DXRD studies of sodium nickel ferrocyanide reactions with equimolar nitrate/nitrite salts

Journal Article · Sun May 01 04:00:00 EDT 1994 · Environmental Science and Technology; (United States)

DOI:https://doi.org/10.1021/es00054a020· OSTI ID:7110766

Dodds, J N; Thomson, W J ^[1]

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1. Washington State Univ., Pullman, WA (United States)

Dynamic X-ray diffraction (DXRD) has been used to identify and quantify the solid-state reactions that take place between sodium nickel ferrocyanide, Na[sub 2]NiFe(CN)[sub 6], and equimolar concentrations of sodium nitrate/nitrite, reactions of interest to the continued environmental safety of certain waste storage tanks at the Hanford site in eastern Washington. The results are supportive of previous work that indicated that endothermic dehydration and melting of the nitrates take place prior to the occurrence of exothermic reactions, which begin about 300[degree]C. The DXRD results show that a major reaction set at these temperatures is the occurrence of a series reaction which produces sodium cyanate, NaCNO, as an intermediate in a mildly exothermic first step. In the presence of gaseous oxygen, NaCNO subsequently reacts exothermally and at a faster rate to form metal oxides. Measurements of the rate of this reaction are used to estimate the heat release, and comparisons of this with heat-transfer rates from a hypothetical [open quotes]hot spot[close quotes] show that, even in a worse case scenario, the heat-transfer rates are approximately eight times higher than the rate of energy release from the exothermic reactions. 20 refs., 7 figs., 3 tabs.

• OSTI ID: 7110766
• Journal Information: Environmental Science and Technology; (United States), Journal Name: Environmental Science and Technology; (United States) Vol. 28:5; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

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