ALKALINE PRETREATMENT OF LIGNOCELLULOSIC BIOMASS

Abstract

Lignocellulose-to-ethanol conversion is a promising technology to supplement corn-based ethanol production. However, the recalcitrant structure of lignocellulosic materials is a major obstacle to the efficient conversion.In order. to increase the cellulose digestibility, the structure needs to be broken up by pretreatment. In this study, NaOH and alkaline peroxide pretreatment of corn stover was investigated to enhance the Lignin removal and to retain as much cellulose as possible. The factors investigated in case of NaOH was time and concentration and the temperature was fixed at 121 °C. At the best pretreatment conditions (121°C, 60 min, and 3.0% NaOH), the removal of lignin was reported to be 84.19%, which was appreciable as per the previous research works, and the cellulose and hemicellulose conversions reached 65.1 and 30.7% respectively. The factors investigated in case of alkaline peroxide were time, temperature and concentration. At the best pretreatment condition ( 75 °C, 4 h and 5% alkaline peroxide), the removal of lignin was reported to be 74.15% and the cellulose and hemicelluloses recovery reached 70.89 % and 55.61% respectively. Experimental results were fitted by generalised linear model procedure in software SAS 9.2 and the factors were analysed using ANOVA and TUKEYS comparison of means. Both NaOH and alkaline peroxide showed great promise as alkaline pretreatment reagents. However NaOH excessively degraded hemicelluloses which was not the case with alkaline peroxide. Although the preliminary results obtained in this work are promising for both pretreatments considered, reflecting their potential for application, further studies, considering enzymatic digestibility and economic aspects should be performed before extending the conclusions to an industrial process..