Density and Viscosity of Aqueous (Piperazine + Carbon Dioxide) Solutions

The density (ρ) and viscosity (μ) of aqueous (piperazine (PZ) + carbon dioxide (CO2)) solutions were measured over a temperature range of (293.15 to 333.15) K and concentration ranges of (1.5 to 7.0) mol·kg−1 PZ ((2 to 20) molal (m) PZ) and (0 to 4.0) mol·kg−1 CO2. Data for density and viscosity are presented in tabular form and include units useful for CO2 capture applications (CO2 loading and PZ concentration in m). Density data are analyzed as the ratio of ρ to the density of water to eliminate the effect of temperature. On this basis, ρ for (5 to 12) m PZ ((3.2 to 5.0) mol·kg−1 PZ) was correlated with a linear regression as a function of CO2 and PZ concentrations to within 0.78 % for all data. A prediction of ρ up to 20 m PZ induces an error of only 1.5 %. Viscosity data are analyzed in a similar way, and a regression for 8 m PZ (4.1 mol·kg−1 PZ) viscosity fit all experimental data within 6.0 %. The applicability of these regressions to online monitoring of a PZ based CO2 capture application is discussed.