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A fast route to obtain manganese spinel nanoparticles by reduction of K-birnessite |
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| Authors: | F Giovannelli T Chartier F Delorme M Zaghrioui |
| Institution: | a LEMA, UMR 6157 CNRS-CEA, Université François Rabelais, 3 place Jean Jaurès 41029 BLOIS, France b LEMA, UMR 6157 CNRS-CEA, Université François Rabelais, parc de Grandmont 37200 TOURS, France c BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 ORLEANS Cedex 2, France d CORNING SAS, CETC, 7 bis Avenue Valvins, 77210 AVON, France |
| Abstract: | The K-birnessite (KxMnO2·yH2O) reduction reaction has been tested in order to obtain manganese spinel nanoparticles. The addition of 0.25 weight percent of hydrazine hydrate, the reducing agent, during 24 hours is efficient to transform the birnessite powder in a hausmanite Mn3O4 powder. Well crystallised square shape nanoparticles are obtained. Different birnessite precursors have been tested and the reaction kinetics is strongly correlated to the crystallinity and granulometry of the precursor. The effects of aging time and hydrazine hydrate amount have been studied. Well crystallised Mn3O4 is obtained in one hour. The presence of feitknechtite (MnO(OH)) and amorphous nanorods has been detected as an intermediate phase during birnessite conversion into hausmanite. The conversion mechanism is discussed. |
| Keywords: | Nanoparticles Birnessite Hausmanite Reduction Spinel |
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