Thermodynamic interpretation of zirconium solubility in the presence of hydroxyacetic, 3-hydroxypropionic, and 2,3-dihydroxypropanoic acids

Abstract

The solubility of zirconium hydroxide in the presence of hydroxyacetic (glycolic, O20), 3-hydroxypropionic (O21), and 2,3-dihydroxypropanoic (glyceric, O201) acids was investigated as a function of pH c = −log [H + ] = 7−13 and total hydroxycarboxylic acid concentrations, [L] tot = 10 −4 −10 −1 mol/dm 3 . The Zr solubility dependences on pH c and [L] tot indicated that ternary Zr(OH) 4 (L) 22− complexes were the dominant soluble species under the experimental conditions. The formation constants of the Zr(OH) 4 (L) 22− complexes were determined by least square fitting analysis of the solubility data and compared to the values for zirconium-poly(hydroxy)carboxylate analogs to elucidate the complexation mechanism of Zr-hydroxycarboxylates.