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Magnetic nanoparticles for applications in separation
and purification processes must satisfy several basic
requirements. They should be superparamagnetic, i.e. possess
low coercivity (Hc) and low retentivity (Mr), to enable re-
dispersion after magnetic capture. In this study, the synthesis of
SiO2 coated g -Fe2O3 nanocomposite
particles has been
attempted to achieve the above magnetic properties. The
synthesis method is based on the decomposition and oxidation
of two metalorganic precursor, iron (III) acetylacetonate and
tetraethylorthosilicate (TEOS) by the chemical vapor
condensation process. The synthesized SiO2 coated
g-Fe2O3
nanoparticles consisted of large amount of amorphous SiO2
phase shell enclosing the crystalline 20~30 nm
g -Fe2O3
nanoparticle core. The Hc and Mr values of SiO2 coated
g-Fe2O3
nanoparticles were 34.5 Oe and 0.118 emu/g, respectively.
These low Hc and Mr values were the results of very fine and
spherical g-Fe2O3 particles well
dispersed in the SiO2 matrix.
Also, from FT-IR analysis it was shown that the surface
properties of the coated nanoparticles were similar to those of
conventional fumed silica. Finally, the feasibility of SiO2 coated g-
Fe2O3 nanoparticle for magnetic
separation media in various bio
processes was discussed.
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