Uranyl alkali

There are a Tew compounds of alkalies, nitrate, and acetate thai have low solubilities, but most of them are quite complex in composition. For example, sodium uranyl acetate, NaUQifCHjCOOh has low solubility. Silver acetate is an exception but its solubility is moderate. 

Goishi and Libby have investigated the extraction of pertechnetate from alkali solutions with pyridine. Later work showed that a better extraction is obtained using a mixture of sodium hydroxide and sodium carbonate as the aqueous phase. Since the uranyl carbonate complex is not extracted into pyridine, this system may be used for the separation of technetium from uranium. Distribution coefficients of fission products in pyridine are given in Table 4. Substituted pyridine such as 2,4-dimethylpyridine or 4-(5-nonyl)pyridine ) are useful for separating technetium from solutions containing appreciable amounts of aluminum nitrate. 

Uranium Peroxide Hydrate. Add a 3% hydrogen peroxide solution dropwise to 5 ml of a 10% uranyl nitrate solution up to complete precipitation. Filter off the product on a small filter, wash it with water, and dry it in a drying cabinet at 70 °C. What is the composition of the product Test the reaction of uranium peroxide hydrate with 10% solutions of acids and alkalies in the cold and when heated. 

Uranyl Thioarsenate is also obtained by double decomposition. It is formed as a dirty yellow precipitate, soluble in excess of the alkali orthothioarsenate.5... 

Uranyl ion forms complexes with many oxy anions. Both U(VI) and U(IV) compounds dissolve in alkali carbonate solutions with formation of carbonato complexes. Those of the larger alkali cations are only slightly soluble KSp = 6 x 10-5 for both K4[U0 tC03)3] and iNHu tUOitCO, ] 2H 0. 

Potassium hexacyanoferrate(II) solution reddish-brown precipitate of molybdenum hexacyanoferrate(II), insoluble in dilute mineral acids, but readily soluble in solutions of caustic alkalis and ammonia [difference from uranyl and copper(II) hexacyanoferrate(II)s]. 

The fusion of uranium oxides with alkali or alkaline earth carbonates, or thermal decomposition of salts of the uranyl acetate anion, gives orange or yellow materials generally referred to as uranates, for example,... 

When alkali metal bases are used to raise the solution pH to moderate levels, the uranium will precipitate from the solution in the form of hydrous uranyl hydroxides or uranates, for example, Na2U207. However, through judicious choice of a base, for example, tetramethylammonium hydroxide, (TMA)OH, or tetramethylaimnoirium trifluoromethansulfonate, the study of the amphoteric behavior of uranyl hydroxides can be undertaken. Polynuclear anions of the form (U02)3(0H)7, (U02)3(0H)g, and (U02)3(OH)io are examples of soluble species in solutions where the pH < 14. When the concentration of the (TMA)OH is increased (>0.6 M OH ), highly soluble ( 0.1M) monomers ofthe form U02(0H) "(n = 3, 4,5) have been reported. These three species are in equilibrium with each other however, in solutions where the [OH ] is greater that 1M, the pentahydroxo complex predominates the speciation. 

Uranous Hydroxide.—The addition of alkali to a solution of a uranous salt produces a reddish-brown gelatinous precipitate, which darkens in colour on boiling the solution. If dried in vacuo it becomes black and has the composition UOg.HgO. This rapidly oxidises in the air and readily dissolves in dilute acids, forming uranous salts. It acts upon a neutral solution of silver nitrate, first precipitating silver oxide and forming a green solution which, however, soon turns yellow, and the oxide is reduced to metallic silver as the uranyl salt forms in solution, thus ... 

Peruranates of the alkali metals are obtained by acting on alkaline solutions of uranyl nitrate with hydrogen peroxide. They are soluble in water, but may be precipitated by the addition of alcohol. Corresponding peruranates of the heavier metals may be obtained by double decomposition with solutions of the sodium salt. 

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