Coprecipitation studies of some tervalent metal ions with aluminium tris-(8-hydroxyquinolate)

Abstract

The coprecipitation of tracer quantities of radioactive scandium, yttrium, cerium and indium with milligram-quantities of aluminium has been studied. The aluminium was precipitated as the tris-(8-hydroxyquinolate) by slow isothermal evaporation of aqueous acetone solutions. In the presence of ammonium acetate less than 0.5 % of the scandium, yttrium or cerium coprecipitates. The fraction of tracer entrained is approximately independent of the fraction of the aluminium precipitated. Surface adsorption of tracer on the glass container or on the precipitate does not occur even when all of the acetone had been removed. Milligram-quantities of yttrium and cerium give gelatinous precipitates from similar systems containing acetone (aluminium absent); the dried yttrium precipitate has the composition Y(C 9H 6NO) 2·OCOCH 3. Even milligram-quantities of yttrium, when present, tend to be rejected by the aluminium precipitate. In the absence of acetate but under conditions where milligram-amounts of yttrium would precipitate, for 10–90% precipitation of the aluminium, yttrium coprecipitation ranges from 1 to 6 %. Removal of all of the acetone results in considerable surface adsorption of the tracer. From acetate solutions fractional precipitation of indium as tracer in the range 10 to 90 % is only slightly different (lower) than the corresponding fractional precipitation of the aluminium. D and λ, the coefficients calculated assuming a homogeneous and a logarithmic distribution, respectively, within the crystals, are approximately equal and constant. Milligram-amounts of indium give a granular precipitate by the slow evaporation procedure from acetate solutions.