abstract
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).
keywords
BINARY DIFFUSION-COEFFICIENTS; CARBON-DIOXIDE; TRANSPORT-COEFFICIENTS; PRESSURE RANGE; LENNARD-JONES; DENSE FLUIDS; WIDE RANGES; FREE-VOLUME; CHROMATOGRAPHY; SOLUBILITY
subject category
Chemistry; Engineering
authors
Leite, J; Magalhaes, AL; Valente, AA; Silva, CM
our authors
Ana Luísa Carvalho Magalhães
Post-doc Fellowship
Anabela Tavares Aguiar Valente
Principal Researcher
Carlos Manuel Silva
Associate Professor
Jorge Filipe Cruz Costa Leite
MSc Studentacknowledgements
A.L. Magalhaes acknowledges a Post-doc grant provided by Fundacao para a Ciencia e a Tecnologia, Portugal (SFRH/BPD/95393/2013). This work was developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement.