Bayerite: Electrochemical Synthesis and Mechanism of Formation

A novel method of synthesis is reported for the preparation of pure and well crystallised bayerite, an aluminium hydroxide generally not obtained alone. The technique used is based on electrolysis with a cation exchange membrane between the anolyte and the catholyte. The obtained compound is then characterised using seven different techniques, namely XRD, SEM, ICP, laser diffraction, BET area, density and TGA. Our study of the kinetics of Al(OH)3 precipitation in aqueous alkali solution and theoretical calculations1 allowed us to propose a reactional mechanism for the nucleation process of crystallised Al(OH)3 and also for formation of an alumino-gel. The existence of an intermediate aluminate species in solution as a precursor of bayerite is shown in this work.