Radiopharmaceutical and hydrometallurgical separations of perrhenate usingaqueous biphasic systems and the analogous aqueous biphasic extraction chromatographic resins
Sk. Spear et al., Radiopharmaceutical and hydrometallurgical separations of perrhenate usingaqueous biphasic systems and the analogous aqueous biphasic extraction chromatographic resins, IND ENG RES, 39(9), 2000, pp. 3173-3180
Poly(ethylene glycol) (PEG)-based aqueous biphasic systems (ABS) and the an
alogous aqueous biphasic extraction chromatographic (ABEC) resins have been
investigated for the separation of perrhenate (ReO4-) from tungstate (WO42
-) in alkaline tungstate media for radiopharmaceutical application and for
the separation of perrhenate from molybdate (MoO42-) in hydrometallurgical
application. Salts of the water-structuring anions OH-, WO42-, and MoO42- f
orm ABS by salting-out PEG, while chaotropic anions such as ReO4- and the s
imilar TcO4- quantitatively partition to the PEG-rich phase in such ABS. Pe
rrhenate can thus be separated from solutions high in WO42- and OH- concent
ration, and the separation factors improve with an increase in the tungstat
e or hydroxide concentration. In addition, the ReO4- anion can be separated
from load solutions high in MoO42- and SO42-. Perrhenate can also be separ
ated under similar conditions using ABEC resins in both batch and chromatog
raphic modes. The retained ReO4- can be eluted from the column with a simpl
e water strip. The chromatographic separation of ReO4- from WO42- provided
97% of the loaded ReO4- in 20 mt. Unlike traditional technetium generators
which are adversely affected by high parent ion concentrations, higher conc
entrations of the parent anion improve the retention of ReO4- onto ABEC res
ins. After exposure of the ABEC resins to radiation doses as high as 500 Mr
ad, an acceptable level of performance was maintained, although degradation
of the resin (monitored using differential scanning calorimetry) was obvio
us.