Clean and Efficient Synthesis of High-Quality Silica From Rice Husk Ash

Abstract Rice husk ash derived from the rice husk, a renewable waste biomass resource from rice production can be used to produce high value-added silica materials with various applications. But present technologies suffer the shortages of using inorganic acid as the precipitating agent, complex salt-containing wastewater post-treatment, higher production cost, lower product quality, and without the recycling of process additives. In this paper, improved clean chemical precipitation characterizing of recycling the by-product and surfactant used is developed with the highest silica product yield of 99.3%, pore size (21-35 nm), and specific surface area (196-462 m2/g). After the by-product solution is reused 5 times, the yield of silica can still reach 99.1%. The recovery yield of surfactant is 95.3%. The properties of the prepared silica meet the standard of silica for specific applications. The process characterized the recycling of the by-product and surfactant in the process, greener CO2 precipitant, ensuring the greenness, process efficiency, and low production cost. This opens up a new industrialization practical way for up-grading utilization of waste biomass and CO2 containing industrial effluents.