Measurement and correlation of binary diffusion coefficients of lithium acetylacetonate in supercritical carbon dioxide and in liquid ethanol

• Brief theoretical background for the CIR and Taylor dispersion methods.
• Effects of injected solute amount, temperature, pressure, density and viscosity on diffusion.
• Diffusion activation energies in supercritical carbon dioxide and in liquid ethanol.
• Correlation of diffusion data measured in this study.

The infinite dilution binary diffusion coefficients D12 of lithium acetylacetonate were measured in supercritical carbon dioxide by the chromatographic impulse response (CIR) method at 308.15–333.15 K and pressures up to 36.00 MPa. The D12 values were also measured in liquid ethanol at 298.15–333.15 K, and at 0.10, 10.00 and 30.00 MPa by the Taylor dispersion method. The effects of temperature, pressure and density of fluid on D12 values were studied. The D12 data increased from 1.140 × 10−9 m2 s−1 in liquid ethanol at 298.15 K and 30.00 MPa to 2.218 × 10−8 m2 s−1 in supercritical carbon dioxide at 333.15 K and 14.00 MPa. It was observed that the D12 data in supercritical carbon dioxide at 15.00, 20.00 and 30.00 MPa can be well correlated as a function of temperature using an Arrhenius type equation, which provided the diffusion activation energies of 17.5, 13.4 and 11.0 kJ mol−1; that in liquid ethanol at 0.10, 10.00, 30.00 MPa gave the diffusion activation energies of 14.0, 14.2 and 13.8 kJ mol−1, respectively. It was found that the proposed correlation based on hydrodynamic approach can well represent all the measured D12 data of lithium acetylacetonate in supercritical carbon dioxide and in liquid ethanol with the average absolute relative deviation (AARD) of 1.7% for 88 data points.

Figure optionsDownload as PowerPoint slide