2024 AIChE Annual Meeting

(146a) Mixed Extractant Systems for Extraction Chromatography

Authors

Boey, A., Defense Center for Public Health - Dayton
The lanthanides and actinides play crucial roles in nuclear medicine, nuclear energy production, and clean energy technologies, necessitating advanced separation processes for their extraction and purification. Modified extractant systems have shown enhanced metal recovery1-3 and/or reduced undesirable phase phenomena using solvent extraction (SX) techniques.4-6 Extraction chromatography (EXC), a subset of liquid-liquid chromatography, employs a stationary phase of a neat (undiluted) metal extractant, or a metal extractant dissolved in a diluent, physisorbed on porous solid support. The extractants commonly used in EXC are typically the same as those used in SX systems, granting EXC the selectivity of SX alongside the multiple separation stages and operational simplicity of chromatography. However, synergism has not been extensively explored using this separation technique.

In this study, two f-element extractants, 2-ethylhexyl 2-ethylhexylphosphonic acid (HEH[EHP]) and tetra-(2‑ethylhexyl)diglycolamide (TEHDGA), were physisorbed on a polymeric porous solid support and evaluated for Eu(III) uptake using batch extraction techniques. The combined extractant system exhibited synergism from 0.14–0.96 M HNO3 but was antagonistic at lower acid concentrations. Furthermore, the TEHDGA + HEH[EHP] EXC material provided a higher maximum Eu(III) adsorption capacity (155 ± 3 μmol g–1) compared to the single extractant HEH[EHP] system (85 ± 8 μmol g–1).

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