功能性还原氧化石墨烯凝胶的制备及在污水处理中的应用

发布时间：2018-04-21 01:02

本文选题：还原氧化石墨烯 + 凝胶　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：纳米粒子(NPs)相对于体状材料具有优异的催化性质,在治理环境污染和解决能源危机方面具有潜在应用。但是催化反应过程中NPs易团聚,从而使比表面积下降,降低其催化活性。因此,一般将NPs负载到合适的催化剂载体。石墨烯具有高电子迁移率、大表面积、高机械性能和特有的吸附性,是理想的催化剂载体。氧化石墨烯常常用作石墨烯的前驱体。石墨烯纳米片之间往往容易团聚和堆叠,加上仅仅依靠传统的化学氧化技术无法彻底降解污染物。基于以上考虑,本文介绍了一种将二维(2D)氧化石墨烯纳米片(GS)组装成三维(3D)还原氧化石墨烯(r GS)凝胶的简便方法,不仅增大催化剂的表面积,而且可以提高NPs的分散性并减小粒径,从而提高催化剂的催化活性。而且借助于凝胶分级多孔结构的物理吸附作用,加快反应溶液的传质和扩散。这样,物理吸附和化学氧化技术相结合,可以提高污染物的降解速率。另外,引入磁性纳米粒子及采用双重载体保护,可以减少催化剂流失,从而改善凝胶材料的循环利用性。具体研究内容包括以下三部分:(1)采用“一步法”制备r GS/Fe_2O_3/聚吡咯(PPy)三元凝胶。通过不同材料形貌对比,研究凝胶形成机理。以H_2O_2降解亚甲基蓝(MB)的Fenton反应作为模型反应测试材料的催化性能,随着催化剂用量增加、MB浓度降低、一定范围内H_2O_2用量的增加,MB降解速率加快。另外,催化剂有磁性,易分离。经过4次循环催化,催化活性仍未有明显降低。(2)采用“一步法”将PdPt合金负载于r GS凝胶制备出r GS/Fe_2O_3-Pd Pt/PPy五元凝胶。经过冷冻干燥,五元凝胶呈分级多孔结构,对染料的吸附效果优于烘干凝胶,并且PdPt合金粒子分布均匀且粒径极小,在Na BH4还原对硝基苯酚(4-NP)的反应中表现出优异的催化性能。(3)采用“两步法”制备r GS/Fe_2O_3/氮掺杂碳纳米片(NCS)凝胶材料。对凝胶的形貌结构及组分进行分析表征,并将该材料用于催化光Fenton反应降解罗丹明B(Rh B)。由于凝胶的吸附作用与Fe_2O_3的高催化活性协同,Rh B降解速率很快。同时,Fe_2O_3有磁性,催化剂能通过外加磁场分离,并具有较好的循环使用性。
[Abstract]:Nanoparticles (NPs) have excellent catalytic properties compared with bulk materials and have potential applications in environmental pollution control and energy crisis resolution. However, NPs is easy to agglomerate during catalytic reaction, which decreases the specific surface area and reduces its catalytic activity. Therefore, NPs is generally supported on the appropriate catalyst carrier. Graphene is an ideal catalyst carrier with high electron mobility, large surface area, high mechanical properties and unique adsorption. Graphene oxide is often used as a precursor of graphene. Graphene nanoparticles are often easy to agglomerate and stack, and traditional chemical oxidation techniques alone can not completely degrade pollutants. Based on the above considerations, this paper introduces a simple method of assembling two-dimensional graphene oxide (2-D) graphene oxide (GSN) into a three-dimensional (3D) reductive graphene oxide (GSR) gel, which not only increases the surface area of the catalyst, but also increases the surface area of the catalyst. Moreover, the dispersion of NPs can be improved and the particle size can be reduced, thus the catalytic activity of the catalyst can be improved. The mass transfer and diffusion of the reaction solution were accelerated by the physical adsorption of the porous structure of the gel. In this way, the combination of physical adsorption and chemical oxidation can improve the degradation rate of pollutants. In addition, the introduction of magnetic nanoparticles and double carrier protection can reduce the loss of catalyst and improve the recycling performance of gel materials. The specific research contents include the following three parts: 1) preparation of r GS/Fe_2O_3/ polypyrrole pyrrolidine ternary gel by "one step method". The gel formation mechanism was studied by comparing the morphology of different materials. The Fenton reaction of H_2O_2 degradation of methylene blue blue (MBB) was used to test the catalytic performance of the model reaction material. With the increase of the concentration of the catalyst, the degradation rate of MB was accelerated with the increase of the amount of H_2O_2 in a certain range. In addition, the catalyst is magnetic, easy to separate. After four cycles of catalysis, the catalytic activity was not significantly decreased. (2) r GS/Fe_2O_3-Pd Pt/PPy quaternary gel was prepared by "one step method" by loading PdPt alloy onto rGS gel. After freeze-drying, the five-component gel showed a hierarchical porous structure, and the adsorption effect of the dye was better than that of the drying gel, and the particle size of the PdPt alloy was very small, and the distribution of the particles was uniform. In the reduction of p-nitrophenol 4-NPs by Na BH4, excellent catalytic performance was obtained. (3) r GS/Fe_2O_3/ nitrogen-doped carbon nanoflake gel materials were prepared by "two-step method". The morphology, structure and composition of the gel were analyzed and characterized, and the material was used to catalyze the photodegradation of Rhodamine B(Rh B(Rh by photocatalytic Fenton reaction. Because of the adsorption of gel and the high catalytic activity of Fe_2O_3, the degradation rate of Rh B is very fast. At the same time, Fe2O3 is magnetic, the catalyst can be separated by external magnetic field, and has good recycling performance.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ427.26;X703

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