Oxalic Acid Pretreatment on Enhancement of Enzymatic Saccharification from Napier Grass for Biofuel Production

¹ Department of Chemical Engineering, Faculty of Engineering, King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand
² Biorefinery and Process Automation Engineering Center, The Sirindhorn International Thai-German Graduate School of Engineering, King Mongkut’s University of Technology North Bangkok, Bangkok, Thailand
³ Department of Chemistry, University of New England: Armidale, New South Wales, Australia
⁴ Department of Mechanical Engineering, Saveetha School of Engineering, SIMATS, Chennai, India
⁵ Food Technology & Engineering Laboratory, Pilot Plant Development & Training Institute, King Mongkut’s University of Technology Thonburi, Bangkok, Thailand

^* Corresponding author: kraipat.c@eng.kmutnb.ac.th

Abstract

Thailand as an agricultural country faces significant challenges in managing the abundant biomass waste generated from agricultural activities. Conventional disposal methods such as incineration contribute to pollution and limited availability of landfill space. To mitigate these issues valorization of this biomass waste has been a solution. This study focuses on the utilization of Napier grass as a renewable energy source. In this experiment, the Napier grass samples were pretreated using oxalic acid with temperature variations (50 – 100 ^°C), time (30 180 min), and oxalic acid concentration (2 10%w/v) to determine the limit of these three factors for optimization studies. The utilization of Box-Behnken Design (BBD) within Response Surface Methodology (RSM) enabled the determination of optimal pretreatment conditions and the exploration of the correlation between pretreatment factors and reducing sugar content. The model predicted pretreatment with an oxalic acid concentration of 6% w/v, pretreated at 100 ^°C for 105 min as the optimal pretreatment condition to produce a maximum reducing sugar concentration of 10.65 mg/ml. Therefore, the sample was pretreated at optimum conditions and the results revealed the amount of reducing sugar obtained was 10.67 mg/ml, which differed from the predicted value with an error of 0.22%. Thus, this study provides insight for future researchers on the optimum condition that can be applied for pretreating biomass with oxalic acid to maximize the sugar yield.