Optimization and Characterization of Bio-Silica Extraction from Rice Straw Using RSM

Egypt produces about 7.86 million tons of rice straw annually. Egyptian farmers have traditionally gathered and burnt rice straws in the field in the open for rapid disposal. Environmentalists have recently attacked the practice, and legislation was passed to limit open burning, which pollutes the environment in many nations. The purpose of this research is to extract amorphous bio-silica from rice straw after burning it to produce ash, then use sodium hydroxide for an alkaline extraction to produce a sodium silicate solution. Hydrochloric acid was added to a solution of sodium silicate to precipitate silica. Temperature, time, and concentration were the three main variables that influenced alkaline extraction. To improve these values, a response surface strategy was adopted. The reaction occurred between 30 and 90 degrees C, extraction time between 1 and 3 h, and had a sodium hydroxide concentration of 1 and 3N. At 90 degrees C, 3N sodium hydroxide concentration, and 3 hours, the highest yield of silica is anticipated to be 83%. The produced bio-silica was characterized using XRF, XRD, FTIR and SEM. The results indicated that precipitated bio-silica can be extracted from rice straw to produce a high yield and used in different applications.