Preparation of Submicron Silica Powders from Sodium Silicate Using Ultrasonic Energy

Abstract

Submicron silica powders were prepared by w/o emulsion method using inexpensive sodium silicate, ammonium sulfate and Triton N-57 as SiO2 source, precipitant and emulsifier, respectively. Nano-sized silica powders with narrow size distribution were prepared at a low temperature of 25°C for 1h by ultrasonic irradiation of the reactants using a commercial ultrasonic cleaner operating at a frequency of 47kHz, whereas silica powders with larger size and broad size distribution were synthesized using the same reactants at the same temperature and for the same time by the conventional process without ultrasounds. The particle size and size distribution of the silica powders obtained by the ultrasonic process were smaller and narrower than those by the conventional process, indicating that the application of ultrasound in the synthesis of silica powders by the w/o emulsion method is an efficient way to have powders with smaller and narrower particle size distribution.