Phase equilibria in the Fe2O3-SeO2-H2O system

The precipitates in equilibrium with Se(IV) solutions having different Se(IV) concentration at different temperatures up to 170 °C were investigated by differential thermal analysis (DTA) and thermogravimetric (TG) analysis as well as XRD and chemical analyses, for a better understanding of the solid phases involved in the Fe2O3-SeO2-H2O system in a wide temperature range. Fe2(SeO3)3·5H2O, Fe2(SeO3)3·3H2O and Fe2Se2O7 were detected depending upon the reaction conditions, Se(IV) concentration of the solution phase, and temperature.