A series of liquid-liquid extraction tests was performed on the ligand hexakis(3-N-picolineamidepropyloxy) calix[6]arene (PAR4). First, a screening campaign was carried out, in order to select the best organic solvent to be coupled to the aforementioned calixarene ligand. 2-Nitrophenyl hexyl ether (NPHE) was chosen to this purpose, and it was used in all the subsequent experiments, because of its excellent properties from both the viewpoints of calixarene solubility and ligand extracting capabilities. In solvent extraction tests, 241Am was used as representative of minor actinides, while 152Eu was employed to simulate lanthanides. Distribution coefficients and separation factors were obtained via ã-spectrometry. In addition, the synergism between the ligand and the lipophilic dicarbollide anion Cesium commo-3,3-cobalta-Bis(8,9,12 tribromo-1,2 dicarbacloso- Dodecarborane)ate(1-) (Br-Cosan) was investigated. Experimental results indicate that at pH ³ 2 a strong synergistic effect between the calixarene ligand and Br-Cosan takes place. At higher acidity, on the other hand, the ligand protonation dramatically affects the efficiency and selectivity of the system.

A Study on Synergistic Effects and Protonation of a Selected Calixarene Based Picolinamide Ligand Used in the An/Ln Separation.

GALLETTA, MICHELE;MACERATA, ELENA;MARIANI, MARIO;GIOLA, MARCO;
2006

Abstract

A series of liquid-liquid extraction tests was performed on the ligand hexakis(3-N-picolineamidepropyloxy) calix[6]arene (PAR4). First, a screening campaign was carried out, in order to select the best organic solvent to be coupled to the aforementioned calixarene ligand. 2-Nitrophenyl hexyl ether (NPHE) was chosen to this purpose, and it was used in all the subsequent experiments, because of its excellent properties from both the viewpoints of calixarene solubility and ligand extracting capabilities. In solvent extraction tests, 241Am was used as representative of minor actinides, while 152Eu was employed to simulate lanthanides. Distribution coefficients and separation factors were obtained via ã-spectrometry. In addition, the synergism between the ligand and the lipophilic dicarbollide anion Cesium commo-3,3-cobalta-Bis(8,9,12 tribromo-1,2 dicarbacloso- Dodecarborane)ate(1-) (Br-Cosan) was investigated. Experimental results indicate that at pH ³ 2 a strong synergistic effect between the calixarene ligand and Br-Cosan takes place. At higher acidity, on the other hand, the ligand protonation dramatically affects the efficiency and selectivity of the system.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/274667
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