SREL Reprint #2551

Crystal chemistry of colloids obtained by hydrolysis of Fe(III) in the presence of SiO4 ligands

Emmanuel Doelsch1, Armand Masion1, Jérôme Rose1, William E. E. Stone1, Jean Yves Bottero1,
and Paul M. Bertsch2

1CEREGE, Europole Méditerranéen de l'Arbois, BP 80, 13545 Aix-en-Provence Cedex 04, France
2AACES-SREL, University of Georgia, PO Drawer E, Aiken, SC 29802, USA

Abstract: The crystal chemistry of a number of Fe-Si systems (Si/Fe 0-4, pH 3-10) was investigated by combining local scale spectroscopic methods (EXAFS, FTIR and NMR) and at the semi local scale (SAXS). The Fe clusters within the precipitates have two growth regimes depending on the Si/Fe ratio: the growth is three and two dimensional for Si/Fe ≤ 1 and Si/Fe ≥ 1 respectively. The presence of Fe-O-Si bonds within the precipitated phases has been demonstrated. Their formation and relative proportion was found to be very dependent on the pH and Si concentration The size of silica domains within the precipitates was shown to increase with increasing Si/Fe and/or decreasing pH. The high fractal dimension (Df) of the aggregates is attributed to the presence of the SiO4 ligands, but the evolution of Df linearly depends on the polymerization state of iron.

SREL Reprint #2551

Doelsch, E., A. Masion, J. Rose, W. E. E. Stone, J. Y. Bottero, and P. M. Bertsch. 2001. Crystal chemistry of colloids obtained by hydrolysis of Fe(III) in the presence of SiO4 ligands. Materials Research Society 658:GG3.36.31 - GG33.36.35.

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