复合材料中工业纳米颗粒的径流冲刷释放与机理
发布时间：2018-10-23 12:44
【摘要】：随着纳米技术的发展,通过添加工业纳米颗粒(Engineered nanoparticles,ENPs)的纳米复合材料因其优异的性能,生产和使用量迅猛增长。导致了ENPs不可避免的随着材料的使用、老化被不断地释放至环境中,使其在水、土壤和大气中的残留量逐渐增多,给环境带来了潜在的生态风险。因此,研究ENPs的释放方式及环境行为是非常必要的。本课题通过实验室模拟,研究了四种环境因素(老化时间、降雨pH、降雨历时、降雨强度)对三种不同涂层中(分别含SiO_2-ENPs,Ag-ENPs和TiO_2-ENPs)ENPs释放行为的影响。通过静态浸出实验发现,三种ENPs的释放浓度均随着老化时间的增长而升高。在较低或较高pH条件下,SiO_2-ENPs,Ag-ENPs的释放量相对较大,而TiO_2-ENPs仅在低pH条件下有较大的释放量。随着降雨历时的增长,SiO_2-ENPs的释放量逐渐降低,Ag-ENPs的释放量逐渐升高,TiO_2-ENPs无明显规律。关于降雨强度对ENPs释放的影响,结果发现随着降雨强度的增加,径流中Si、Ag和Ti的浓度均呈现出升高的趋势。总而言之,涂层中Ag-ENPs和TiO_2-ENPs的释放量相对较低(ppb级别),SiO_2-ENPs相对较高(ppm级别)。另外,动态光散射检测发现SiO_2-ENPs释放到环境当中多数以团聚态的形式存在,只有很少一部分粒径小于0.1μm。鉴于涂层中SiO_2-ENPs的释放量相对较大,本研究还针对SiO_2-ENPs在环境中的行为规律(不同环境因素对ENPs的影响)进行了研究。实验过程中,为了全面和深入地探究ENPs与自然环境因素的相互作用规律,主要对SiO_2-ENPs在不同的盐离子及有机质溶液中的平均粒径、表面电位、纳米级别颗粒含量进行测定分析。研究结果发现,随着盐离子强度增加,SiO_2-ENPs团聚程度增大,二价(Ca2+)相对于单价离子(Na+)对SiO_2-ENPs团聚有更大的促进作用。腐殖质(Nature organic matter,NOM;主要包括腐殖酸(Humic acid,HA)和富里酸(Fulvic acid,FA))吸附到SiO_2-ENPs表面,能使SiO_2-ENPs表面携带更多的负电荷,因此颗粒之间静电斥力增大。另外,研究还发现SiO_2-ENPs在HA中的粒径大于FA,这主要跟FA和HA的特性有关。在Ca2+与NOM的混合溶液中,SiO_2-ENPs的平均粒径相对其他溶液更大,原因可能是Ca2+的离子架桥作用(Ca2+-NOM)。至于纳米级别颗粒含量,结果证实NOM溶液中纳米级别SiO_2质量百分比在高pH条件下大于低pH条件。在盐离子溶液以及混合液中,纳米级别SiO_2质量百分比符合如下规律:pH7pH9pH5。
[Abstract]:With the development of nanotechnology, the production and usage of nanocomposites with industrial nanoparticles (Engineered nanoparticles,ENPs) are increasing rapidly due to their excellent properties. As a result, ENPs is inevitably released into the environment with the use of materials, resulting in a gradual increase of residues in water, soil and atmosphere, which brings potential ecological risks to the environment. Therefore, it is necessary to study the release mode and environmental behavior of ENPs. The effects of four environmental factors (aging time, rainfall pH, rainfall duration, rainfall intensity) on the ENPs release behavior in three different coatings (including SiO_2-ENPs,Ag-ENPs and TiO_2-ENPs) were studied by laboratory simulation. The static leaching experiments showed that the release concentration of ENPs increased with aging time. Under the condition of lower or higher pH, the release of SiO_2-ENPs,Ag-ENPs was relatively larger, while that of TiO_2-ENPs was only larger under the condition of low pH. With the increase of rainfall duration, the release of SiO_2-ENPs decreased gradually, the release of Ag-ENPs increased gradually, and there was no obvious rule of TiO_2-ENPs. As to the effect of rainfall intensity on the release of ENPs, it is found that the concentration of Si,Ag and Ti in runoff increases with the increase of rainfall intensity. In a word, the release of Ag-ENPs and TiO_2-ENPs in the coating is relatively low (ppb level) and SiO_2-ENPs is relatively high (ppm grade). In addition, dynamic light scattering (DLS) measurements show that most of the SiO_2-ENPs released into the environment exist in the form of agglomeration, and only a few of the particles are less than 0.1 渭 m in size. In view of the relatively large amount of SiO_2-ENPs released in the coating, the behavior of SiO_2-ENPs in the environment (the influence of different environmental factors on ENPs) was also studied. In order to study the interaction between ENPs and natural environment factors, the average particle size, surface potential and nano-particle content of SiO_2-ENPs in different salt ions and organic solution were measured and analyzed. The results show that the degree of SiO_2-ENPs agglomeration increases with the increase of salt ion strength, and the bivalent (Ca2) ion (Na) has a greater effect on SiO_2-ENPs agglomeration than univalent ion (Na). Humus (Nature organic matter,NOM; mainly includes humic acid (Humic acid,HA) and fulvic acid (Fulvic acid,FA) adsorbed on the surface of SiO_2-ENPs, which can make the surface of SiO_2-ENPs carry more negative charges, so the electrostatic repulsion between particles increases. In addition, it is found that the diameter of SiO_2-ENPs in HA is larger than that of FA, which is mainly related to the characteristics of FA and HA. In the mixed solution of Ca2 and NOM, the average particle size of SiO_2-ENPs is larger than that of other solutions, which may be due to the Ca2 NOM). Of Ca2. As for the content of nanoparticles, the results show that the mass percentage of nano-grade SiO_2 in NOM solution is larger than that in low pH solution under the condition of high pH. In salt ion solution and mixed solution, the mass percentage of nanoscale SiO_2 conforms to the following rule: pH7pH9pH5.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X132
本文编号：2289278
[Abstract]:With the development of nanotechnology, the production and usage of nanocomposites with industrial nanoparticles (Engineered nanoparticles,ENPs) are increasing rapidly due to their excellent properties. As a result, ENPs is inevitably released into the environment with the use of materials, resulting in a gradual increase of residues in water, soil and atmosphere, which brings potential ecological risks to the environment. Therefore, it is necessary to study the release mode and environmental behavior of ENPs. The effects of four environmental factors (aging time, rainfall pH, rainfall duration, rainfall intensity) on the ENPs release behavior in three different coatings (including SiO_2-ENPs,Ag-ENPs and TiO_2-ENPs) were studied by laboratory simulation. The static leaching experiments showed that the release concentration of ENPs increased with aging time. Under the condition of lower or higher pH, the release of SiO_2-ENPs,Ag-ENPs was relatively larger, while that of TiO_2-ENPs was only larger under the condition of low pH. With the increase of rainfall duration, the release of SiO_2-ENPs decreased gradually, the release of Ag-ENPs increased gradually, and there was no obvious rule of TiO_2-ENPs. As to the effect of rainfall intensity on the release of ENPs, it is found that the concentration of Si,Ag and Ti in runoff increases with the increase of rainfall intensity. In a word, the release of Ag-ENPs and TiO_2-ENPs in the coating is relatively low (ppb level) and SiO_2-ENPs is relatively high (ppm grade). In addition, dynamic light scattering (DLS) measurements show that most of the SiO_2-ENPs released into the environment exist in the form of agglomeration, and only a few of the particles are less than 0.1 渭 m in size. In view of the relatively large amount of SiO_2-ENPs released in the coating, the behavior of SiO_2-ENPs in the environment (the influence of different environmental factors on ENPs) was also studied. In order to study the interaction between ENPs and natural environment factors, the average particle size, surface potential and nano-particle content of SiO_2-ENPs in different salt ions and organic solution were measured and analyzed. The results show that the degree of SiO_2-ENPs agglomeration increases with the increase of salt ion strength, and the bivalent (Ca2) ion (Na) has a greater effect on SiO_2-ENPs agglomeration than univalent ion (Na). Humus (Nature organic matter,NOM; mainly includes humic acid (Humic acid,HA) and fulvic acid (Fulvic acid,FA) adsorbed on the surface of SiO_2-ENPs, which can make the surface of SiO_2-ENPs carry more negative charges, so the electrostatic repulsion between particles increases. In addition, it is found that the diameter of SiO_2-ENPs in HA is larger than that of FA, which is mainly related to the characteristics of FA and HA. In the mixed solution of Ca2 and NOM, the average particle size of SiO_2-ENPs is larger than that of other solutions, which may be due to the Ca2 NOM). Of Ca2. As for the content of nanoparticles, the results show that the mass percentage of nano-grade SiO_2 in NOM solution is larger than that in low pH solution under the condition of high pH. In salt ion solution and mixed solution, the mass percentage of nanoscale SiO_2 conforms to the following rule: pH7pH9pH5.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X132
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