FT-IR analyses of the oxidative decomposition products of cyanoferrate wastes

The Hanford Site (Fig. 1) near Richland, Washington, operated by the US Department of Energy, Richland Field Office, had produced nuclear materials for the nation's defense programs for more than 50 years. The radioactive liquid waste resulting from the processing of irradiated nuclear materials is stored temporarily in single-shell carbon steel tanks (Fig. 2) at the Site. The tanks are buried underground in tank farms with several feet of soil cover above the tank closure (Fig. 3). As part of a program to conserve tank space in the 1950s', a precipitation process was developed to scavenge radioactive cesium from the waste supernates. Ferrocyanide was added to the radioactive wastes and cesium-depleted supernates were discharged into cribs. Hexacyanoferrates [Fe(CN)63- and Fe(CN64-] are generally considered to be extraordinarily stable and even called-kinetically inert. However, recent 2 safety concerns have focused on the stability of cyanoferrate-bearing tanks containing large quantities of nitrates and nitrites. One strategy to resolve this concern involves oxidative decomposition of the cyanoferrates with common oxidants such as ozone (O3) and hydrogen peroxide. This paper describes the results of the initial studies on the treatment of simulated cyanoferrate wastes with ozone and ozone-hydrogen peroxide mixtures. The oxidative decomposition products were analyzed by a Fourier transform infrared spectroscopic method