Enzyme Hydrolysis of Hydrogen Peroxide Pretreated Lignocellulosic Content of Rice Husks Prior to Bioethanol Formation
John O. Ojowu *
Department of Biological Sciences, Federal University of Agriculture, Makurdi, Nigeria.
Michael I. Ortese
Department of Biological Sciences, Federal University of Agriculture, Makurdi, Nigeria.
Esin E. Etim
Department of Biological Sciences, Federal University of Agriculture, Makurdi, Nigeria and Department of Biomedical Sciences, University of Westminster, London, United Kingdom.
*Author to whom correspondence should be addressed.
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.
Keywords: Agricultural wastes, hydrogen peroxide, lignocelluloses, pretreatment, rice husks, saccharification