Thermo-physical properties of alkanolamine-ethanol hybrid solutions: experimental measurements and modelling.

Abstract

This study presents the measured densities (!), viscosities (") and refractive indices (nD) of Monoethanolamine (MEA) + Ethanol (ETOH), N-Methyldiethanolamine (MDEA) + ETOH and Diethanolamine (DEA) + ETOH mixtures over the entire range of amine concentration, at temperatures from 293.15 to 333.15 K, with 5 K intervals and at atmospheric pressure. Densities and viscosities of the studied binary mixtures were measured using the combined DSA 5000 M and Lovis 2000 M/ME. Also, a commercial digital refractometer, Atago, RX-7000 α, was used to measure the refractive indices of the samples studied in the present work. The experimental data of the pure amines were compared with those reported in literature and the low values of average absolute deviations (%AARD) confirm the reliability of the methods and the equipment applied in this work. The excess molar volume values for the studied mixtures (V"#) were determined through experimental density data and correlated using Redlich- Kister equation as a function of amine mole fraction. The sing and value of excess molar volume provide a better understanding of the structural effect and intermolecular interactions in the binary mixtures. Other thermo-physical properties including partial molar volume (V$), partial molar volume at infinite dilution (V$"&), and apparent molar volume ( V'), were also obtained from V"#"values and Redlich- Kister adjustable parameters. The viscosity results were used to calculate the deviation in viscosity of studied mixtures. Also, the values of viscosity deviation were correlated using Redlich-Kister equation as a function of amine mole fraction. The values of V"# for all the solutions were found to be negative that shows the volume contraction of the studied mixtures when an alkanolamine and ethanol are mixed. The values of Δη for all the solutions are negative, which reveals the weak interactions between unlike molecules. Following experimental studies, several well-known and previously reported correlations were applied to calculate the densities, viscosities, and refractive indices of the studied binary systems that are discussed in detail in the subsequent chapters. The accuracies of the applied models were determined by calculating the average absolute deviations. The results show that the models/correlations can represent the experimental data with acceptable accuracies.