Asian Journal of Environment & Ecology

The enzymatic production of fermentable-sugar from rice husk was examined using diluted sulfuric-acid as a pretreatment medium. In this study, 10 g of rice husk were separately pretreated with 0.5 M, 1.0 M and 1.5 M sulfuric acid at different time interval of 2-24 hours, prior to saccharification by cellulase-enzyme at 37°C and pH of 4.5. Then the quantity of monosaccharide produced was determined spectrophotometrically. After two hours of pretreatment, the 1.5 M H₂SO₄ pretreated samples yielded 88.05 mg/g (39.11%) of glucose, 1.0 M H₂SO₄  pretreated samples yielded 68.4 mg/g (30.38%), and 0.5M H₂SO₄ pretreated samples yielded 68.7 mg/g (30.51%) respectively, when compared with the un-pretreated sample (20.4 mg/g). However, after two hours, the production of glucose significantly reduced with increase time, except with 1.0 and 0.5 M H₂SO₄ pretreated sample which significantly increase at 4-hours (82.5 and 76.5 mg/g respectively). The result suggests that sulfuric acid enhances the release of fermentable-sugar, and that the yield is dependent on the concentration of acid and the time of treatment. The reduction in glucose yield over time as shown in the results could be due to the ability of the acid to liberate sugar which may be washed off during the washing process to remove the acid prior to the hydrolysis by enzyme.