Abstract

The aim of this study was to develop synthetic magnetite nanoparticles (Fe3O4) and its impregnated onto rice husk ash for
possible environmental applications as adsorbents. The synthetic magnetite – nanoparticles (MNP – Fe3O4) obtained through the
chemical coprecipitation of both Fe2+ and Fe3+ ions (Fe2+/Fe3+ = 2:3 ratio). The resulting particles were characterized by Fourier-
transform infrared spectroscopy, UV visible spectrophotometer, and X-ray diffraction spectrophotometer. Fe3O4 displayed a
wide specific surface area (160 m2 g-1) with particles reaching a size of about 27 nm and its impregnated ones (Fe3O4/RHA)
estimated at 17 nm while showing a surface area of 179 m²g-1. The magnetization measurements, at room temperature, showed
that the particles are in the superparamagnetic regime. Magnetite was also synthesized in acid solutions in basic environment
(26% ammonia solution), a medium that allows to proceed by the chemical coprecipitation process in two step reaction. The
superparamagnetic behavior is preserved, although its saturation is probably due to the contribution of the smallest particles.