Analytical Sciences

Abstract − Analytical Sciences, 30(4), 513 (2014).

Comprehensive Extraction Study Using N,N-Dioctyldiglycolamic Acid
Kojiro SHIMOJO,* Ayaka NAKAI,*,** Hiroyuki OKAMURA,* Takumi SAITO,*** Akira OHASHI,** and Hirochika NAGANAWA*
*Division of Chemistry for Nuclear Engineering, Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195, Japan
**College of Science, Ibaraki University, Mito, Ibaraki 310-8512, Japan
***Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
We report on the acid dissociation constants (Ka) of diglycolamic acid-type ligands together with comprehensive data on the extraction performance of N,N-dioctyldiglycolamic acid (DODGAA) for 54 metal ions. The pKa of the diglycolamic acid framework was determined to be 3.54 ± 0.03 in water (0.1 M LiCl, 25°C) by potentiometric titration, indicating that DODGAA is strongly acidic compared with acetic acid. DODGAA can quantitatively transfer various metal ions among the 54 metal ions through a proton-exchange reaction, and provides excellent extraction performance and separation ability for rare-earth metal ions, In(III), Fe(III), Hg(II), and Pb(II) among the 54 metal ions.