Sorption characteristics of radionuclides on synthetic birnessite-type layered manganese oxides

The removal of trace caesium (Cs-137), trace strontium (Sr-89, Sr-90/Y-90) and trace cobalt (Co-57) from aqueous solution by synthetic sodium and potassium birnessites has been studied by a batch technique. Distribution coefficients were determined as a function of pH in four solutions: water, 0.005 M sodium tetraborate, 0.005 M sodium citrate and 0.0001 M EDTA. Other effects studied were increasing sodium ion, potassium ion and complexing agent concentration. Key synthesis parameters (ageing time, MnO4-/Mn2+ ratio) were tuned in order to maximise trace cobalt sorption efficiencies. The optimised material was tested for the removal of caesium, strontium and cobalt from a nuclear power plant floor drain simulant. A sodium birnessite sample was also screened for the removal of Ni-63, Mn-54, Fe-59, Zn-65 and Pu-236 radionuclides.