 and 323.15) K under 101.3 kPa. Cloud-point method was applied to determine the solubility curves data. Distribution coefficient and separation factors for 1,6-hexanediol were calculated from the measured tie-line data to evaluate the extraction effect of alcohols on 1,6-hexanediol. The reliability of experimental LLE data were tested by Othmer–Tobias equation and Hand equation, NRTL and UNIQUAC models were applied to correlate the measured data and the calculated results show that both models can fit the experimental data very well.

Introduction

1,6-Hexanediol(HDOL) is an important chemical raw material and has a wide range of applications in chemical industry, such as coating, acrylates, and polyester resins [1]. The performance of materials which prepared by using HDOL instead of ethylene glycol, such as flexibility, caustic resistance and hydrolytic stability, have been improved, and the demand for HDOL has increased in recent years. Moreover, the market scale of HDOL will continue to grow in the future [2]. The traditional preparation method of HDOL is hydrogenation of dimethyl adipate or other petroleum-based materials. With the in-depth study of biomass materials, the preparation of HDOL from bio-based materials has attracted more and more attention [3], [4]. However, the large-scale industrial production has not been realized. In order to realize industrial production of HDOL from bio-based materials, it is necessary to achieve the separation of HDOL and water or waste-water [5], [6]. As we all known, extraction technology [7], [8], [9] is one of the practical methods to separate water and organic matters and hermodynamic liquid–liquid equilibrium (LLE) data and the selection of available solvents for extraction plays an important role in the extracting process [10], [11], [12].

It is a common choice to extract solutes from water with organic solvents, among which alcohols are mostly used. Hyun JiKim [13] studied the ternary system of water + 2,3-butanediol + 3-methyl-1-butanol and found that 3-methyl-1-butanol is a potential solvent for 2,3-butanediol extraction. LLE data of water + 1,6-diaminohexane + 3-methyl-1-butanol reported by Yonghui Dou [14] suggested that 3-methyl-1-butanol can be selected for extracting 1,6-diaminohexane from aqueous media. LLE data of ternary systems of water + HDOL + 1-butanol or 2-methyl-1-propanol were determined in our previous work [15]. It was found that the two solvents could extract HDOL from water and the separation factor values were in the range of 7.48–14.87 and 7.51–19.23, respectively. In this paper, three more solvents (1-pentanol, 3-methyl-1-butanol and 2-methyl-2-butanol) were selected and the solubility and LLE data of ternary systems at T=(293.15, 303.15, 313.15 and 323.15) K are reported. The reliability of measured LLE data were assessed by using of Othmer-Tobias [16] and Hand equations [17]. Besides, the Aspen Plus V8.4 software was applied to fit the experimental data and the binary model parameters of NRTL [18] and UNIQUAC [15] activity-coefficient models were obtained.

Section snippets

Materials

Chemicals used in this work are listed in Table 1 and information such as CAS number, supplier and molar mass of chemicals are shown in the table. Meanwhile, three-dimensional structure of chemicals used in this work are shown in Fig. 1. The conductivity of deionized water prepared by pure water machine was 0.09μS•cm−1. A gas chromatography was used to analyse the purity of chemicals and the results are also listed in Table 1. From the table, the purity of materials are >0.995 (mass),

Experimental results

Table 2, Table 3, Table 4 show the compositions of mixtures on the binodal solubility curve at T= (293.15, 303.15, 313.15 and 323.15) K under 101.3 kPa, and the mutual binary solubility of water and solvents are also included. Besides, the determined binary solubility data of water-1-pentanol/ water-3-methyl-1-butanol/ water-2-methyl-2-butanol together with the literature data [20], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34] are listed in Tables S1–S3 and plotted in

Conclusions

In this work, LLE data for the ternary systems of (water + HDOL + 1-pentanol), (water + HDOL + 3-methyl-1-butanol) and (water + HDOL + 2-methyl-2-butanol) were measured at (293.15–323.15) K under 101.3 kPa. The experimental data were tested by using Othmer-Tobias and Hand equations, and the results show that the data have a high degree of consistency. The calculated distribution coefficients and separation factors proving that solvents used in this work are able to extract HDOL from water. The

Supporting information

Liquid-liquid equilibrium double-jacketed glass vessel; comparison of measured and published solubility data of alcohols in water; comparison of calculated and published distribution coefficients and separation factors of different solvents; Hands and Othmer-Tobias plots for tie-line data.

CRediT authorship contribution statement

Xingchuan Yang: Conceptualization, Investigation, Data curation, Formal analysis, Writing - original draft. Huanxin Li: Methodology, Writing - review & editing. Chunmei Cao: Validation, Visualization. Li Xu: Methodology, Supervision, Project administration. Guoji Liu: Resources, Funding acquisition.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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