Cation-cation complexes of PuO2+and NpO2+with Th4+and UO22+

Abstract

Cation-cation complexes of NpO2+and PuO2+with UO22+and Th4+were studied using laser-induced photoacoustic spectroscopy (LIPAS). An equilibrium constant of 2.4±0.2 M-1was measured at an ionic strength of 6.0 M for the NpO2+· UO22+complex which is in good agreement with previous measurements using conventional absorption spectroscopy and Raman spectroscopy. Equilibrium constants of 1.8±0.9 and 2.2±1.5 M-1were measured for NpO2+· Th4+and PuO2+· UO22+complexes at an ionic strength of 6.0 M, respectively. This is the first time that LIPAS has been used to study cation-cation complexes and the first time that the PuO2+· UO22+cation-cation complex has been reported.