Interactions between natural waters, minerals and rocks, and living organisms occur at interfaces. Understanding the combined water-electrolyte-mineral-biomolecule interface is the key to the geochemical cycling of many chemical elements including metals and nutrient species. Many experimental studies have focused on oxides such as alumina and titanium dioxide, but these have limited relevance. Similarly, the 1:1 electrolytes typically studied over a narrow range of ionic strengths in experiments are completely different to the compositions of natural soil and ground waters. Consequently, most surface complexation models can only be applied to fitting simple systems and have no predictive power. In contrast, the extended triple-layer model (ETLM) places surface complexation on a predictive basis by using Born solvation, crystal-chemical, and electrostatic theory. Recent progress involving direct spectroscopic comparisons with modeling will be described. Excellent agreement is obtained between the number and type of surface species, and the dependence on environmental conditions.

Theoretical modeling of adsorption at mineral-water interfaces: A predictive synthesis from protons to biomolecules

251st National Meeting (2016)

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