Size-controlled synthesis of Fe2O3 and Fe3O4 nanoparticles onto zeolite by means of a modified activated-coprecipitation method: effect of the HCl concentration during the activation

Synthetic sodium type A zeolite bearing Fe2O3 and Fe3O4 nanoparticles composites have been prepared by means of a coprecipitation method with two different activation methodologies, one using Sn and the other using Sn/Pd nanoparticles as activators. Sn activation generates hematite nanoparticles while Sn/Pd produces magnetite nanoparticles. Amount of HCl used during the activation of the zeolite with SnCl2 showed a correlation between the stannous activating species and the particle size. Both Sn and Sn-Pd activated nanocomposites show nearly narrow size distributions but only those iron oxides obtained with Sn-Pd showed supermagnetism.