Enzyme Hydrolysis of Hydrogen Peroxide Pretreated Lignocellulosic Content of Rice Husks Prior to Bioethanol Formation

Abstract

Aims: This work was aimed at evaluating the production of sugar from the bio-fermentation of rice husk using hydrogen peroxide as a pre-treatment medium. Methodology: Different samples of rice husks were pretreated with 1%, 1.5%, 2%, and 2.5% (w/v) hydrogen peroxide respectively and allowed to delignify for 2 hours prior to saccharification by cellulose at 37°C and pH of 4.7. The experiment was repeated at varying time intervals spanning 2-24 hours. Amount of reducing sugars produced was determined spectrophotometrically and documented. Results: High reducing sugar yields at concentrations of 1%, 1.5%, and 2%, H2O2 were observed as 0.81 mg/ml with saccharification of 10.47%, 1.15 mg/ml with saccharification of 14.87%, and 1.42 mg/ml with saccharification of 18.36% respectively. Pretreatment with 2.0% H2O2 was found to achieve highest reducing sugars yield (1.42 mg/ml with saccharification of 18.36%) after pretreatment time of 8 hours as against other concentrations. Conclusion: The result suggests that degree of saccharification is dependent on concentration of hydrogen peroxide used and time of pre-treatment. The reduction in sugar yield at 2% H2O2 may be as a result of hydrogen peroxide solubilizing lignin which may act as an inhibitor during enzyme hydrolysis.