Journal of Nuclear Fuel Cycle and Waste Technology

Hydrazine based reductive dissolution applied on magnetite oxide was investigated. Dissolution of Fe(Ⅱ) and Fe(Ⅲ) from magnetite takes place either by protonation, surface complexation, or reduction. Solution containing hydrazine and sulfuric acid provides hydrogen to break bonds between Fe and oxygen by protonation and electrons for the reduction of insoluble Fe(Ⅲ) to soluble Fe(Ⅱ) in acidic solution of pH 3. In terms of dissolution rate, numerous transition metal ions were examined and Cu(Ⅱ) ion was found to be the most effective to speed up the dissolution. During the cycle of Cu(I) ions to Cu(Ⅱ) ions, the released electron promoted the reduction of Fe(Ⅲ) and Cu(Ⅱ) ions returned to Cu(I) ion due to the oxidation of hydrazine. In the experimental results, the addition of a very low amount of cupric ion (about 0.5 mM) to the solution increased the dissolution rate about 40% on average and up to 70% for certain specific conditions. It is confirmed that even though the coordination structure of copper ions with hydrazine is not clear, the Cu(Ⅱ)/H+/N2H4 system is acceptable regarding the dissolution performance as a decontamination reagent.

Keywords

제염,환원용해,금속산화물,원자로냉각재계통,폐기물 저감,촉매 효과