Influence of natural organic acids on the interactions between colloids and radionuclides

Coordination geometry of An(IV) or Ln(III) - organic ligands that contain OH- and COO- functional groups were investigated by means of potentiometry, NMR and EXAFS. The chemistry of the reactions is important in nuclear waste management because these ligands, mainly humic and fulvic acids (HA/FA), occur in nature as a result of microbiological degradation of organic material, and strongly stimulate the sorption of the radionuclide to the colloids. In the present work, the formation of ternary metal-OH-ligand type poly-nuclear species was firstly confirmed, and the mechanism of the complex formation reaction was extensively discussed. (author)