纳米银溶胶的固液分离研究

以次磷酸钠液相还原法制备纳米银溶胶,通过添加试剂破坏银溶胶的稳定性,使银粒子产生聚沉或絮凝,分析了纳米银溶胶的稳定条件.考查了加入氨水的工艺条件对从银溶胶中过滤分离纳米银粉的影响,控制溶胶的pH范围可以得到不同粒度的纳米银.用有机碱性混合试剂可使溶胶中的银粒子絮凝,易于固液分离,干燥后的银粉经快速渗透剂T分散后,银粉的粒度小（10 nm～20 nm）、稳定性好.提供了从银溶胶中过滤纳米银粉的新方法,该方法工艺简单、对设备要求低、能耗小、银粉的收率高,易于实现工业化.试样经TEM分析发现,该法制备的纳米银粉粒度小（10nm～40 nm）,分散性好.XRD物相分析证实其为纯的金属银.

Study on the Separation of Silver Nanoparticles from Silver Sol

Silver nanoparticles were prepared by the reduction reaction of silver nitrate solution with sodium hypophosphite in polyvinylpyrrolidone solution. The silver sol was coagulated by adding ammonia solution. Some technical conditions, such as pH value, ammonia concentration, ammonia dropping velocity and stirring rate were tested in order to get silver nanoparticles by filtrating silver sols. The results showed that the separation of solid silver nanoparticles with liquid solution was improved and the silver nanoparticles with different sizes were prepared using this method. The silver powders with particle size of 10 nm~20 nm were successfully separated from the silver sol by adding mixed solution of flocculent and organic alkaline agents. This process is simple and ordinary, needs some simply apparatuses only and consumed less energy with a high silver production capacity. Therefore, it is feasible for industrialized preparation of silver nanoparticles. The products were analyzed by transmission electron microscope (TEM) and X-ray diffraction (XRD) and shown that the particles were pure metal silver with high dispersible spherical form and diameters from 10 nm to 40 nm.