4. Conclusion

The coupling of matter transfer and chemical reaction is at the heart of the processes involved in liquid-liquid extraction, rightly referred to as reactive extraction. Far from being a laboratory curiosity, this coupling is put to good use in proven industrial applications in hydrometallurgy, notably in the nuclear industry (PUREX process, in particular).

The introduction of the Hatta criterion has several merits. It allows us to establish analogies and similarities between two important unit operations in process engineering: gas-liquid absorption and liquid-liquid extraction. The comparison between the Hatta criterion and the Thiele criterion, an otherwise important parameter in heterogeneous catalysis, further reinforces the relevance of this approach.

From a practical point of view, estimating the Hatta criterion provides information...