大尺寸层状复合金属氢氧化物的可控制备及红外吸收性能研究

发布时间：2018-04-10 14:28

本文选题：二维层状复合金属氢氧化物 + 选择性红外吸收　；参考：《北京化工大学》2015年硕士论文

【摘要】：太阳光是地球生命的能量基本来源,其中红外线是太阳光谱的主要组成部分,由于红外线是太阳光中热量最高的部分,供给地球生物以热量,对生命的延续具有重要意义。波长8～14μm范围内的红外线对于提高人体免疫力和促进植物生长具有重要作用,因此,研究选择性红外吸收材料具有重要意义。二维层状复合金属氢氧化物(Layered double hydroxides,简称LDHs)由于其特殊的层间结构以及其层板间的离子具有可交换性,使LDHs及其插层产物和复合材料在特定红外波段内具有良好的红外吸收性能。同时LDHs是一种绿色环保的材料,符合国家环保部门对于环境保护提出的要求。根据米氏(Mie)定律,除自身化学性质和化学组成直接影响材料的红外吸收波段之外,材料微观粒径的物理尺寸对材料的红外吸收具有重要的影响,在化学组成、化学结构及性质相同的情况下,不同粒径的材料的红外吸收作用不同,因此研究材料粒径对材料红外吸收性能的影响是很有必要的。本论文主要研究内容和成果如下：(1)以可溶性镁盐、铝盐和沉淀剂为原料,采用均匀沉淀法制备大尺寸微米级MgAl-CO3-LDHs。材料在1500～700 cm-1范围内的红外吸收性能良好,且粒径为7.50μm的LDHs红外消光系数最大,数值为0.122m2·g-。以硬脂酸钠为改性剂对MgAl-CO3-LDHs进行表面改性增强材料表面活性,并进一步增大红外消光系数,改性后数值为0.132 m2·-1。同时,对MgAl-CO3-LDHs进行了工程化放大实验,样品的粒径为7.80 μm,在1500～700 cm-1范围内MgAl-CO3-LDHs的红外消光系数为0.130 m2·g-1,与实验室结果相一致。通过调控物料浓度研究了MgAl-CO3-LDHs粒径的变化规律,发现粒径大小与物料浓度成反比。相比于HMT和Na2CO3的混合沉淀剂,仅以HMT为沉淀剂时MgAl-CO3-LDHs的粒径增加了约1倍。样品粒径大小与沉淀剂HMT比Al3+的比值(即f值)成反比例。盐的种类不同(硝酸盐、氯盐、硫酸盐)制备LDHs情况下,使用硝酸盐得到的样品粒径最大。对LDHs的生长机理进行了探讨,推测了规则六方片和不规则六方片LDHs的形成机理。(2)以大尺寸微米级MgAl-CO3-LDHs为前驱体,通过离子交换法制备MgAl-H2PO4-LDHs样品。与前驱体相比仅层间距发生变化,粒径未发生改变。制备得到的MgAl-H2PO4-LDHs改性后在1500～700 cm-1的波段内红外消光系数达到0.143 m2·g-1优于MgAl-CO3-LDHs的0.132 m2·g-1。此外,对MgAl-H2PO4-LDHs进行了工程化放大实验,样品在波数1500～700cm-1范围内,红外消光系数为0.139m2.g-1,与实验室结果基本一致。(3)以MgAl-CO3-LDHs和石墨为原料,化学法制备LDHs@C复合红外吸收材料。在石墨的表面和断面上MgAl-CO3-LDHs片状结构均匀生长,样品断面被MgAl-CO3-LDHs包覆。得到的LDHs@C复合材料在1500～700cm-1范围内红外消光系数为0.140 m2·-1,大于MgAl-CO3-LDHs材料的0.132 m2·g-1,同时具有较好的绝缘性质。
[Abstract]:Solar light is the basic source of energy of the earth's life, in which the infrared ray is the main component of the solar spectrum. Because the infrared ray is the part with the highest heat in the solar light, it is of great significance for the continuation of life to supply the earth's living things with heat.Infrared radiation in the wavelength of 814 渭 m plays an important role in improving human immunity and promoting plant growth. Therefore, it is of great significance to study the selective infrared absorption materials.Due to its special interlaminar structure and exchangeability of ions between its laminates, two-dimensional layered metal hydroxides (LDHs) make LDHs and its intercalation products and composites have good infrared absorption properties in a specific infrared band.At the same time, LDHs is a kind of green material, which meets the requirements of the national environmental protection department for environmental protection.According to Miex's law, in addition to its own chemical properties and chemical composition directly affecting the infrared absorption band of the material, the physical size of the material's microscopic particle size has an important effect on the infrared absorption of the material.Under the same chemical structure and properties, the infrared absorption of materials with different particle sizes is different, so it is necessary to study the influence of material particle size on the infrared absorption properties of the materials.The main contents and results of this thesis are as follows: (1) using soluble magnesium salt, aluminum salt and precipitator as raw materials, large size micrometer MgAl-CO _ 3-LDHs were prepared by homogeneous precipitation method.The infrared absorption property of the material is good in the range of 1500 ~ 700 cm-1, and the infrared extinction coefficient of LDHs with the diameter of 7.50 渭 m is the largest, and the value is 0.122m2 g-.The surface activity of MgAl-CO3-LDHs was enhanced with sodium stearate as modifier, and the infrared extinction coefficient was further increased. The modified value was 0.132 m ~ 2 ~ (-1).At the same time, the engineering amplification experiment of MgAl-CO3-LDHs was carried out. The particle size of the sample was 7.80 渭 m, and the infrared extinction coefficient of MgAl-CO3-LDHs was 0.130 m ~ (2) g ~ (-1) in the range of 1500 ~ 700 cm-1, which was consistent with the experimental results.The variation of MgAl-CO3-LDHs particle size was studied by controlling the concentration of the material. It was found that the particle size was inversely proportional to the concentration of the material.Compared with the mixed precipitant of HMT and Na2CO3, the particle size of MgAl-CO3-LDHs increased by about twice when only HMT was used as precipitant.The particle size of the sample is inversely proportional to the ratio of HMT to Al3 (f value).When LDHs was prepared with different kinds of salt (nitrate, chloride, sulfate), the particle size of the sample obtained by using nitrate was the largest.The growth mechanism of LDHs was discussed, and the formation mechanism of regular hexagonal and irregular hexagonal LDHs was inferred.Compared with the precursor, only the interlayer spacing changed, but the particle size did not change.The infrared extinction coefficient of the modified MgAl-H2PO4-LDHs is 0.143 m ~ 2 g ~ (-1) at 1 500 ~ 700 cm-1 band, which is better than that of 0.132 m ~ 2 g ~ (-1) of MgAl-CO3-LDHs.The MgAl-CO3-LDHs flake structure grows uniformly on the surface and section of graphite, and the cross section of the sample is covered by MgAl-CO3-LDHs.The infrared extinction coefficient of LDHs@C composites in the range of 1500~700cm-1 is 0.140 m2 -1, which is larger than that of MgAl-CO3-LDHs materials 0.132 m2 g -1, and has good insulation properties.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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