abstract
In this work, a predictive model for binary diffusivities at infinite dilution (D-12) in SC-CO2 is proposed. It combines two terms - background and singular - with the objective to represent D-12 accurately not only far but also near the critical point, where critical enhancement is always observed. The model provides an average error of 6.20% for a large database including 149 systems and 4469 data points over wide ranges of temperature and pressure. The models selected for comparison (Wilke-Chang, Scheibel, Lusis-Ratcliff, Lai-Tan, Tyn-Calus and Reddy-Doraiswamy) achieve scattered and biased results, with average errors from 11.62% to 75.17%. In the whole, the new model exhibits an excellent performance for any kind of molecules in terms of size, molecular weight, polarity and sphericity, in all critical region. In order to help interested readers, a spreadsheet for the calculation of D-12 is given in Supplementary data. The input data is: temperature, pressure, CO2 viscosity, and solute properties (acentric factor, critical constants, molar volume at normal boiling point, and molecular weight - given in this paper for the systems studied). (C) 2014 Elsevier B.V. All rights reserved.
keywords
IMPULSE-RESPONSE METHOD; TAYLOR DISPERSION TECHNIQUE; FLUID CHROMATOGRAPHY SFC; PARTIAL MOLAR VOLUMES; ACID METHYL-ESTERS; EQUATION-OF-STATE; CARBON-DIOXIDE; INFINITE-DILUTION; TRACER DIFFUSION; RETENTION FACTORS
subject category
Chemistry; Engineering
authors
Vaz, RV; Magalhaes, AL; Silva, CM
our authors
Ana Luísa Carvalho Magalhães
Post-doc Fellowship
Carlos Manuel Silva
Associate Professor
Graça Raquel Veiga Vaz
PhD Studentacknowledgements
R.V. Vaz and Associate Laboratory CICECO thank PhD grant SFRH/BD/69257/2010 and project PEst-C/CTM/LA0011/2013 provided by Fundacao para a Ciencia e a Tecnologia, Portugal.