Synthesis Of Functionalized Fe₃O₄ Micro/Nano Structures For Cr???adsorption

Due to the good biocompatibility,unique magnetic properties,Fe₃O₄ has shown great application prospect in many fields,for example magnetic recording materials,absorbing materials,catalysts,magnetic materials,magnetic resonance imaging,magnetic storage medium materials as well as drug carrier and so on,and has a wide range of application prospects in the field in heavy metal waste water treatment and other environmental protection.In this study,we used hydrothermal to prepare the Fe₃O₄ particles with different morphologies.We used solvethermal method to synthesize Fe₃O₄ nanoparticles with different particle sizes,and selected the particles with uniform size and good dispersion sample as the adsorbent for the adsorption of Cr???in aqueous solution.The main contents of this paper include:?1?the synthesis and properties of magnetite grains with different morphologiesWe used ferrous sulfate and sodium acetate as raw material,triethanolamine?TEA?as additive to prepare Fe₃O₄ particles with different morphologies by hydrothermal method,and the product was characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,vibrating sample magnetometer?VSM?.In this experiment,the morphology of Fe₃O₄ can be easily adjusted by changing the amount of sodium acetate and TEA.Experiments showed that using triethanolamine alone as the alkali source,the synthesized Fe₃O₄ nanoparticles were similar to cube structure,with average particle size of about 50 nm.When the addition amount of triethanolamine was remained unchanged,gradually increasing the content of sodium acetate leaded to increasing OH-concentration in solution,the morphology of Fe₃O₄ with similar spherical structure with 700 nm diameter evolved into octahedral structure with the particle size of about 1.5?m,then changed to edge and corner truncated octahedra with the average particle size about 2.0?m,and finally the formation of diameter of about 30 nm spherical.Research the mechanism of evolution of morphology of Fe₃O₄ by ion selective adsorption of OH-on crystal surfaces.?2?Synthesis and adsorption properties of Fe₃O₄ microspheres with different particle sizesFe₃O₄ microspheres with different particle sizes were synthesized by solvothermal method,using ferric chloride,sodium acetate as raw material,triethanolamine as an additive.The properties such as crystal structure and morphology of the products were characterized by XRD,SEM,TEM,FT-IR and VSM.The experimental results showed that with the increasing of the content of triethanolamine in the preparation process,particle size of Fe₃O₄ microspheres decreased.The well dispersed samples in aqueous was used as absorbent for the adsorption of Cr?VI?ion.The effects of temperature,pH and initial Cr?VI?ion concentration on the adsorption properties of Fe₃O₄ nanoparticles were studied.The adsorption isotherm and presumed mechanism of Cr???adsorption were studied.After 60 min,the equilibrium time of the Cr???adsorption was basically reached at pH 2.0.With the increasing of the initial concentration,the adsorption capacity of Fe₃O₄ nanoparticles for Cr???ion gradually increased e and the saturation adsorption capacity was 56.6mg/g.The adsorption capacity increased with the solution temperature increasing.The fitting results showed that the adsorption process was in accordance with the Langmuir isotherm model.By XRD and XPS analysis for the Cr???-loaded sample,the adsorption process was combined with physical adsorption and chemical adsorption and the morphology and magnetic properties of the adsorbent were still good after adsorption.