A surface complexation model of the carbonate mineral-aqueous solution interface

Journal Article · Sun Aug 01 00:00:00 EDT 1993 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(93)90135-J· OSTI ID:6064462

Van Cappellen, P ^[1]; Charlet, L ^[2]; Stumm, W ^[3]; Wersin, P ^[4]

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1. Georgia Inst. of Technology, Atlanta (United States)
2. Univ. of Bern (Switzerland)
3. Swiss Federal Inst. of Technology, Duebendorf (Switzerland)
4. Stanford Univ., CA (United States)

A surface complexation model for the chemical structure and reactivity of the carbonate-water interface is presented. The model postulates the formation of the hydration species >CO[sub 3]H[sup 0] and >MeOH[sup 0] at the surface of a divalent metal carbonate MeCO[sub 3] (Me = Ca, Mn, Fe, etc.). The existence of these primary hydration species is supported by spectroscopic data. The following reactions are proposed to govern surface speciation in the MeCO[sub 3](s)-H[sub 2]O-CO[sub 2] system: >CO[sub 3]H[sup 0] [Leftrightarrow] >CO[sub 3][sup [minus]] + H[sup +]; >CO[sub 3]H[sup 0] + Me[sup 2+] [Leftrightarrow] >CO[sub 3]Me[sup +] + H[sup +]; >MeOH[sub 2][sup +] [Leftrightarrow] >MeOH[sup 0] + H[sup +]; >MeOH[sup 0] [Leftrightarrow] >MeO[sup [minus]] + H[sup +]; >MeOH[sup -] + CO[sub 2] [Leftrightarrow] >MeHCO[sub 3][sup 0]; and >MeOH[sup 0] + CO[sub 2] [Leftrightarrow] >MeCO[sub 3][sup [minus]] + H[sup +]. It is shown in this paper that the surface complexation model provides a systematic explanation of surface charge development and dissolution kinetics of carbonate minerals. The intrinsic stability constants of the surface complexation reactions agree well with the equilibrium constants of the corresponding complexation reactions in homogeneous solution. 61 refs., 11 figs., 3 tabs.

• OSTI ID: 6064462
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 57:15; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540310* -- Environment
Aquatic-- Basic Studies-- (1990-)
ALKALINE EARTH METALS
CALCIUM
CARBON COMPOUNDS
CARBON CYCLE
CARBONATE MINERALS
CARBONATES
CHEMICAL REACTION KINETICS
DISSOLUTION
ELEMENTS
HYDRATION
INTERFACES
IRON
KINETICS
MAGNESIUM
METALS
MINERALS
OXYGEN COMPOUNDS
REACTION KINETICS
ROCK-FLUID INTERACTIONS
SEDIMENT-WATER INTERFACES
SOLVATION
SURFACE PROPERTIES
TRANSITION ELEMENTS