A study on the effect of using different type of organic acid on the pre-treatment of extraction silica from rice husk ash (RHA)

Rice husk is an abundant agricultural by-product, which contain high amount of silica which is about 60% and can be made into raw materials that can produce silica gel and powders. There are abundant uses of silica which are for the glass production, adsorbent, cleansing agent and others. Synthesis was done by using different acids namely, acetic acid, citric acid, and formic acid. The sample was collected from rice mill that located in Sabah. The proximate analysis of the sample was determined the moisture content, volatile matter, fixed carbon and ash by using the thermobalance TGA/SDRA51e according to ASTM D5142-02a. Rice husks were used in this research and were carbonized at 600°C for four hours to decrease the carbonaceous materials in the rice husk therefore increasing the amount of silicon dioxide (SiO₂). 10 grams each of carbonized rice husk sample were dispersed in 6M of acetic acid, oxalic acid and formic acid respectively for acid pre-treatment and this dispersion were being stirred for 2 hours using magnetic stirrer. The filtrate is then being dispersed in 1M of NaOH to produce sodium silicate before being titrated using 1M of hydrochloric acid. At the pH of 7, silica gel was produced and being dried in oven at 140°C for 8 hours before being weigh. The percentage of the silica being extracted were being compared to the previous research. The characterization of the silica obtained determined by the Fourier Transform Infrared Spectrograph (FTIR) and BET surface area instrument.