Preparation
Pigment quality Fe3O4, so called synthetic magnetite, can be prepared using processes that utilise industrial wastes, scrap iron or solutions containing iron salts (e.g. those produced as by-products in industrial processes such as the acid vat treatment (pickling) of steel):
- Oxidation of Fe metal in the Laux process where nitrobenzene is reacted with iron metal using FeCl2 as a catalyst to produce aniline :
- C6H5NO2 + 3 Fe + 2 H2O → C6H5NH2 + Fe3O4
- Oxidation of FeII compounds, e.g. the precipitation of iron(II) salts as hydroxides followed by oxidation by aeration where careful control of the pH determines the oxide produced.
Reduction of Fe2O3 with hydrogen:
- 3Fe2O3 + H2 → 2Fe3O4 +H2O
Reduction of Fe2O3 with CO:
- 3Fe2O3 + CO → 2Fe3O4 + CO2
Production of nano-particles can be performed chemically by taking for example mixtures of FeII and FeIII salts and mixing them with alkali to precipitate colloidal Fe3O4. The reaction conditions are critical to the process and determine the particle size.
Read more about this topic: Iron(II,III) Oxide
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