Chemical reactivity, mineral-water interface

Chemical relaxation methods can be used to determine mechanisms of reactions of ions at the mineral/water interface. In this paper, a review of chemical relaxation studies of adsorption/desorption kinetics of inorganic ions at the metal oxide/aqueous interface is presented. Plausible mechanisms based on the triple layer surface complexation model are discussed. Relaxation kinetic studies of the intercalation/ deintercalation of organic and inorganic ions in layered, cage-structured, and channel-structured minerals are also reviewed. In the intercalation studies, plausible mechanisms based on ion-exchange and adsorption/desorption reactions are presented steric and chemical properties of the solute and interlayered compounds are shown to influence the reaction rates. We also discuss the elementary reaction steps which are important in the stereoselective and reactive properties of interlayered compounds. 

These properties and principles govern the transfer of organic chemicals between different environmental compartments. Of particular interest to halogenated hydrocarbon reactivity discussed in this treatise is the air-water interface (emissions, water column outgassing), and the solid-water interface (sorptive processes, sequestration, mineral-mediated reactions). For example, the role of air-water diffusive exchange in large aquatic systems may provide a source or sink for volatile compounds such as the halomethanes... 

An understanding of the acid-base properties of solid surfaces is extremely important in almost all fields of science and engineering. For example, the solid/ gas interface intervenes when solid acids (or bases) are used as heterogeneous catalysts in the oil refining and chemical industries. The solid/liquid interface between rocks, minerals, and soils and natural waters is continuously transformed by weathering processes that result in the geohydrochemical circuit of elements. These are only two examples in which the primary reactivity factor is determined by the acid-base chemistry at solid interfaces, usually confined to molecule-sized spaces. 

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