Paper Details
Bibliographic Data:
Code: |
RMWP04 |
Paper Type: |
Article |
Author(s): |
Ridley MK, Machesky ML, Wesolowski DJ, Palmer DA |
Title: |
Modeling the surface complexation of calcium at the rutile-water interface to 250 °C |
Journal: |
Geochimica et Cosmochimica Acta
Volume: 68 Year: 2004 Pages: 239-251
ISSN-Print: 0016-7037; 0016-1258 |
Internal Storage: |
V2057 |
DOI: |
10.1016/S0016-7037(03)00420-4 |
Abstract: |
The adsorption behavior of metal-(hydr)oxide surfaces can be described and rationalized using a variety of surface complexation models. However, these models do not uniquely describe experimental data unless some additional insight into actual binding mechanisms for a given system is available. This paper presents the results of applying the MUlti SIte Complexation or MUSIC model, coupled with a Stern-based three layer description of the electric double layer, to Ca2+ adsorption data on rutile surfaces from 25 to 250°C in 0.03 and 0.30 m NaCl background electrolyte. Model results reveal that the tetradentate adsorption configuration found for Sr2+ adsorbed on the rutile (110) surface in the in situ X-ray standing wave experiments of Fenter et al. (2000) provides a good fit to all Ca2+ adsorption data. Furthermore, it is also shown that equally good fits result from other plausible adsorption complexes, including various monodentate and bidentate adsorption configurations. These results amply demonstrate the utility of in situ spectroscopic data to constrain surface complexation modeling, and the ability of the MUSIC model approach to accommodate this spectroscopic information. Moreover, this is the first use of any surface complexation model to describe multivalent ion adsorption systematically into the hydrothermal regime. |
Comment: |
application of the MUSIC model and CD-MUSIC model, coupled with a Stern-based three layer description of the electric double layer, to Ca<2+> adsorption data on rutile surfaces from 25 to 250 °C; input of »Ti-OH<-0.31> and »Ti2-O<-0.62> surface groups not possible in RES³T; logK values for [(»Ti-OH<-0.31>)2(»Ti2-O<-0.62>)2]-Ca<2+> (logK = 17.596), [(»Ti-OH<-0.31>)(»Ti2-O<-0.62>)]-Ca<2+> (logK = 6.288), [(»Ti2-O<-0.62>)2]-Ca<2+> (logK = 4.796), [(»Ti-OH<-0.31>)2]-Ca<2+> (logK = 7.726), [(»Ti2-O<-0.62>)]-Ca<2+> (logK = -0.17), [(»Ti-OH<-0.31>)]-Ca<2+> (logK = 1.304); application of the 1-pK model |
Surface Area
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Site Density / Protolysis
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Complex Formation
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Formatted Citation
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