An investigation into the mechanism of the complexation reaction between Eu and DTPA in concentrated lactate media has been completed. This system is of interest due to its relevance to the TALSPEAK process for separating trivalent lanthanide and actinide ions in the nuclear fuel cycle. As the concentrations of [H+], [Lac-], and [HLac] are interdependent on one another, a series of experiments were performed to determine the role of each species on the complexation kinetics. It is found that the concentrations of lactate ion and hydrogen ion have the most significant effect on the rate constants of formation and dissociation respectively. At DTPA concentrations above 15 mM the observed rates begin to level off indicating a DTPA saturation effect. A rate law is provided which attempts to fit the observed effects of the individual components of lactic acid and the DTPA saturation effect.

Complexation kinetics and mechanism of Eu and DTPA under TALSPEAK-like aqueous conditions

244th National Meeting (2012)

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