Recently, solid, aqueous, semi-clathrate systems formed from aqueous tetra- alkylammonium halides, such as tetra-n-butylammonium chloride (TBAC), have been extensively studied due to their potential applications in industry. It is believed that these semi-clathrate structures continue to exist in aqueous solutions upon melting, up to moderate temperatures, before they become thermally unstable. In this study, thermodynamic properties, such as osmotic coefficients of the water (Φ) and the mean molal stoichiometry activity coefficients of the solutes (i.e., TBAC (γTBAC) and NaCl (γNaCl)), are determined for the binary TBAC-H2O and NaCl-H2O systems as well as those for the ternary TBAC-NaCl-H2O system as a function of concentration, ionic strength fraction of TBAC, and temperature. These results will be used to characterize the effect of adding a normal electrolyte, such as NaCl, on the thermodynamic properties of the TBAC-H2O semi-clathrates. These are investigated by measuring the water activities of both the binary and ternary systems over the temperature range from 20 to 50 oC. This data will be analyzed using methodology that was originally developed by Scatchard, Rush and Johnson (SRJ), modified by Leifer and Wigent (SRJ-LW), and more recently expanded by Wigent to determine the contributions to the total excess free energy of mixing due to each component (i.e., TBAC, NaCl and H2O) and the various interaction types (IT) (i.e., pairs, triplet, quadruplets, etc.) that occur between the ions TBA+, Na+ and Cl- in the mixed system as a function of total ionic strength and ionic strength fraction of TBAC. It is expected that sodium chloride, with its common chloride anion, will affect the TBAC semi-clathrate structures.

Effect of adding sodium chloride on the thermodynamic characterizations of tetra-n-butylammonium chloride/water semi-clathrate system

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.