Study of Thermodynamic and Acoustic Properties of Niacin in Aqueous Hexylene Glycol and Propylene Glycol at Different Temperatures.

The densities and speed of sound for liquid mixtures containing vitamin B (niacin) at 0.01, 0.03, and 0.05 mol·kg concentrations in aqueous propylene glycol and hexylene glycol at the variation of temperatures from 293.15 to 308.15 K have been measured using an Anton Paar DSA 5000 M. From volumetric experimental data, apparent molar volume ( ), partial molar volume ( ), and partial molar volume of transfer (Δ ) are calculated along with the apparent molar isentropic compression ( ), partial molar isentropic compression ( ), and partial molar isentropic compression of transfer (Δ ) using experimental acoustic data. The positive volumetric data (i.e., apparent molar volume and partial molar volume) indicates strong solute-solvent interactions inside the mixture. Along with these values, the empirical constants , , and with the pair and triplet coefficients ( , , , ) are also calculated.