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Title: Fluoride adsorption on goethite in relation to different types of surface sites

Abstract

Metal (hydr)oxides have different types of surface groups. Fluoride ions have been used as a probe to assess the number of surface sites. The authors have studied the F{sup {minus}} adsorption on goethite by measuring the F{sup {minus}} and H{sup +} interaction and F{sup {minus}} adsorption isotherms. Fluoride ions exchange against singly coordinated surface hydroxyls at low F{sup {minus}} concentrations. At higher concentrations also the doubly coordinated OH groups are involved. The replacement of a surface OH{sup {minus}} by F{sup {minus}} suggests that all F charge ({minus}1) is located at the surface in contrast to oxyanions which have a charge distribution in the interface due to the binding structure in which the anion only partially coordinates with the surface. Analysis of their F{sup {minus}} data with the CD-MUSIC approach shows that the formation of the fluoride surface complex is accompanied by a redistribution of charge. This is supposed to be due to a net switch in the H bonding as a result of the change of the type of surface complex from donating (FeOH, FeOH{sub 2}) to proton accepting (FeF). The modeled redistribution of charge is approximately equivalent with the change of a donating H bond into an accepting Hmore » bond. At high F{sup {minus}} concentrations precipitation of F{sup {minus}}, as for instance FeF{sub 3}(s), may occur. The rate of formation is catalyzed by the presence of high electrolyte concentrations.« less

Authors:
;
Publication Date:
Research Org.:
Wageningen Univ. (NL)
OSTI Identifier:
20075581
Resource Type:
Journal Article
Journal Name:
Journal of Colloid and Interface Science
Additional Journal Information:
Journal Volume: 225; Journal Issue: 1; Other Information: PBD: 1 May 2000; Journal ID: ISSN 0021-9797
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 36 MATERIALS SCIENCE; SURFACE PROPERTIES; FLUORIDES; GOETHITE; ADSORPTION

Citation Formats

Hiemstra, T., and Van Riemsdijk, W.H. Fluoride adsorption on goethite in relation to different types of surface sites. United States: N. p., 2000. Web. doi:10.1006/jcis.1999.6697.
Hiemstra, T., & Van Riemsdijk, W.H. Fluoride adsorption on goethite in relation to different types of surface sites. United States. doi:10.1006/jcis.1999.6697.
Hiemstra, T., and Van Riemsdijk, W.H. Mon . "Fluoride adsorption on goethite in relation to different types of surface sites". United States. doi:10.1006/jcis.1999.6697.
@article{osti_20075581,
title = {Fluoride adsorption on goethite in relation to different types of surface sites},
author = {Hiemstra, T. and Van Riemsdijk, W.H.},
abstractNote = {Metal (hydr)oxides have different types of surface groups. Fluoride ions have been used as a probe to assess the number of surface sites. The authors have studied the F{sup {minus}} adsorption on goethite by measuring the F{sup {minus}} and H{sup +} interaction and F{sup {minus}} adsorption isotherms. Fluoride ions exchange against singly coordinated surface hydroxyls at low F{sup {minus}} concentrations. At higher concentrations also the doubly coordinated OH groups are involved. The replacement of a surface OH{sup {minus}} by F{sup {minus}} suggests that all F charge ({minus}1) is located at the surface in contrast to oxyanions which have a charge distribution in the interface due to the binding structure in which the anion only partially coordinates with the surface. Analysis of their F{sup {minus}} data with the CD-MUSIC approach shows that the formation of the fluoride surface complex is accompanied by a redistribution of charge. This is supposed to be due to a net switch in the H bonding as a result of the change of the type of surface complex from donating (FeOH, FeOH{sub 2}) to proton accepting (FeF). The modeled redistribution of charge is approximately equivalent with the change of a donating H bond into an accepting H bond. At high F{sup {minus}} concentrations precipitation of F{sup {minus}}, as for instance FeF{sub 3}(s), may occur. The rate of formation is catalyzed by the presence of high electrolyte concentrations.},
doi = {10.1006/jcis.1999.6697},
journal = {Journal of Colloid and Interface Science},
issn = {0021-9797},
number = 1,
volume = 225,
place = {United States},
year = {2000},
month = {5}
}