Synthesis of silica nanoparticles from sugarcane bagasse ash and nano-silicon via magnesiothermic reactions

Nanoparticles of SiO2 were synthesized via sol-gel route using sugarcane bagasse ash as a silica source. The influence of the synthesis operational conditions, as well as, the use of different purification methods, such as chemical treatments, on morphological, structural and chemical properties of the synthesized nanoparticles were evaluated. The results showed that the sol-gel synthesis is a feasible alternative method for obtaining silica xerogel using ashes with high impurities contents, such as iron and aluminum oxide. Amorphous SiO2 nanoparticles with an average size of similar to 10 nm were obtained by controlling the main synthesis variables (pH, temperature and SiO2/H2O molar ratio). The purification methods investigated allowed to obtain nanosilica with different levels of purity, greater than 96%. The combined morphological features, i.e., large specific surface and pore volume, allow these materials to have applications in several technological fields, such as optical, electronics and biomedical and additionally, as a source of nano-silicon via magnesiothermal reduction.