Method for preparing core-shell structured SiO2/Fe3O4 compound magnetic particle

Abstract

The invention discloses a method for preparing a core-shell structured SiO2 / Fe3O4 magnetic particle. The core-shell structured SiO2 / Fe3O4 magnetic particle is characterized in that Fe3O4 is used as the magnetic core and SiO2 is used as the shell to form the SiO2 / Fe3O4 core-shell covering structure. The method comprises the following steps: under the heat condition of a solvent glycol, taking ferric chloride as the Fe source, sodium acetate as a reducing agent and a right amount of polyethylene glycol as a dispersing agent, heating the system to 150-180 DEG C and then preserving heat for several hours; and after washing and drying, mixing the synthesized Fe3O4 powder with a right amount of absolute ethyl alcohol, deionized water and surfactants, dropwise adding a certain amount of stronger ammonia water, after ultrasonic dispersion, slowly dropwise adding tetraethoxysilane under the condition of stirring, continuing stirring for reaction for several hours and then washing and drying the product, thus obtaining the SiO2 / Fe3O4 compound particle. The method has the following advantages: the process is simple; the cost is low; the reaction conditions are easy to control; the core-shell structured SiO2 / Fe3O4 magnetic particle can be produced in a large scale; and therefore, the method has a good application prospect.

Description

technical field [0001] The invention relates to a core-shell structure SiO used as a magnetic carrier 2 / Fe 3 o 4 The particle preparation method belongs to the technical field of nanometer material preparation. technical background [0002] Magnetic Fe 3 o 4 As a new type of functional material, microspheres have good magnetic properties, such as superparamagnetism and high saturation magnetization, and are used as magnetic recording materials, magnetic liquids, sensors, catalyst carriers, permanent magnetic materials, pigments, radar wave Absorbing materials and other aspects have broad application prospects. However, due to the high specific surface area and strong aggregation tendency of magnetic nanoparticles, and the low chemical stability and easy oxidation, it is difficult to be directly applied. To solve these problems, surface modification of magnetic nanoparticles is necessary to stabilize them. In recent years, the inorganic material SiO 2 Due to its exce...

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Problems solved by technology

SiO prepared by microemulsion method 2 / Fe 3 o 4 The size of the magnetic composite particles is uniform and the dispersion is good. However, due to the limitation of the stability of the microemulsion system, the adjustable particle size range of the synthesized magnetic composite particles is limited, and the microemulsion system is very sensitive to the preparation temperature and component changes. However, the sol-gel method is favored by people because of its simple process, environmental friendliness and advantages of large-scale production. However, the structure and structure of the composite magnetic particles obtained by this method The morphology is easily affected by the shape and particle size of the prepared magnetic core, and the preparation process of the original magnetic core is highly demanding

Therefore, the sol-gel method is currently being used to form SiO 2 / Fe 3 o 4 In the reports of composite magnetic nanoparticles, due to the poor control of the structure of the magnetic core, many composite particles did not form a shell-core structure with a more obvious coating effect, and SiO 2 The thickness of the cladding layer is uneven, and the agglomeration between the magnetic cores is serious

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