Limiting activity coefficient measurements in binary mixtures of dichloromethane and 1-alkanols (C1–C4)

doi:10.1016/j.fluid.2015.11.037

Fluid Phase Equilibria

Volume 411, 15 March 2016, Pages 59-65

https://doi.org/10.1016/j.fluid.2015.11.037 Get rights and content

Abstract

Limiting activity coefficients γ^∞ in binary mixtures of dichloromethane with four lower 1-alkanols (C1–C4) were experimentally determined employing alternatively the techniques of inert gas stripping, comparative ebulliometry, Rayleigh distillation, and differential distillation. For each case, the suitable technique was chosen on the basis of the limiting relative volatility of the solute and/or volatility of the solvent. The measurements yielding data of good accuracy (relative standard uncertainty of γ^∞ from 0.01 to 0.03) were carried out at several temperatures in the range from (283–333) K. The variation of limiting activity coefficients with temperature was fitted by a suitable two- or three-parameter equation and compared with available literature information on both limiting activity coefficients and calorimetric partial molar excess enthalpies at infinite dilution. The performance of the leading prediction method Modified UNIFAC was further examined using these new data. Concentration dependences of activity coefficients calculated from their infinite dilution values using van Laar equation were found to agree well with those inferred from reliable VLE data from the literature. The occurrence of an azeotropic point was tested for the systems under study and the temperature dependence of the azeotropic composition was estimated for mixtures of dichloromethane with methanol and ethanol.

Introduction

Dichloromethane (DCM) is a commonly used solvent with a worldwide production of several hundred thousand tonnes per annum. DCM has found widespread applications in many industrial fields serving as a solvent for the synthesis and extraction of chemicals and for paint removal, for metal cleaning in the automotive and electronic industry, as a blowing agent in urethane foam production, in manufacture of films and fibers, as a flame retardant in a mixture with flammable organic components in aerosol propellants, etc. The popularity of DCM stems from its unique properties, namely very high solvency power, low flammability, biological degradability, possibility of easy and cost efficient recycling, and last but not least negligible effect on ozone depletion and global warming. Despite current studies indicate only low toxicity and a rather negligible carcinogenicity potential of DCM, high level exposure presents severe health risks [1] and hence the use of DCM is subject to regulation in many countries [2]. A possibility to reduce the amount of DCM in use is offered by its application in mixtures with other organic solvents, e.g. alkanols. Reliable data on behavior of components in suitable blends are then necessary for their efficient treatment and regeneration.

In this paper, we present results of our measurements of limiting activity coefficients γ^∞ in binary systems consisting of dichloromethane and four 1-alkanols (C₁–C₄). The selected components give 8 solute (1) – solvent (2) pairs in all, but only half of them were previously studied. In total 10 experimental values of γ^∞ were found in the literature, 5 of them were published by Landau et al. [3] who measured the limiting activity coefficients of dichloromethane (1) in methanol, ethanol, and 1-butanol as solvents (2) using non-stationary gas liquid chromatography. Clearly, this fragmentary information is insufficient and calls for improvement. To extend the information and improve its reliability, here we determine values of limiting activity coefficients systematically at both concentration limits of dichloromethane + 1-alkanol (C₁–C₄) systems as a function of temperature using four different experimental methods. Due care is paid to the selection of suitable experimental method for each particular case to ensure the best accuracy of our measurements. New data on limiting activity coefficients presented in this work are used to test the prediction performance of the Modified UNIFAC (Dortmund) method. We also demonstrate that when coupled with a suitable two-parameter excess Gibbs energy model, our new data can predict well the concentration dependences of the activity coefficients in the entire composition range and the temperature dependence of azeotropic compositions in the systems studied.

Section snippets

Materials

Methanol (p.a., >99.8%, Penta, Czech Rep.) was refluxed with magnesium activated by iodine and subsequently fractionally distilled on a 1.5 m long filled column. Ethanol (absolute, >99.8%, Riedel-de Haën) was used without purification. 1-Propanol (p.a., >99.5%) and 1-butanol (p.a., >99%), both supplied by Lachema Czech Rep., were pre-dried by calcium oxide and each fractionally distilled on a 1 m long packed column. Dichloromethane (p.a., >99.9%, Lachema, Czech Rep.) was shaken with a 1%

Results of measurements and comparison to literature data

The saturated vapor pressure data for dichloromethane measured in this work are listed in Table 1, together with parameters of Antoine equation obtained by the maximum-likelihood fit and fit deviations. As seen the measured vapor pressure data are very smooth, effectively to 1 mK and 1 Pa. Nevertheless, to account for uncertainties in the calibration of respective devices, reasonable estimates of the experimental standard uncertainties are u(T) = 20 mK and u(p) = 7 Pa. As demonstrated in detail

Conclusion

Accurate data on limiting activity coefficients in binary mixtures containing dichloromethane and 1-alkanol (C1–C4) were systematically determined in this work using four suitable methods and proved to provide valuable and representative information on thermodynamic behavior of these systems. Established temperature dependences of γ^∞ have been shown to be consistent with related calorimetric data allowing thus reliable extrapolation beyond the temperature range of underlying experimental data.

Acknowledgments

We thank to Mr. Dan Rozbroj for his help with some experiments. This work was funded by the Ministry of Education of the Czech Republic (grant MSM 604 613 7307).

References (28)

V. Dohnal et al.
Fluid Phase Equilib.
(1991)
V. Dohnal et al.
Fluid Phase Equilib.
(1985)
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10094, accessed October...
REACH Enforcement (Amendment) Regulations
(2014)
I. Landau et al.
Ind. Eng. Chem. Res.
(1991)
S. Hovorka et al.
J. Chem. Eng. Data
(1997)
P. Vrbka et al.
Z. Phys. Chem. (Munich)
(1999)
V. Dohnal et al.
Collect. Czech. Chem. Commun.
(1986)
M. Bernauer et al.
J. Chem. Eng. Data
(2008)
J.C. Leroi et al.
Ind. Eng. Chem. Process Des. Dev.
(1977)

D. Ambrose et al.

Pure Appl. Chem.

(1989)

J.G. Hayden et al.

Ind. Eng. Chem. Process Des. Dev.

(1975)

J.M. Prausnitz et al.

Computer Calculations for Multicomponent Vapor-Liquid and Liquid-Liquid Equilibrium

(1980)

CDATA

Database of Thermodynamic and Transport Properties for Chemistry and Engineering

(1991)

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Limiting activity coefficient measurements in binary mixtures of dichloromethane and 1-alkanols (C1–C4)

Abstract

Introduction

Section snippets

Materials

Results of measurements and comparison to literature data

Conclusion

Acknowledgments

Fluid Phase Equilib.

Fluid Phase Equilib.

REACH Enforcement (Amendment) Regulations

Ind. Eng. Chem. Res.

J. Chem. Eng. Data

Z. Phys. Chem. (Munich)

Collect. Czech. Chem. Commun.

J. Chem. Eng. Data

Ind. Eng. Chem. Process Des. Dev.

Pure Appl. Chem.

Ind. Eng. Chem. Process Des. Dev.

Computer Calculations for Multicomponent Vapor-Liquid and Liquid-Liquid Equilibrium

Database of Thermodynamic and Transport Properties for Chemistry and Engineering