Experimental and Computational Insights into the Thermophysical Properties of Glycerol and Triethanolamine Mixtures

Abstract The density and viscosity of binary mixtures of triethanolamine (TEA) and glycerol were investigated over the full composition range at temperatures from 293.15 K to 323.15 K, under atmospheric pressure. The experimentally measured density and viscosity data were correlated with temperature-dependent equations. The excess molar volume ( V E ) and viscosity deviation ( Δη ) were determined and fitted using the Redlich–Kister polynomial equation. In addition, thermodynamic parameters, including partial molar volumes, apparent molar volumes, and thermal expansion coefficients, were evaluated to provide further insight into the mixing behavior of the system. Negative values of V E and Δη were observed over the entire range of temperatures and compositions investigated, indicating the presence of strong specific interactions between TEA and glycerol molecules. These interactions were further elucidated through Density Functional Theory (DFT) calculations. The computational results are consistent with the experimental observations, providing molecular-level support for the non-ideal volumetric and viscosity behavior of the mixtures.