Effects of Temperature and Sulfuric Acid and Iron (II) Concentrations on the Efficacy of Decontamination of Spent Ion-Exchange Resins Containing Hematite

The effect of H2SO4 and FeSO4 concentrations and temperature on the efficacy of decontamination of spent ion-exchange resins was estimated. The study was performed on model spent ion-exchange resins purposefully contaminated with hematite and Co-57 radionuclide. It was found that an increase in solution temperature up to 50 degrees C and the addition of FeSO4 increases the efficacy of decontamination of spent ion-exchange resins by 1 M and 2M H2SO4 solutions by 1-2 orders of magnitude, whereas the decontamination factor value here is >10(3). Since under static conditions, the secondary adsorption of Co-57 was observed, the extra washing of ion-exchange resins by 3 M solution of NaNO3 is required. Decontamination under dynamic conditions excludes the secondary adsorption of Co-57, so that the necessity of the extra stage of washing can be skipped. Under dynamic conditions, the consumption of a solution of the composition H2SO4 (1 mol/L) + FeSO4 (0.2 mol/L) is 1.5-fold lower in comparison with the 2M solution of H2SO4 at compatible values of the decontamination factor. Such an approach enables reduction in the volume of secondary waste and the equipment corrosion due to the decrease in H2SO4 concentration.

Automated summary

The effect of H2SO4 and FeSO4 concentrations and temperature on the decontamination of spent ion-exchange resins was studied. It was found that increasing the solution temperature and adding FeSO4 significantly improved the efficacy of decontamination, especially under dynamic conditions. Extra washing steps were required to remove secondary adsorption under static conditions. The use of H2SO4 (1 mol/L) + FeSO4 (0.2 mol/L) solution reduced the volume of waste and equipment corrosion.