Magnetite in nanoparticulate form
The present invention relates to a process for the polyol-type synthesis of nanoparticulate magnetite starting from mixtures of Fe 0 and Fe1 III in the presence of a mineral acid. The magnetite particles obtainable from the process have uniform size characteristics and have even presented higher SAR (Specific Absorption Rate) values than those of magnetosomes.
1. A process for preparing magnetite nanoparticles, said process comprising a step (ii) wherein said nanoparticles are prepared from a mixture comprising a polyalcohol solvent, metallic iron, Fe III from a salt soluble in the polyalcohol solvent, a catalyst and a quantity of water in a molar amount equal to 1.5-5 times the moles of the salt.
2. Process according to claim 1 wherein said polyalcohol solvent is selected from the group consisting of glycerine, propylene glycol and ethylene glycol.
3. Process according to claim 1 wherein said catalyst is chosen from mineral acids.
4. Process according to claim 1 wherein the salt comprises iron acetate.
5. Process according to claim 1 wherein said Fe III salt is added to the mixture in the form of a polyalcohol solution.
6. Process according to claim 1 wherein said Fe III is added to the reaction mixture at a rate such that a temperature variation during the addition is less than 10° C.
7. Process according to claim 1 wherein step (ii) is preceded by a preparation step (i) of a polyalcohol solution of Fe III starting from Fe 0 , wherein said step (i) comprises the following steps:
(a) preparing a Fe II solution starting from Fe 0 in a polyalcohol solvent and in the presence of an organic acid; and
(b) preparing a Fe III solution by bubbling air into the solution obtained from step (a).