Abstract:

Oxidative pyrolysis can effectively increase the volume reduction ratio of radioactive waste cation exchange resin, but higher pyrolysis temperature is likely to cause nuclides to volatilize. However, the high pyrolysis temperature can easily lead to the volatilization of nuclide. To lower the pyrolysis temperature, a series of resins containing an increasing Co loading were prepared by ion exchange method, using Co(NO₃)₂·6H₂O and cation exchange resin (Amberlite IRN-97H) as raw materials. The effect of Co with different contents on the pyrolysis of resin was investigated on a thermogravimetric analyzer. When the Co content was 10－40 g/L, the peak temperature of the mass loss peak of the copolymer matrix of resin was reduced by 232－263℃ compared to that of pure resin, while the volume reduction ratios were almost the same. The XRD, FT-IR, XPS and elemental analysis of the solid residue were performed. The results showed that the CoO formed by the conversion from Co²⁺ had a catalytic effect on the oxidative pyrolysis of the copolymer matrix, which promoted the breakdown of sulfurbridge (—S—).

Key words: waste treatment, cation exchange resin, catalysis, pyrolysis, cobalt oxide, thermogravimetric analysis

摘要：

氧化裂解能有效增大放射性废阳离子交换树脂的减容比，但是较高的裂解温度易导致核素挥发。为了降低裂解温度，以硝酸钴和阳离子交换树脂为原料，制备了不同钴含量的含钴树脂，在热重分析仪上考察了钴含量对树脂裂解反应的影响。采用离子交换的方法掺入10~40 g/L的钴离子，可以使树脂共聚物基体裂解峰的峰值温度降低232~263℃，而对减容比的影响较小。通过对残渣的XRD、FT-IR、XPS及元素分析，发现由钴离子转化形成的氧化钴对共聚物基体的裂解具有催化作用，促进了硫键（—S—）的断裂，使裂解温度降低。

关键词: 废物处理, 阳离子交换树脂, 催化, 裂解, 氧化钴, 热重分析