Solubility and thermodynamic properties of SO2 in three low volatile urea derivatives

• The SO2 solubility in three dipolar aprotic urea derivatives has been reported.
• The experimental data were fitted with reaction equilibrium thermodynamic model.
• Henry’s constants and several absorption parameters were obtained.
• The performances of present urea derivatives and other solvents were compared.

The solubilities of SO2 in three dipolar aprotic urea diversities, 1,1,3,3-tetramethylurea (TMU), 1,3-dimethyl-2-imidazolidinone (DMI), and 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H)-pyrimidinone (DMPU) was measured at temperatures ranging from (293.15 to 323.15) K and pressure up to 120 kPa. By correlating the solubility results with a reaction equilibrium thermodynamic model (RETM), Henry’s constants (Hm), reaction equilibrium constants (K°), and enthalpy (ΔHr) in the absorption process were obtained. The results indicate that the three solvents exhibit both strong physical and weak chemical interactions with SO2. Further comparison of the capture performance with ILs, deep eutectic solvents (DESs), and several organic solvents, DMI, DMPU and TMU are noted to be excellent absorbents for acidic SO2.