| 11. |
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| 12. |
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| 13. |
- Poornejad, Nafiseh, et al.
(author)
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Improvement of Ethanol Production from Spruce by Solvent Pretreatment
- 2010
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Conference paper (other academic/artistic)abstract
- Lignocelluloses are abundant and inexpensive resources that can be used for production of bioethanol. However, these materials, especially softwoods, are resistant to enzymatic hydrolysis and a pretreatment process is necessary for efficient conversion to ethanol. The pretreatment is intended to render the cellulose amenable to enzymatic hydrolysis and subsequent fermentation to bioethanol. Several methods has been suggested for the pretreatment of lignocelluloses. The pretreatment with cellulose solvents are among the promising methods since they can perform in mild processing conditions. N-Methylmorpholine-N-oxide (NMMO) is among the industrial solvents which can dissolve cellulose by breaking intermolecular interactions. NMMO is nowadays used in the industrial Lyocell process, which is one of the modern and environmentally friendly industrial fiber-making technologies. It does not produce any toxic waste pollutants, and can be recovered over 98%. The pretreatment of lignocellulose by NMMO can modify the crystal structure of cellulose. In the current work a commercial grade 50% (W/W) NMMO solution was used for pretreatment of spruce. The NMMO solution was concentrated by vacuum evaporation to 85% NMMO. The pretreatment performed at 120ºC for 3 h. The pretreated wood species were then regenerated by addition of boiling distilled water, followed by vacuum filtration and washing. The pretreated and untreated spruce species were enzymatically hydrolyzed by commercial cellulase (celluclast 1.5L, Novozyme, Denmark) and Β-glucosidase (Novozyme 188, Novozyme, Denmark) at 45ºC for 96h. A thermotolerant strain of Saccharomyces cerevisiae was used for fermentation. Inoculum was aerobically cultivated at 30 °C and 120 rpm for 24 h. The enzymatic hydrolyzate was supplemented with necessary nutrient and fermented by the yeast for 24h at 30 °C and 120 rpm. The liquid samples were analyzed by HPLC. The results showed that the yield of ethanol increased from 7.2 g/g to 77 g/g, when the wood treated with the solvent. Formation of glycerol and other metabolites were also detected and discussed. It can be concluded that the method can be a promising alternative for pretreatment of softwoods for bioethanol production.
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| 14. |
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| 15. |
- Rodríquez, Emir Cabrera, et al.
(author)
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Improvement of Enzymatic Hydrolysis of Spruce by Sodium Hydroxide Pretreatment at Low Temperature
- 2010
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Conference paper (other academic/artistic)abstract
- The supply of fermentable sugars is likely to be a limiting factor for large-scale production of biofuels such as bioethanol. Therefore, processes are being developed to produce sugars from lignocellulose material by enzymatic hydrolysis. However, the cellulose fraction of lignocelluloses are not readily accessible for the hydrolyzing enzymes. Efficient hydrolysis of lignocelluloses requires pretreatment, since these materials are resistant to enzymatic hydrolysis. Several processes have been investigated for this pretreatment, in which alkali processes are among the promissing methods. In the current work, effect of NaOH pretreatment of spruce on the chemical composition and the subsequent enzymatic hydrolysis was investigated. Native spruce specie (Picea abies) was obtained from the forest around the city of Borås in Sweden. They were debarked and ball milled. The wood species was analyzed for carbohydrate and lignin fractions according to NREL methods. The wood species was chemically pretreated using 7% sodium hydroxide solution with 5% solid content at 0°C for 30, 60, 120 and 180 minutes. After the pretreatment, the residual solids were washed with distilled water to remove chemicals and neutralized to pH 7. The neutralized samples were filtered and stored for subsequent hydrolysis. Enzymatic hydrolysis of the pretreated wood was carried out at pH 4.8, 45°C and 5% dry substances. Commercial enzymes, cellulase (Celluclast 1.5L, Novozyme, Denmark) and β- glucosidase (Novozyme 188, Novozyme, Denmark) were used in the enzymatic hydrolysis. 30 FPU cellulase and 50 IU b-glucosidase per grams of the wood species were used for enzymatic hydrolysis. The pretreatments resulted in changes on the composition of the material. There were less than 1% losses in carbohydrate, suggesting no significant carbohydrate hydrolysis. Xylans were the most affected components by the pretreatments. The largest xylan removal was almost 50%, and it was occurred by using sodium hydroxide solution for 180 minutes. The profile of released sugars were also analyzed and compared. Significant improvement on the yield of enzymatic hydrolysis was observed as a results of the pretreatment.
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| 16. |
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| 17. |
- Shafiei, Marzieh, et al.
(author)
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Techno-economic study of ethanol from spruce by N-methylmorpholine-N-oxide (NMMO) pretreatment
- 2011
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Conference paper (other academic/artistic)abstract
- Pretreatment is necessary to open up the crystalline structure of the cellulose fibers. It is believed that pretreatment is a “key process” to have an economically feasible ethanol production from lignocelluloses. N-methylmorphilne-N-oxide (NMMO) is a cellulose solvent, which has an industrial application in viscose process for fiber production. NMMO does not produce any toxic waste pollutant and is an environmentally friendly solvent. Considering NMMO as a promising alternative for pretreatment of wood, a novel process for ethanol production from wood was developed in this work. Wood is pretreated by concentrated NMMO and ethanol is produced by NSSF process. Biogas and solid residues are the valuable by products of this process. Simulation of the process with Aspen Plus® was applied to solve the process mass and energy balance; finding the bottlenecks of the process, optimizing the equipment configuration, and providing the necessary data for the equipment design. The economical feasibility of the developed biorefinery for five different plant capacities was studied by Aspen Icarus Process Evaluator®. The base case was designed to utilize 200,000 tons of spruce wood per year and needed M€ 58.3 as total capital investment. Ethanol production yield, based on experiments, was as high as one liter of ethanol per 4 kilograms of wood. Effect of price of feedstock, enzyme, methane, carbon dioxide and solid residue as well as nutrient load on the production cost were investigated.
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| 18. |
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