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

Abstract

Liquid-liquid extraction for the removal of pertechnetate (99TcO4-) and perrhenate (ReO-) 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.