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Chemical Engineering Journal 214 (2013) 139-148
Sequential precipitation of a new goethite-calcite nanocomposite and its possible application in the removal of toxic ions from polluted water
German Montes-Hernandez 1, François Renard 1, Rodica Chiriac 2, Nathaniel Findling 1, Jaafar Ghanbaja 3, François Toche 2

This study proposes a simple and innovative synthesis route for a goethite-calcite nanocomposite. This synthesis is summarized by three sequential precipitation reactions: (1) precipitation of nanosized acicular goethite (α-FeOOH) using a high OH/Fe molar ratio (=5); (2) instantaneous precipitation of portlandite (Ca(OH)2) by adding CaCl2 salt to a goethite alkaline suspension (2NaOH + CaCl2=Ca(OH)2 + 2NaCl) and; (3) sub-micrometric calcite precipitation by injection of CO2 into a goethite-portlandite alkaline suspension (Ca(OH)2 + CO2=CaCO3+H2O). The XRD patterns have confirmed the goethite and calcite mineral composition in the composite precipitated at 30 and 70°C. FESEM and TEM observations have revealed the formation of nanosized goethite particles well dispersed with sub-micrometric calcite particles, leading to an orange-brown colour nanocomposite with high specific surface area of around 92 m2/g for a composite synthesized at 30°C and 45 m2/g for a composite synthesized at 70°C. Both values were determined using the conventional BET method on N2 sorption isotherms. Finally, a goethite/calcite weight ratio equal to 0.8 in the composite was determined by thermogravimetric analysis (TGA). Additionally, some adsorption experiments carried out at two different pH values revealed that the goethite-calcite composite has a good sequestration capacity for Cu>Cd>As(III)>Se(IV)>As(V). Conversely, the Se(VI) did not show any chemical affinity with the goethite-calcite composite under the physico-chemical conditions studied. In practice, the goethite-calcite composite can neutralise acidic wastewater by slight calcite dissolution, enhancing the removal of heavy metals (e.g. Cu and Cd) at the calcite-solution interfaces.
1 :  Institut des sciences de la Terre (ISTerre)
CNRS : UMR5275 – IFSTTAR – Université de Savoie – Université Joseph Fourier - Grenoble I – INSU – OSUG – Institut de recherche pour le développement [IRD] : UR219
2 :  Laboratoire des Multimatériaux et Interfaces
CNRS : UMR5615 – Université Claude Bernard - Lyon I
3 :  Institut Jean Lamour : Matériaux -Métallurgie - Nanosciences - Plasma - Surfaces (IJL)
Université Henri Poincaré - Nancy I – CNRS : UMR7198 – Institut National Polytechnique de Lorraine (INPL) – Université Paul Verlaine - Metz

Sciences de l'environnement/Ingénierie de l'environnement

Planète et Univers/Interfaces continentales, environnement

Sciences de l'environnement/Milieux et Changements globaux
Goethite – Calcite – Nanocomposite – Precipitation – Removal – Metalloids – Heavy metals
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CEJ-D-12-02738.pdf(2.9 MB)