纳米银胶体的制备和表征.pdf

天津大学硕士学位论文纳米银胶体的制备和表征姓名:包洪滨申请学位级别:硕士专业:化学工艺指导教师:王虹 20070601 摘要作为一种纳米材料,纳米银具有体积效应、表面效应、量子尺寸效应和宏观量子隧道效应,在超导、光电、抗菌、催化等领域具有极大的开发潜力和应用价值。要使纳米银走出实验室,实现产业化,必须掌握纳米银晶体的生长规律和影响因素,探索出一套快速、稳定而又绿色的制各方法。国内外纳米银的制备方法繁多,其中液相化学还原法是目前实验室和工业上广泛采用的一种方法。该方法工艺条件易控制,设备要求相对不高,生产速度快、产率高,便于工业化大规模生产。本实验以硝酸银为原料,鞣酸为还原剂和保护剂,控制反应条件,制备出了球形、分散性和稳定性好、粒度可控的纳米银溶胶, 同时原料对环境无害,生产过程中杂质少,符合环境友好的要求。实验结果表明,AgN03和鞣酸溶液的浓度、反应温度、pH等条件都会对纳米银胶体的粒度产生影响,其***@AgN03溶液浓度的影响最大,调节其浓度,。,纳米银的产率最高。超声分散有利于提高纳米银胶体的分散性和稳定性,通过对比发现,间歇超声的分散效果更好。通过紫外可见吸收光谱、X射线衍射、红外光谱、透射电镜等手段对纳米银胶体颗粒进行了表征。结果表明,纳米银颗粒的形态为球形或类球形,晶体为面心立方,分散比较均匀。纳米银颗粒的粒度变大,最大吸收波长红移,胶体的外观颜色变深。纳米银颗粒与羟基发生电荷吸附作用,固定在鞣酸的空间网状结构中,稳定存在。关键词:纳米银;鞣酸;胶体;超声 ABSTRACT Due t0也eir volume effect,suI' effect,quantum dimension effect and macroscopic quantum tunneling effect,Ag nanoparticles are theprominent candidates forapplications insuperconduction,electronics,antibacterial actions and catalysis·It is ofgreatimportance toknow thegrowth rulesofAg nanocrystal and thefactors which influence thegrowth process in order toget afast,stableandgreen way ofAg nanoparticles preparation. There are many methods toprepare Ag nanoparticles domestic and abroad,in which thechemical reduction inliquid phase isthemethod we often use inpresent laboratory and industry because ofitsmultiple advantages such aslow cost and high thispaper,sphere—shaped Ag nanoparticles were prepared using silver nin- acid asbothreducing agent and monodispersity and stability of Ag nanoparticles call be well controlled and meets the environment-benign demand. The experiment results show that the average size ofAg nanoparticles ISm relationtothetemperature and theconcentration ofsilver nitrateand tannic acid· Among them,the concentration ofsilver nitratemakes thebiggest means ofadjusting theamount ofsilvernitrate,the sizeofAg nanoparticles Call be controlled between 20and yield ofAgnanoparticles getshigher when the pH isdbout