Simultaneous removal of multi-nuclide (Sr2+, Co2+, Cs+, and I-) from aquatic environments using a hydrate-based water purification process

This study investigates the removal characteristics of a hydrate-based water purification process used to remove the major radionuclides monitored in nuclear accident areas. The effect of the coexistence of salt ions on the removal of radioactive materials is also evaluated. Previous studies have found existing processes such as ion exchange and membrane separation to be reliable methods for radionuclide removal from contaminated water. However, these processes cannot remove all contaminants at once and cause additional environmental problems by generating secondary wastes. In a previous study, we observed that water purification by the gas hydrate process could simultaneously remove various ions from seawater and hypersaline water in a single step without pre- or post-treatment. Therefore, the removal characteristics of Sr2+, Co2+, Cs+, and I- radionuclides are evaluated in only one context: the hydrate-based water purification process. More than 85% of the total ions were simultaneously removed regardless of the presence or absence of coexisting ions, and the time required for the removal process was about 70 min. In addition, it was observed that most of the contaminant ions were attached to hydrate crystal surfaces. Therefore, an efficient purification process is proposed that includes a hydrate crystal exterior partial dissolution step.