PRODUCTION AND CHARACTERIZATION OF PRECIPITATED SILICA FROM PALM OIL MILL FLY ASH USING CO₂ IMPREGNATION AND MECHANICAL FRAGMENTATION

ABSTRACT

In this research, sol-gel precipitation using CO₂ impregnation and mechanical fragmentation method was applied to produce precipitated silica from Palm Oil Mill Fly Ash (POMFA). Carbon dioxide (CO₂) was used in order to reduce the cost of the process and to enable sodium hydroxide recovery. The precipitation process was done in a stirred temperature-controlled baffled glass precipitator. The response surface method with the central composite design was applied to optimize the stirring speed and the CO₂ flow rate. The pH and the temperature of the precipitation process were varied for tailoring the specific surface area of the precipitated silica. The mechanical fragmentation and wet crushing process were applied to control the agglomerate particle size of the precipitated silica obtained. The results show that precipitated silica with a specific surface area in the range of 50 - 140 m²/g can be obtained.

Key words:
Carbon dioxide; Mechanical fragmentation; Palm oil mill fly ash; Precipitated silica; Sol-gel precipitation