Water—mineral reactions, status

A brief summary of the status of the thermodynamic properties for water-mineral reactions using the ion-association theory and revised data is ... 

Therefore, oxidation-reduction processes in nature control the behavior of elements or substances. During oxidation-reduction, the potential for reactions to take effect changes because the redox status of elements changes. A summary of soil-water mineral-ion properties known to be affected by redox chemistry is listed below ... 

Clay minerals behave like Bronsted acids, donating protons, or as Lewis acids (Sect. 6.3), accepting electron pairs. Catalytic reactions on clay surfaces involve surface Bronsted and Lewis acidity and the hydrolysis of organic molecules, which is affected by the type of clay and the clay-saturating cation involved in the reaction. Dissociation of water molecules coordinated to surface, clay-bound cations contributes to the formation active protons, which is expressed as a Bronsted acidity. This process is affected by the clay hydration status, the polarizing power of the surface bond, and structural cations on mineral colloids (Mortland 1970, 1986). On the other hand, ions such as A1 and Fe, which are exposed at the edge of mineral clay coUoids, induce the formation of Lewis acidity (McBride 1994). 

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