Comparative Studies on Effect of Pretreatment of Rice Husk for Enzymatic Digestibility and Bioethanol Production

Three common pretreatment processes based on dilute sulfuric acid, dilute sodium hydroxide and heat treatment (autoclaving) followed by enzymatic hydrolysis were evaluated to provide comparative performance data. Among them, the best result was obtained when the pretreatment of rice husk was carried out with 3% of NaOH solution. The pretreatment of rice husk with NaOH substantially increased the lignin removal, enzymatic digestibility of cellulose, the accessibility of cellulose and fermentable sugar production. The highest glucose concentration, glucose yield and ethanol concentration were 14.54 g/L, 59.6% and 6.22 g/L; which were 5.44, 3.77 and 6.15 times higher than the untreated control samples, respectively. Moreover, the SEM analysis of the pretreated sample illustrated significant physical changes of the rice husk after NaOH pretreatment.