Solubility of argon and nitrogen in aqueous solutions of tetra-n-butylammonium bromide (TBAB) from 283.15 to 298.15 K and 101.325 kPa partial pressure of gas

doi:10.1016/j.jct.2018.07.001

The Journal of Chemical Thermodynamics

Volume 126, November 2018, Pages 105-110

https://doi.org/10.1016/j.jct.2018.07.001 Get rights and content

Highlights

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Effect of tetrabutylammonium bromide on the solubility of argon and nitrogen in aqueous solution is discussed.
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Solubility of argon and nitrogen increases as the concentration of the salt becomes larger.
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Solubilization mechanism is not mediated by micelle formation.

Abstract

This paper reports the solubility of argon and nitrogen in aqueous solutions of tetra-n-butylammonium bromide (TBAB) in a concentration interval ranging from 0.2 to 1.0 mol kg⁻¹ and temperatures between 283.15 K and 298.15 K, at 101.325 kPa partial gas pressure. Measurements were done in saturation equipment which measures the pressure decrease of the gas. The value for solubility at 101.325 kPa partial pressure was calculated using Henry’s law. It was found that the solubility of argon and nitrogen increases as the concentration of TBAB becomes larger. The results show that the solubilisation mechanism is not mediated by micelle formation. Standard thermodynamic functions for the dissolution process of argon and nitrogen in aqueous solutions of TBAB were calculated from solubility data. The effect of salt is described using a modified Sechenov equation.

Introduction

Behaviour of symmetrical salts of tetraalkylammonium halides is important, because in aqueous solution, they might lead to a change of the solubility of non-ionic solutes. Despite all studies performed, the molecular mechanism involved in this phenomenon is not well understood [1], [2], [3], [4].

The salt effect is related to the change in the solubility of a non-electrolyte in water when the ionic force of the aqueous solution is modified. Sechenov’s semi-empirical equation is the most common used to quantify such effect [5]: $log(s_{0} /s) = k_{s} I_{s}$ where $s_{0}$ and $s$ are the solubility of the solute in pure water and in the saline solution respectively, $k_{s}$ is the Sechenov constant, and $I_{s}$ corresponds to the ionic force of saline solution. Some authors apply a similar equation that uses natural logarithm and concentration instead of ionic force [6], [7], [8]. Positive values of $k_{s}$ indicate a salting-out effect, whereas negative values of $k_{s}$ are related to salting-in effects.

The salting-in effect caused by tetrabutylammonium bromide on different solutes in aqueous solution has been studied using several experimental techniques. Ultrasonic absorption spectrometry [9], dielectric spectroscopy, neutron diffraction and small-angle x-ray diffraction (SAXS), as well as osmotic and activity coefficient measurements [10]. The results suggest the association between TBA⁺ cations and/or the formation of ionic pairs. In 2008, Dopierala y Prochaska [11] suggested, based on studies of static and dynamic superficial tension, dynamic light diffraction and electric conductivity, that interactions in aqueous solutions of TBAB at room temperature promote the formation of micellar aggregates. According to the authors, such aggregates are formed at concentrations lower than 0.01 mol L⁻¹. Bhowmik and co-workers [10] applied neutron diffraction techniques on an aqueous solution of TBAB 0.75 mol L⁻¹. The experiment was complemented with measurements of small-angle neutron diffraction (SANS), neutron diffraction, flight time and eco-spin and did not evidence aggregation between the TBA⁺ cations. In 2013, van der Post and collaborators [12], used polarization-resolved femtosecond infrared spectroscopy to study, among others, the dynamic of water molecules in aqueous solutions of TBAB. Authors concluded that TBA⁺ form clusters with Br⁻ anions and water molecules. Such interaction strongly depends on the concentration of salt.

In a previous work, the solubility of nitrogen in TBAB solutions was measured at high pressures and several concentrations and temperatures, nevertheless, due to the low solubility of the nitrogen, and high uncertainty of the measurements, was not possible obtain conclusions about the effect of temperature and concentration. However, the effect of the pressure was well stablished as an increase of the solubility with the increase of the pressure, as is expected for aqueous systems [13].

In this work, the solubility of argon and nitrogen in aqueous solutions of tetrabutylammonium bromide (TBAB) at several temperatures is studied. The results present the salting-in effect of TBAB on the solubility of argon and nitrogen in aqueous solutions, in function of the salt concentration and temperature. Results are reported in a concentration interval ranging from 0.2 to 1.0 mol kg⁻¹ and temperatures between 283.15 K and 298.15 K, at 101.325 kPa partial gas pressure.

Section snippets

Materials

Table 1 shows the characteristics of the reagents used. The purity is reported according to the certificates of analysis. TBAB solutions were prepared by weight using ultrapure, degassed water with resistivity of 18.2 MΩ cm. Mass measurements were made using a double-range balance Mettler Toledo AT 261. TBAB was placed in a desiccator for at least 72 h before use.

Experimental method

The gas solubility in the liquid was measured using special designed equipment based on the gas drop pressure method. The liquid and

Results and discussion

Table 2 shows the density values for the aqueous solutions of TBAB in the temperature range from 283.15 K to 328.15 K at intervals of 5 K. Fig. 1 shows a comparison of experimental data of this work and several sources at same concentrations. Each box represents one concentration and one temperature. As can be seen, measured values agree to previous works.

Gas solubility was calculated according to Eq. (2). The results of solubility of argon and nitrogen in aqueous solutions of TBAB at

Conclusions

The solubility of argon and nitrogen at 101.325 kPa partial gas pressure in aqueous solutions of TBAB was determined as a function of temperature. For the systems studied, gas solubility becomes larger as the concentration of TBAB increases following the behaviour observed with other large tetraalkylammonium salts. The solubility of both gases decrease as temperature increases. The effect of salt concentration on the experimental results of gas solubility and the monotonic behaviour of

Acknowledgments

This work was supported by Universidad Nacional de Colombia, Universidad de Bogotá Jorge Tadeo Lozano and Instituto Colombiano para el Desarrollo de la Ciencia y la Tecnología, Francisco José de Caldas – COLCIENCIAS.

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Thermodynamic modeling of gas solubility in aqueous solutions of quaternary ammonium salts with the e-CPA equation of state
2020, Fluid Phase Equilibria
Citation Excerpt :
The solubility of N2 in pure H2O is about 1/100 of that of CO2, so more accurate data are needed for the measurement of the solubility of N2. Due to the low solubility of N2, and high uncertainty of the measurements, it is hard to obtain very clear salt-effects regions [74]. Muromachi et al. [21] also stated that their measurements were not accurate enough to evaluate the temperature dependency in pure H2O.
The study of gas solubility in aqueous electrolyte solutions is important, e.g. for hydrate applications, and it is also a challenging task, as metal halide salts show salting-out effects on gas in water, while some quaternary ammonium salts (QAS) show salting-in effects. This work presents a modeling study of gas solubility in aqueous solutions of several QAS (tetra-n-methyl-ammonium bromide, tetra-n-ethyl-ammonium bromide, tetra-n-propyl-ammonium bromide and tetra-n-butyl ammonium bromide) with the electrolyte Cubic-Plus-Association Equation of State (e-CPA). The ion size and ion-water interaction parameters are obtained by fitting the experimental data of mean ionic activity coefficients and osmotic coefficients of corresponding binary mixtures. The results show that e-CPA can reasonably correlate the mean ionic activity coefficients of QAS in aqueous solutions. The ion-gas interaction parameters are obtained by fitting the experimental data of gas solubility and the results show that e-CPA can correlate the gas solubilities (for nitrogen, carbon dioxide, methane and ethane) reasonably well from a quantitative point of view. For example, e-CPA gives deviations of 9.2% and 5.7% for the solubilities of carbon dioxide and methane in TBAB, respectively. The salting-in and salting-out effects and the influencing factors are also studied.
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View full text

Solubility of argon and nitrogen in aqueous solutions of tetra-n-butylammonium bromide (TBAB) from 283.15 to 298.15 K and 101.325 kPa partial pressure of gas

Highlights

Abstract

Introduction

Section snippets

Materials

Experimental method

Results and discussion

Conclusions

Acknowledgments

Chem. Phys. Lett.

J. Mol. Liq.

Geochim. Cosmochim. Acta

J. Colloid Interface Sci.

J. Chem. Thermodyn.

J. Chem. Thermodyn.

J. Chromatogr. A

Fluid Phase Equilib.

The salting-in of nonpolar gases in aqueous tetraalkylammonium bromide solutions and the apparent molal volume of these salts in water

J. Phys. Chem.

Salting-in of alcohols in aqueous solutions by tetraalkylammonium bromides at the freezing temperature

J. Solut. Chem.

The IUPAC-NIST solubility data series: a guide to preparation and use of compilations and evaluations

J. Phys. Chem. Ref. Data

Density, viscosity, solubility and diffusivity of N2O in aqueous amino acid salt solutions

J. Chem. Eng. Data

Solubility of hydrogen in aqueous solutions of sodium and potassium bicarbonate from 293 to 333 K

J. Chem. Eng. Data

Uncommon ultrasonic absorption spectra of tetraalkylammonium bromides in aqueous solution

J. Phys. Chem.

Study of tetrabutylammonium bromide in aqueous solution by neutron scattering

Eur. Phys. J. Special Topics

Water dynamics in aqueous solutions of tetra-n-alkylammonium salts: hydrophobic and coulomb interactions disentangled

J. Phys. Chem. B

Solubility of nitrogen gas in aqueous solution of tetra-n-butylammonium bromide

Int. J. Thermophys.

Solubility of argon and nitrogen in aqueous solutions of tetra-n-butylammonium bromide (TBAB) from 283.15 to 298.15 K and 101.325 kPa partial pressure of gas

Density, viscosity, solubility and diffusivity of N₂O in aqueous amino acid salt solutions