Diffusional group contribution method in liquid-liquid extraction systems

液体中的传质控制着许多单元操作的速度。如果不知道多组分的扩散系数，就不可能确定多组分体系中的质量通量。然而，工程师们仍然很难有把握地计算它们，特别是当考虑非理想系统时。Fei和他的同事提出了一种新的、实用的基于基团贡献法的扩散系数预测方法。在基团贡献法的基础上，将uniAC模型视为系数。考虑到uniAC模型是预测热力学平衡的成功方法，对扩散系数也采取了类似的方法。这项工作的目标是适应和改进现有的模式。首先，并不能正确地隐含uniAC基团相互作用参数，缔合因子是一个合适的参数，而不是来自热力学来源，因此活化能应该从现有的数据中关联出来。由此可见，基团扩散率模型处于非常基本的状态，应使其与uniAC参数相容。在现有传质池中的初步实验应该验证从群扩散方法得出的预测。国家自然科学基金委员会(中国)的下一步工作应该是提高数据/组的数量和验证。

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.