Dissolution Behavior of Uranium Oxides with Supercritical CO2 Using HNO3-TBP Complex as a Reactant
Dissolution Behavior of Uranium Oxides with Supercritical CO2 Using HNO3-TBP Complex as a Reactant
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DOI：
10.1080/18811248.2001.9715141
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发表时间：
2001-12
影响因子：
1.2
通讯作者：
O. Tomioka;Y. Meguro;Y. Enokida;I. Yamamoto;Z. Yoshida
中科院分区：
文献类型：
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作者：
O. Tomioka;Y. Meguro;Y. Enokida;I. Yamamoto;Z. Yoshida
研究了以HNO 3-TBP络合物为反应物的超临界CO2介质中U3 O 8和UO 2的溶解行为。随着HNO 3-TBP复合物中HNO 3/TBP比例的增加和HNO 3-TBP复合物在超临界CO2相中浓度的增加，氧化物的溶解速率增加。当反应物中HNO 3/TBP的比例大于约10%时，U3 O 8的溶解速率显著增加。结果表明，2：1的络合物（HNO_3）_2TBP对氧化物的溶解起促进作用。作为溶解动力学指标的半溶解时间（t1/2）由铀溶解量与溶解时间之间的关系（溶解曲线）确定。t1/2的倒数的对数值与超临界CO2中HNO 3、CHNO 3的对数浓度成比例。U3 O 8和UO 2的（l/t½）与ln CHNO 3曲线的斜率彼此不同，表明U3 O 8和UO 2溶解的反应机理或速率决定步骤不同。用超临界CO2介质溶解铀氧化物的原理适用于从固体基质中去除铀的方法。
Dissolution behavior of U3O8 and UO2 using supercritical CO2 medium containing HNO3-TBP complex as a reactant was studied. The dissolution rate of the oxides increased with increasing the HNO3/TBP ratio of the HNO3-TBP complex and the concentration of the HNO3-TBP complex in the supercritical CO2 phase. A remarkable increase of the dissolution rate was observed in the dissolution of U3O8 when the HNO3/TBP ratio of the reactant was higher than ca. 1, which indicates that the 2:1 complex, (HNO3)2TBP, plays a role in facilitating the dissolution of the oxides. Half-dissolution time (t½ ) as an indication of the dissolution kinetic was determined from the relationship between the amount of uranium dissolved and the dissolution time (dissolution curve). A logarithmic value of a reciprocal of the t½ was proportional to the logarithmic concentration of HNO3, CHNO3, in the supercritical CO2. The slopes of the (l/t½ ) vs. ln CHNO3 plots for U3O8 and UO2 were different from each other, indicating that the reaction mechanisms or the rate-determining steps for the dissolution of U3O8 and UO2 are different. A principle of the dissolution of uranium oxides with the supercritical CO2 medium is applicable to a method for the removal of uranium from solid matrices.