Uranyl peroxide

Dapex [Di-alkylphosphoric acid extraction] A process for the solvent extraction of uranium from sulfuric acid solutions using di-(2-ethylhexyl) phosphoric acid (HDEHP). The HDEHP is dissolved in kerosene containing 4 percent of tributyl phosphate. The uranium is stripped from the organic phase by aqueous sodium carbonate and precipitated as uranyl peroxide (yellow cake). The process was no longer in use in 1988. See also Amex. 

The peroxide method involves the precipitation of uranyl peroxide by addition of H202 to uranyl nitrate solutions according to equation (103). Below 50 °C, U04-4H20 precipitates, while... 

Uranium in solution as uranyl nitrate can be purified by addition of hydrogen peroxide, which selectively precipitates pale yellow uranyl peroxide U02(02) 2H2 0. Addition of sodium hydroxide to uranyl nitrate solution precipitates sodium diuranate Na2U207. Addition of ammonium hydroxide precipitates ammonium diuranate ... 

The most common oxides are uranium dioxide (UO2), uranium trioxide (UO3), triuranium octoxide (UjOg), and uranyl peroxide (UO4 or UO2 Oj). The main properties of these compounds are summarized in Table 1.5. It should be noted that there are several other oxides in which the oxidation states are not well defined as either tetra-valent or hexavalent, like UO2.1, U2O5, U3O7, U12O35, etc. Detailed discussions of the uranium-oxygen system and its complex phase diagram were presented elsewhere, for example, by Allen and Tempest (1982) and Grenthe (2006). 

Fig. 6-10. Schematic flow diagram for decontaminating uranium by uranyl peroxide precipitation.

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