Continuous synthesis of magnetite nanoparticles in supercritical methanol

Magnetite (Fe3O4) nanoparticles are synthesized continuously in supercritical methanol (scMeOH) without using reducing agents at 30 MPa, 400 °C and a residence time of 38 s. XRD analysis reveals that particles synthesized in scMeOH retain magnetite crystalline structure while particles synthesized in supercritical water retain hematite (α-Fe2O3) crystalline structure. The scMeOH acts both as a reaction medium and a reducing agent. The magnetite nanoparticles are spherical in shape with an average diameter of 21 ± 2 nm, as measured using SEM and TEM. The saturation magnetization of the magnetite nanoparticle is 76.6 emu/g.