Liquid–liquid equilibrium of the ternary system water + acetic acid + sec-butyl acetate

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Abstract

Experimental liquid–liquid equilibrium (LLE) of the water–acetic acid–sec-butyl acetate ternary system was investigated at 298.15, 303.15, 308.15 and 313.15 K and at atmospheric pressure. Separation factors were also evaluated for the immiscibility region. The NRTL and UNIQUAC models were applied to fit the experimental data for the ternary system. The binary interaction parameters obtained from both models were found to be successfully correlated with the equilibrium compositions. The UNIFAC group contribution method was employed to predict the observed ternary LLE data. It was found that four types of the UNIFAC model (UNIFAC, UNIFAC-LL, UNIFAC-DMD, and UNIFAC-LBY) did not provide a good prediction of the LLE data for this ternary system.

Introduction

Liquid–liquid extraction plays an increasingly important role in the field of separation technology, and it has experienced a steady growth in the last decades [1]. The recovery of organic acids from dilute solutions produced from fermentation processes and from other industrial manufacture process is very important. Many solvents have been attempted so as to improve the recovery of organic acids. For example, acetates and alcohols have been used as solvents to increase the recovery of acetic acid from dilute solutions by means of liquid–liquid extraction, etc. [2], [3], [4], [5]. Acetic acid, an important chemical reagent and industrial chemical, has been extensively used in many manufacturing processes of organic chemicals such as polyethylene terephthalate (the material for making soft drink bottles), cellulose acetate (the material for making photographic film), and polyvinyl acetate (the material for wood glue, as well as synthetic fibers and fabrics). Although many technologies have been explored to improve the recovery of acetic acid existed in industry solution, convenient and efficient methods, which are suitable for recovering acetic acid at low concentration, are highly needed.

This paper reported the use of sec-butyl acetate as an organic solvent for the separation of water + acetic acid mixture using liquid–liquid extraction at atmospheric pressure. The purpose of this work was to study the liquid–liquid equilibrium (LLE) of the ternary system, water + acetic acid + sec-butyl acetate, at several temperatures and to test the capability of the different thermodynamic models to correlate these data. To the best of our knowledge, LLE data for this ternary system have not yet been reported in the literatures.

Experimental LLE data for the partially miscible system water + acetic acid + sec-butyl acetate were determined at 298.15, 303.15, 308.15, and 313.15 K and at atmospheric pressure. The NRTL and UNIQUAC models were used to correlate the experimental LLE data. The experimental data were also compared to the values predicted by the UNIFAC method (UNIFAC, UNIFAC-LL, UNIFAC-DMD, and UNIFAC-LBY).

Section snippets

Chemicals

Sec-butyl acetate (>99.0 mass%, AR) was supplied by Shanghai Aladdin. Acetic acid (99.8 mass%, GR) was purchased from Merck. Ultrapure water was produced by MILIPORE. The water content (mass%) was determined by the Karl-Fischer titration method. The same method was used for sec-butyl acetate and acetic acid, with water content determined to be around 0.03% and 0.09%, respectively.

At 298.15 K, the refractive indexes of the pure components were measured using an ATAGO NAR-3T refractometer, with a

Experimental data

At atmospheric pressure, the LLE data and selectivity of the system water + acetic acid + sec-butyl acetate at 298.15, 303.15, 308.15, and 313.15 K are presented in Table 2 and shown in Fig. 2. The concentration of each component is given in mole fractions. To check the accuracy of the method, our data for water (1) + sec-butyl acetate (3) were compared with those reported by Stephenson and Stuart [12] which was shown in Table 3. It can be seen that the agreement is very well for the aqueous phase,

Conclusions

Experimental LLE data of water + acetic acid + sec-butyl acetate were determined at 298.15, 303.15, 308.15, and 313.15 K and at atmospheric pressure. The results demonstrated that the temperature had slight impact on the size of immiscibility region in the investigated temperature ranges. The temperature was also found to have almost no impact on the selectivity at the temperatures studied like systems of water + acetic acid + isobutyl acetate and water + acetic acid + N-butyl acetate. The NRTL and UNIQUAC

Acknowledgments

The authors gratefully acknowledge the financial support from the National Key Technology R&D Program in the 11th Five-Year Development Plan of China (No. 2006AA030204) and the National Natural Science Foundation of China (No. 20906016).

References (21)

  • A. Cháfer et al.

    Fluid Phase Equilibr.

    (2008)
  • A. Naylor

    J. Chem. Technol. Biotechnol.

    (1992)
  • U. Dramur et al.

    Chem. Eng. Data

    (1993)
  • M.A. Faihm et al.

    J. Chem. Eng. Data

    (1997)
  • A. Colombo et al.

    J. Chem. Eng. Data

    (1999)
  • E. İnce et al.

    Braz. J. Chem. Eng.

    (2002)
  • B. Gonzalez et al.

    J. Chem. Eng. Data

    (2004)
  • M.M. Palarologoo

    J. Chem. Eng. Data

    (1996)
  • N.L. Cheng, Solvents Handbook, 4th ed., Beijing: Chemical Industry Press, China,...
  • J.A. Riddick et al.

    Organic Solvents

    (1986)
There are more references available in the full text version of this article.

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