Analytical Sciences

Solvent Extraction of Technetium(VII) and Rhenium(VII) Using a Hexaoctylnitrilotriacetamide Extractant

Kojiro SHIMOJO,*,** Hideya SUZUKI,*** Keiichi YOKOYAMA,* Tsuyoshi YAITA,* and Atsushi IKEDA-OHNO**

*Materials Sciences Research Center, Japan Atomic Energy Agency (JAEA), 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
**Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, Dresden 01328, Germany
***Nuclear Science and Engineering Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Ibaraki 319-1195, Japan

Liquid–liquid extraction for the removal of pertechnetate (⁹⁹TcO₄⁻) and perrhenate (ReO₄⁻) is reported based on using the tripodal extractant N,N,N′,N′,N″,N″-hexa-n-octylnitrilotriacetamide (HONTA) composed of three amide groups and a tertiary amine. The extraction behaviors were compared with those using alkyldiamideamines (ADAAM(Oct) and ADAAM(EH)), and the commercial amine-type extractant, trioctylamine (TOA). HONTA quantitatively extracted ⁹⁹TcO₄⁻ and ReO₄⁻ in the pH range from 1.0 to 2.5 by the co-extraction of protons. The extraction performance of the extractants was improved in the order of HONTA > ADAAM(Oct) > ADAAM(EH) > TOA. ⁹⁹TcO₄⁻ and ReO₄⁻ in the extracting phase were successfully stripped using neutral aqueous solutions as the receiving phase, and the extraction ability of HONTA was maintained after five repeated uses.

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