Efficient separation of thorium from rare earths with a hydrogen-bonded oligoaramide extractant in highly acidic media

A novel design based on condensation of a simple bifunctional monomer led to hydrogen-bonded oligoaramide extractant 1 that could segregate Th(IV) from rare earths(III) [REs(III)] and U(VI) under strongly acidic conditions in a highly efficient and selective fashion by solvent extraction process. The extractant demonstrated a high extractability of 94.5–99.0 % and selectivity for extraction of Th(IV) from REs in 2.0–6.0 M HNO 3 . Particularly, REs were extracted only in <9 % in a simulated multi-component mixture in 4.0 M HNO 3 , which contrasts sharply with 88 % extraction of Th(IV). The presence of NaNO 3 as the salting-out agent significantly improved the extraction selectivity of Th(IV).