酸和碱催化制备二氧化硅溶胶及其稳定性

Preparation and Stability of Silica Sol Catalyzed by Hydrochloric Acid and Ammonia

以正硅酸乙酯(TEOS)为原料,氨水和盐酸为催化剂,制备了SiO2溶胶;研究了pH值对溶胶的稳定性以及SiO2粒子生长方式的影响.结果表明,在酸性条件下,随着pH值的增加,凝胶时间呈现先变长后变短的趋势;而在碱性条件下,凝胶时间随pH的增大快速增加.透射电镜(TEM)和动态光散射(DLS)分析结果表明,溶胶中的SiO2粒子处于纳米量级,且两种催化条件下粒子的粒径分布存在明显差异.

Two kinds of silica sol were prepared from tetraethylorthosilicate （TEOS） in the presence of hydrochloric acid and ammonia as catalysts. The influence of pH value on the stability of the silica sol and growth of SiO2 particles was studied. Results show that the time for silica gel to emerge varied with varying pH value. Namely, under acidic condition, the time for silica gel to form was initially elongated and then shortened with increasing pH value. And under alkaline condition, the time for silica gel to generate rapidly increased with increasing pH value. Besides, transmission electron microscopic analysis and dynamic light scattering analysis indicated that the SiO2 particles had a nanoscale size, and the size distribution of the particles was significantly different depending on catalyst type.