Solubility of Sodium Acetate in Ternary Mixtures of Methanol, 1‐Propanol, Acetonitrile, and Water at 298.2 K

The solubility of sodium acetate in ternary solvent mixtures of water + methanol (MeOH) + acetonitrile (ACN), water + MeOH + 1-propanol (PrOH), water + PrOH + ACN, and MeOH + PrOH + ACN at 298.2 K is reported and mathematically represented using two numerical analyses (based on measured solubility data in 54 ternary mixtures containing the particular solvents in the mass fraction ranges between 0.08 and 0.84). In the first analysis, the solubility is predicted using the Jouyban−Acree model constants for the binary mixtures of the respective solvent pairs that were used to prepare the ternary mixtures. By this approach, the overall mean percentage deviation (OMPD) of the predicted data in ternary solvents is 57 %. The largest OMPD for this model was up to 80 % for a mixture of water, PrOH, and ACN. To improve the model, an additional term (with ternary constants Ji ∥) was included, reflecting the combined effect of all three solvents in a mixture. By this numerical analysis, the experimental ternary solubility data is used to calculate the additional ternary constants. After employing the calculated constants, the prediction of the solubility in the ternary mixtures was improved significantly by a factor of 2 with an OMPD of 25 %. As an additional ability of the Jouyban−Acree model, the density of the solute saturated solutions in the solvent mixtures is predicted using three numerical methods; i.e., (i) data of solute saturated solutions in the binary solvent mixtures, (ii) ternary mixtures, and (iii) density data of solute free binary solvent mixtures with predicting errors (OMPD) of 1.2 %, 3.0 %, and 2.8 %, respectively. ■ INTRODUCTION It is important to know the solubility of salts in organic and mixed solvent systems in many industrial and natural processes such as solubilization, crystallization, liquid extraction, distillation, and inorganic salt absorption. The solubility of electrolytes in nonaqueous solvents is essential for theoretical studies concerning the liquid phase structure and its thermodynamic properties. Also, the solubility of inorganic salts plays a significant role in determining the physical and chemical properties of ionic solutions. However, such solubility phenomena are less studied and often very scarce. Sometimes the published data measured by different researchers are even contradictory. Sodium acetate is an important material in many fields of science and technology. In food industries, it is used as a buffer constituent in controlling the pH during various stages of processing and is used as a seasoning. It is one of the FDA recommended materials as a food additive. In petroleum and textile industries, it is used as a buffering agent and for the neutralization of sulfuric acid waste streams, respectively. In medical applications, it is used as a fluid bath for hemodialysis and as a source of sodium for addition to large volume intravenous fluids to prevent or correct hyponatremic patients. The rubber industries, tanning, concrete, and heating pads are other application areas involving sodium acetate (or other features). In analytical sciences, sodium acetate is an important buffering constituent in high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) systems. Because of the importance of sodium acetate in the areas mentioned above, we found it worth reporting the solubility data of this salt in ternary solvent mixtures of water + MeOH + PrOH, water + MeOH + ACN, water + PrOH + ACN, and MeOH + PrOH + ACN at 298 K and to apply the Jouyban− Acree model for correlation and/or prediction of the measured data. Over the past few decades, several models have been developed to predict the solubility of salts and nonionic materials. The previously used electrolyte activity coefficient based models such as the Pitzer’s model, e-Wilson model, eNRTL model, UNIQUAC, and LIQUAC models were used for Received: June 2, 2014 Accepted: July 16, 2014 Published: August 4, 2014 Article