Diffusional group contribution method in liquid-liquid extraction systems

• Applicant: Professor Dr.-Ing. Hans-Jörg Bart
• Subject Area: Chemical and Thermal Process Engineering
• Term: from 2000 to 2002
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5266292

The mass transport in the liquid phase controls the rate of many unit operations. The determination of mass fluxes in multicomponent systems is not possible without the knowledge of multicomponent diffusion coefficients. However, it ist still difficult for engineers to calculate them with confidence, expecielly when non-ideal systems are considered. Fei and co-workers proposed a new and practical approach to predict the diffusion coefficients based on the group contribution method. Considering the UNIFAC model as coefficients based on the group contribution method. Considering the UNIFAC model as successfully used predicting the thermodynamic equilibria, a similar approach is undertaken for diffusivities. The objective of this work is to adapt and improve the existing model. First of all, the UNIFAC group interaction parameters are not correctly implied, the association factor is a fit parameter and not from a thermodynamic source, the activation energies should then be correlated from existing data. As can be seen, the group diffusivity model is in a very basic state and should be made compatible to UNIFAC parameters. Preliminary experiments in existing mass transfer cells should verify the predictions derived from the group diffusion method. The future work sponsored by the NSFC (China) should be in the improvement of the quantity and the verification of data/groups.

• DFG Programme: Research Grants