Attached
Rice is a staple food in Sri Lanka and most of the other South Asian Countries.
Rice husk (RH) is one of the most abundant agricultural wastes available in rice producing
countries. Following the green concept, there is a significant interest of convening this
waste material into useful value added product. RH can be used as a fuel and then as the
silica source. Gonabai u. Kahawanu, Patchaperumal, Dahunaia and Suwandel are some of
the traditional rice varieties, which are becoming popular due to the awareness of medicinal
and nutritional values. The objective of this research is to extract silica from traditional
RHs.
Moisture content, ash content, volatile matter and fixed carbon of RH were
determined as the proximate analysis of RH. comparatively with that of the improved one.
Ash content of RHs of traditional rice varieties (more than 20.0%) was-higher than that of
the genetically improved one ( -13.1%). Acid washing step is required to purify white rice
husk ash (WRHA). The mineral content of WRHA was determined using atomic absorption
spectrometer (A AS). WRHA of both traditional rice varieties and genetically improved rice
variety (BW 364) contains relatively higher amount of K (0.97% - 1.24%). But WRHA of
traditional rice varieties contains lower content of Fe (0.01% - 0:02%) and WRHA of BW
364 contains lower content of Mn (-0,006%). Percentage of reduction (PR) of minerals has
been calculated. According to the PR values, almost all the minerals have been leached out
through the acid washing step.
Acid washed WRHA was used to extract silica as it is an economically valuable
material. High silica content was extracted from RHs of traditional rice varieties (more than
23.0%) than that of BW 364 i-16.2%). Major chemical groups present in rice husk silica
(RHS) were determined using Fourier transform infrared (FTIR) spectra. FT1R spectrum of
RHS was almost similar to the FTIR spectra of commercially available precipitated silica
and silica used for thin layer chromatography (TLC - GF254). TLC plates prepared using
RHS worked almost similar to the laboratory available TLC plates. Therefore there is a
potential usage of RH.
