Volumetric and Ultrasonic Studies of Molecular Interactions of PEG 400 and PEG 4000 in Aqueous Niacin Solutions at Different Temperatures
Nabaparna Chakraborty, K.C. Juglan, Harsh Kumar
Abstract
At multiple temperatures, 288.15–318.15 K, the density and speed of sound values for PEGs of molecular weights 400 and 4000 in aqueous niacin solutions were measured at concentrations of 0.07, 0.08, and 0.09 mol·kg–1. Utilizing these experimental data, the apparent molar properties and partial molar properties were determined to analyze the interactions in aqueous niacin solutions with poly(ethylene glycol)s (400/4000). The volumetric parameters, such as apparent molar volume, Vϕ, partial molar volume, Vϕ0, and partial molar volume of transfer, ΔVϕ0, are obtained using experimental density values, while the acoustic parameters, i.e., apparent molar isentropic compression, Kϕ,S, partial molar isentropic compression, Kϕ,S0, and partial molar isentropic compression of transfer, ΔKϕ,S0, are determined with the speed of sound data. These positive volumetric apparent and partial molar properties suggest the presence of strong solute–solvent interactions. The partial molar expansibilities (Eϕ0) along with their first derivative (∂Eϕ0/∂T)P were calculated. Further, pair and triplet coefficients are obtained using partial molar isentropic compression and partial molar volume of the transfer, respectively.