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Multiple Oxidant Synergism in Chromium Separation from Hanford High Level Nuclear Waste Components

Jennifer E. Holland, Office of River Protection, United States Department of Energy, PO Box 450, MS H6-60, Richland, WA 99352

Combining ozone (O3) and hydrogen peroxide (H2O2), the process known as peroxone, produces intermediate species with even greater oxidizing power than either parent oxidant, including trioxide (H2O3 or HO3), ozonide (O3), the hydroxyl radical (OHŸ) and the peroxyl radical (HO2Ÿ).  The production mechanism of these species has been determined experimentally and through quantum calculations to initiate through the formation of a ring species ([HO2][HO3]).  The only other well known example is the combination of H2O2 and permanganate (MnO4-) in phosphate buffer, resulting in an oscillating reaction in which MnO4- is regenerated, but intermediate species that are involved in this phenomenon have not been identified.  This paper presents the approach and preliminary findings of scoping experiments designed to understand the interactions of O3, MnO4-, H2O2, peroxynitrite (ONOO-), ferrate (FeO42-), and peroxyacetate (CH3CO(O)O-) in the alkaline oxidation of chromium (from Cr(III) to Cr(VI)).  This method is being evaluated as an optimization of the baseline method for the Hanford Waste Treat Plant (WTP).