THE RELATIVE INFLUENCE OF LOW-MOLECULAR-WEIGHT, COMPLEXING ORGANIC ACIDS ON THE HYDROLYSIS AND PRECIPITATION OF ALUMINUM

The stability constants of the complexes of aluminum and the low-molecular-weight organic acids decreased in the order: citric acid > malic acid > tannic acid > aspartic acid > p-hydroxybenzoic acid. This order of affinity of organic ligands to aluminum was in agreement with the sequence of the effectiveness of the organic acids to hinder and perturb the normal course of hydrolytic and precipitation reaction of aluminum. In systems where organic acids were present in varying concentrations, the hindrance to the hydrolytic reactions of aluminum increased with the increasing concentration of organic acids present during aluminum transformation.