Thermodynamics of Extraction of Plutonium(VI) in PolyEthylene Glycol (PEG) based Aqueous Biphasic System (ABS) using 18-Crown-6 and 15-Crown-5

We present a molecular dynamics study of 18C6, 15C5 crown ethers and their acyclic polyether analogues at the water/supercritical-CO 2 interface. The aqueous and CO 2 components form distinct phases, separated by an interface, where in all systems, the ethers are found to concentrate. Simulations of the inclusive K + &18C6 Pic À complexes led to decomplexation of K + and accumulation of the crown ethers on the CO 2 side of the interface, while Pic À anions stack in the aqueous phase. When the K + cations are constrained to form inclusive complexes with 18C6, all complexes concentrate at the interface, be the counterions free to move, or constrained to coordinate to K + . In the presence of nitric acid, modeled by equimolar mixtures of HNO 3 , NO 3À and H 3 O + forms, the ethers remain surface active, as does the neutral form of the acid. These simulations demonstrate the importance of interfacial phenomena in assisted ion extraction to supercritical-CO 2 .

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Importance of counter-ions in alkali and alkaline-earth cation extraction by 18-crown-6: molecular dynamics studies at the water/sc-CO₂interface

Vayssiere

Wipff

2003

Phys. Chem. Chem. Phys.

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We present a molecular dynamics study of concentrated solutions of K + and Sr 2+ cations and their complexes with 18C6 at the water/supercritical-CO 2 interface, and compare picrate '' Pic À '' vs. perfluorooctanoate '' PFO À '' counter-ions at 305 and 350 K. The results allow to understand why K + is poorly extracted in conditions where Sr 2+ is transferred to the supercritical fluid. In all cases, the solutes are found to concentrate near the interface, with interesting differences, depending on the cation, counter-ion and extractant. With the two anions, the SrX 2 salts are surface active, as a result of cation-anion pairing, while the distribution of the K + ions depends on X À . The inclusive K + &18C6 complexes partially decomplex, and decomplexation is more effective at 350 K than at 305 K. The most remarkable result is the extraction of Sr 2+ &18C6,2PFO À complexes in which the anions axially co-complex the cation, while retaining CO 2 -philic interactions via their perfluorinated chain. This Sr 2+ extraction is confirmed by several computational tests which point to the importance of concentration effects and agree with experiment. It contrasts with the formation of an interfacial film with Sr 2+ &18C6,2Pic À complexes, assembled via bridging Pic À Á Á ÁSr 2+ Á Á ÁPic À and stacking Pic À Á Á ÁPic À interactions.

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Thermodynamics of Extraction of Plutonium(VI) in PolyEthylene Glycol (PEG) based Aqueous Biphasic System (ABS) using 18-Crown-6 and 15-Crown-5

Cited by 5 publications

References 8 publications

Extraction and separation of a lysine-rich protein by formation of supramolecule between crown ether and protein in aqueous two-phase system

Extraction and separation of a lysine-rich protein by formation of supramolecule between crown ether and protein in aqueous two-phase system

Ethers, crown ethers and 18-crown-6 K⁺complexes at a water/SC-CO₂interface: a molecular dynamics study

Importance of counter-ions in alkali and alkaline-earth cation extraction by 18-crown-6: molecular dynamics studies at the water/sc-CO₂interface

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Thermodynamics of Extraction of Plutonium(VI) in PolyEthylene Glycol (PEG) based Aqueous Biphasic System (ABS) using 18-Crown-6 and 15-Crown-5

Cited by 5 publications

References 8 publications

Extraction and separation of a lysine-rich protein by formation of supramolecule between crown ether and protein in aqueous two-phase system

Extraction and separation of a lysine-rich protein by formation of supramolecule between crown ether and protein in aqueous two-phase system

Ethers, crown ethers and 18-crown-6 K+complexes at a water/SC-CO2interface: a molecular dynamics study

Importance of counter-ions in alkali and alkaline-earth cation extraction by 18-crown-6: molecular dynamics studies at the water/sc-CO2interface

Contact Info

Product

Resources

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Ethers, crown ethers and 18-crown-6 K⁺complexes at a water/SC-CO₂interface: a molecular dynamics study

Importance of counter-ions in alkali and alkaline-earth cation extraction by 18-crown-6: molecular dynamics studies at the water/sc-CO₂interface