Extraction of uranium with 2,3-dihydroxynaphthalene and cetyltrimethylammonium bromide, and its fluorimetric determination in silicate rocks

A novel procedure for the extraction of uranium has been described. UO sub 2 exp 2+ forms a 1:3 anionic complex with 2,3-dihydroxynaphthalene in the pH range. 4-12. This anionic complex is best extracted into ethyl acetate at pH 11-12 under the influence of a counter cation, cetyltrimethylammonium bromide. This extraction technique has been extended to the separation of uranium from silicate rock matrices for its determination by fluorimetry. Except Co, Cr, and Fe, most elements present in silicate rocks do not interfere. While the interferences of Co and Cr are suppressed by the addition of EDTA, iron is removed by prior extraction at pH 4-5 as its neutral complex with 2,3-dihydroxynaphthalene. The results compare favorably with those obtained from the conventional technique, i.e., extraction of uranium in ethyl acetate from NHO sub 3 medium under the influence of Al(NO sub 3 ) sub 3 9H sub 2 O as salting out agent. The extraction system under study is capable of separating even ultra-trace amounts of uranium quantitatively from complex matrices of rock samples. Besides, the method is simple, rapid, cost effective and precludes the use of reagents like nitric acid and aluminum nitrate (salting out agent) required in bulk quantities in the conventional system.