两种氨基MOFs对水中有机污染物吸附性能的研究

发布时间：2018-06-19 01:28

  本文选题：金属-有机骨架材料 + 染料　； 参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：随着经济全球化和科技的飞速发展,由染料、酚类等有机污染物造成的水污染现象日趋严峻,如何高效的去除水中污染物是生物环境领域中的重要课题。吸附法具有操作简单、经济和可回收利用等优点,是高效去除水中污染物的常见方法之一。但活性炭、沸石等传统多孔吸附剂的选择性和吸附量均不理想,因此开发具有高吸附性能的多孔材料具有重要意义。金属-有机骨架材料(Metal-organic frameworks,MOFs)是一类由有机配体和金属中心自组装形成的多孔性结晶材料。MOFs具有比表面积大、孔隙率高、孔径结构可调和金属活性位点等优点,因此具有良好的吸附性能。MOFs在吸附去除水体有机污染物领域具有良好的应用前景,并引起了人们对MOFs材料的设计开发及应用领域的广泛关注。本文制备了两种性能优异的氨基MOFs材料,分别应用于对水体污染物染料和酚类的吸附,探索其在吸附过程中可能存在的机理。主要研究内容如下:(1)利用溶剂热法制备了NH2-MIL-101(Fe),并通过FT-IR、XRD、SEM、N2吸附-脱附测试对制得的MOFs进行表征。将其作为吸附剂对阴离子染料刚果红和阳离子染料孔雀石绿的吸附动力学、等温线和热力学进行了研究。动力学曲线符合伪二级动力学和颗粒内扩散模型,表明在吸附过程中物理吸附和化学吸附共存,膜扩散和颗粒内扩散共同决定反应速率。吸附等温线符合Langmuir吸附模型,吸附剂对刚果红和孔雀石绿的最大吸附量分别为1386.96 mg·g-1和1164.14 mg·g-1,远高于活性炭。静电作用、氢键和π-π共轭在吸附过程中起着非常重要的作用。热力学数据分析表明该吸附过程是自发的、放热的、熵值减小的过程。(2)利用溶剂热法制备了NH2-UiO-66(Zr),并通过FT-IR、XRD、SEM、N2吸附-脱附测试对制得的MOFs进行表征。研究其对氯酚化合物的吸附行为并讨论吸附机理。通过测定不同浓度下的动力学曲线,并进行伪二级动力学和颗粒内扩散模型的拟合分析,表明吸附过程中物理吸附与化学吸附共存,疏水作用、氢键作用和π-π共轭是吸附过程中的主要机理,膜扩散和颗粒内扩散共同决定反应速率。吸附等温线符合Freundlich吸附模型,为多分子层吸附,50℃下2-氯苯酚、2,4-二氯酚和2,4,6-三氯酚的吸附容量分别为248.27 mg·g-1、372.11 mg·g-1和517.62mg·g-1。热力学数据分析表明该吸附过程是自发的、吸热的、熵值增加的过程。
[Abstract]:With the rapid development of economic globalization and science and technology, water pollution caused by organic pollutants such as dyes and phenols is becoming more and more serious. How to efficiently remove pollutants in water is an important issue in the field of biological environment. Adsorption method has the advantages of simple operation, economy and recyclability. It is one of the common methods to remove pollutants in water efficiently. However, the selectivity and adsorption capacity of traditional porous adsorbents such as activated carbon and zeolite are not ideal, so it is of great significance to develop porous materials with high adsorption performance. Metal-organic frameworks (MOFs) are a kind of porous crystalline materials composed of organic ligands and metal centers. MOFs have the advantages of large specific surface area, high porosity, and the pore structure can be reconciled with the active sites of metals. Therefore, MOFs have a good application prospect in the field of adsorption and removal of organic pollutants in water body, and have attracted extensive attention to the design, development and application of MOFs materials. In this paper, two kinds of amino MOFs with excellent properties were prepared, which were used to adsorb dyes and phenols, respectively, and to explore the possible mechanism in the adsorption process. The main contents of this study are as follows: (1) NH2-MIL-101 Feon was prepared by solvothermal method and characterized by FT-IRN XRDX SEMN _ 2 adsorption-desorption test. The adsorption kinetics, isotherm and thermodynamics of anion dye Congo red and cationic dye malachite green were studied. The kinetic curves are in accordance with pseudo-second-order kinetics and intra-particle diffusion model. It is shown that physical adsorption and chemical adsorption coexist in the adsorption process and the reaction rate is determined by membrane diffusion and intraparticle diffusion. The adsorption isotherm was consistent with Langmuir adsorption model. The maximum adsorption capacity of Congo red and malachite green was 1386.96 mg g ~ (-1) and 1164.14 mg g ~ (-1), respectively, which was much higher than that of activated carbon. Electrostatic interaction, hydrogen bond and 蟺-蟺 conjugation play a very important role in the adsorption process. Thermodynamic data analysis showed that the adsorption process was spontaneous, exothermic, and entropy decreased. (2) NH _ 2-UiO-66 zirconium was prepared by solvothermal method, and the MOFs were characterized by FT-IRN XRDX SEMN _ 2 adsorption-desorption test. The adsorption behavior of chlorophenol compounds and its adsorption mechanism were studied. By measuring the kinetic curves at different concentrations and fitting the pseudo-second-order kinetics and the in-particle diffusion model, it is shown that physical adsorption and chemical adsorption coexist and hydrophobicity occurs during the adsorption process. Hydrogen bonding and 蟺-蟺 conjugation are the main mechanisms in the adsorption process. Film diffusion and intraparticle diffusion jointly determine the reaction rate. The adsorption isotherm accords with the Freundlich adsorption model. The adsorption capacities of 2-chlorophenol and 2-chlorophenol at 50 鈩，

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