Alkali Metal Chloride Effects on Thermodynamic and Transport Properties in Aqueous Glutathione Solutions: A Volumetric, Ultrasonic, and Viscometric Study

This study investigated the effects of alkali metal chlorides (LiCl, NaCl, and KCl) on the thermodynamic and transport properties of aqueous glutathione (GSH) solutions. Density, speed of sound, and viscosity measurements were conducted for GSH in aqueous electrolyte media (0.1 to 0.5 mol·kg –1 ) across a temperature range of 293.15 to 318.15 K under atmospheric pressure. To understand the volumetric, ultrasonic, and viscometric properties, physicochemical behavior of the systems was characterized using apparent molar volume ( V Ø ), limiting apparent molar volume ( V Ø 0 ), apparent molar isentropic compressibility (κ s,ϕ ), hydration number ( n h ), and thermodynamic properties. Existing molecular interactions were interpreted in terms of solute–solute, solute–solvent, and ion–solvent interactions. The limiting apparent molar volume ( V Ø 0 ) of GSH exhibits a strong dependence on both temperature and the electrolyte medium. It increased with rising temperature in all systems, indicating changes in electrostrictive hydration and ion–dipole interactions surrounding the zwitterionic solute. Negative S v in all alkali systems indicates that solute–solute interactions are weak. Additionally, ultrasonic analysis confirmed the molecular interaction gained by the volumetric properties. Furthermore, thermodynamic characteristics revealed the structure-making tendencies and spontaneity of the solutes in the aqueous medium.