Comprehensive extraction study of metal ions using an acidic diamide-type ligand

Shimojo, Kojiro   ; Yabe, Makoto*; Sugita, Tsuyoshi   ; Okamura, Hiroyuki   ; Ohashi, Akira*; Naganawa, Hirochika  

Solvent extraction is an effective method for the separation and purification of metal ions (e.g. recovery of rare metal and removal of toxic metal). The extractant plays a key role in the extraction efficiency and the separation operation. To date, much effort has been devoted to the development of novel extractants. Most approaches, however, have encountered problems on expensive production cost and low solubility in alkane solvents, and are far from ideal extraction system for practical use. In previous study, we developed inexpensively a diglycolamic acid-type extractant (DODGAA) with monoamide and carboxy group connected by an ether chain, and reported that DODGAA performed better than commercial extractants. In this study, we have synthesized a novel acidic diamide-type extractant (TONTADA) with diamide and carboxy group connected by a nitrogen donor, and have comprehensively investigated the extraction performance. It was found that the TONTADA selectively extracts valuable metal ions such as Cu(II), Ni(II), and Co(II) from base metal ions compared with DODGAA.