Extraction of Silica and other related products from Rice Husk
ABSTRACT
The main objective of the present work is the synthesis of silica from rice husk and to study its characterization studies. The alkaline method succeeded by acid precipitation is done for the extraction of silica. The optimization of the concentration of sodium hydroxide and the amount of rice husk ash that goes with it for attaining the maximum yield of silica is done. X-ray Diffraction and Fourier Transform Infrared Spectrometry studies are executed for acquiring its characteristic. Activated carbon and silica gel are the intermediate products formed during the synthesis process of silica.
EXPERIMENTAL PROCEDURE
1. Rice Husk gradation (sieving):
Rice Husk is sieved using 20-200 mesh size sieves. The major fraction, which usually consists of
20 mesh size, is used for the experiment
2. Washing and drying:
Rice husk obtained after sieving is washed with distilled water for cleaning purpose and sun dried for 48 hours.
3. Carbonization of rice husk:
The rice husk obtained above is carbonized at 500 0 C and 700 0C separately. At or below 500 0C incomplete carbonization is obtained. At or above 700 0C complete carbonization and nano-silica is obtained.Minimum time of duration of carbonization is 2 hours. During the experiment 3 hours of
carbonization is done.
4. Treating with activating agent (alkaline extraction):
The carbonization process result Rice Husk Ash from Rice Husk is further treated with activating agent that is Sodium Hydroxide ,Stirred in Magnetic stirrer for period of 2 hrs at 60 0C. This makes the silica soluble in the activating agent and subjects the rice husk to have more surface area.
5. Filtration:
The above solution obtained is filtered with whatman filter paper. The residue that is obtained on the filter paper is CARBON which is further washed ,treated with Phosphoric acid and carbonized at 700-900 0C to get ACTIVATED CARBON Pure sodium silicate solution is obtained through filtration.
6. Formation of Silica gel (precipitation method
Silica gel formation is obtained by adding concentrated sulfuric acid to the filtered solution until PH 7 is reached. As PH