Use of aluminosilicate minerals for the removal of radionuclides and heavy metals from aqueous wastes by sorption and in combination with precipitation processes

The sorption characteristics of aluminosilicate minerals from Bulgarian locations in natural and modified forms have been studied. The possible application of mineral sorbents (zeolites and vermiculites) for decontamination of aqueous waste containing radionuclides (Cs-137, Sr-90, Co-60, Ag-110m, Tl-204, Ce-144, Ru-106), as well as for decontamination of waste waters containing lead, cadmium, zinc or silver, were studied. The static exchange capacity of clinoptilolite and vermiculite in different cationic forms has been determined together with the influence of different competitive ions on the capacity. The thermodynamics of ion exchange on the sodium form of clinoptilolite has been studied and the distribution coefficients and the diffusion coefficients for the specified radionuclides were determined. The potential of combining processes for the treatment of wastes of complex composition has been examined by applying precipitation and sorption processes under static or dynamic conditions. The decontamination coefficients for caesium, strontium, cobalt manganese cerium and zirconium were determined at different values of pH and different doses of precipitates and sorbents. (author). 19 refs, 5 figs, 12 tabs