| Özet notu |
'ABSTRACT Two different plants namely Phoenix canariensis and Opuntia ficus-indica were used as substrate for reducing sugar generation and ethanol production. Dilute acid, alkaline and steam explosion were used as pretreatment methods in order to depolymerize lignin and/or hemicellulose and recover cellulose. Among these methods, alkaline pretreatment with 2.5% NaOH enhanced (71.08% for P. canariensis and 74.61% for O. ficus-indica) lignin removal and cellulose recovery (81.84% for P. canariensis and 72.66% for O. ficus-indica) yields were obtained. Pretreated materials were hydrolyzed by cellulase with high efficiency (87.0% and 84.5% cellulose conversion yields for P. canariensis and O. ficus-indica) and used as substrate for fermentation. Maximum ethanol production of 15.75 g/L and 14.71 g/L were achieved from P.canariensis and O. ficus-indica respectively. Structural differences were observed by XRD, FTIR and SEM for untreated, pretreated, hydrolyzed and fermented samples and were highly correlated with compositional analysis results. Each type of pretreatment was carefully investigated and throughly evaluated to elucidate the most required condition to be applied. İn sodium hydroxide pretreatment, the following conditions were optimized, which includes percentage NaOH v/v, temperature, estimated time (t), raw material concentration needed for the pretreatment of P. canariensis and O. Ficus indica lignocelluloses.The optimized conditions for alkaline (NaOH) pretreatment were 2.5% NaOH, temperature of 600C, 120 min interval, and raw material concentration of 1g/L. Optimal conditions evaluated during H2SO4 pretreated P. canariensis and O. Ficus indica was, 5 % Sulfuric acid in 98% acid concentration v/v, temperature of 600C, 120 min time interval and raw material concentration of 1g/L. The above optimized conditions were selected considering the amount of celluloses recovered (%), lignin removal, solubilized hemicelluloses and total reducing sugars (TRS) obtained after evaluation of all the conditions scientifically and carefully examined for further investigation. Other pretreatments investigated in this study includes Steam explosion with acid, and non- acid treated steam. During the evaluation for the above, acid steam optimized conditions were 4% dilute H2SO4, temperature of 2600C, 5 min and raw material concentration of 1g/L. Non-acid steam efficiency was best at 2600C, in 5 min (t) interval and at raw material concentration of 1g/L. Comparison of all the pretreatment processes were wholesomely evaluated as indices for continuation and were in terms of amount of sugar yields. Alkaline (NaOH) pretreated P. canariensis and O. Ficus indica samples were found to be more efficient because of the highest lignin removal, cellulose recovery and TRS yield. Keywords: Lignocellulose, Pretreatments, Cellulose accessibility, Enzyme, Hydrolysis, Fermentation, CrI, XRD, SEM, FTIR, Protein synthesis.' |