Membrane extraction in preconcentration of uranium, fission products and corrosion radionuclides

The membrane extraction consists in transport of solutes through a mobile liquid membrane formed by organic solvent in double water (strippant) / oil (extractant) / water (feed) emulsions. This work was undertaken to evaluate the advantages and drawbacks of membrane extraction in preconcentration of radionuclides from water solutions to use it in radiochemical analysis, hydrometallurgy of uranium leach solutions and radioactive waste water treatment. The approach involved: (a) theory development, (b) search for stable emulsion systems, (c) techniques of absolute preconcentration, (d) suppressing a contamination of the feed with strippant, (e) development of hybrid analytical and radioanalytical methods. The extraction of cesium, strontium, cobalt(II), uranium(VI), cerium (III) and technetium(VII) was investigated with chelating agents (di-2-ethylhexylphosphoric acid, 8-hydroxyquinoline, KELEX 100, LIX 64N and ABF) and in ion exchange systems (e.g. with quaternary ammonium salts and bis(1,2-dicarbollyl)cobalt(III)). (author)