功能化四氧化三铁的合成和表征及其对钙离子的吸附

结合磁性纳米颗粒及功能基团各自的特性,设计了具有可以螯合金属离子的功能型磁性纳米颗粒,以获得选择性高、操作简易且回收后可重复利用的钙离子吸附剂.以三氯化铁和硫酸亚铁为铁源,采用化学共沉淀法在氩气保护下制备磁性纳米颗粒四氧化三铁;通过硅烷化反应在磁性纳米颗粒上依次包覆二氧化硅及γ-氨丙基三乙氧基硅烷.以甲基丙烯酸及乙二胺为原料通过迈克尔加成及酰胺化反应合成了含酰胺键、酯基、氨基功能基团的磁性纳米颗粒.X-射线粉末衍射线、傅立叶红外、扫描电镜、热重分析、X-射线光电子能谱等技术的分析结果表明已合成各中间体及功能化的纳米颗粒.原子吸收光谱研究表明该纳米颗粒可通过其配位基团按理论配比螯合钙离子.随着功能基含量的增加,吸附钙离子的能力也会随之增强,因此,含较多功能基的该类磁性纳米颗粒有望用作水中钙离子的吸附剂.

Synthesis and adsorption of calcium ions of functionalized core-shell Fe3O4 nanoparticles

Combining the characters of magnetic nanoparticles and function groups, the functionalized magnetic nanoparticles having chelating ability were designed in order to obtain calcium（II） adsorbent having higher selectivity, easy operation and recovery. Fe3O4 magnetic nanoparticles were synthesized by chemical co-precipitation in argon atmosphere using FeCl3 and FeSO4·7H2O as iron sources. Magnetic nanoparticles orderly coated with silica （Fe3O4 @ SiO2 ） and （3-aminopropyl） triethoxysilane （Fe3O4 @ SiO2-NH2 ） were prepared by silanization reaction. Amide/ester and amino groups- containing magnetic nanoparticles were obtained through Michael addition and amidation reaction using methyl acrylate （MA） and ethylenediamine （EDA） as materials. The intermediates and the functionalized nanoparticles have been obtained, which have been confirmed by X-Ray diffraction, Fourier infrared spectroscopy, Scanning electron microscope （SEM）, Thermogravimetric analysis, X- ray photoelectron spectroscopyspectra. The study of atomic absorption spectrum shows that the nanoparticles chelate calcium ions in accordance with the theoretical proportionality. The ability to absorb calcium（II） increases with the increase of the content of the functional groups, so this kind of magnetic nanoparticles with higher content of functional groups has potential to be used as a adsorbent of calcium（II） in water.