Molar heat capacity of several aqueous solutions of n-[tris(hydroxymethyl)methyl-3-amino]propanesulfonic acid (TAPS) + glycol

The molar heat capacity (Cp) of a potential solvent system for CO2 absorption, containing water, glycol and n-[tris(hydroxymethyl)methyl-3-amino]propanesulfonic acid (TAPS), was measured at 30–80 °C and different concentrations via differential scanning calorimetry. Each of the glycols – diethylene glycol (DEG), triethylene glycol (TEG), tetraethylene glycol (T4EG), propylene glycol (PG), dipropylene glycol (DPG) and tripropylene glycol (TPG) – was mixed with TAPS + H2O to form ternary systems consisting of a fixed amount of the glycol (40 mass%) and variable TAPS/H2O proportions (4–16 mass% TAPS or 56–44% H2O). An extended Redlich–Kister-type equation was used to correlate heat capacity with concentration and temperature; the average absolute deviation (AAD) of the 198 data points from the corresponding values predicted by the correlation was 0.04%. The new set heat capacity data or the correlation, reported for the ternary system considered, can be used with high degree of accuracy in process design calculations for systems that will utilize these solvent systems.

► The molar heat capacities for several aqueous TAPS + glycol systems at 30–80 °C were measured.
► The glycols considered were diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol and tripropylene glycol.
► The measured data were reported as functions of temperature and composition.
► The measured data were represented satisfactorily by the applied correlations.