层状氢氧化物的吸—脱附行为及催化性能研究

发布时间：2018-01-28 23:19

本文关键词： 水滑石层状稀土氢氧化物吸附脱附催化　出处：《北京化工大学》2016年硕士论文　论文类型：学位论文

【摘要】：层状氢氧化物包括层状多金属氢氧化物和单一金属氢氧化物,其中的金属元素具有优越的可调控性,包括普通金属、过渡金属和稀土金属等。由于层状氢氧化物结构和性质的特殊性,即融合了二维层状纳米材料和金属离子两者的优点,在吸附、分离、催化、生物和光电磁等领域被广泛的应用。本论文基于两种层状氢氧化物,即层状双金属氢氧化物(水滑石)和层状单一稀土金属氢氧化物,分别系统地研究了它们的吸附、催化性能以及在分析领域的应用。具体研究内容如下：(1)以层状双金属氢氧化物(碳酸根插层的水滑石)为吸附剂,通过静电吸引作用表面吸附阴离子染料(甲基橙)。以聚合物聚乙烯亚胺为脱附剂,研究甲基橙的脱附行为。实验结果表明,在不同的pH值条件下,聚乙烯亚胺都能够将甲基橙从水滑石表面脱附下来。脱附机理研究证明,在低pH值条件下(9.5),质子化的聚乙烯亚胺通过静电吸引作用将负电性的甲基橙从碳酸根水滑石表面脱附下来;在高pH值条件下(9.5),脱附机理源于两种作用力的协同作用：1)甲基橙的磺酸根官能团和电中性的聚乙烯亚胺的氨基官能团之间的氢键作用力,2)溶液中大量存在的氢氧根与碳酸根水滑石表面吸附的甲基橙之间的离子交换作用。连续五次吸附-脱附循环利用之后,再生的碳酸根水滑石仍然能保持80%的吸附率,远高于0.1 M NaOH溶液作为脱附剂时水滑石的再生吸附率。聚乙烯亚胺作为一种新型、有效的脱附剂,为解决水滑石表面阴离子吸附-脱附问题开辟了新的途径。(2)以水滑石为主体,将碳源(柠檬酸钠)和表面活性剂(十二烷基硫酸钠)作为客体共同插入水滑石层间,再原位水热合成有机改性的水滑石-石墨烯量子点复合型吸附剂,研究其对非离子型有机分子(2,4,6-三氯苯酚)的吸附性能。实验结果表明,有机改性的水滑石-石墨烯量子点复合物对2,4,6-三氯苯酚表现出优异的吸附性能(119 mg/g),并且吸附行为符合Langmuir吸附等温线和拟二级动力学模型。吸附机理研究证明,吸附性能提升的原因来自于复合物层间的石墨烯量子点和十二烷基硫酸钠对2,4,6-三氯苯酚的协同吸附效应,即石墨烯量子点和2,4,6-三氯苯酚之间的氢键作用力和π-π相互作用以及十二烷基硫酸钠的疏水长链和2,4,6-三氯苯酚之间的疏水相互作用。因此,这种新型复合吸附剂不仅可以应用于吸附其他非离子型有机分子,而且为开发基于有机改性水滑石和石墨烯量子点的复合型吸附剂提供了新的思路。(3)以层状单一稀土金属氢氧化物(Y-NO_3-LRHs)及其煅烧产物(Y_20_3)作为催化剂,研究其表面化学吸附氧对催化发光选择性的影响。实验结果表明,Y-NO_3-LRHs只对乙醚有催化发光信号,表现出特异的选择性；然而Y_20_3则能催化氧化多种挥发性有机化合物产生光信号。机理研究证明两种催化剂的催化发光选择性差异来源于二者表面化学吸附氧量的不同。对于表面有较少化学吸附氧的Y-NO_3-LRHs,只有乙醚能被催化氧化至乙醛的电子激发态中间体(CH_3CHO~*),当CH_3CHO~*由激发态回到基态时以辐射跃迁的形式发射出光；但是Y_20_3表面有足够多的化学吸附氧,不仅能够将乙醚催化氧化至CH_3CHO~*,还能将其他有机挥发物催化氧化至二氧化碳的电子激发态中间体(C02~*)。因此,利用Y-NO_3-LRHs和Y_20_3作为催化剂模型,证明了催化剂表面化学吸附氧对催化发光选择性有至关重要的影响。
[Abstract]:Multi layered double hydroxides including layered metal hydroxide and single metal hydroxide, metal element which has excellent regulation performance, including ordinary metal, transition metal and rare earth metals. Because of the particularity of the structure and properties of layered double hydroxides, which combines the advantages of the two, two dimensional layered nano materials and metal ions in the adsorption and separation. Catalytic, biological and photoelectric magnetic fields are widely used. This paper is based on two layered double hydroxides, namely layered double hydroxides (LDHs) and layered single rare earth metal hydroxide, were systematically studied its adsorption, catalytic performance and application in the field of analysis. The specific contents are as follows: (1) with layered double hydroxides (carbonate intercalated hydrotalcite) as adsorbent by electrostatic adsorption surface of anionic dyes (Jia Jicheng). As a polymer Polyethyleneimine as desorption agent, the desorption behavior of methyl orange. The experimental results show that under different pH conditions, polyethyleneimine can be removed from the methyl orange hydrotalcite. The surface of the study on the removal mechanism of that, under low pH conditions (9.5), protonated polyethylene imine will be charged the methyl orange off from carbonate hydrotalcite adhered to the surface by electrostatic attraction; at high pH conditions (9.5), the synergistic effect mechanism of desorption from two factors: 1) the hydrogen bond interaction between polyethyleneimine methyl sulfonic group and neutral amino groups, 2) ion exchange interaction there are a lot of solution between hydroxyl and carbonate hydrotalcite surface adsorption of methyl orange. Five consecutive adsorption desorption cycles using carbonate hydrotalcite after regeneration can still keep 80% of the adsorption rate, far higher than the 0.1 M NaOH Solution as desorption agent regeneration adsorption rate. Hydrotalcite polyethylenimine as a new, effective desorption agent, to solve the anionic surface adsorption - desorption opens up a new way. (2) using hydrotalcite as the main carbon source (sodium citrate) and surfactant agent (twelve sodium dodecyl sulfate) as the object of the common insertion of LDHs, and in situ hydrothermal synthesis of Organic Modified Hydrotalcite - gqds composite adsorbent of organic molecules on nonionic (2,4,6- three chloro phenol) adsorption performance. The experimental results show that the Organic Modified Hydrotalcite graphene quantum dot complexes of 2,4,6- three chlorophenol showed excellent adsorption properties (119 mg/g), and the adsorption behavior with Langmuir isotherm and pseudo two order kinetics model. The adsorption mechanism that causes adsorption performance from composite layer CO adsorption effect of gqds and twelve sodium dodecyl sulfate 2,4,6- three chlorophenol, interaction between 2,4,6- and graphene quantum three chloro phenol hydrogen bonds and pi pi interactions and twelve hydrophobic long chain alkyl sodium sulfate and 2,4,6- three chloro phenol hydrophobic. Therefore, this new type of the composite adsorbent can be applied not only to absorb other nonionic organic molecules, but also for the development of organic compound adsorbent of hydrotalcite and graphene quantum dots provides new ideas. (3) based on layered single rare earth metal hydroxide (Y-NO_3-LRHs) and its calcined product (Y_20_3) as catalyst, effect study on the surface chemical adsorption oxygen on the catalytic selective luminescence. Experimental results show that the Y-NO_3-LRHs catalytic luminescence signal of ether, exhibit specific selectivity; however Y_20_3 can catalytic oxidation A variety of volatile organic compounds to produce light signals. The results proved that the catalytic mechanism of two kinds of catalyst selectivity difference comes from the two light emitting surface chemical adsorption of oxygen on the surface. There are fewer chemical adsorption oxygen Y-NO_3-LRHs, ether can be only electronically excited intermediate catalytic oxidation to acetaldehyde (CH_3CHO~*), when CH_3CHO~* from excited state to the ground state in the form of radiation transition to emit light; but Y_20_3 surface chemical adsorption oxygen enough, not only can the ether catalytic oxidation to CH_3CHO~*, but also other volatile organic compounds by catalytic oxidation of carbon dioxide to the electronic excited state intermediate (C02~*). Therefore, the use of Y-NO_3-LRHs and Y_20_3 as the catalyst model, surface chemical oxygen adsorption catalyst have a vital effect on selective catalytic luminescence is proved.

【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O643.36;O647.33

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