The kinetics of dissolution of alumina in aqueous solutions of H2SO4 was studied at ambient temperature under continuous-flow conditions. The results are consistent with a model involving rapid hydration of the surface, adsorption-desorption of H+ to form precursor sites, and rate-determining parallel reactions of the precursor sites to form dissolved aluminum and an insoluble surface species. The model also involves renewal of a precursor site after each dissolution step.
The adsorption-desorption of H+ was represented by a Langmuir isotherm. The dissolution data were correlated by a kinetic equation that was developed by assuming the dissolution step is first order in precursor concentration, and the deactivation step is second order in precursor concentration.