Preparation and characterization of magnetite-silica nano-composite as adsorbents for removal of methylene blue dyes from environmental water samples

Magnetite-silica nano-composites (Fe₃O₄/SiO₂) adsorbent, which have been synthesized and characterized and were tested as an effective sorbent material for methylene blue (MB) dye removal from water samples. The nano-composites were prepared by a simple procedure via a coprecipitation of iron (II) and iron (III) ion mixture in ammonium hydroxide and then was impregnated by a sodium silicate, in various iron to silica ratios. The prepared samples were characterized using zeta potential, XRD, VSM, TEM and porosity analysis. The result of characterization showed that the prepared Fe₃O₄ nano-particles have been successfully coated by silica, to form Fe₃O₄/SiO₂ nano-composite. The nano-composite showed super-paramagnetic behavior at room temperature and contains both meso- and micro-porosity systems, in which the meso-porosity dominantly contributes to the pore volume. Adsorption performance of magneticsilica nano particles were examined by its ability to adsorb methylene blue (MB) dye in aqueous solution. Based on 20 mg/L MB as initial concentration, 1 gr/L adsorbent (Fe₃O₄/SiO₂) dose, when the Fe₃O₄/SiO₂ with ratio of iron to silica 3:1 was used, the remaining MB in solution was 13,3%. The composite was effective to adsorb MB in water and can be easily recovered from treated water with helping of external magnetic bar.