Research On The Synthesis Of β-FeOOH And Their Reduction Progress

β-FeOOH is an excellent functional material, it can be used as pigments, catalysts, precursor of magnetic recording medium, magnetic coating and a gas sensor,etc. β-FeOOH is good precursor for the synthesis of a variety of magnetic material (such as Fe3O4, y-Fe2O3 and Fe, etc). For example, the excellent properties of materials (iron or y-Fe2O3) used in video tape is obtained from P-FeOOH after high temperature calcination. This method can obtaining magnetic with excellent properties and low cost, therefore, it has good prospects of application. However, the controlled synthesis of P-FeOOH precursor, reduction process and conversion crafts of product are worth continuing to explore. In this paper, the requirements of high performance magnetic materials, combined with the features of reduction and environmentally friendly, focused on the design and preparation of P-FeOOH. And try to achieve a crafts approach to production all kinds of magnetic nanomaterials by use p-FeOOH as precursor. To study the features of reduction product and its conversion technologies, and exploring the possible formation mechanism of various magnetic products, etc.The main content of this thesis are as follows:1. Detailed description the research status of β-FeOOH, for example, the conventional production method, current main research direction, relationship between P-FeOOH and other iron oxides, main application and structural characteristics of β-FeOOH, etc. Based on the induction and summary, we suggested the possible research content solutions of β-FeOOH.2. Using different synthesis methods, successfully designed prepared five kinds of forms of β-FeOOH nanocrystals; we achieved a stable and low cost mass production of synthetic P-FeOOH nanomaterials. Morphology and properties of the products were characterized by XRD, SEM, TGA, etc. Compare and analysis the differences of products.3. Studied the reduction process of β-FeOOH nanocrystalline in the H2 atmosphere with reduction temperature from 100 ℃ to 650 ℃. We found it include four processes:dehydration (β-FeOOHâ†'2O3), partially reduced (Fe2O3â†'Fe3O4) and then fully restored (y-Fe2O3â†'Fe3O4/Fe). We achieved partially reduced and got polycrystalline Fe3O4 on the surface of the β-FeOOH nanorods.4. Focus on the possibility pressure-induced structural changes of layered structure β-FeOOH nanocrystalline,explored its reduction process and its possible mechanism in the sodium borohydride solution at 70 ℃. At a certain temperature, a closed water system, a concentration of sodium borohydride and β-FeOOH nanocrystalline had interaction; the transition of β-FeOOH can be described as: β-FeOOH â†'γ-FeOOH â†'Fe3O4. Under certain conditions, the structure can be controlled to obtain stable γ-FeOOH and Fe3O4 nano materials.5. By adding an appropriate amount of glucose, achieved an effective composite of two layered structure nanomaterials β-FeOOH and BiOCl. We successfully obtained excellent visible catalytic β-FeOOH/BiOCl composite photocatalyst. Photocatalytic experiments show that the new composite catalyst we obtained can effectively degrade methyl orange and the degradation rate is about 70%.6. Summarized the current research results, on the basis of existing work, we made an expectation of the research content, and provides some feasible experiment scheme for the study of late work.In short, the work expanded synthesis and transformation methods of β-FeOOH nanomaterials. Under the condition of gas and liquid phases, respectively, to explore gradual reduction inquiry of β-FeOOH nanocrystalline, let’s have a deeper understanding of the β-FeOOH reduction process, and successfully prepared an excellent catalytic β-FeOOH/BiOCl nanocomposites. These efforts can provide a new design reference for the development of new magnetic materials. It expected to provide new ideas for the establishment of organic pollutant control technology based on catalyst visible with practical value.