Abstract
Inorganic deposits formed during operation and intermediate storage contain radionuclides, whose removal during the chemical decontamination of spent ion-exchange resins used in filters for special water purification at nuclear power plants has proved to be a challenge. In such deposits, radionuclides of the corrosion group (58.60Co, 54Mn, 51Cr) are typically located in the crystal lattice of poorly soluble iron oxides. The present work discusses the possibility of using mechanochemical activation in the decontamination of spent ion-exchange resins polluted with deposits of activated corrosion products from structural materials. Samples of natural and synthesised on the surface of the KU-2-8 cation exchanger in the presence of the 57Co label magnetites were used as model deposits. It was shown that an increase in the duration of mechanochemical activation leads to an increase in the dissolution rate of magnetite in model decontamination solutions based on еthylenediaminetetraacetic acid disodium salt (Trilon B) and nitric acid. It was shown that, when using Trilon B, magnetite dissolves more efficiently, which is explained by the interaction between the oxide surface and organic complexing agents. It can be assumed that solid-phase reactions occur during the mechanochemical activation of magnetite in the presence of dry reagents (Trilon B, oxalic, ascorbic and citric acids). Therefore, a poorly soluble shell formed on the oxide surface hinders the dissolution at a low magnetite/solution ratio. Unlike the reagent-free activation, for magnetite activated in the presence of oxalic acid, an increase in the solution/magnetite ratio promotes the dissolution of iron oxides. Using the example of a model cation exchanger, it was shown that the rate and efficiency of decontamination of spent ion-exchange resins polluted with deposits containing activated corrosion products increase significantly after mechanochemical activation in the presence of oxalic acid.
Highlights
Treatment and disposal of Journal of Nuclear Engineering and Radiation spent radioactive ion-exchange resins produced in Science. 2019
The final manuscript has been read and approved by all the co-authors
Summary
Где Aк – активность образца, Бк; A0 – исходная активность образца, Бк. Перед отбором проб для анализа проводили центрифугирование при скорости 2000 об./мин в течение 2 мин с использованием центрифуги МТ-45 (Hangzhou MIU Instruments Co Ltd., КНР). 2. Распределение и медианное значение размера частиц (врезка) магнетита: исходный образец (1); образцы после МХА в течение 10 (2), 20 (3), 30 (4), 60 (5) и 90 (6) мин Fig. 2. Существенное различие в растворении магнетита объясняется не только химией растворов этих кислот (диссоциация и комплексообразование), но и влиянием их структурных различий на поверхностное комплексообразование: щавелевая кислота занимает меньшую площадь на поверхности оксида, поэтому концентрация поверхностных комплексов выше [22], а в отношении аскорбиновой кислоты преобладает механизм восстановительного растворения (для щавелевой он дополняет поверхностное комплексообразование). 3. Относительное содержание железа в 0,02 М раствора трилона Б (а) и 3 М раствора HNO3 (b) в зависимости от времени растворения образцов: исходного магнетита (1) и магнетита после МХА в течение 10 (2), 20 (3), 30 (4), 60 (5) и 90 (6) минут. Относительная концентрация железа, перешедшего в 0,05 М растворы кислот при растворении магнетита, активированного в течение 30 мин (Ж:Т – 100 мл/г)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
