Extraction and Characterization of Bio-Silica from Sri Lankan Traditional Rice Husks and Evaluation to TLC Application

Rice husk (RH) is one of the most abundant agricultural wastes, but can be identified as a useful bio resource. Gonabaru, Kahawanu, Patchaperumal, Dahanala and Suwandel are five immerging traditional rice varieties, competing with genetically improved rice in Sri Lankan rice market. Ash content of RHs of traditional rice varieties (>20.0%) was comparatively higher than genetically improved rice. It was identified that additional acid washing step was essential to improve the purity of bio silica. Mineral impurities such as Na, K, Ca, Fe and Mn were determined using atomic absorption spectrometer (AAS). High silica content was extracted from RHs of traditional rice varieties (>23.0%) than that of improved variety, BW 364 (~16.2%). The functional groups present in Rice husk ash (RHA) and rice husk silica (RHS) were determined using Fourier transform infrared (FTIR) analysis. The potential application of purified RHS was observed by preparing and analyzing the thin layer chromatography (TLC) in comparison with commercial TLC silica.