Esam A. Gomaa

Barium Diphenylamine-4-Sulfonate (BDPA) Ion-Ion Interactions and Solvation Volumes in Acetonitrile–Water Mixed Solvents

The aim of this work is to calculate ion-ion interaction, density of organic-aqueous mixtures of Acetonitrile-water (AN-H 2 O), density of saturated solutions of BDPA, salvation volumes (Van der Waals volume V M , molar volume V M and electrostriction volume V e ) and solvated radii (r o ) from solubility experiments. It was found that values of the log activity coefficient ( γ + ) of BDPA in (AN-H2O) mixture were decreases by increasing in the content of the organic solvent used. The values of the log γ + found to decrease with the increase in temperature. The densities and the molar volumes of the saturated solutions of BDPA decrease by increasing ratio of AN and also increases by increasing in temperature. All the electrostriction volumes calculated for BDPA having negative values. The electrostriction volumes increase in negativity on increasing the percentages of the organic solvent. The solvated radii of BDPA are increased as the organic solvent content increase and as the temperature increase.

Calculations of Ion-ion Interactions, Densities, and Different Volumes of Barium Diphenylamine Sulfonate in Ethanol-water at Different Temperatures

The ionic strength of a solution is a measure of the concentration of ions in that solution. Ionic compounds, when dissolved in water, dissociate into ions. The total electrolyte concentration in solution will affect important properties such as the dissociation or the solubility of different salts. One of the main characteristics of a solution with dissolved ions is the ionic strength. Various models have been used to predict the cosolvent/water solubility profiles. These include parabolic and log-linear models. The log-linear model of Yalkowsky and Rosemann[1] describes an exponential increase in non-polar drug solubility with a linear increase in cosolvent concentration. There are also numerous parabolic models that have been used to predict the cosolvent/water solubility profile for semi-polar solutes. Paruta et al.[2] correlated the cosolvent solubility with a parabolic function of the dielectric constant of the solvent mixture. Martin et al.[3-5] proposed a parabolic relationship between solute solubility and the solubility parameter of a solvent mixture. Recently, Ruckenstein et al.[6] applied fluctuation theory to generate a new parabolic relationship. These parabolic relationships are based on regular solution theory. As was shown by Hilderbrand and Scatchard[7] and later reiterated by Yalkowsky,[8] regular solution theory is not applicable to solutions where hydrogen bonding or ionic interactions are dominant. Ethanol is the most commonly used cosolvent due to its low toxicity and low cost. Ethanol/water systems have the most data available, and therefore, ethanol will be used as the model solvent for this study. A lot of published data[9-12] for BDPA and other substances that states that they are very important materials for different fields.