Preparation,Characterization And Properties Of Iron-based Magnetic Functional Nanomaterials

The nanometer scale magnetic material has the magnetism performance which does not have in the macroscopic condition,has the important theory significance to the magnetism chemistry,the interfacial chemistry,the photocatalysis reaction and so on the domain.The functional materials based on the corresponding principle can be applied in the fields of environmental protection,biomedicine and clinical diagnosis,and have broad and far-reaching application prospect.Iron-based magnetic functional nanomaterials,as one of the most important classes,because of its special magnetic properties,such as super paramagnetic,high coercivity,low curie temperature and high magnetic susceptibility and interfacial chemical activity,have received extensive attention from academic and practical perspectives.It is one of the main themes of chemistry to prepare new functional substances and to solve the major ecological and environmental problems.The previous study found that iron-based magnetic functional nanomaterials have important application value in the photocatalytic treatment of refractory organic pollutants and in the diagnosis of cancer:First,the difficulty of solving the problem of natural environmental pollution lies in the continuous accumulation of refractory organics with the emission of industrial and domestic waste.Photocatalytic technology is one of the main solutions.It is a major challenge for the development of related technologies to produce high efficiency photocatalysts with nano size and specific morphology（inhibition of optical carrier recombination）,excellent performance and easy separation after use.Second,the further development of magnetic resonance imaging（MRI）as a major diagnostic technique for cancer is the preparation of a single dispersion of magnetic resonance contrast agents with superparamagnetic,high relativity and bio-compatibility.The results show that the unique properties of iron-based magnetic functional nanomaterials can be used to solve these two problems.However,the preparation and characterization of this kind of materials,as well as the relationship between magnetic and interfacial structures and the chemical kinetics properties of the materials have not been analyzed and discussed in detail,which restricts the deep development and wide application of such materials.In the present dissertation,we investigated the preparation,characterization and magnetic properties ofα-Fe₂O₃,α-Fe₂O₃@Ag,MnFe₂O₄,Fe₃O₄,CoFe₂O₄,NiFe₂O₄and ZnFe₂O₄ magnetic nanomaterials and explored the potential applications in photocatalysis and magnetic resonance imaging.The magnetic properties,crystallinity,stability,catalytic properties and in vitro imaging properties of the above materials were analyzed thoroughly,and their important application prospects in photocatalysis and magnetic resonance imaging were discussed.The main contents include:First,α-Fe₂O₃ based nanomaterials were prepared and characterized systematically;the relationship between theα-Fe₂O₃ based nanomaterials and their photocatalytic properties and the nanostructure（size,morphology,etc.）were investigated,and the photocatalytic properties were enhanced through silver coating.Iron-based magnetic nanomaterials such asα-Fe₂O₃ nanoflowers,α-Fe₂O₃@Ag composite andα-Fe₂O₃ nanoparticles were successfully prepared by template-free solvothermal method.Theα-Fe₂O₃ nanoflowers were modified by coating Ag nanoparticles.The size,morphology,crystallinity and magnetic properties of the products were characterized and measured using X-ray diffraction（XRD）,Scanning electron microscopy（SEM）,Transmission electron microscopy（TEM）,High resolution transmission electron diffraction（HRTEM）,X-ray photoelectron spectroscopy Analyzer（XPS）,Fourier transform infrared spectroscopy（FTIR）,fully automatic specific surface area and pore Analyzer（BET）and Superconducting quantum interference device（SQUID）.The effects of reaction time and reaction temperature on the nano properties of the samples were systematically studied.The photocatalytic activity of the samples prepared at various experimental conditions toward organic dyes rhodamine B and methyl orange was studied systematically.The experimental results showed thatα-Fe₂O₃ nanoflowers（S1）,α-Fe₂O₃@Ag composite andα-Fe₂O₃ nanoparticles（S6）exhibited excellent photocatalytic performance compared with those samples prepared under other conditions was due to the special morphology（Theα-Fe₂O₃ nanoflowers（S1）surface has short pricks,with short charge carrier diffusion distances）and sizes of the samples,Ag is coated on the surface ofα-Fe₂O₃ nanoscale,and produces plasma resonance on the surface of a-Fe₂O₃@Ag composite nanomaterial,which makes the catalyst enhance the absorption efficiency and improve its photocatalytic performance,and could be used as potential photocatalyst substitute for current related materials used in sewage treatment.Second,the magnetic resonance imaging properties and optimization rules of a seriesofsuperparamagneticironbasednanoparticleswerediscussed.Superparamagnetic MFe₂O₄（M=Mn,Fe,Co,Ni,Zn）nanoparticles were successfully prepared by template-free solvothermal method.The size,morphology,crystallization and magnetic properties of the as prepared products were characterized using（XRD）,（SEM）,（TEM）,（HRTEM）,（XPS）,（FTIR）,（BET）and（SQUID）.We investigated systematically the effects of reaction time and reaction temperature on the size,morphology,crystallinity and magnetic properties of the as prepared samples.On the comprehensive analysis of the above properties and colloidal stability of the prepared samples,we selected the superparamagnetic MnFe₂O₄（MF1）,Fe₃O₄（F1）,CoFe₂O₄（CF1）,NiFe₂O₄（NF1）and ZnFe₂O₄（ZF1）as research object to investigate the magnetic resonance imaging properties using using the low field NMR imaging and Analysis System（MESOMR23-060H-I）.The experimental results showed that the superparamagnetic Fe₃O₄（F1）,CoFe₂O₄（CF1）and Ni Fe₂O₄（NF1）nanoparticles exhibit a good T₂-weighted imaging effect and could be used as a potential substitute for clinically relevant magnetic resonance contrast agent for clinical medical diagnosis.To sum up,this research has obtained the progress of preparation method and functional analysis of iron-based magnetic functional nanomaterials,which provides the chemical kinetics and magnetic basis for the application of this kind of nanomaterials in wastewater treatment and magnetic resonance imaging.On this basis,it expands its practical research and industrial application of materials,and paves the way for further in-depth study of the working efficiency and in-depth mechanism of this kind of functional materials,which has important theoretical value and practical application value.