Volumetric properties of betaine hydrochloride drug in aqueous NaCl and KCl solutions at different temperatures

• Densities and speeds of sound are measured for B.HCl drug in aq. NaCl and KCl.
• Solvation behavior of B.HCl drug is studied in aqueous NaCl and KCl solutions.
• Cosphere overlap model used to understand the transfer partial molar volume values.
• Hepler’s constant values are positive for B.HCl drug in studied systems.

Densities (ρ) and speeds of sound (u) of betaine hydrochloride (B.HCl) drug (0.01–0.06) mol kg−1 in (0.10, 0.20 and 0.30) mol kg−1aqueous NaCl and KCl solutions have been reported as a function of temperature at T = (293.15 –313.15) K and at atmospheric pressure. Using experimental data the apparent molar volume (V2,ϕ), partial molar volume (V2∞), transfer partial molar volume (ΔtV2∞), apparent molar isentropic compressibility (Ks,2,ϕ), partial molar isentropic compressibility (Ks,2∞), transfer partial molar isentropic compressibility (ΔtKs,2∞), partial molar expansion (E2∞) and Hepler’s constant (∂2V2∞/∂T2)P were calculated. Further, all these parameters are employed to understand the temperature and cosolute effects on B.HCl drug–solvent interactions. Cosphere overlap model is used to analyze the hydrophilic/ionic-ionic interactions in (B.HCl drug + NaCl/KCl + H2O) ternary mixture. The sign of Hepler’s constant have been used to interpret the structure making or braking tendency of B.HCl drug in aqueous NaCl and KCl solutions at probed compositions and temperatures.