Volumetric and acoustic studies of binary liquid mixtures of propylene glycol monopropyl ether + n-alkylamine at 288.15, 298.15 and 308.15 K

Abstract

The densities, ρ, and the speeds of sound, u, for binary liquid mixtures containing propylene glycol monopropyl ether (PGMPE) and n- butylamine (BA), dibutylamine (DBA) or tributylamine (TBA) have been measured as a function of composition using a vibrating tube densimeter and sound analyzer Anton-Paar model DSA-5000 at temperatures 288.15, 298.15 and 308.15 K and atmospheric pressure. From these data excess molar volumes, V_m^E , the thermal expansion coefficient, α^E, and deviations in isentropic compressibility, ∆κ_s, have been calculated._. The V_m^E values are negative over the whole mole fraction range for the systems propylene glycol monopropyl ether + n-butylamine, and dibutylamine, and positive for the system propylene glycol monopropyl ether + tributylamine. whereas the ∆κ_s values are negative over the entire range of composition for all mixtures with the exception of tributylamine. Also, in the present study, thermophysical parameters such as apparent molar volume ,v_Ф,i, and apparent molar isentropic compressibility, K _φ,i are studied for the PGMPE with BA, DBA or TBA. The results reveal the dominance of ether – BA or DBA as compared to ether –TBA interactions which are found to increase with elevation of temperature but decrease with increasing the chain length of alkylamine. Further, the deviation of the speeds of sound u^D from their ideal values u^id in an ideal mixture have been calculated for all measured values of mole fraction x₁. Sign and magnitude of V_m^E, ∆κ_s and u^D with respect to the composition and temperature have been used to analyze the mixing behavior of the components.