Eco-friendly Synthesis and Characterization of Amorphous Nanosilica from Rice Husk

Background: A significant amount of rice production waste is rice husk. It is not humifiable and turns into a significant environmental pollutant if not properly utilized. Rice husk contains silica nanoparticles, which is a major inorganic component. High purity amorphous silica nanoparticles can thus be produced using simple thermo-chemical procedures without polluting the environment by cutting out the release of carbon dioxide during the process. Methods: A study was carried out to extract amorphous silica nanoparticles from rice husk ash using an environmentally benign chemical process. Utilising a variety of material characterization techniques viz., X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDS) and Particle size analyser (PSA), the extracted nanoparticles properties were confirmed. Result: The amorphous behaviour of the silica sample was confirmed using transmission electron microscopy-selected area electron diffraction patterns and X-ray diffraction analyses, whilst siloxane and silanol groups were primarily discovered using Fourier-transform infrared spectroscopy. Images obtained using scanning electron and transmission electron microscopy showed initial nanoparticles to be present along with secondary microparticles, possibly as a result of their agglomeration. The extracted amorphous silica has particles with an average diameter of 35 nm. This synthesized silica nanoparticles can be used in agriculture, nano-additives, microelectronics, sensors and in other fields.