Synthesis of iron oxide nanoparticles with different morphologies by precipitation method with and without chitosan addition

Abstract

In this work, iron oxide nanoparticles with various morphologies were synthesized by the precipitation method from aqueous solutions of iron oxide chlorides and urea in the absence or presence of chitosan. Synthesis conditions were selected to yield magnetite nanoparticles with three different morphologies. By adding chitosan, we were able to change the morphologies of the Fe3O4 nanoparticles from cubo-octahedral, flower-like, and rod-like structures to cubic, quasi-spherical, and rice-seed-like structures, respectively. The size of these iron oxide structures were in the range of 28125 nm, while the longitudinal sizes of the rod-like and rice-seed-like structures were 1101000 and 75290 nm, respectively. Transmission electron microscopy (TEM) results showed that the magnetite nanostructures synthesized in the presence of chitosan have a mesoporous structure and are composed of many nanocrystals. The mechanisms responsible for the formation of differently shaped iron oxides in the presence or absence of chitosan are analyzed and discussed. We observed that the growth mechanism changed from the classical route to the reverse growth mechanism, when chitosan was added to the synthesis solution.