Influence of Preparation Conditions of Nano Silica Sol on Its Particle Size and Stability
Silica sol is a colloid formed by homogeneous dispersion of silicon dioxide particles without fixed form in water.Silica sol has a strong activity due to the surface of silica particles containing a large number of hydroxyl groups.In this experiment,sodium silicate was used as raw material to prepare silica sol with different particle size by ion exchange method and mother liquor growth method.The effects of reaction temperature,reaction time,stirring speed and raw material type on silica sol particle size and dispersion were investigated.The results indicated that the best reaction conditions for preparing silica sol with small particle size were as follows:stirring strength 150 r·min-1,reaction temperature 75℃,reaction time 4 h,using NaOH to adjust pH.The optimum reaction conditions for preparing silica sol with large particle size were as follows:stirring strength 150 r·min-1,reaction temperature 95℃,reaction time 6 h,and adjusting pH with sodium silicate.Under these conditions,after three times of particle size increased,the silica sol product with the maximum particle size of 11.69 nm was prepared,and it had good stability and dispersion and was not easy to gel.
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