Studies into production of Bioethanol from Corncob Using Crude Cellulase Enzyme and Dilute Acid
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Date
2015
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Obafemi Awolowo University(2015)Studies into the Production of Biothanol from Corncob using Crude cellulase Enzyme and Dilute acid
Abstract
This study investigated the production of bioethanol from corncob using crude cellulase enzyme and dilute tetraoxosulphate (VI) acid. The conversion of the cellulosic content of corncob to glucose and the fermentation of the hydrolysates to bioethanol was also studied. This is with the view to converting this abundant agricultural waste into value-added product.
The dried corncob was pretreated mechanically by milling with a hammer mill, sieved with a screen of 1mm, then chemically pretreated with sodium hydroxide in concentrations ranging from (1- 2) %v/v. The enzymatic hydrolysis was carried out on a portion of the substrate with the use of crude cellulase enzyme in liquid form which was isolated from corncob-decomposing bacterium (Bacillus pantothenticus) by mixing with the pretreated biomass and thoroughly agitated. The acid hydrolysis was done by adding the dilute tetraoxosulphate (VI) acid to the pretreated substrate, then thoroughly agitated and heated. The concentration of the glucose yields obtained during hydrolysis was determined using the Dinitrosalicylic acid (DNS) method. Fermentation of the glucose was done with the use of fermenting organism Saccharomyces cerevisaie (Brewers’ yeast). Shake culture experiment was carried out on the glucose for the ethanol production by introducing 5 % innoculum size into each glucose sample. Acid dichromate method was used in determining the bioethanol concentration. The study was carried out as a fractional factorial design with temperature A (50, 60, 70 oC), NaOH concentration B (1, 1.5, 2 %v/v) and H2SO4 concentration C (1.5, 2, 2.5 mol/dm3) as factors that generated twenty experimental runs. Response Surface Methodology (RSM) was used for the analytical and optimization studies using the Central Composite Design (CCD).
Results obtained showed that the factors A, B and C are significant model terms (p<0.05). in the production of glucose and ethanol from acid hydrolysis. The highest glucose obtained during acid hydrolysis was 1467.78 g/L at 60 oC temperature, 1.5%v/v NaOH concentration and 2.5 mol/dm3 H2SO4 while the lowest glucose yield obtained was 141.43 g/L at 70 oC temperature, 1.5%v/v NaOH concentration and 2.00 mol/dm3 H2SO4 concentration. The highest and lowest ethanol yield obtained from fermentation of acid hydrolysates was 45.34 g/L and 30 g/L respectively. The optimum condition for the ethanol production from acid hydrolysates was found to be temperature (69.74 oC), NaOH concentration (2.00%v/v) and H2SO4 concentration (2.50 mol/dm3). The highest and lowest glucose obtained during enzymatic hydrolysis was 253.99 g/L and 23.23 g/L respectively while the highest and lowest bioethanol yields were 91.81 g/L and 54.52 g/L. The optimum conditions for the highest bioethanol yields from enzymatic hydrolysates are 1 oC temperature, 1.5% v/v NaOH concentration.
It can be concluded from this study that crude cellulase enzyme is more effective and cheap in converting corncob to bioethanol than dilute tetraoxosulphate (VI) acid.
Description
Pages 98,xviii
Keywords
Bioethanol, Crude Cellulase Enzyme, Corncob, Farm waste Materials, Nigeria
Citation
Agbonjinmi Omowumi Sarah