Seohyun Kim  Yong Ha Kim  Yong Sun Won

Vol. 31,  No. 3, pp. 207-215, Sep.  2025
10.7464/ksct.2025.31.3.207

Rice husk Silica Sol-Gel Extraction

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Rice is a staple food for 40% of the world, so rice production is high to match its demand. As a result, rice husks account for a significant amount of agricultural waste. Rice husk is known to contain a large amount of silica (92 ~ 94 wt%), which if extracted at a high purity, could be used in the semiconductor and battery industries. This study attempted to extract high-purity silica from rice husk based on the environmental, social, governance (ESG) perspective that has recently emerged as an issue. The basic extraction procedure involved preparing the rice husk ash containing nanostructured silica through a hydrochloric acid pretreatment and calcination, mixing the rice husk ash in a NaOH solution to use the sol-gel method, and then appropriate it using sulfuric acid, and finally performing calcination to obtain amorphous nanostructured silica from the silica gel. Cross-experiments were conducted with 0.2 M and 0.5 M NaOH solutions and 600 o C and 850 o C final calcination temperatures as factors affecting the yield and purity of silica, respectively. An optimal purity of 98.5% and yield of 97.2% were obtained with 0.5 M NaOH and 850 o C. A typical process flow diagram (PFD) was then presented and an economic analysis was followed to recommend a potential country where the proposed process could be applied.