偕胺肟基螯合氧化硅的合成及其Cu^(2+)亲和性能

Synthesis and Copper(Ⅱ) Affinity Performance of Amidoxime Functionalized Mesoporous Silica

以氯化钾为晶体结构导向剂,以正硅酸乙酯和2-氰乙基三乙氧基硅烷为硅源,聚(乙二醇)-聚(丙二醇)-聚(乙二醇)三嵌段共聚物为模板剂,合成了偕胺肟基螯合氧化硅(AO-SBA-15)。通过X射线衍射(XRD)、低温氮气吸附–脱附、傅里叶红外光谱(FT-IR)、Zeta电位分析和元素分析技术对样品的结构、孔性质和螯合官能团等进行了表征。XRD分析结果表明,偕胺肟基螯合氧化硅材料具有有序的二维六方结构,通过氮气物理吸附数据计算得到材料的平均孔径和比表面积分别为3.96 nm和435 m^2/g。FT-IR分析表明将氰基成功地引入材料中并转化为偕胺肟基螯合官能团,元素分析发现材料的偕胺肟基含量约为1.6 mmol/g,此外,Zeta电位分析表明材料呈现电负性。相对未改性的氧化硅材料(SBA-15),AO-SBA-15对铜离子吸附容量提高了2倍;相对氰基功能化氧化硅(CN-SBA-15),AO-SBA-15吸附容量提高了3.6倍。这表明通过引入偕胺肟基螯合官能团,SBA-15对铜离子的亲和力得到显著提高。

Amidoxime-functionalized mesoporous silica was synthesized with tetraethylorthosilicate and 2-cyanoethyl triethoxysilane as silicon source, potassium chloride as the crystal structure directing agent and poly（ethylene glycol）-poly（propylene glycol）-poly（ethylene glycol） three block copolymers as template. The structure of the samples, pore properties and chelating function groups were characterized by X-ray powder diffraction（XRD）, Fourier-transform infrared spectroscopy（FT-IR）, N_2 adsorption desorption isotherms and elemental analysis. XRD spectra and N_2 physical adsorption-desorption results indicate that amidoxime functioned mesoporous silica has ordered two-dimensional hexagonal structure with average pore size of 3.96 nm and specific surface area of 435 m^2/g. FT-IR spectra shows that cyano is introducted into silica and converted into amidoxime successfully. Amidoxime concentration is about 1.6 mmol/g by elemental analysis and Zeta potential analysis results show that the adsorbent is electronegative. Compared with the Cu^（2＋） adsorption capacities of unmodified silica material（SBA-15） and cyano functionalization of porous silicon oxide（CN-SBA-15）, the adsorption capacity of AO-SBA-15 increases by 2 fold and 3.6 fold, respectively. This shows that with the introduction of amidoxime chelating function groups, affinity performance of SBA-15 to the copper ions are markedly improved.