Continuous preparation of Fe3O4 nanoparticles using impinging stream-rotating packed bed reactor and magnetic property thereof

• Fe3O4 nanoparticles were prepared continuously through IS-RPB reactor.
• Gravity factor, liquid flow rate and the reactant concentration were optimized.
• Superparamagnetic and monodispersied Fe3O4 nanoparticles were obtained.
• Production rate of Fe3O4 nanoparticles reached 2.23 kg/h.

A novel impinging stream-rotating packed bed (IS-RPB) was adopted for preparing Fe3O4 nanoparticles via reactive precipitation using aqueous solutions of FeCl3/FeCl2 and NaOH as raw materials. In order to establish the optimum conditions for the preparation of monodispersed magnetite Fe3O4 particles, experimental conditions such as high gravity factor, liquid flow rate and reactant concentration were investigated in detail. It shows that the size of Fe3O4 nanoparticles became smaller under the higher gravity factor, liquid flow rate and reactant concentration. And the as-prepared Fe3O4 nanoparticles displays superparamagnetic behavior with the saturation magnetizations in the range from 39.0 to 74.0 emu/g. Based on the experimental results, a set of suitable operating parameters (high gravity factor of 65.32, liquid flow rates of 60 L/h and FeCl3·6H2O concentration of 0.321 mol/L) were recommended for the preparation of Fe3O4 nanoparticles. Under this condition, the as-prepared Fe3O4 nanoparticles is monodispersed quasi-spherical nanoparticles with an average diameter of about 8.9 nm and saturation magnetization of 60.5 emu/g, and the production rate reaches 2.23 kg/hour. Through the strong micromixing intensification performance of IS-RPB, this novel approach is suitable for industrial production of magnetic nanoparticles at massive scale.

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