Acta Scientiarum Universitatis Pekiniensis (Naturalum)

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VOLUMETRIC DETERMINATION OF URANIUM BY REDUCTION WITH STANNOUS CHLORIDE

Kao Sheau-shya, Liu Chia-shu, Wu Wan-hsien and Lee An-mo 2 ?

(Department of Chemistry)

ABSTRACT

The catalytic effect of iron salts and phosphoric acid on the reduction of U(VI) to U(IV) with stannous chloride has been investigated. It is found that U(VI) may be quantitatively reduced to U(IV) in 4—6M hydrochloric acid solution containing not less than 0.5M phosphoric acid. In contrast to the observations made by Main", we found that the addition of iron catalyst is not necessary, thu’ avoiding the correction for the volume of dichromate solution consumed by the catalyst.

The catalytic nature of phosphoric acid has bzen studied polarographically. It is found that phosphoric acid stabilizes U(IV) with respect to U(V) due to complex formation, so that in a solution containing more than 0.5M phosphoric acid, U(V1) can be reduced to U(IVY) quantitatively.

The method can be adopted for the routine determination of uranium in

materials rick in this element.