Characterization of the sorption of europium(III) on calcite by site-selective and time-resolved luminescence spectroscopy

Sorption of europium(III) on calcite from aqueous solution was investigated by kinetics and sorption isotherms at 323 K and by site-selective and time-resolved luminescence spectroscopy at 15 K. Three sorption sites (A, B, C) were characterized by this last technique. B constitutes a major family which appears in all samples with sorbed Eu and is characterized by an environment involving water or hydroxyl ions. The C family is observed only for the highest Eu concentrations. In these sites, the environment is more hydrated than in sites B. Site A constitutes a minority but appears in all samples. It corresponds to the centrosymmetric structural Ca site of calcite in position 2b, thus demonstrating that sorbed Eu(III) can substitute for Ca in calcite. (C) 1997 Academic Press.