Understanding interface formation and extractant distribution at the liquid-liquid interface
Résumé
Lanthanide ions recycling has grown in importance in recent years as the demand for these elements has increased, and the rate of extraction from rare metals has decreased [1]. One of the approaches for recycling metals is liquid-liquid extraction, which separates solutes based on the difference in their solubility between two liquids. In the nuclear industry, many processes based on liquid-liquid extraction are employed to recycle nuclear fuel, where lanthanide ions are separated from nuclear waste. DIAMEX (DIAMide Extraction) process is one such technique [2], where the reference molecule for separation of smaller lanthanides between two liquid phases is N-N’-DiMethyl-N-N’dioctyl-2-hexylethoxymalonamide (DMDOHEMA) [3].
In our research, we use classical Molecular Dynamics (MD) to investigate the structural properties of the liquid-liquid interface between aqueous and organic phases with amphiphilic extractant (DMDOHEMA or TODGA). The main objective is to characterize and describe the species distribution at the interface and in the bulk. Initially, we examined how the initial box configuration impacts the formation of the interface, as well as how the ratio between the two phases affects the shape and structure of the interface in comparison with experimental and theoretical data. Further, we study the distribution of extractant at the interface and in the bulk organic phase at various extractant concentrations, where we will compare the behavior of two different extractants. Additionally, our investigation extends to understanding the micelle formation with ions and extractants within the bulk organic phase alongside we will also explore the ion transfer from aqueous to organic phase, distribution of extractants, salts, and micelles formed in the system during extraction.
[1] K. Binnemans et al., J. Clean. Production, 2013, 51, 1-22.
[2] G. Modolo et al., Sep Sci Technol., 2007, 42, 439-452.
[3] P. Baron et al., GLOBAL 2001 Paris, France, 2001