تبديل موثر كاه برنج به قندهاي قابل تخمير و توليد بيواتانول با استفاده از پيش فرآوري توسط كربنات سديم

چكيده انگليسي :

Efficient Conversion of Rice Straw to Fermentable Sugars and Bioethanol by Sodium Carbonate Pretreatment Sayed Mohammad Amin Salehi a salehi@ce iut ac ir March 5 2012 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors Assist Prof Keikhosro Karimi karimi@cc iut ac ir Assist Prof Tayebeh Behzad tbehzad@cc iut ac ir Abstract Increasing demand for energy in addition to various environmental concerns intensify the significance of using renewable resources for energy production Among different renewable resources biomasses especially lignocellulosic materials are the most promising alternative for liquid biofuel production Bioethanol should be considered as the most convenient biofuel to replace fossil fuels Lignocellulosic materials mostly include waste materials are found in the cell wall of plants and composed of three major polymers cellulose hemicelluloses and lignin These polymers have strong interaction event by chemical bonds and make lignocellulosic materials stiff and inaccessible to various organisms Cellulose polymer of glucose monomers could be enzymatically hydrolyzed to sugars and then microbially fermented to bioethanol Unfortunately these materials are recalcitrant to both acid and enzymatic hydrolysis leading to low hydrolysis yield Because of that a pretreatment step is necessary prior to hydrolysis to unlock packed and complex structure of these materials and reduce interaction of these polymers and therefore enhance hydrolysis yield of them Among various pretreatment methods chemical pretreatments are more convenient in term of energy consumption and efficiency In this study rice straw as one of the most produced lignocellulose was treated with sodium carbonate prior to enzymatic hydrolysis and fermentation All pretreatments were done in a high pressure reactor at 90 120 150 and 180 C with sodium carbonate concentration of 0 25 0 5 and 1 Molar To eliminate any preheating effect the initial straw was injected to the reactor at desired temperature and at different time a 50 ml sample was taken Enzymatic hydrolysis of untreated and all treated straws was conducted at 45 C for 72 h with enzyme loading of 20 FPU g cellulase and 30 IU g glucosidase The hydrolysis was done in a shaker incubator with the speed of 100 rpm at 45 C Straw treated with Na2CO3 0 5 Molar at 180 C for 120 min was the best sample in term of sugar released This pretreatment has improved glucose released from 1 8 g l for untreated straw to 8 7 g l for treated one Untreated and some treated straws were subjected to simultaneous saccharification and fermentation to ethanol using s cerevisiae as fermenting organism The fermentation performed in a shaker incubator with the speed of 80 rpm at 38 C Ethanol production was enhanced from 90 2 g l for untreated straw to 351 4 g l for treated one Lignin removal effect of pretreatment step was investigated by determination of lignin content of all treated samples Lignin was reduced from 19 2 in untreated straw to 9 4 for treated straw At low temperatures lignin removal was the dominant phenomenon during pretreatment However at higher temperatures xylan removal was the prominent cause leads to observed improvements FTIR analysis and SEM image confirm crystallinity reduction and morphological modification effect of pretreatment step as one of the main reason of improved hydrolysis and fermentation Furthermore bond absorbance obtained by FTIR also certifies lignin and xylan removal effect of pretreatment step Key Words Alkaline delignification lignocellulose pretreatment rice straw sodium carbonate

صالحي، محمدامين

تبديل موثر كاه برنج به قندهاي قابل تخمير و توليد بيواتانول با استفاده از پيش فرآوري توسط كربنات سديم

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