Aggregation in Solvent Extraction Systems Containing a Malonamide, a Dialkylphosphoric Acid and their Mixtures

Antonio, Mark R.; Chiarizia, R.; Gannaz, Benoît; Berthon, Laurence; Zorz, Nicole; Hill, C.; Cote, Gérard

doi:10.1080/01496390802121537

Cited by 73 publications

(56 citation statements)

References 27 publications

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“…Figure 6 portrays ESI‐MS data for dilute (0.048 M ) and concentrated (0.159 M ) Eu III organic phases, showing peaks that correspond to several Eu–malonamide species that involve two to seven malonamide molecules for each metal center. The influence of the cone voltage was explored and the intensity of ions, such as [EuL x ] 3+ , where x ≥5, strongly decrease as the cone voltage increases, showing that these species are not very stable and are probably formed during the ionization process as already observed for Nd extraction 22e. The data show that the malonamide:Eu III complex stoichiometries in the organic phase depend on the europium concentration.…”

Section: Resultsmentioning

confidence: 82%

Complexation‐Induced Supramolecular Assembly Drives Metal‐Ion Extraction

Ellis

Meridiano

Muller

et al. 2014

Chemistry A European J

103

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Combining experiment with theory reveals the role of self-assembly and complexation in metal-ion transfer through the water-oil interface. The coordinating metal salt Eu(NO3)3 was extracted from water into oil by a lipophilic neutral amphiphile. Molecular dynamics simulations were coupled to experimental spectroscopic and X-ray scattering techniques to investigate how local coordination interactions between the metal ion and ligands in the organic phase combine with long-range interactions to produce spontaneous changes in the solvent microstructure. Extraction of the Eu(3+)-3(NO3(-)) ion pairs involves incorporation of the "hard" metal complex into the core of "soft" aggregates. This seeds the formation of reverse micelles that draw the water and "free" amphiphile into nanoscale hydrophilic domains. The reverse micelles interact through attractive van der Waals interactions and coalesce into rod-shaped polynuclear Eu(III) -containing aggregates with metal centers bridged by nitrate. These preorganized hydrophilic domains, containing high densities of O-donor ligands and anions, provide improved Eu(III) solvation environments that help drive interfacial transfer, as is reflected by the increasing Eu(III) partitioning ratios (oil/aqueous) despite the organic phase approaching saturation. For the first time, this multiscale approach links metal-ion coordination with nanoscale structure to reveal the free-energy balance that drives the phase transfer of neutral metal salts.

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Section: Resultsmentioning

confidence: 82%

Complexation‐Induced Supramolecular Assembly Drives Metal‐Ion Extraction

Ellis

Meridiano

Muller

et al. 2014

Chemistry A European J

103

View full text Add to dashboard Cite

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“…However, to dissolve the polar extractants in a non‐polar diluent medium, the organic ligands are made with sufficiently organophilic character by attaching a long chain alkyl or aryl groups. In view of this, the ligands employed in liquid–liquid extractions are usually amphiphilic, containing both polar metal coordinating functional groups and non‐polar organophilic moieties …”

Section: Introductionmentioning

confidence: 99%

Dynamic Light Scattering and FTIR Spectroscopic Investigations on the Reverse Micelles Produced During the Extraction of Nd(III) and Nitric Acid in Tetra Ethylhexyl Diglycolamide

et al. 2017

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The aggregation behaviour of reverse micelles, formed during the extraction of neodymium nitrate and nitric acid, in an organic phase composed of tetra‐bis(2‐ethylhexyl) diglycolamide (TEHDGA) in n‐dodecane (n‐DD) was studied, at various temperatures. The organic phase, 0.2 M TEHDGA/n‐DD was equilibrated with aqueous solutions of nitric acid in the presence and absence of neodymium nitrate. At certain nitric acid and Nd(III) concentration in aqueous phase, the organic phase underwent splitting into two phases, with top phase known as “diluent rich phase”, the other one known as “third phase” or “metal ion rich phase”. Dynamic light scattering, attenuated total reflectance (ATR) ‐Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopic methods were employed for probing the size and distribution of aggregates present in the organic phase before and after splitting. The investigations revealed that the aggregates, formed in organic phase, interact efficiently with the extracted metal ions and these interactions increased with increase in the concentration of nitric acid and neodymium nitrate in organic phase. In addition, the interaction among the reverse micelles in third phase appear to be very strong as compared to that observed in the organic phase before third phase formation, and such strong interactions resulted in a merger and narrow distribution of reverse micelles in third phase.

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“…It is now well established that the organic phases involved in the DIAMEX process are not molecular solutions [20][21][22][25][26][27][28][29]. Malonamide extractants diluted in organic solvent self-organise in reverse micelles with low aggregation numbers (from 3 to 10).…”

Section: Introductionmentioning

confidence: 99%