Diffusional group contribution method in liquid-liquid extraction systems

液相中的质量传递控制许多单元操作的速率。如果不知道多组分扩散系数，就不可能确定多组分体系的质量通量。然而，工程师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等人提出了一种基于基团贡献法的预测扩散系数的新方法。以基团贡献法为基础，将CNOAC模型作为系数。考虑到成功地用于预测热力学平衡的CNOAC模型，对扩散系数采取类似的方法。这项工作的目的是调整和改进现有模式。首先，没有正确地暗示C2 H4基团相互作用参数，缔合因子是一个拟合参数，而不是来自热力学来源，活化能应该从现有数据中关联。可以看出，基团扩散率模型处于非常基本的状态，并且应该与MAAC参数兼容。在现有的传质池的初步实验应验证来自集团扩散方法的预测。国家自然科学基金（中国）资助的未来工作应是提高数据/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.