Mixed Ca²⁺/UO₂ ²⁺/CO₃ ^2-complex formation at different ionic strengths

Abstract

Fluorescence spectroscopy was used to study the Ca 2+ /UO 2 2+ /CO 3 2- solution system at different ionic strengths. Fluorescent titrations confirmed formation of Ca 2 UO 2 (CO 3 ) 3 complex for which the values of log β 213 were measured at 0.1, 0.3, 0.7, 1.0 and 3.0 m (NaClO 4 ) at pcH = 8.1. Specific Interaction Theory (SIT) was used to correlate the log β 213 values as a function of ionic strength. The value obtained for log β 0 213 (I = 0) was 29.8 ± 0.7, indicating that Ca 2 UO 2 (CO 3 ) 3 was the predominant specie at the pH 8 in calcium rich, oxic waters.