Silica nanoparticles and frameworks from rice husk biomass.

Biogenic silica nanoparticles (25-30 nm in diameter) were synthesized from rice husks. The characterizations revealed that the silica nanoparticles were composed of smaller primary particles (ca. 4.2 nm in diameter), and their clustering led to a porous structure with a surface area of 164 m(2)/g. Under the controlled melting catalyzed by K(+), such silica nanoparticle clusters can gradually fuse to form semicrystalline porous silica frameworks with tunable pore size and structural integrity.