基于氢气纳米气泡的贵金属颗粒的合成及性质研究

发布时间：2018-04-17 06:11

本文选题：H_2纳米气泡气液分散体系 + 贵金属纳米颗粒　；参考：《华东师范大学》2015年硕士论文

【摘要】：纳米气泡是水溶液中亚微米级别的溶气腔。在超纯水中加入表面活性剂可以极大的促进纳米气泡的稳定性。纳米气泡具有特殊的物理、化学和生物效应。气体分子从纳米气泡中不断的溶进与溶出。纳米气泡以下几个独特的优势使其蓄气能力强：比表面积大、悬浮时间长、由于表面张力有一定的内压。体相中的纳米气泡表面存在一定厚度的非扰动层,会产生一定的反压力,使纳米气泡之间由于屏蔽效应减少扩散损失而稳定存在。从纳米气泡中缓释出的气体可以作为反应物。本文使用泵前进气回流式压力溶气释放法,制备了富含H2纳米气泡的气液分散体系。使用纳米颗粒追踪技术(NTA)、Zeta电位分析、衰减全红外分析、氧化还原电势测定等方法表征了H2纳米气泡的基本性质、结构以及稳定的机理。使用H2纳米气泡分散体系作为还原剂,调控反应的温度、金属粒子与包裹剂的不同比例、包裹剂的类别等条件来制备不同形貌、单分散性好的贵金属纳米颗粒。经过试验探究,得到如下结论：(1)纳米气泡气液分散体系含有溶解态和分散态两种不同状态的气体。纳米气泡的存在极大的增加了气体的含量。从纳米气泡中缓释出来的气体可以作为特定的反应物。(2)本论文使用泵前进气回流式压力溶气释放法,制备出的气液分散体系中含有两种粒径的H2纳米气泡,且两种直径成倍数关系。表面活性剂的加入极大地提高了H2纳米气泡的稳定性,纳米气泡浓度数量级稳定在108个/mL。(3)加入聚丙烯酸钠制作H2纳米气泡气液分散体系,包裹剂分子吸附在气液界面上,其憎水基团伸向气泡的内部,亲水基团伸向外部的液相,形成稳定的氢键层笼状结构。经过衰减全反射红外测试,验证了笼状结构的形成。(4)H2纳米气泡气液分散体系的氧化还原电势值低,可以作为特定反应的还原剂。在本实验中,加入不同的金属源,金属离子吸附在纳米气泡表面,被气泡内部缓释出的H2分子还原为不同形貌的金属纳米颗粒。本文通过NTA技术、Zeta电位测试、紫外-可见吸收分光光度计测试等表征手段探究了纳米金属颗粒形成的机理。(5)以壳聚糖作为包裹剂,以H2纳米气泡气液分散体系作为还原剂制备不同形貌金属纳米颗粒的实验条件还有待优化。
[Abstract]:Nanometer bubble is a kind of solution gas chamber in the submicron level of aqueous solution.The addition of surfactants in ultrapure water can greatly promote the stability of nanometer bubbles.Nanometer bubbles have special physical, chemical and biological effects.Gas molecules are constantly dissolved and dissolved from nano-bubbles.Nanometer bubbles have the following unique advantages: large specific surface area, long suspension time and certain internal pressure due to surface tension.There is a certain thickness of unperturbed layer on the surface of the nano-bubble in the bulk phase, which will produce a certain reverse pressure, which makes the nano-bubble exist stably because of the shielding effect to reduce the diffusion loss.The gas released slowly from nanometer bubble can be used as reactant.In this paper, a gas-liquid dispersion system rich in H _ 2 nanometer bubbles was prepared by pump forward gas reflux pressure dissolved gas release method.The basic properties, structure and stabilization mechanism of H _ 2 nanoscale bubbles were characterized by means of nano-particle tracing technique such as Zeta potential analysis, full-infrared attenuation analysis and redox potential measurement.Noble metal nanoparticles with different morphology and good monodispersity were prepared by using H _ 2 nano-bubble dispersion system as reducing agent, controlling the reaction temperature, the different ratio of metal particles to encapsulating agent, and the type of encapsulating agent.The experimental results show that: 1) Nano-bubble gas-liquid dispersion system consists of dissolved and dispersed gases.The presence of nanometer bubbles greatly increases the gas content.The gas released slowly from nanometer bubble can be used as a specific reactant in this thesis. In this thesis, the gas-liquid dispersion system contains two kinds of H _ 2 nano-bubbles with two sizes by using the pressure-dissolved gas release method of pump forward gas reflux.And the two diameters are multiple.The addition of surfactant greatly improved the stability of H _ 2 nano-bubble, and the concentration of nano-bubble was in the order of 108 / m 路L ~ (-3)) sodium polyacrylate was added to prepare the gas-liquid dispersion system of H _ 2 nano-bubble, and the encapsulant molecules were adsorbed on the gas-liquid interface.The hydrophobic group extends to the interior of the bubble and the hydrophilic group to the external liquid phase to form a stable hydrogen bond layer cage structure.The results of the attenuated total reflectance infrared spectroscopy show that the formation of cage structure. 4H _ 2 nano-bubble gas-liquid dispersion system has a low redox potential and can be used as a reductant for a specific reaction.In this experiment, metal ions were adsorbed on the surface of nano-bubble by adding different metal sources, and reduced to metal nanoparticles with different morphology by H _ 2 molecules slowly released from the bubble.In this paper, the mechanism of metal nanoparticles formation was investigated by means of NTA and UV-Vis absorption spectrophotometer. Chitosan was used as encapsulant.The experimental conditions of preparing metal nanoparticles with different morphologies using H _ 2 nano-bubble gas-liquid dispersion system as reducing agent need to be optimized.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O647.11

【相似文献】