Alkaline Pretreatment of Sunflower Stalks on the Bioethanol Production
Date Issued
2008
Date
2008
Author(s)
Yang, Che-Wei
Abstract
In this study, sunflower stalks which contained 32.09% cellulose, 15.13% semicellulose, 18.83% lignin, 21.98% others, 7.29% ash , 3.02% acetic acid and 1.66% moisture, was first pretreated by 0.5% and 4.0% NaOH solution at 95℃for 90 mins under atmosphere pressure. In the next step, we change the pretreatment parameters such as temperature, immerse time and second hydrogen peroxide pretreatment. In order to find the best pretreatment process, dried solid fraction was hydrolyzed by enzymes of cellulase from Trichoderma reesei C2730 ( Celluclast 1.5L ) under conditions of pH 4.5 and 50℃ for 72 hours with shaking water bath. In hydrolysis step, different mixing enzyme proportion, loadings and substrate ratios were studied to find out the optimum hydrolysis parameters. And then the hydrolysate was fermented with Saccharomyces cerevisiae under conditions at 37℃ and 120 rpm for 24 hours. The glucose, xylose, acetic acid and ethanol concentration were investigated in fermentation step.s result, 0.12~0.43 mg/mL of glucose and 0.16~0.30 mg/mL of xylose were observed in liquid fraction. In hydrolysis step, the enzyme loading of 21 FPU/g Celluclast 1.5L plus 4.2 CBU/g Novozyme 188 represented the best balance between economy and efficiency. 260.60 mg/mL of glucose yield and 60.96% of conversion ratio were obtained under this enzyme loading with 5% substrate ratio and rising the substrate ratio did help improving the concentration of glucose and reducing sugar in the hydrolysate. In fermentation step, the four kind of hydrolysates without sterilization and detoxification were fermented for 24 hours and comsuming the most part of glucose. The ethanol concentration was measured around 13.14~15.40 mg/mL, corresponding to 89.82~94.79% of theoretical ethanol yield.
Subjects
Alkaline pretreatment
Sunflower stalks
Bioethanol
Enzymatic hydrolysis
Fermentation
Type
thesis
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