Density studies of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-glycerol and CO2-DBU-glycerol solutions at temperatures between 288.15 K and 328.15 K

The binary system of glycerol and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) possesses promising potential for CO2 absorption, and critical physical properties, especially density, analysis are important for its application. In this work, density of DBU-glycerol system before and after CO2 absorption at temperatures between 288.15 K and 328.15 K was studied by the pycnometer method. In DBU-glycerol system, the density decreases with increases in both temperature and DBU concentration. Excess molar volumes (V-E) of DBU-glycerol system are negative in the entire composition range and are well correlated with Redlich-lister equation. Four different models are successfully adopted for correlating and predicting the densities of DBU-glycerol binary solutions. In CO2-DBU-glycerol system, densities are 0-6% higher than that in the DBU-glycerol system when the mass content of CO2 (omega(CO2)) based on the total mass of DBU and glycerol is less than 8%. Two different models were set up to correlate the densities with the mole fraction of DBU, temperatures, and CO2-loadings. The Jouyban-Acree method and the proposed modified proportionality method are preferred respectively for calculating the densities of the CO2 unloaded and CO2-loaded DBU-glycerol mixtures due to their simplicity and precision. The density data are useful in the engineering design for CO2 capture using DBU-glycerol solvent. (C) 2018 Elsevier Ltd.