Thermodynamic Studies of Binary and Ternary Mixtures of Duloxetine Hydrochloride and myo-Inositol: A Volumetric, Acoustic, and Viscometric Approach

The experimental data of densities (ρ), speed of sound (u) and viscosities (η) of myo-inositol (MI) in aqueous, duloxetine hydrochloride (DHCl) in aqueous and aqueous MI solution of different molal concentrations at seven temperatures in the range of (288.15–318.15) K has been reported. The thermophysical parameters like apparent molar volume (V_ϕ) of solute, limiting apparent molar volume (V_ϕ⁰), partial molar volume of transfer (Δ_trV_ϕ⁰), thermal expansion coefficient (α*), limiting apparent molar expansibilities (E_ϕ⁰), isentropic compressibility (κ_S) of solution, apparent molar isentropic compression (K_ϕ) of solute, limiting apparent molar isentropic compression of solute (K_s,ϕ⁰), partial molar compression of transfer (Δ_trK_s,ϕ⁰), and hydration number (n_H) were derived. The viscosity data have been used to determine the Falkenhagen coefficient A and Jones–Dole coefficient B on the basis of the Jones–Dole equation. By using the Nightingale, Benck, and Eyring equation, the free energy (ΔE₂^0≠), enthalpy (ΔH₂^0≠), and entropy of activation (ΔS₂^0≠) were calculated. The solvation behavior of DHCl and MI in aqueous systems has been presented. Results are discussed in terms of solute–solute, solute–solvent, hydrophobic hydration, and H-bonding interactions in the studied systems. It is observed that DHCl behaves as a structure maker in both binary and ternary systems.