磁性纳米颗粒/SiO_2多孔复合干凝胶的制备及表征

Preparation and Characterization of Magnetic Nanoparticles/SiO_2 Porous Composite Xerogels

采用溶胶-凝胶伴随相分离法通过原位合成镍铜铁氧体尖晶石纳米颗粒制备出新型磁性复合多孔SiO_2干凝胶,并对其显微结构、磁性和吸附性能进行了表征。结果表明:前驱体中水解缩合的乙醇酸以有机分子链的形式与无机分子相结合并构成骨架,形成双连续孔结构,尖晶石纳米颗粒均匀分布在二氧化硅基体中。随热处理温度的升高,样品的比表面积迅速下降,但磁化强度增强。经过700℃热处理后的样品S3,孔隙率为73.22%,体积密度为0.32 g/cm3,平均粒度为16μm,能够有效吸附溶液中的Ce(IV),最大吸附容量为100.67 mg/g。此外,样品S3呈现出较好的磁性分离特性和重复利用性。

A magnetic porous aerogel composite was prepared via a sol-gel method and in-situ synthesis of Ni/Cu ferrite spinel. The microstructure, magnetism and adsorption ability were characterized. The results show that the organic molecular chain of glycollic acid in precursor is combined with inorganic phase to form the skeleton and the doublely-connected pore structure, the porosity of as-synthesized composite aerogels is 73.22%, and the bulk density is 0.36 g/cm^3, with an average grading of 16 μm; the magnetic nanoparticles distribute uniformly in the SiO2 matrix. The specific surface area of samples decreases and the saturation magnetization increases with the increase of the calcination temperature. The composite as-prepared presents a maximum capacity of 100.67 mg/g, can adsorb Ce（IV） from aqueous solution at a a superior performance of recycle ability, and can be separated by a magnetic field.