Preparation And Performance Study Of Sepiolite@triferroferric Oxide Magnetic Orientation Material

In this paper,natural mineral sepiolite was used as the matrix,iron salt hydrate as the magnetic source,polyethylenimine as the surfactant,sodium citrate as the dispersant,and the core-shell structure Sep@Fe₃O₄ ferromagnetically oriented composite was prepared by coprecipitation method.By X-ray diffraction（XRD）,transmission electron microscopy（TEM）,infrared spectrum and polarization microscope,hysteresis loop,such as characterization method,studied the dosage of ferric salts,alkali adding order,kind,add the order and amount of dispersants,and the preparation conditions on the Sep@Fe₃O₄ composite material of the structure,morphology,sepiolite is ferroferric oxide coated effect,discusses the system composition of Sep@Fe₃O₄ composite gel the effect on the stability of the system.The results are as follows:（1）The optimal preparation process of Sep@Fe₃O₄ was determined:firstly,sepiolite was modified with PEI,then sepiolite was modified with iron salt according to the molar ratio of Fe³⁺:Fe²⁺=2:1 for 5 min,and the system was alkalized with concentrated ammonia water for 30 min to prepare Sep@Fe₃O₄ composite.（2）Sodium citrate can effectively avoid the aggregation of ferric oxide nanoparticles.When the concentration of sodium citrate in the system is 50 mg/L,Sep@Fe₃O₄composite material with uniform shell and core structure can be prepared.After drying,Sep@Fe₃O₄ composite material has obvious orientation under transmission electron microscope,which means that Sep@Fe₃O₄ composite material with magnetogenic orientation and superparamagnetic properties has been obtained.（3）Sep@Fe₃O₄ has different colloid stability in different systems.Stable colloid could be formed in the hydrochloric acid（HCl）system at 0.01 mol/L.However,when the concentration was 0.01 mol/L,the strong polar solvent dimethyl sulfoxide and magnesium chloride solution could not form stable Sep@Fe₃O₄ colloid.（4）Sep@Fe₃O₄ ferromagnetic orientation composite material colloids have obvious characteristics of magnetotropism and liquid crystal.