International Research Symposium on Pure and Applied Sciences (IRSPAS)
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Item Preparation, characterization and properties of activated carbon derived from rice husk(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Perera, P. L. R. A.; Rajapakse, C. S. K.Rice, the staple food of the Sri Lankans is one of the important crops occupying 34% of the total cultivated area in the country. Thus, rice processing generates a large quantity of rice husk as waste material. The main objective of the present work was to investigate the potential of using this agricultural waste, rice husk as a precursor for the production of low-cost activated carbon (AC) as an adsorbent for the removal of heavy metals (Pb(II), Cd(II) etc.). Therefore, the present study was carried out to evaluate the effect of carbonization time and activating agent on AC production from rice husk and its Pb(II) removal capacity. Cleaned and dried rice husks samples (12.00 g) were separately carbonized at 400 °C under constant nitrogen flow for 60 minutes -150 minutes (60 min, 90 min, 120 min, 150 min) and chemically activated by HCl. The AC yield was calculated in each sample. In order to determine the lead removal percentages (Pb%) of AC derived from rice husk at different carbonized temperatures, first AC samples were added (1.00 g) separately to a Pb(II) standard solution (5.00 mg L-1), stirred for 1 hour at pH 7 at room temperature. The solutions were filtered and the residual Pb was determined by Atomic Absorption Spectrophotometry (AAS). All the experiments were performed in duplicate. Further, the AC with the highest Pb removal capacity was characterized by Scanning Electron Microscopy & Energy Dispersive Spectroscopy (SEM/EDAX), and Fourier Transform Infrared Spectroscopy (FT-IR). Proximate analysis, of the AC were also studied. The percent yield of AC prepared from rice husk with HCl activation, and its corresponding % Pb removal potential were fluctuated with increasing carbonization time. The highest AC yield (20.50%), the highest % Pb removal (93.31%) was observed for the AC prepared by carbonization of rice husk at 400 °C for 120 minutes with HCl activation. The results of the proximate analysis revealed that the ash content, moisture content volatile matter content and fixed carbon content of the AC were 32.47%, 34.94%, 24.20%, and 8.39% respectively. Based on the results, it can be concluded that AC derived from rice husk can be considered as an efficient and cost-effective adsorbent for the removal Pb(II) from wastewaterItem Production of bio-ethanol using pretreated lignocellulosic materials (rice husk, water hyacinth).(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Arasaretnam, S.; ayasundara, J. M. P. W.Production from food sources such as corn, sugarcane etc. is the most predominant way of producing ethanol. This has led to a shortage in food, imbalance in food chain, increased food price and indirect land use. This study thus explores the use of alternative nonfood materials for the production of ethanol from cellulose. Rice husk and water hyacinth were selected as raw material in this study. The powdered rice husk and water hyacinth were subjected to physical pretreatment by washing with distilled water to remove all the soluble impurities in the materials followed by air-drying, cutting (water hyacinths), oven drying for 6 hours at 60 ℃ and finely powdered samples were stored inside a container at room temperature. Chemical pretreatment (acid pretreatment) was performed by physically soaking each lignocellulosic substrate in 1 M H2SO4 for 24 hours and shaking (150 rpm) at room temperature. Each solid sample was recovered by filtration and washing repeatedly with distilled water until the water pH was 7.0. Subsequently each sample was dried at 80 ℃ to a constant weight in oven prior to enzymatic hydrolysis. Both pretreatments were used to optimize the conditions for maximum ethanol productivity from rice husk and water hyacinth. Enzymatic hydrolysis of pretreated rice husk and water hyacinth gave the highest yield of reducing sugar. As a result of qualitative test, pretreatment methods had been applied on rice husk and water hyacinth in order to increase the available cellulose content and thus improve the enzymatic hydrolysis efficiency. The result of FTIR characterization of pretreated rice husk and water hyacinth implies that both samples contain bio-ethanol.Item Effect of root-application of rice husk as a natural silicon (Si) source on the nutritional quality of bitter gourd (Momordica charantia L.).(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Ratnayake, R.M.R.N.K.; Daundasekera, W.A.M.; Ariyarathne, H.M.; Ganehenege, M.Y.U.Silicon (Si) has proven its beneficial effects on growth, yield and disease resistance in many agricultural crops. Synthetic Si in the form of potassium silicate, sodium silicate, calcium silicate etc. and natural Si sources like rice husk are being tested across the world to achieve such favorable effects. Our previous investigations revealed that the amendment of growth media with powdered raw rice husk (PRH) or rice husk ash (RHA) extends the shelf life of bitter gourd (Momordica charantia L.) by enhancing its physico-chemical properties and inducing resistance against postharvest fungal pathogens. These changes were associated with increased Si levels in fruits from rice husk-treated plants. Si application is also known to either improve or hinder uptake of certain nutrients depending on the crop. Aim of this study was to test the effect of rice husk application on some major nutrients in bitter gourd. M. charantia cultivar ‘Matale green’ was grown in pots containing sand: top soil: compost at 2:1:1 ratio. The growth medium was amended with rice husk in two different forms viz. PRH or RHA at a rate of 200 mg Si/ kg soil, once a week, up to 28 days. Growth medium without husk amendment served as controls. Each treatment consisted of 20 pots. Ten fruits from each treatment were harvested at standard harvesting maturity and crude protein, fat, fiber, total carbohydrates, ash, nitrogen (N), phosphorous (P), and potassium (K) of the fruit pericarp tissues were assayed using AOAC (Association of Official Analytical Chemists) methods. Data analysis was done by one-way analysis of variance. Total N, crude protein, fat and ash contents of fruits from husk-amended plants were significantly higher (p < 0.05) than that of controls whereas the other parameters were not affected significantly by husk amendment. Accordingly, average total N content in PRH, RHA and controls were 0.14±0.002, 0.13±0.001 and 0.08±0.002% respectively. Means of the crude protein content ranged as 0.94± 0.12,0.91± 0.09 and 0.58± 1.28% in that order and the total ash content in PRH treated fruit (1.24± 0.006%) was significantly higher than that of RHA treatments (1.12± 0.01%) while the lowest (1.04± 0.01%) was observed in control fruit. Crude fat content in control fruit (1.4± 0.01%) was lower than that of husk amended samples and difference between PRH (1.8 ± 0.07%) and RHA (2± 0.05%) was not significant. Therefore rice husk can be suggested as an eco-friendly and less costly soil supplement which improves the protein quality of bitter gourd without any negative effect on its basic nutritional status.