Measurement and modelling of tracer diffusivities of gallic acid in liquid ethanol and in supercritical CO2 modified with ethanol

作者：Leite J; Magalhaes A L; Valente A A; Silva Carlos M^*

来源：Journal of Supercritical Fluids, 2018, 131: 130-139.

DOI：10.1016/j.supflu.2017.09.004

• Chromatography peak broadening method
• Cosolvent
• Gallic acid
• Modelling
• Tracer diffusion coefficient
• Supercritical carbon dioxide

The tracer diffusion coefficients, D-12, of gallic acid in liquid ethanol and in supercritical carbon dioxide (SC-CO2) modified with 16 mol.% ethanol were measured using the chromatographic peak broadening technique of Taylor-Axis. The diffusivity in ethanol ranged 0.485 x 10(-5)-0.905 x 10(-5)cm(2).s(-1) (303.15-333.15 K and 1-100 bar) and in SC-CO2/ethanol 3.256 x 10(-5)-4.978 x 10(-5)cm(2).s(-1) (313.15-333.15 K and 150-250 bar). The dependencies of D12 upon temperature, pressure and Stokes-Einstein coordinates were examined in detail. With respect to modelling, lower deviations were achieved in both systems by: four 2-parameter correlations of Magalhaes et al. (error 0.9-3.0%;); the 1-parameter TLSMd model (5.8% and 2.9% of error); and the 2-parameter Dymmond-Hilbrand-Batchinski (DHB) expressions (5.7% and 1.6% of error). The Wilke-Chang correlation cannot be applicable, due to consistent overpredictions of 133.0% (gallic acid/ethanol) and 114.0 % (gallic acid/ SC-CO2/ethanol).

• 出版日期2018-1