Effect of 1-butyl-4-methyl pyridinium iodide, [C4mpy]I, ionic liquid on hydration behaviour of aqueous solutions of α-amino acids at different temperatures through volumetric and ultrasonic study

The apparent molar volume (V∅) and isentropic compression (K∅s) of glycine, L-alanine and L-valine have been studied in (0.025, 0.05, 0.075 and 0.1) mol·kg−1 aqueous 1-butyl-4-methyl pyridinium iodide [C4mpy]I solutions over a range of temperatures (288.15, 293.15, 298.15, 303.15 and 308.15) K from the values of densities (ρ) and ultrasonic speeds (u) respectively. The limiting apparent molar volumes (V∅0), and limiting apparent molar isentropic compressions (K∅,s0) are obtained and have been interpreted in terms of solute-solvent and solute-solute interactions. The corresponding transfer quantities (ΔV∅0 and ΔK∅,s0) from water to aqueous solutions of [C4mpy]I have been interpreted by cosphere overlap model. Volumetric and acoustic parameters are used to understand mixing effects and other complex biological processes between head and side chain groups of amino acids and ionic liquid in aqueous solution. The decrease in hydration number with increase in temperature indicates the reduction in electrostriction.