Extraction of 137Cs and 90Sr from Alkaline Solutions with High NaNo3 Content with Tetrahexyldicarbollide

Abstract

The extraction properties of a new extractant, tetrahexyldicarbollylcobaltate, were studied. The reagent is stable in contact with alkaline solutions and permits (with the addition of PEG 400 or Slovafol 909) the extraction of both 95 Sr and 137 Cs from 1 M NaOH ϩ 4 M NaNO 3 . The system studied was mainly 0.06 M reagent in isopropylbenzene ϩ 1 vol% PEG 400. The extraction results compare well with the analogous reference system of nonsubstituted dicarbollylcobaltate in nitrobenzene. Possible ways of backextraction are discussed, and the system seems to be a candidate for further study for the separation of elements from high level waste in alkaline form and with a high NaNO 3 content. The reagent and its application for the treatment of alkaline nuclear wastes was first proposed at Los Alamos National Laboratory, USA.

Extraction with Metal Bis(dicarbollide) Anions

“…The former compound appeared in the literature already in the 1960s [74]. This has been confirmed by their good extraction properties under alkaline conditions [121,123]. The resulting alkyl derivatives 70, 71 are soluble in aromatic solvents such as mesitylene and ethylbenzene and are reasonably stable in alkaline solutions, due to steric shielding of the boron positions adjacent to skeletal carbon atoms by the bulky alkyl chains.…”

“…Two main features of these compounds that differ from previous dicarbollides are their high lipophilicity, and solubility in some nontoxic solvents less polar than nitrobenzene. 123. Among the proposed tetraalkyl substituted derivatives, tetrahexyl-dicarbollide (71) ( Table 8) appeared to be the best and its extraction characteristics compared well with the classical dicarbollide 1 [120].…”

“…7 [215]. These combinations are characterized by third organic phase formation and the research must be directed into finding the conditions at which the third phase does not form.…”

“…This discovery opened the possibility that dicarbollide-based extractants can be dissolved in nonpolar solvents like mesitylene or diethylbenzene. After 1 month, without any apparent change of color, the solid compound decomposed (distribution ratios of Cs + from solutions of the latter in isopropyl benzene dropped significantly [123]). The extraction behavior of 71 was further studied in Ref.…”

Tungstate-based glass–ceramics for the immobilization of radio cesium

“…This can result in significant cost savings by permitting the disposal of the treated bulk liquid as low level waste grout [6,7]. Such volume and/or heat load reduction strategies have been the subject of a significant research effort resulting in the introduction of several new separations materials and methods [8][9][10][11][12][13][14][15][16].…”