Assessment of an ultrafiltration technique for the fractionation of radionuclides associated with humic material

Experiments have been carried out with well characterised laboratory solutions to establish the physico-chemical behaviour of a suite of radionuclides in the presence of humic and fulvic acids using single flat membrane ultrafilters. Because of the uncertainties associated with the methodology, an approach has been adopted using mass balance determinations to assess the performance of the ultrafiltration process and facilitate the interpretation of the fractionation data. The size distribution of radionuclide-ligand complexes are reported and the results are discussed in the context of interpreting environmental data with more confidence.