The effect of air on oxidation decomposition of uranium-containing cationic exchange resins in Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 molten-salt system.

With the development of nuclear energy, spent cationic exchange resins after purification of radioactive wastewater must be treated. Molten-salt oxidation (MSO) can minimize the disposal content of resins and capture SO 2 . In this work, the decomposition of uranium-containing resins in carbonate molten salt in N 2 and air atmospheres was investigated. Compared to N 2 atmosphere, the content of SO 2 released from the decomposition of resins was relatively low at 386-454 °C in an air atmosphere. The SEM morphology indicated that the presence of air facilitated the decomposition of the resin cross-linked structure. The decomposition efficiency of resins in an air atmosphere was 82.6% at 800 °C. The XRD analysis revealed that uranium compounds had the reaction paths of UO 3 → UO 2.92 → U 3 O 8 and UO 3 → K 2 U 2 O 7 → K 2 UO 4 in the carbonate melt, and sulfur elements in resins were fixed in the form of K 3 Na(SO 4 ) 2 . The XPS result illustrated that peroxide and superoxide ions accelerated the conversion of sulfone sulfur to thiophene sulfur and further oxidized to CO 2 and SO 2 . Besides, the ion bond formed by uranyl ions on the sulfonic acid group was decomposed at high temperature. Finally, the decomposition of uranium-containing resins in the carbonate melt in an air atmosphere was explained. This study provided more theoretical guidance and technical support for the industrial treatment of uranium-containing resins.