A new diphosphonic acid extractant N,N-n-octylamine di(methylene phenylphosphinic acid) for extraction and separation of zirconium and hafnium in hydrochloric acid

Abstract Nuclear grade zirconium and hafnium are the key to promoting the development of nuclear industry. We designed and synthesized a new diphosphonic acid extractant N , N - n -octylamine di(methylene phenylphosphinic acid) (OADMPPA) with excellent extraction ability and priority for extraction of zirconium. This paper focused on the changes in extraction mechanisms and composition of complexes. With increasing concentration of HCl, cation exchange mechanism gradually changed into solvation mechanism, and complexes converted in the order of ZrOA, Zr(HA) 2 Cl 2 and ZrCl 4 ·H 2 A. Compared with bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex272), OADMPPA could increase the extraction rates of zirconium and hafnium by 7.2 and 12.6 times. Graphic abstract