Absorption of phosphate during the oxidation of ferrous ions

GEOC 28

Xavier Châtellier, xavier.chatellier@univ-rennes1.fr, Géosciences Rennes, CNRS-University of Rennes 1, Campus de Beaulieu, Building 15, Avenue du General Leclerc, 35042 Rennes Cedex, France, Mustapha Abdelmoula, Laboratoire de Chimie Physique et Microbiologique pour l'Environnement, UMR 7564 CNRS-Université Henri Poincaré-Nancy 1, 405 rue de Vandoeuvre 54600 Villers-Les-Nancy, Nancy, France, Ken Kemner, kemner@anl.gov, Environmental Research Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, Gary G. Leppard, National Water Research Institute, Burlington, ON L7R 4A6, Canada, Christian Mustin, christian.mustin@limos.uhp-nancy.fr, LIMOS, Nancy, France, Bruce D. Ravel, bravel@anl.gov, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, and Marcia Reid, westm@mcmaster.ca, Faculty of Health Sciences, McMaster University, Hamilton, ON L8N 3Z5, Canada.
Iron and phosphate are known to interact strongly in the environment. However, the incorporation of phosphate ions during the oxidation of Fe(II) has received very little attention. In our study, ferrous ions were oxidized at pH 6.0 in the presence of an excess of dissolved oxygen and increasing quantities of phosphate. The resulting precipitates were characterized by TEM, SEM, XRD, IR spectroscopy, Mössbauer spectroscopy, EXAFS, and chemical analyses. The kinetics and the stoichiometry of oxidation were also measured. Chemical analyses revealed that virtually all the phosphorus introduced was adsorbed in the precipitates up to an introduced P/Fe elemental ratio of 0.6-0.7. In the presence of an excess of phosphate, the maximal P/Fe ratio of the precipitates was found to be equal to about 0.86 ± 0.02. The properties of the precipitates, as obtained from the various techniques used, will be presented. We are now examining the reduction of these iron phosphates by bacteria.
 

Physical Chemistry of Soil and Aquifer Systems: A Symposium in Honor of Garrison Sposito
1:30 PM-5:10 PM, Sunday, 10 September 2006 Moscone Center -- Room 256, Oral

Division of Geochemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006