Highly selective removal of cesium in a column process utilizing newly developed silica support loaded with copper-potassium hexacyanoferrate - 5113

Full text of publication follows. The ever increasing pressure to reduce the release of radioactive and other toxic substances from environment requires constant improvement/upgrading of processes and technologies for remediation waste treatment and in case of radioactive effluent for dose minimization. Recently, the Fukushima disaster illustrated the need to develop appropriate processes for the removal of radionuclides from accidental discharge. These effluents may contain a great variety of non-radioactive ions, such as alkaline and alkaline earth ions in concentrations several orders of magnitude greater than the levels reached by radionuclides. Thus the developed extraction process must be highly selective for removing these trace radionuclides in these concentrated saline solutions. Among radionuclides, ¹³⁷Cs is considered as the most abundant and hazardous element due to its presence in many wastes and to its relatively long half-live (30 years). An innovative inorganic material was recently developed by CEA laboratory to decontaminate liquid effluents containing radioactive cesium in a continuous column process. The material is made of meso-porous silica support loaded with a copper-potassium hexacyanoferrate, chosen to entrap selectively cesium from aqueous effluent. This work highlights the sorption results obtained from this newly developed material. Sorption properties were obtained by batch and column experiments and shown high distribution coefficient of ¹³⁷Cs in saline solutions, very fast kinetics and a high ionic exchange capacity (0,20 mmol/g). The experimental sorption isotherms indicated a total ion exchange mechanism between a K⁺ ion from the solid and a Cs⁺ ion from the liquid, without any Cu release. These data were modelled with success by this ionic exchange reaction. The very fast kinetics of sorption of this material allowed applying very high flow rates in a column process with an ideal breakthrough curve. This material is a promising candidate for application in the case of column decontamination processes and will be soon synthesized at pilot scale. (authors)