Molar heat capacities of aqueous 2-amino-2-ethyl-1,3-propanediol solutions and their ternary mixtures containing piperazine or lithium salts

Abstract

The molar heat capacities of a primary sterically hindered amine 2-amino-2-ethyl-1,3-propanediol (AEPD) and its aqueous solutions, in the whole range of concentrations, were measured at temperatures from 303.15K to 353.15K by heat flow differential scanning calorimetry. The molar heat capacities of aqueous ternary solutions of AEPD with PZ or salt (LiCl or LiBr) at different amine and salt concentrations were also presented. The excess molar heat capacities of the binary solutions were determined, and the data were correlated with temperature and amine mole fraction using a Redlich–Kister-type equation. For the ternary systems, the heat capacity differences were obtained, and the heat capacity data were represented as a function of temperature and solute concentration using the Sohnel and Novotný equation. The applied correlations well represented the experimental data heat capacities of the studied solvents as suggested by the low values of average absolute deviation, which are 0.2%, 0.1%, and 0.2% for the pure, binary, and ternary systems, respectively.