Selective separation of scandium from rare-earth elements with a novel carboxylic acid type extractant

Sasanuki, Takemaru; Sugita, Tsuyoshi   ; Ueda, Yuki   ; Okamura, Hiroyuki   ; Naganawa, Hirochika  ; Shimojo, Kojiro   

Scandium (Sc) is an important metal in industries such as the airframes and but the solid oxide fuel cells. The commercially available extractants have been used Sc from REEs, however, they have the serious drawbacks for extraction ability or stripping. In this study, we developed a novel carboxylic acid type extractant, Tetraoctyl nitriloacetic acid diacetamide (TONAADA). TONAADA is the tetradentate ligand that connected two amide groups and one carboxyl group by nitrogen donor. We investigated the extraction of REEs using TONAADA, and the separation ability for Sc using TONAADA was compared with that of commercially available extractants. TONAADA has the high extraction and separation ability for Sc, and the quantitative stripping is possible by 5 M HNO or HCl.