An efficient Ni-based adsorbent for selective removal of Kr and CH in radioactive contaminants from nuclear process off-gas stream.

Efficient adsorbents for radioactive gas treatment in nuclear energy cycle is crucial for eliminating negative environmental impacts caused by wide nuclear applications. A Ni-based MOF material called JUC-86(Ni) which is based on 1-H-benzimidazole-5-carboxylic acid (HBIC) linker was synthesized for adsorbing the Kr, CH from off-gas stream. It was disclosed that there is a suitable pore environment for Kr and CH preferred adsorption in JUC-86 and the adsorption capacity could even reach 2.79 mmol/g (Kr) and 2.54 mmol/g (CH) which are almost higher than all the adsorbents. The Kr/N and CH/N IAST selectivities of the resulting sample are satisfactory (11.63 and 9.43) and well matched with the breakthrough experiments where the breakthrough times of Kr and CH are much longer than N. What's more, the adsorption heats of Kr and CH are less than 30 kJ/mol which indicated a stronger affinity than N and a low-energy regeneration. As simulation results showed that the adsorption distribution follows a-spiral-pattern which could be attributed to the N atom in the CN, this is also the dominant factor of the Kr and CH preferable adsorption.