PRODUCTION OF BIOETHANOL FROM RICE HUSKS

ABSTRACT Bioethanol is an attractive and sustainable energy source to fuel transportation. It is seen as a good alternative fuel as it emits zero net carbon output into the atmosphere. In this study, bioethanol was produced from rice husks using Saccharomyces cerevisiae. Pretreatment of rice husks using alkaline peroxide (H2O2/NaOH) was optimized with Response Surface Methodology (RSM) to determine the optimal operating conditions for the pretreatment process. The optimized pretreated rice husks passed through acid hydrolysis process where the concentration of sugar was measured in BRIX and optimized using RSM. After obtaining the optimal conditions, the optimal BRIX was standardized to measure the actual sugar concentration. A fresh new sample was pretreated was hydrolyzed at the optimum conditions after which the resultant solution was fermented using Saccharomyces cerevisiae for 5 days and the ethanol concentration was analyzed every day using UV-spectrophotometer. The optimal pretreatment conditions were 1.52M hydrogen peroxide and for 142mins to yield maximum delignification of 44.48%. The optimum hydrolysis conditions were obtained at 1M sulfuric acid concentration, 56.45o C hydrolysis temperature and time 123.4mins to produce maximum sugar concentration of 49.57g/l. The fermentation reaction yielded 25.01g/l which translated to 52.52% yield of bioethanol from rice husks. In validating the model, there is no significant difference between the predicted and experimental results. This study showed that commercial production of ethanol from rice husks is possible in Nigeria using Separate Hydrolysis and Fermentation (SHF).