Accurate hydrodynamic models for the prediction of tracer diffusivities in supercritical carbon dioxide
authors Magalhaes, AL; Vaz, RV; Goncalves, RMG; Da Silva, FA; Silva, CM
nationality International
journal JOURNAL OF SUPERCRITICAL FLUIDS
author keywords Carbon dioxide; Modeling; Prediction; Stokes-Einstein; Supercritical fluids; Tracer diffusion coefficients
keywords BINARY DIFFUSION-COEFFICIENTS; SIMULATED MOVING-BED; FLUID CHROMATOGRAPHY SFC; IMPULSE-RESPONSE METHOD; TAYLOR DISPERSION TECHNIQUE; PARTIAL MOLAR VOLUMES; LENNARD-JONES FLUID; ACID METHYL-ESTERS; HARD-SPHERE THEORY; INFINITE-DILUTION
abstract The tracer diffusion coefficients, D-12, are fundamental properties for the design and simulation of rate-controlled processes. Nowadays, under the scope of the biorefinery concept and strict environmental legislation, the D-12 values are increasingly necessary for extractions, reactions, and chromatographic separations carried out at supercritical conditions, particularly using carbon dioxide. Hence, the main objective of this work is the development of accurate and simple models for the pure prediction of D-12 values in supercritical CO2. Two modified Stokes-Einstein equations (mSE(1) and mSE(2)) are proposed and validated using a large database comprehending extremely distinct molecules in terms of size, molecular weight, polarity and sphericity. The global deviations achieved by the mSE1 (Eqs. (2) and (13)) and mSE(2) (Eqs. (5), (13), (3), (4)) models are only 6.38% and 6.75%, respectively, in contrast to the significant errors provided by well known predictive correlations available in the literature: Wilke-Chang, 12.17%; Tyn-Calus, 17.01%; Scheibel, 19.04%; Lusis-Ratcliff, 27.32%; Reddy-Doraiswamy, 79.34%; Lai-Tan, 25.82%. Furthermore, the minimum and maximum deviations achieved by the new models are much smaller than those of the reference equations adopted for comparison. In conclusion, our mSE(1) and mSE(2) models can be recommended for the prediction of tracer diffusivities in supercritical CO2. (C) 2013 Elsevier B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0896-8446
year published 2013
volume 83
beginning page 15
ending page 27
digital object identifier (doi) 10.1016/j.supflu.2013.08.001
web of science category Chemistry, Physical; Engineering, Chemical
subject category Chemistry; Engineering
unique article identifier WOS:000327171600003

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