Synthesis and size control of ferric oxide nanoparticles via a hydrothermal stripping route

A simple, environmentally friendly hydrothermal stripping route for synthesizing highly size-controlled spherical ferric oxide nanoparticles was developed that involved stripping ferric ion from iron-loaded organic phase. The particle size was found to be influenced by the initial concentration of iron in organic phase, stripping temperature and time, and a mathematical model about the size was established based on the experimental results and theoretical analysis. The model suggests that the process apparent activation energy of stripping iron from organic phase is 97.3 kJ·mol−1, the energy of crystal growth is 51.6 kJ·mol−1, and the synthesis of Fe2O3 is controlled by the crystal growth of embryo at low temperature (T < 590 K). The sizes calculated by the model comparatively accord with the experimental data and this provides a method for controlling the sizes.