【作者】 李传常； 任艳萍； 唐爱东； 杨艳；

【Author】 Chuanchang Li,Yanping Ren,Aidong Tang,Yan Yang (School of Chemistry and Chemical Engineering,Central South University,Changsha 410083,China)

【机构】 中南大学化学化工学院；

【摘要】 以高岭土所制硅酸钠溶液为原料,采用化学沉淀法经恒温干燥、真空旋转干燥和冷冻干燥制备纳米二氧化硅,比较了不同干燥方法对产物比表面积的影响.通过扫描电镜、X射线衍射、红外光谱、气体吸附比表面积测试、热重分析(TG)等分析手段对纳米二氧化硅的物理化学性质进行了表征.结果表明:冷冻干燥法制备的二氧化硅比表面积最高,可达到494.22m~2/g,试验发现,同样是采用冷冻干燥,陈化5 h比陈化1 h样品的比表面积降低了44.8%,可见,团聚现象在陈化的过程中就已开始出现,因此,制备过程中控制陈化时间也是一个不容忽视的重要环节.更多还原

【Abstract】 Using sodium silicate solution from kaolin as raw material,nano-silica were prepared by chemical precipitation method with conventional constant temperature dying routes,circumvolving drying and freeze dying technique.And this paper compared effect of different drying method on the specific surface area of the products.Its physical and chemical characters were characterized by scan electron microscope,X-ray diffraction,infrared spectrum,thermograrimetric analysis and the gas adsorption method(BET method).The results show that nano-silica were prepared by freeze drying has the highest specific surface area,which is up to 494.22 m~2/g.The surface area of the sample prepared by the same freeze dying method quiet time for 5h reduces 44.8%than for 1h.It is obvious that agglomeration exists in the quiet process.Therefore,it does not allow us to neglect to control the quiet process.更多还原