Kinetics of Reactions of 8-Quinolinol and Acetate with Hydroxyaluminum Species in Aqueous Solutions. 2. Initial Solid Phases

Abstract

The effects of pH and concentrations of 8-quinolinol and acetate on the rate of release of mononuclear Al from an initial solid phase formed by the rapid precipitation of mononuclear Al cations and from another formed by the precipitation of polynuclear hydroxyaluminum cations with NaOH were determined. With the solid formed by precipitation of the mononuclear Al cations, the rate was governed by the rate of dissolution of the solid. Dissolution occurred because the solution was undersaturated with respect to the solid. With the solid formed by the precipitation of the polynuclear cations the reaction behaved as if the rate determining step in the release of the mononuclear Al was the decomposition of the polynuclear cations after dissolution of the solid, indicating that the polynuclear cations persisted as such in the precipitate.Independent evidence that the two initial solid phases were entirely different was indicated by the fact that the one formed by precipitation of mononuclear cations developed into gibbsite in a few days whereas the other did not.