应用光谱-电镜-热解析手段表征两种金属有机配合物及其对多环芳烃的吸附性能研究

The Characterization of Two Metal-Organic Complexes Investigated by Spectroscopy,Electron Microscope and Thermogravimetric Analysis and Their Adsorption Behaviour for Polycyclic Aromatic Hydrocarbons

近几年来,金属有机配合物（MOFs）作为环境中痕量多环芳烃（PAHs）的吸附预富集材料仅局限于几种经典的配合物,在实际的分离检测过程中,很少能分析分离结构性质相似的目标物,对相近性质目标物的吸附选择性较差。本文选择配体5-氨基间苯二甲酸以及主体锌离子和铜离子为原料,应用溶剂热合成法合成2种金属有机配合物：锌-5-氨基间苯二甲酸和铜-5-氨基间苯二甲酸,研究了主体不同的配合物应用于固相萃取预富集10种PAHs的吸附效果、吸附行为和吸附选择性。结果表明：12种金属配合物对PAHs的平衡吸附量均在30 mg/g以上,在40 h内对PAHs的吸附率达75%以上,吸附选择性因子（αij）最高可达11.4,高于经典MOF-5材料（αij=10.9）;2种配合物吸附PAHs符合拟二级动力学模型,相关系数（R2）的范围为0.9179-0.9995;吸附行为符合Langmuir和Freundlich方程。2扫描电镜、X射线粉末衍射、红外光谱等结构表征表明,锌-5-氨基间苯二甲酸和铜-5-氨基间苯二甲酸分别呈棒状和块状结构,且颗粒大小均匀一致,都可以作为选择性预富集材料应用于吸附结构相似的混合PAHs,并通过优化后作为色谱柱固定相分析分离检测PAHs。由于锌-5-氨基间苯二甲酸和铜-5-氨基间苯二甲酸比表面积分别为20.392 m^2/g和7.44 m^2/g,锌-5-氨基间苯二甲酸的预富集能力和吸附效果均优于铜-5-氨基间苯二甲酸,且对PAHs的吸附效果相近,可以作为预富集材料使用,而铜-5-氨基间苯二甲酸对PAHs的吸附存在差异,可以作为选择性吸附材料使用。

The classification of metal-organic framework（ MOFs） is presently restricted to a few classical structures of MOFs for solid phase extraction of polycyclic aromatic hydrocarbons（ PAHs）. However,separation of a similar construction of analytes and selectivity are not satisfactory using these MOFs in many cases. In the work presented herein,aminoisophthalic was selected as the ligand and copper ion and zinc ion as the subjects to prepare two metal-organic frameworks（ [Zn（ C8NH5O4）（ H2O） ] and [Cu（ C8H6NO4）2（ H2O） ]） by the hydrothermal synthesis method. Adsorption capacity,adsorption behavior and adsorption selectivity of two MOFs were studied for ten PAHs. The results indicate that 1 the equilibrium adsorption capacity for PAHs are 〉30 mg / g and adsorption rates are〉 75%. The highest selectivity of two as-prepared MOFs reached 11. 4,exceeding the classical MOF-5（ αij= 10. 9）. Adsorption of PAHs on two as-prepared MOFs could be well described by the pseudo-second order kinetic model,with correlation coefficients R^2 of 0. 9179- 0. 9995. The PAHs adsorption behavior of two MOFs is in accordance with the Langmuir model and Freundlich equation with correlation coefficients R^2 of 0. 8452- 0.9993. 2The shapes of [Zn（ C8NH5O4）（ H2O） ] and [Cu（ C8H6NO4）2（ H2O） ] are rod and bulk,respectively,with homogeneous distribution from evidence of Scanning Electron Microscopy,X-ray Photoelectron Spectroscopy and Infrared Spectroscopy. Specific surface areas of [Zn（ C8NH5O4）（ H2O） ] and [Cu（ C8H6NO4）2（ H2O） ] are20. 392 m^2/ g and 7. 44 m^2/ g,respectively. Adsorption capacity of [Zn（ C8NH5O4）（ H2O） ] is better than[Cu（ C8H6NO4）2（ H2O） ]. Comparatively,[Zn（ C8NH5O4）（ H2O） ] can be applied as the material for preconcentration of PAHs and [Cu（ C8H6NO4）2H2O] as the packing column material for separation of PAHs.