Mechanisms for Hydrogen to Aluminum Transformations in Clays

The rates of Al release from montmorillonite and kaolinite clays by acid‐dissolution techniques were determined. For kaolinite the release of Al obeyed pseudo zero order kinetics and form ontmorillonite the release of Al obeyed pseudo first order kinetics. The kinetic studies indicate a difference in mechanism of H attack on these two clays. A diffusion controlled edge attack is proposed in the case of kaolinite and an all surface attack is proposed for montmorillonite. Kinetic studies using different size fractions of the two clays support the proposed mechanisms.