Equilibirium studies of mixed ligand complexes fo uranyl ion with amino acids and carboxylic acids in aqueous solution

Abstract

The stability constants of ternary uranyl ion complexes involving amino acids and carboxylic acids were determined by pH titrations at a temperature of 31 ± 0.1°C and an ionic strength μ, of 0.1 mol dm^-3 (NaClO₄). The stability values clearly show the discriminating qualities of the uranyl ion-amino acid 1:1 complex towards the secondary ligand to be coordinated. The values of log K_2YX are linearly related to the product of the acid dissociation constants of the secondary ligands. The overall stability is found to be dependent on the binary stabilities. Preferential coordination by the uranyl-amino acid 1:1 complex towards O?O donors compared to O?S donors is observed.