(12a) Multiple Oxidant Synergism in Chromium Separation from Hanford High Level Nuclear Waste Components

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 (OH^Ÿ) and the peroxyl radical (HO₂^Ÿ).  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 (FeO₄^2-), 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).