Use of physico-chemical properties of the hydroxo complexes for removal of radionuclides from liquid radioactive waste

Behaviour of radionuclides in such processes as sorption, ion exchange, ultrafiltration, etc., that are used for removal of radionuclides from solution, is largely determined by their speciation in solution. The hydrolysis of metal ions in solution is particularly interesting in that respect, since most of the liquid radioactive wastes are aqueous solutions. The following forms of metal ions (Mez+) occur in aqueous solution as the pH increases from acidic to basic conditions: Hydrated cations (Me(H2O)z+); Mononuclear hydroxocomplexes (Me(OH)qz-q+); Polynuclear hydroxocomplexes (Mep(OH)qpz-q+); Pseudocolloids. Each of these forms possesses specific physico-chemical properties that can be effectively used for separation of radionuclides and for their removal from solution. Therefore, the knowledge of the radionuclide hydrolytic speciation in solution and physico-chemical properties of various hydroxocomplexes is very important for development of liquid radioactive waste treatment technologies