The dissociation kinetics of dissolved metal–humate complexes
Abstract
The dissociation of Eu(III)–HS (HS = fulvic or humic acid) complexes has been investigated using iz.: an easily exchangeable fraction of Eu (calculated using a single equilibrium constant) and three kinetically hindered fractions (calculated from three consecutive pseudo-first order rate expressions). With larger amounts of resin, the easily exchangeable Eu(III) becomes negligible. The slowest dissociation step, which probably is the most important with regard to radionuclide transport, has a half life of ≈200 h. The fraction of Eu(III) in the kinetically hindered sites increased with metal–HS
contact time, pH,