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Accepted Manuscript
Determination of water activity, osmotic coefficients, activity
coefficients, solubility and excess Gibbs free energies of NaCl-
sucrose-H2O mixture at 298.15 K
Brahim Messnaoui, Abdelfetah Mounir, Abderrahim Dinane,
Samaouali Abderrahim, Bahija Mounir
PII: S0167-7322(18)35854-9
DOI: https://doi.org/10.1016/j.molliq.2019.03.156
Reference: MOLLIQ 10697
To appear in: Journal of Molecular Liquids
Received date: 25 November 2018
Revised date: 24 March 2019
Accepted date: 26 March 2019
Please cite this article as: B. Messnaoui, A. Mounir, A. Dinane, et al., Determination
of water activity, osmotic coefficients, activity coefficients, solubility and excess Gibbs
free energies of NaCl-sucrose-H2O mixture at 298.15 K, Journal of Molecular Liquids,
https://doi.org/10.1016/j.molliq.2019.03.156
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Determination of Water Activity, Osmotic Coefficients, Activity
Coefficients, solubility and Excess Gibbs Free Energies of
NaCl-Sucrose-H2O Mixture at 298.15 K
Brahim Messnaoui1 Abdelfetah Mounir2, Abderrahim Dinane3,4*, Samaouali
Abderrahim4, Bahija Mounir5
1Laboratoire d’Analyse et Conception des Procédés Industriels, Ecole Nationale des Sciences
Appliquées ENSA- Safi, Université Cadi Ayyad Marrakech, Route Sidi Bouzid, Safi 46000,
Maroc.
2Institut Supérieur des Professions Infirmières et Techniques de Santé Marrakech, Rue
Abdelouahab Derraq, Marrakech 40000, Maroc.
3Ecole Royale Navale, Département de Recherches et Projets, Laboratoire de
Thermodynamique, Boulevard Sour Jdid, Casablanca 20000, Maroc.
4Equipe de Thermodynamique et Energétique, Centre de Recherches en Energie, Département
de Physique, Faculté de Sciences, Université Mohammed V, Agdal, B.P.1014, 10090, Rabat,
Morocco.
5Laboratoire Matériaux, Substances Naturelles, Environnement & Modélisation (LMSNEM),
Faculté Polydisciplinaire de Taza, Université Sidi Mohamed Ben Abdellah, Fès, Route
d’Oujda, B.P. 1223 Taza, Maroc.
* Corresponding author: (A. Dinane)
E-mail: [e-mail]
Tel.: [phone]
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Abstract
The relative humidities on ternary NaCl-sucrose-H2O solution of 0.5, 1.0, 2.0,
4.0 and 5.5 mol.kg-1 of sucrose have been determined by the hygrometric
method at 298.15 K in the molality range from 0.5 to 6.0 mol.kg-1 of NaCl. The
obtained data allow the deduction of the water activities and osmotic
coefficients. The experimental results are compared with the predictions of the
extended composed additivity (ECA) rule, the Lin et al. equation, and Lietzke
and Stoughton (LS II) models. The obtained results were interpreted by using
Pitzer-Simonson-Clegg model. The four mixture parameters are determined
and used to predict the activity coefficients of NaCl and sucrose in the mixed
solution. The solubility, excess Gibbs energy and The Gibbs energies of
transfer of sodium chloride are also calculated for this system.
Key words
water activity; osmotic coefficient; activity coefficient; excess Gibbs energy;
NaCl-sucrose-H2O; solubility; Pitzer-Simonson-Clegg model.
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1. Introduction
Electrolyte and non electrolyte solutions play an important role in several
fields of science and technology such as biology, chemical and pharmaceutical
industries, biochemical systems, and in other applications. Atmospheric aerosol
is composed of solid particles, mainly electrolytes suspended in the air, and
plays an important role in the environmental domain, for example air quality,
cloud formation and climate system regulation.
The physicochemical properties of these solutions has been performed by
several methods such as the emf techniques [1-3], isopiestic vapour pressure
[4-7], and vapour pressure lowering [8-10].
We have developed in our previous studies the hygrometric method [11] which
it is very adequate to determine directly the water activity of aqueous
electrolyte solutions, such as binary aqueous electrolytes [12, 13], and mixed
electrolytes [14-18]. In this study, we develop the application of this method to
the aqueous mixture of an electrolyte and non-electrolyte in order to determine
the physicochemical properties of the system NaCl-sucrose-H2O. This system
has been extensively studied by Robinson R. A. et al. [19] using the isopiestic
vapour pressure for mixed solutions of sucrose and sodium chloride at total
molalities from 0.5152 mol.kg-1 to about 11.677 mol.kg-1 at 298.15 K. Wang J.
et al. [20] have determined the mean activity coefficients by emf measurements
of NaCl in aqueous solutions of 10, 20 and 30 mass% of sugar (glucose and
sucrose) in the molality range from 0.006 mol.kg-1 to 2.0 rnol.kg-1 at 298.15 K.
Hu Y. F. and Guo T.M. [21] have applied the Pitzer-Simonson-Clegg (PSC)
equation for describing the salt activity coefficients and solubilities in ternary
systems NaCl-n-H2O (n: sucrose and mannitol) at 298.15 K. Comesan J. F. et
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al [22] have determined the water activities using an electric hygrometer for the
binary system of sugar-water and for ternary system of sugar-sodium chloride-
water for different types of sugar ( xylose, glucose, fructose, sucrose) at 35 °C,
and their results have been correlated with an empirical equation proposed by
Lin et al. [23]. Shalaev E.Yu. and Franks F. [24] have established equilibrium
phase diagram of water-sucrose-NaCl system by DSC measurements.
We have performed the measurement of the relative humidities of mixture
of NaCl-sucrose-H2O for different molalities of the sucrose of 0.5, 1.0, 2.0, 4.0
and 5.5 mol.kg-1 in the molality range of NaCl from 0.5 to 6.0 mol.kg-1 at
constant temperature of 298.15 K. From these measurements, the osmotic
coefficients were deduced. Our results are compared with the values obtained
by other methods. The solute activity coefficients, excess Gibbs energy, Gibbs
energy of transfer of sodium chloride, and NaCl solubility in water-sucrose
system are calculated by using the Pitzer-Simonson-Clegg model [25-27] with
our new ionic Pitzer parameters and are compared with data of literature [19-
21].
2. Experimental section:
The apparatus used for the hygrometric method is the same to the one
described in our previous investigations [11, 12] for the measurement of the
relative humidities surrounding non-volatile electrolytes. The chosen aqueous
ternary system in this study is the mixture of electrolyte with non-electrolyte as
NaCl-sucrose-H2O.
The procedure used is based on hygrometric measurements of the aqueous
solutions. The relative humidity above the studied solution is determined from
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