Impact of branching position and degree on uranium extraction by amines; A Supramolecular and thermodynamic study

Guerinoni, E.*; Giusti, F.*; Dourdain, S.*; Dufrche, J.-F.*; 元川 竜平; 上田 祐生; 青柳 登; Zemb, T.*; Pellet-Rostaing, S.*

Journal of Molecular Liquids, 403, p.124820_1 - 124820_11, 2024/06

https://doi.org/10.1016/j.molliq.2024.124820

In uranium production, liquid-liquid extraction using the AMEX (AMine EXtraction) process employs tertiary amines solubilized in an aliphatic diluent. Practical constraints as phase stability problems and co-extraction of competitive elements highlight the need for in-depth investigation and optimization. Modifying gradually the alkyl chain structure of tertiary amines, we investigate here the large variation in extraction performance in terms of Gibbs free energy of transfer using the ienaic decomposition taking into account long range interactions. We show hereby that structuration of the solvent phase can change uranium distribution by 2 orders of magnitude, which is incompatible with standard complexation theory of liquid-liquid extraction. We observe that co-extracted water is required to obtain extraction while extraction is quenched and no pair core can be formed when less than four as effective aggregation number. We conclude that the film term in the ienaic decomposition of the Gibbs energy of transfer, is the one that governs extraction performance. It shows that metal transfer is beyond complexation, and that organization of the solvent phase must be considered to quantitatively interpret the distribution coefficients.