SREL Reprint #2449

Speciation and crystal chemistry of iron (III) chloride hydrolyzed in the presence of SiO4 ligands. 1. An Fe K-edge EXAFS study

Emmanuel Doelsch1, Jérome Rose1, Armand Masion1, Jean Yves Bottero1, Daniel Nahon1, and Paul M. Bertsch2

1CEREGE (UMR 6635, CNRS-Aix-Marseille III), Europole Méditerranéen de l'Arbois,
BP 80, 13545 Aix-en-Provence Cedex 04, France
2Savannah River Ecology Laboratory, AACES, University of Georgia, PO Drawer E,
Aiken, South Carolina 29802

Abstract: The hydrolysis of Fe-Si systems with Si/Fe ratios between 0 and 4 leads to the formation of poorly crystalline or, more frequently, of long-range disorganized precipitates. The increase of Si/Fe molar ratios results in an dramatic change of Fe polymerization. The formation of double and single corner-sharing Fe linkages is reduced compared to pure Fe hydrolysis products. The growth regime depends on the Si concentration in the system. Three-dimensional and two-dimensional growth of Fe colloids occurs at low and high Si/Fe ratios, respectively, systems with Si/Fe ratios around 1 representing a crossover between these two regimes. Though Si neighbors cannot be detected unequivocally by Fe K-edge EXAFS, their presence in the close environment of Fe atoms is evident from the change in Fe speciation.

SREL Reprint #2449

Doelsch, D., J. Rose, A. Masion, J. Y. Bottero, D. Nahon, and P. M. Bertsch. 2000. Speciation and crystal chemistry of iron (III) chloride hydrolyzed in the presence of SiO4 ligands. 1. An Fe K-edge EXAFS study. Langmuir 16:4726-4731.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).