(84av) Economic Comparison of Nano-Porous Silica Production Processes from Rice Husk and Sand

Environmental problems caused by global warming continue to make efforts to produce energy from sustainable resources or high value-added products from waste. Rice husk generated during rice milling is an agricultural by-product and contains 18-20 wt% silica. Silica is a compound of silicon and oxygen, and it is used in various applications such as paint ingredients, reinforced rubber additives (tires), concrete mixtures, coating additives, and nano-fibers. In the conventional process, the nano-porous silica is produced from sand, which contains 98% silica. Sodium silicate is produced from silica and sodium carbonate at 1300 °C heated by natural gas. Nano-porous silica (NPS) is produced through several steps in the downstream process. The sodium silicate is combusted at 650-850 °C from rice husk ash, and electricity can be generated exploiting combustion heat.

This study compared the economic feasibility such as total capital investment (TCI) and production cost and the environmental impact for the NPS production processes from sand and rice husks. The NPS production process included combustion, hydrothermal synthesis reactor, ultrafiltration, condensation reaction with H₂SO₄, dryer, wastewater and flue gas treatment. The effect of the NPS production process from rice husk on carbon neutrality was analyzed.