سید مجید هاشمی

Magnetite (Fe3O4) nanoparticles were prepared using Cystoseira brown algae extract and FeCl3.6H2O salt. These nanoparticles were characterized by XRD and FESEM methods. XRD pattern showed that the particles were crystalized in a cubic structure with a size of 22 nm for the crystallites. FESEM images showed that the particles are spherical with an average size of 28 nm. ZnFe2O4/Fe3O4 nanoparticles were synthesized using Fe3O4 and ZnSO4 salt in the presence and in the absent of Cystoseira brown algae extract. These nanoparticles were characterized by XRD, FESEM, EDX, VSM and FTIR methods. XRD patterns showed that both the nanoparticles were crystlized in cubic structure with a size of 13.2 nm for the nanocrystallites prepared in the presence of the algae extract and 15 nm for the nanocrystallites prepared in the absence of the algae extract. FESEM images showed spherical particles with an average size of 30 nm in both cases. VSM results showed that the two prepared ZnFe2O4/Fe3O4 nanoparticles have similar magnetic properties but smaller than Fe3O4 nanoparticles. The tendency of prepared nanoparticles for adsorption of methylene blue dye from aquous solution at 25 ?C at 3 different pH was studied by means of UV-Vis spectrometer. It was shown that the ZnFe2O4/Fe3O4 nanoparticles prepared in the presence of algae extract were better adsorbant than the ZnFe2O4/Fe3O4 nanoparticles prepared in the presence of algae extract or Fe3O4 nanoparticles. It could be due to greater amount of porosity and the higher surface area of these nanoparticles. The specific surface area was determination by BET method to be 47.0589 m2/g. The average pore diameter and cumulative surface area of pores were determined by BJH method to be 5.9736 nm and 57.14 m2/g respectively. The adsorption-desorption isotherm of BET showed the presence of cylindrical pores using the IUPAC method.