マグネタイトの水熱合成に及ぼす Ni^<2+>, Co^<2+>, Cu^<2+>, Pd^<2+>イオン添加の影響

概要

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A new approach for the synthesis of spinel-type ferrites under hydrothermal conditions has been investigated using the Schikorr reaction method. Magnetite was synthesized using ferrous sulfate solution containing small amounts of metal ions, including Ni2+, Co2+, Cu2+ and Pd2+ ions, respectively. Other workers have achieved the synthesis of magnetite above 160 °C by the Schikorr reaction, but the present work shows addition of Ni2+ ions is the most influential factor effecting acceleration of the reaction. In this study, low temperature (at 110 °C) magnetite synthesis was achieved by addition of Ni2+ (Ni / Fe = 0.34 mol%). Ni2+ is likely to be reduced by H2 generated during the Schikorr reaction, with the newly formed Ni metal providing the catalyst to accelerate the dehydrogenation reaction. The most effective reaction mechanism for synthesis of magnetite above 150 °C is the Schikorr reaction, although other magnetite formation mechanisms may be effective at reaction temperatures less than 150 °C. During the Schikorr reaction, Fe2+ in solution is oxidized to Fe3+ accompanying the oxidation of Fe2+ to Fe3+ due to reduction of SOM42-.
社団法人資源・素材学会の論文
2003-08-25