Rice straw capabilities for production of silica nanostructures

Annually huge amount of un-used rice straw after rice harvesting were burned due to no specific utilization. Whereas, based on the biorefinery concept there is possibility to use these agricultural residues for production of high value added products. So, this study was aimed to extract the silica from the rice straw (Oryza Sativa var Indica) as one of the important agro-industrial residues in the country and its capabilities for production of silica nanostructures based on the mentioned concept. After washing, drying and grinding of rice straw samples, some of them were separately leached with a hydrochloric acid and some ones with a sulphuric acid at concentration of 0.5 M for 30 min with constant stirring. Afterwards, the silica content of acid-leached and un-leached rice straw samples was measured in a muffle furnace with varying temperatures at 500,600, 700, 800 and 900°C for 2 h. The results were obtained from Energy Dispersive X-ray (EDX) and X-ray Fluorescence (XRF) demonstrated the maximum presence of silica into the rice straw ash. Two of aforementioned spectroscopy methods explored the higher content and purity of acid-leached rice straw samples in comparison to un-leached rice straw ones. The Field Emission Scanning Electron Microscopy (FESEM) images demonstrated that the prepared silica nanostructures had a spherical shape and their average particle sizes were 30 nanometer for un-leached rice straw samples and less than 12 nanometer for acid-leached ones.