Modification of Activated Carbon by a Mixed Molten Salt Template Method for Enhanced Kr/Ar Separation

Krypton (Kr) has significant applications in industry and medicine. Separating and collecting highly pure Kr from nuclear facilities is environmentally friendly and economically beneficial. Activated carbon (AC) is a cost-effective and promising adsorbent for the separation of Kr from nuclear reactors. For the thorium-based molten salt reactor (TMSR) off-gas system, we have developed a modification method for enhanced Kr/argon (Ar) separation via high-temperature etching of activated carbon using a mixed molten salt. Etching AC with a mixed molten salt produced a large number of micropores close to the molecular size of Kr, resulting in a 19% higher Kr uptake capacity (at 293 K and 1 bar) and a 15% increase in the IAST-predicted selectivity for a Kr/Ar (20/80) mixture at 1 bar compared to the pristine AC. As a result, modified AC manifested a 71% increase of total Kr adsorption capacity and a 113% increase of Kr breakthrough time compared with the initial AC during dynamic column Kr/Ar separation under identical conditions. This enhancement can facilitate the potential application of AC in nuclear reactor off-gas treatment.