In removing the ruthenium volatilized during the ²³⁵U nuclear fuel reprocessing and waste treatment, it is important to not only to trap volatilized ruthenium but also to transform it into stable compound to prevent subsequent revolatilization.
A calcination temperature and air velocity were varied to observe the volatility of ruthenium species from calciner off-gas during the evaporation of simulated ruthenium nitric acid solution. The adsorbents such as ferric oxide, titanium dioxide, manganese dioxide, barium carbonate and the mixtures of barium carbonate and above metal oxide were used to remove gaseous ruthenium species and also removal efficiencies for each adsorbents were measured. The mixture adsorbents removed effectively volatiole ruthenium.
It is considered that ruthenium can be effectively preverted from volatilizing as RuO₄ by being bonded to a support such as the mixture of barium carbonate and the metal oxide and that volatile ruthenium species spontaneously can react with the above adsorbents to yield the stable mixed metal ruthenates at temperatures over 500 ℃. The spectra of UV-visible and IR may be suggested that volatile species is a more stable nitrosyl ruthenium gas complex than RuO₄ in the presence of NO_x. There fore the mechanism of adsorption is deduced that the nitrosyl ruthenium complex is adsorbed, then it converts to the stable state, N₂ being desorbed by catalytic decomposition of nitric oxide on ruthenium.