EMU Volume 10 – Chapter 8

Chapter 8: Dissolution, sorption/(re)precipitation, formation of solid solutions and crystal growth phenomena on mineral surfaces: implications for the removal of toxic metals from the environment

Athanasios Godelitsas and José M. Astilleros

Sorption of dissolved heavy metals, at low-temperature conditions, mediated by mineral surfaces, plays an important role in controlling both the dispersion and accumulation of these pollutants as well their geoavailability and bioavailabity in near-surface environments. In parallel to sorption, dissolution of mineral surfaces always occurs as an unavoidable coupled phenomenon at the mineral-water interface. The main sorption mechanisms, related to metal uptake from aqueous solutions, can be considered absorption (including ion-exchange), adsorption and surface (co)/(re)precipitation leading to subsequent crystal-growth phenomena and formation of solid-solutions. The mineral reactivity depends on the chemical composition of the interacting solid, which in turn is related to particular physicochemical characteristics such as the porosity, the specific surface area (SSA), the cation exchange capacity (CEC), and the zeta-potential/pHPZ. Of special interest, for industrial and environmental technology, is the interaction of carbonate (e.g. calcite), sulphate (e.g. gypsum) as well as aluminosilicate and Mn-oxide micro/nanoporous minerals (e.g. various zeolites and todorokite) with ‘ultra’ heavy toxic metals including actinides (e.g. Hg, Pb, Th, U).

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