The effect of a systematic variation of the basicity of the pyridine nitrogen atom in calix[6]arene-based picolinamide ligands on the actinide(III)/lanthanide(III) separation by solvent extraction has been investigated. The distribution coefficients for trivalent metal ions (DM) decrease by increasing the nitric acid concentration, but for ligands (2 and 4) possessing a much less basic aromatic nitrogen atom, DM values are considerably higher than those of ligands (1 and 5) having more basic pyridine nuclei. Also in terms of selectivity ligands 2 and 4 behave better than ligand 1 especially at nitric acid concentrations very close to those of the nuclear waste. At [H+] = 1 mol L−1, SFAm/Eu are still 3.23 and 1.92 for 2 and 4, respectively. A simple quantitative relationship between the efficiency of these extractants and the gas-phase basicity of suitably chosen model compounds is proposed, in order to explain the experimental extraction data, on one hand, and to orient future syntheses of ligands for An/Ln separation, on the other hand.

Calix[6]arene-picolinamide extractants for radioactive waste: effect of modification of the basicity of the pyridine N atom on the extraction efficiency and An/Ln separation / M. Galletta; L. Baldini; F. Sansone; F. Ugozzoli; R. Ungaro; A. Casnati; M. Mariani. - In: DALTON TRANSACTIONS. - ISSN 1477-9234. - 39(2010), pp. 2546-2553. [10.1039/b922500p]

Calix[6]arene-picolinamide extractants for radioactive waste: effect of modification of the basicity of the pyridine N atom on the extraction efficiency and An/Ln separation

BALDINI, Laura;SANSONE, Francesco;UGOZZOLI, Franco;UNGARO, Rocco;CASNATI, Alessandro;
2010

Abstract

The effect of a systematic variation of the basicity of the pyridine nitrogen atom in calix[6]arene-based picolinamide ligands on the actinide(III)/lanthanide(III) separation by solvent extraction has been investigated. The distribution coefficients for trivalent metal ions (DM) decrease by increasing the nitric acid concentration, but for ligands (2 and 4) possessing a much less basic aromatic nitrogen atom, DM values are considerably higher than those of ligands (1 and 5) having more basic pyridine nuclei. Also in terms of selectivity ligands 2 and 4 behave better than ligand 1 especially at nitric acid concentrations very close to those of the nuclear waste. At [H+] = 1 mol L−1, SFAm/Eu are still 3.23 and 1.92 for 2 and 4, respectively. A simple quantitative relationship between the efficiency of these extractants and the gas-phase basicity of suitably chosen model compounds is proposed, in order to explain the experimental extraction data, on one hand, and to orient future syntheses of ligands for An/Ln separation, on the other hand.
Calix[6]arene-picolinamide extractants for radioactive waste: effect of modification of the basicity of the pyridine N atom on the extraction efficiency and An/Ln separation / M. Galletta; L. Baldini; F. Sansone; F. Ugozzoli; R. Ungaro; A. Casnati; M. Mariani. - In: DALTON TRANSACTIONS. - ISSN 1477-9234. - 39(2010), pp. 2546-2553. [10.1039/b922500p]
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11381/2307969
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