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- Boily, J F, et al.
(author)
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Benzenecarboxylate surface complexation at the goethite (alpha-FeOOH)/water interface : I. A mechanistic description of pyromellitate surface complexes from the combined evidence of infrared spectroscopy, potentiometry, adsorption data, and surface complexation modeling
- 2000
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In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 16:13, s. 5719-5729
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Journal article (peer-reviewed)abstract
- An investigation combining IR spectroscopy, potentiometric titrations, and adsorption experiments was carried out to study pyromellitate (1,2,4,5-benzenetetracarboxylate) sorption at the goethite (α-FeOOH)/water interface. The IR spectra show evidence of outer-sphere complexation throughout the pH range from 3 to 9. Below pH 6 additional IR spectroscopic features appear, which are tentatively assigned to inner-sphere complexes. A normalized IR peak area plot for each peak indicative of inner- and of outer-sphere complexes as a function of pH provided a semiquantitative surface speciation scheme. This scheme was successfully reproduced using surface complexation theory with a multisite complexation model calibrated on potentiometric titration and on adsorption data. The surface speciation was described with a binuclear outer-sphere complex on the {110} plane of goethite and a mononuclear inner-sphere complex on the {001} plane. Furthermore, as the IR spectra also indicated partial protonation of pyromellitate complexes at low pH, a partially protonated outer-sphere species on the {110} plane was included in the model.
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