银纳米线的合成与杀菌作用研究

发布时间：2018-11-25 08:14

【摘要】：生活饮用水安全与人体健康息息相关。研究表明，在我国，细菌超标是造成生活饮用水不安全的首要原因。而在许多地区尤其是边远农村，因经济、地理原因，无法保证安全卫生的饮用水。因此，开发饮用水除菌杀菌的新方法、新材料，具有现实意义。据文献调研，通电银纳米线对水中大肠杆菌具有快速高效杀菌作用，为此，本论文开展对银纳米线的合成、负载、杀菌性能的研究工作，并对一种基于银纳米线的杀菌净水器进行了初步设计。研究得到以下主要结果和结论：以20mL乙二醇为还原剂，90mg硝酸银为银源，运用微波加热合成法可快速制备银纳米线。为使产物形态以纳米线为主，需投加氯离子控制还原速度，需投加PVP（聚乙烯吡咯烷酮）引导银晶种一维方向成长，并控制适当的反应时间。较好的合成条件为：氯化钠投量2.5-5.0mg、PVP/AgNO_3摩尔比例2-5，微波功率320W，反应时间3.5min。过低的微波功率如80W、160W令银纳米线长度短，而过高的微波功率如800W则导致产物形态颗粒化。另外，运用800W0.5min+320W2.5min组合功率进行合成，能够显著提高银纳米线产量与长度，并进一步减少副产物银颗粒的生成。使用电子显微镜、XRD、UV-Vis、SAED等手段对银纳米线形貌、晶体结构进行表征，其线径为50-70nm，长度最高达10μ m，，为孪晶结构。运用UV胶作为粘胶剂，实现银纳米线在碳布上的负载。施加UV胶令纳米线稳定负载，却会降低材料杀菌效能；足够的银纳米线负载量能在碳纤维表面构成导电网络，从而发挥高效的杀菌性能；银纳米线杀菌率与通电电压正相关。最佳的施胶浓度为1.25%；理想的银纳米线负载量为2.16mg，施加10V电压，对106CFU/mL大肠杆菌菌液杀菌率达83.3%，同比碳布仅为47.6%；银纳米线杀菌率受进水菌浓度、盐度变化的影响小，在菌液浓度变化（10~2-10~6CFU/mL）和盐度变化（5-20mM）时，稳定保持81.4%-94.4%较高杀菌率；若滤速增大则显著降低银纳米线杀菌率。银纳米线-碳布的杀菌机理包括：（1）通电银纳米线表面产生高电场，击穿并灭活细菌；（2）通电碳布对细菌的直接和间接氧化作用。（3）电解含氯化钠菌液过程产氯溶解于水中，自由氯的强氧化性起杀菌作用。初步设计了一种基于银纳米线的便携式杀菌净水器，包括水体预处理、杀菌组件和电源；并设计了手摇自发电装置和升压装置，使净水器具备自供电功能和杀菌电压可调功能。
[Abstract]:The safety of drinking water is closely related to human health. The study shows that bacteria exceeding the standard is the primary cause of unsafe drinking water in China. In many areas, especially in remote rural areas, for economic and geographical reasons, there is no guarantee of safe and hygienic drinking water. Therefore, it is of practical significance to develop new methods and materials for sterilization of drinking water. According to the literature investigation, the silver nanowires have a rapid and efficient bactericidal effect on Escherichia coli in water. Therefore, the research work on the synthesis, loading and bactericidal properties of silver nanowires has been carried out in this paper. A bactericidal water purifier based on silver nanowires was designed. The main results and conclusions are as follows: silver nanowires can be rapidly prepared by microwave heating with 20mL glycol as reducing agent and 90mg silver nitrate as silver source. In order to make the product form nanowires, it is necessary to add chlorine ion to control the reduction rate, to add PVP (polyvinylpyrrolidone) to guide the growth of silver seed in one dimension direction, and to control the appropriate reaction time. The optimum conditions are as follows: the dosage of sodium chloride is 2.5-5.0 mg / g PVP / Agno _ 3 molar ratio 2-5, microwave power 320W, reaction time 3.5min. Too low microwave power such as 80WN 160W makes the length of silver nanowires short, while too high microwave power such as 800W leads to the morphology granulation of the products. In addition, the production and length of silver nanowires can be significantly increased by 800W0.5min 320W2.5min combined power synthesis, and the formation of silver particles can be further reduced. The morphology and crystal structure of silver nanowires were characterized by means of electron microscope and XRD,UV-Vis,SAED. The diameter of silver nanowires was 50-70 nm and the maximum length was 10 渭 m. Silver nanowires loaded on carbon cloth were realized by using UV adhesive as viscose agent. UV glue can stabilize the loading of nanowires, but it will reduce the bactericidal efficacy of the materials; adequate loading of silver nanowires can form a conductive network on the surface of carbon fiber, thus exerting efficient bactericidal properties; the bactericidal rate of silver nanowires is positively correlated with the current voltage. The optimum sizing concentration was 1.25, the optimal loading amount of silver nanowires was 2.16 mg, the sterilization rate of 106CFU/mL Escherichia coli solution was 83.3%, and the carbon cloth was only 47.6%. The bactericidal rate of silver nanowires was little influenced by influent concentration and salinity. When the concentration of bacteria solution (10~2-10~6CFU/mL) and salinity (5-20mM) changed, the bactericidal rate of silver nanowires was 81.4% -94.4%. If the filtration rate is increased, the bactericidal rate of silver nanowires will be significantly reduced. The bactericidal mechanism of silver nanowires-carbon cloth includes: (1) the surface of silver nanowires has a high electric field, which breaks down and inactivates bacteria; (2) direct and indirect oxidation of bacteria by electrified carbon cloth. (3) chlorine production from electrolytic solution containing sodium chloride dissolved in water, and the strong oxidation of free chlorine played a bactericidal role. A portable sterilizing water purifier based on silver nanowires was designed, including water pretreatment, sterilization module and power supply, and a manual self-generating device and a voltage booster device were designed to enable the water purifier to have the function of self-supply power and adjustable sterilization voltage.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU991.2

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