Extraction properties of trivalent rare earth ions from nitric acid using a triamide-amine extractant
Uchino, Seiko*; Narita, Hirokazu*; Kita, Keisuke*; Suzuki, Hideya*; Matsumura, Tatsuro
; Naganawa, Hirochika*
; Sakaguchi, Koichi*; Oto, Keisuke*
The extraction of trivalent rare earth ions (RE
) from HNO
solution using a triamide amine, tris(N,N-di-2-ethylhexyl-ethylamide)amine (DEHTAA), was conducted, and the extraction mechanism was estimated from extraction behavior of HNO
and RE
and the relationship between atomic number and extraction percentages (E%) for RE
. A DEHTAA molecule dominantly formed a DEHTAA HNO
at 1.0 M HNO
and a DEHTAA(HNO
)
at 6.0 M HNO
in the acid-equilibrated organic phase. This would provide the unique dependence of E% for the light RE
on the HNO
concentration, in which the E% value had a minimum and maximum at
0.5 M and
2 M HNO
, respectively. The results of the slope analyses for the distribution ratios for RE
suggested that the dominant RE
complex was RE(NO
)
DEHTAA(DEHTAA HNO
) at 1.0 M HNO
. The E% for RE
decreased from La
to Lu
at 1.0 M HNO
; on the other hand, those increased from La
to Nd
at 0.25 M and from La
to Sm
and 6.0 M HNO
.