Iron Oxide Nanoparticles, The Preparation And Thermodynamic Properties Of The Suspension

As the important industry materials, iron oxide nanomaterials have been widely used in various important fields, such as catalysis, pigments, gas sensor, magnetic recording material and biomedicine. Therefore, the controlled fabrication iron oxide nanomaterials have attracted more and more attention in recent years. In this paper, iron oxide nanomaterials have been successfully synthesized via hydrothermal method. The effects of the difference synthetic conditions on the shape, size, structure and phase composition were studied systematically, Moreover, the formation mechanisms of the as-prepared samples were discussed. The main works completed are summed up as following:Water-based hematite (α-Fe2O3) nanofluid was prepared via hydrothermal route with the FeCl3·6H2O and L-glutamic acid as the starting materials at low reaction temperature. L-glutamic acid was introduced into the reaction system, which played a key role in the formation of the stable hematite nanofluids. The molar heat capacities of the obtained nanofluids, basefluids and hematite nanoparticles were measured by a high-precision automatic adiabatic calorimeter in the temperature range of 290-335 K, respectively. Based on the as-obtained molar heat capacities, the excess heat capacities of nanofluids were calculated. The experimental data revealed that the stable hematite nanofluids exhibit unique properties compared with the unstable nanofluids. These obtained molar heat capacities are very useful to further study the heat conductivity process for nanofluids.Different morphologies ofβ-FeOOH nanomaterials including rod-like and spindle shape were synthesized via a hydrothermal reaction with the FeCl3·6H2O and urea as the starting materials at low temperature. The molar heat capacities of rod-like and spindle shapeβ-FeOOH nanomaterials were determined by a high-precision automatic adiabatic calorimeter in the temperature range of 78-390K, respectively. The experimental results show that the molar heat capacities were different between rod-like and spindle shapeβ-FeOOH nanomaterials at the same temperature. In addition, the as-prepared samples were also characterized by X-ray powder diffraction (XRD), Transmission electron microscopy (TEM) and Thermal gravimetric analysis (TGA).One-dimensional goethite (α-FeOOH) nanorods were successfully fabricated by a ligand-assisted hydrothermal synthetic route. X-ray diffraction (XRD), Transmission electron microscopy (TEM), High-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectrum (FT-IR) have been used to characterize the as-prepared samples, respectively. The experimental results reveal that the concentration of the iron salts and ethylenediaminetetraacetic acid (EDTA) have great influences on the phase composition and morphology of the as-synthesized products. In addition, the influence of the reaction temperature, inorganic salts and surfactants on the as-synthesized products has also been studied. The experimental results indicated that the reaction temperature, inorganic salts and surfactants have greatly influence on the sizes of the as-prepared samples. Moreover, the possible formation mechanism for the one-dimensional goethite nanorod has also been discussed.A simple and novel one-step hydrothermal route to the preparation of magnetite (Fe3O4) has been successfully developed by use of FeCl3·6H2O as iron precursor and trisodium citrate as the reducing reagent. The particle sizes of the as-prepared Fe3O4 nanoparticles can be controlled by adjusting the concentration of trisodium citrate. The experimental results reveal that the concentration of Fe3+, the reaction temperature, and the concentration of NaOH have significant effect on the morphologies and phase composition of the final products. The synthesized Fe3O4 nanoparticles can be well dispersed in distilled water to form Fe3O4 suspensions. The as-prepared Fe3O4 nanoparticles exhibit a superparamagnetic behavior with with negligible coercivity and remanence. Furthermore, a possible reaction mechanism was proposed to explain that why the magnetite nanoparticles can be formed in the trisodium citrate solution.