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Supercritical fluid extraction of thorium from tissue paper matrix employing β-diketones

  • Pradeep Kumar , Ankita Rao and K. L. Ramakumar
Published/Copyright: September 25, 2009

Abstract

Various β-diketones viz. acetylacetone (AA), trifluoroacetylacetone (TFA), hexafluoroacetylacetone (HFA), thenoyltrifluoroacetylacetone (TTA) and heptafluorobutanoylpivaroylmethane (FOD) were evaluated as chelating agents for the supercritical fluid extraction of thorium from tissue paper matrix. In-situ chelation mode was found to be more effective than online chelation mode. A combination of tributyl phosphate (TBP) and β-diketones further enhanced the extraction efficiency. The extraction efficiency trend observed in all the cases was: TTA>FOD>HFA>TFA>AA. A correlation was observed between extraction efficiency and degree of fluorination in the side arms of β-diketones. This could be attributed to the fact that in supercritical CO2, higher fluorination results in higher percentage of enol content, greater dissociation into enolate ion and higher solubility and stability of β-diketones as well as of Th-β-diketone chelates. Highest extraction efficiency with TTA was probably due to the presence of aromatic thenoyl group. The spectra of the extracted Th-chelates displayed peaks in the visible region, which shifted towards UV region with increasing fluorination. In the Th-TTA chelate spectrum, red shift was observed.


* Correspondence address: Bhabha Atomic Research Centre, Trombay, Radioanalytical Chemistry Section, Radiochemistry, 400 085 Mumbai, Indien,

Published Online: 2009-09-25
Published in Print: 2009-02

© by Oldenbourg Wissenschaftsverlag, München, Germany

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