磁性金属有机骨架材料 Fe3O4＠NH2-MIL-53（Al）的制备及对铅的吸附研究

摘要

Metal organic framework,a novel class of organic inorganic hybrid functional materials,has been widely used in the fields of gas adsorption,catalysis,separation,and biological medicine due to its large specific surface area,diverse structural, and adjustable channel.In this work,a new amine-functionalized magnetic metal-organic framework material was synthesized. Nano-Fe3 O4 was prepared by a solvothermal method,after which polyvinyl pyrrolidone was employed to modify Fe3 O4 .Finally, amino groups were introduced to prepare Fe3 O4 @NH2-MIL-53(Al).The crystal structure and functional groups of the material were characterized by means of X-ray diffraction (XRD)and Fourier transform infrared spectrometry (FT-IR).Combined with flame atomic absorption spectroscopy (FAAS),the adsorption of lead by the magnetic adsorbent was investigated.The magnetic adsorbent possesses high adsorption capacity because of the large specific surface area of Fe3 O4 @NH2-MIL-53(Al)and the coor-dination between amino group and lead.Experimental conditions affecting the adsorption percentage were discussed and the ex-perimental operation parameters were optimized (pH value of 6.0 and adsorption time of 120 min).Kinetics and thermodynamics studies were conducted for the adsorption process.Langmuir/Freundlich and pseudo-first-order/pseudo-second-order models were applied to analyze the experimental data.Thermodynamic functions,i.e.,changes of Gibbs energy,entropy,and enthal-py,were calculated from temperature experiments.In addition,the regeneration of the adsorbent was considered with hydro-chloric acid as the desorption solution.Several adsorption and desorption experiments were carried out,illustrating that the Fe3 O4 @NH2-MIL-53(Al)adsorbent can be used repeatedly.%金属有机骨架材料（metal organic framework）是一种新型的有机无机杂化功能材料，因具有大的比表面积、结构多样性和孔道可调控性，在气体吸附、催化、分离、生物医学等方面有着广泛的应用。研究合成了一种新型磁性金属有机骨架材料，首先通过溶剂热法合成纳米四氧化三铁，然后用聚乙烯吡咯烷酮对四氧化三铁进行表面修饰，并在合成过程中引入氨基，制备得到了氨基功能化的磁性材料 Fe3 O4＠NH2-MIL-53（Al）。通过 X 射线衍射（XRD）、傅里叶红外光谱（FTIR）表征手段，考察了 Fe3 O4＠NH2-MIL-53（Al）的晶体结构和功能基团。结合火焰原子吸收光谱法，研究其对铅的吸附性能。由于 Fe3 O4＠NH2-MIL-53（Al）具有大的比表面积及氨基对铅的配位作用，使磁性吸附剂对铅有较高的吸附能力。讨论了实验条件对吸附效率的影响，优化了实验操作参数（pH 值：6．0，吸附时间：120 min）。从动力学和热力学角度研究了Fe3 O4＠NH2-MIL-53（Al）对铅的吸附过程，分别通过 Langmuir／Freundlich 吸附模型和拟一级／拟二级动力学模型对实验结果进行了分析。通过温度实验，计算了热力学函数，即吉布斯自由能变、焓变、熵变。另外，用盐酸作为解吸液进行了多次吸附解吸实验，考察了该材料的再生性能，证明 Fe3 O4＠NH2-MIL-53（Al）可以实现重复使用。