Solvent Extraction of Tc (VII) by Calixarenes Bearing Pyridino Groups

Abstract

The distribution of Tc(VII) between aqueous acidic solutions and organic solutions of nitrogen-containing extractants is investigated in order to establish the relationships between extraction power towards the Tc(VII) -anion, ligand molecular structure, influence of the media and the speciation in this ion-pair extraction. Ligands belonging to the class of calixarenes, derivatized with pyridino groups were newly devloped for these purposes. The number of substituents per calixarene, the position of the nitrogen and the size of calixarene are varying structural parameters. The nitrogen atoms are either protonated or quaternized to allow ion-pair extraction. The aqueous phase contains nitrate or chloride at varying or constant ionic strength. Experiments using Aliquat-336 were conducted under similar conditions.

Solubility and solution enthalpy of a cesium-selective calixarene in supercritical carbon dioxide

“…As mentioned in several reviews however [11][12][13][14][15], the main application of calixarenes is the chelation of metallic cations and neutral species. Calixarenes have notably been used to extract the following species from aqueous solutions: α-amines and α-amino acid methylesters [16], gold [17], copper [18], technetium [19], americium and europium [20], uranium [21], alkaline earth metals [22] and alkali metal cations [23]. Cesium extraction is of particular interest because of the huge volumes of 137 Cs-polluted waste awaiting decontamination.…”

Applications of Nano-Baskets of Calixarenes in Chromatography

“…3) and anions ( Fig. 3) [59][60][61][62][63][64][65] shows an increase in the ability of calixarene derivatives in solvent extraction of alkaline earth metal cations [66][67][68][69][70][71][72][73][74][75][76][77], transition metal ions [78][79][80][81][82][83][84][85][86][87][88][89][90], molecular compounds [91][92][93][94][95][96][97][98][99][100][101][102][103][104][105] and anions [106][107][108].…”

Technetium(VII) and Rhenium(VII) Extraction by a New Diamide Reagent, 2,2&apos;-(Imino)bis(<i>N,N</i>-dialkylacetamide) (IDAA)

“…Few extractants for TcO 4 -have been developed up to now, because the TcO 4 -ion, which includes four oxygen atoms, is not readily extracted. High extractability of Tc can be obtained by using trioctylamine, calixarene and tetraphenylarsonium [1][2][3], however these extractants require a polar solvent as diluent [4][5][6]. The extractants, CMPO (octylphenyl-N,N-diisobutyl-carbamoylmethylphosphine oxide) and malonamide used for the effective recovery of An(III) give the low D(Tc) values (lower than 1) from nitric acid to n-dodecane.…”