Thermodynamic Properties: Determination of the (NaCl + l-Proline + H2O) Ternary System Based on Potentiometric Measurements at T = (293.2, 303.2 and 313.2) K

In this work, the thermodynamic properties of the ternary (NaCl + l-proline + H2O) system are reported, based on the potentiometric technique. The potentiometric measurements were carried out by using self-made ion selective electrodes (ISE) on the galvanic cell of type Na-ISE | NaCl (mB), l-proline (mA), H2O | Ag/AgCl in various series of the l-proline aqueous solution (mA = 0.2227, 0.4571, 0.7043 and 0.9651) mol·kg−1 and NaCl in pure water over NaCl molalities ranging from (0.01 to 4.00) mol·kg−1 at T = (293.2, 303.2, and 313.2) K and p = 101.3 kPa. Correlation of the experimental data was performed based on the Pitzer model as modified by Esteso et al. (MP). The MP parameters obtained were used to calculate the natural logarithm of the ratio of l-proline activity coefficients in NaCl and water mixtures to l-proline activity coefficients in pure water (ln(γA/γA0)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ln ({{\gamma_{{\text{A}}} } \mathord{\left/ {\vphantom {{\gamma_{{\text{A}}} } {\gamma_{{\text{A}}}^{0} }}} \right. \kern-\nulldelimiterspace} {\gamma_{{\text{A}}}^{0} }})$$\end{document}), osmotic coefficients (φ), excess Gibbs energy (GE/RT) and water activity (aw) for different series of l-proline molality. The NaCl transfer Gibbs energy and McMillan–Mayer parameters were also calculated for the system. Good consistency was found between the MP and McMillan–Mayer model parameters.