How does silica accumulate to make it disperse?
But obviously, in your experiment, Fe has been oxidized to Fe2O3, so it failed. It may be the amount of H2O2 used. It may be that O2 is in contact with the reaction system.The ideal Fe3O4 magnetic current is a black liquid that actually belongs to a colloidal dispersion system.If it is slightly brown, it means that some Fe2O3 is generated, as long as not much, and does not affect the nature of the magnetic fluid.And a little brown is to make sure that most of the Fe is converted to Fe3O4, because FeO is also black, and if it's only black, it's hard to tell whether a conversion has occurred.
The reaction is ferrous salt, such as FeCl2, oxidant, commonly used H2O2, easy to control, the environment is generally alkaline environment, alkaline environment of H2O2 oxidation is not too strong, but also easy to control. Note that N2 protection is used to avoid O2 contact because the Fe (OH) 2 generated during the process is oxidized to Fe (OH) 3 when exposed to O2.In the experiment, the dosage of H2O2 should be strictly controlled, and only part of Fe can be oxidized to + 3.
It is difficult to break even if the existing magnetite is broken and dispersed into the solvent. So it is usually prepared by reaction.
Fe3O4 has magnetic properties and can make magnetic fluids, whereas FeO and Fe2O3 do not have such properties.Magnetic fluid is actually magnetite, dispersed in a specific solvent with very small particles, and can be a mixed solvent of polyethylene glycol and water.
