Obtaining Biogenic Silica from Sugarcane Bagasse and Leaf Ash

Besides mineral sources, silica can be found in plants, particularly in the epidermis, since during their growth plants absorb the mono-silicic acid present in the soil, storing it as a natural form of protection, insect pest control and transpiration regulator. Among the plants that present high levels of silica in their ashes, we can highlight sugarcane, with Brazil being the largest producer of sugarcane derived (sugar and bioethanol) in the world, accounting 615 million tons per year. Thus, the increasing of the international demand encourages an increase of the availability of sugarcane wastes, pushing its use for the generation of electric power, as for other purposes enabling a sustainable development. In this work, high purity silica nanoparticles (up to 95%) with predominantly amorphous microstructure were obtained after thermal (500 to 700 °C) and chemical treatments (1 molar hydrochloric acid solution, 10% volume) of sugarcane bagasse and leaves ashes. The obtained results indicate the possibility of using this silica in ceramics, glasses, refractory materials and construction applications, as well as in the cosmetic and pharmaceutical industry, molecular sieves and mesoporous membranes. The silica obtained in this research also proved to be suitable for obtaining porous silicon (using magnesiothermic reduction), where the experimental procedure employed is described elsewhere. Graphic Abstract