CONDITIONS IN SOLUTION DURING THE FORMATION OF GIBBSITE IN DILUTE ALUMINUM SALT SOLUTIONS: III. HYDROXYALUMINUM PRODUCTS OF REACTIONS DURING THE NEUTRALIZATION OF ALUMINUM CHLORIDE SOLUTIONS WITH SODIUM HYDROXIDE

Abstract

Experiments were made to determine the relative amounts of solid phase hydroxyaluminum to polynuclear ionic hydroxyaluminum formed, according to methods developed by one of the authors, during titrations of dilute AlCl3 solutions with a base. With both 10−3 and 10−2 M AlCl3 solutions, and with both fast (less than 5 minutes) and slow (12 hours) titrations, the solid phase and the polynuclear ions were present at each degree of neutralization at which measurements were made. During the greater part of the titrations the solid phase was the major product with the fast titrations, and the polynuclear ions were the major product with the slow titrations. Beyond about 80% neutralization the polynuclear ions began to decrease in concentration until at 100% the solid phase approached 100% of the products regardless of the rate of titration. There was a considerable amount of Cl associated with the solid phase during most of each titration, but the Cl/Al molar ratio of the solid approached zero as neutralization approached 100%.