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Shahab Sokhansanj - One of the best experts on this subject based on the ideXlab platform.
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bulk density and compaction behavior of knife mill chopped switchgrass wheat straw and Corn Stover
Bioresource Technology, 2010Co-Authors: Nehru Chevanan, Alvin R Womac, Venkata S P Bitra, C Igathinathane, Yuechuan T Yang, Petre I Miu, Shahab SokhansanjAbstract:Abstract Bulk density of comminuted biomass significantly increased by vibration during handling and transportation, and by normal pressure during storage. Compaction characteristics affecting the bulk density of switchgrass, wheat straw, and Corn Stover chopped in a knife mill at different operating conditions and using four different classifying screens were studied. Mean loose-filled bulk densities were 67.5 ± 18.4 kg/m3 for switchgrass, 36.1 ± 8.6 kg/m3 for wheat straw, and 52.1 ± 10.8 kg/m3 for Corn Stover. Mean tapped bulk densities were 81.8 ± 26.2 kg/m3 for switchgrass, 42.8 ± 11.7 kg/m3 for wheat straw, and 58.9 ± 13.4 kg/m3 for Corn Stover. Percentage changes in compressibility due to variation in particle size obtained from a knife mill ranged from 64.3 to 173.6 for chopped switchgrass, 22.2–51.5 for chopped wheat straw and 42.1–117.7 for chopped Corn Stover within the tested consolidation pressure range of 5–120 kPa. Pressure and volume relationship of chopped biomass during compression with application of normal pressure can be characterized by the Walker model and Kawakita and Ludde model. Parameter of Walker model was correlated to the compressibility with Pearson correlation coefficient greater than 0.9. Relationship between volume reduction in chopped biomass with respect to number of tappings studied using Sone’s model indicated that infinite compressibility was highest for chopped switchgrass followed by chopped wheat straw and Corn Stover. Degree of difficulty in packing measured using the parameters of Sone’s model indicated that the chopped wheat straw particles compacted very rapidly by tapping compared to chopped switchgrass and Corn Stover. These results are very useful for solving obstacles in handling bulk biomass supply logistics issues for a biorefinery.
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flowability parameters for chopped switchgrass wheat straw and Corn Stover
Powder Technology, 2009Co-Authors: Nehru Chevanan, Alvin R Womac, Venkata S P Bitra, D C Yoder, Shahab SokhansanjAbstract:Abstract A direct shear cell to measure the shear strength and flow properties of chopped switchgrass, wheat straw, and Corn Stover was designed, fabricated, and tested. Yield loci (r2 = 0.99) determined at preconsolidation pressures of 3.80 kPa and 5.02 kPa indicated that chopped biomass followed Mohr–Coulomb failure. Normal stress significantly affected the displacement required for shear failure, as well as the friction coefficient values for all three chopped biomass types. Displacement at shear failure ranged from 30 to 80 mm, and depended on preconsolidation pressure, normal stress, and particle size. Friction coefficient was inversely related to normal stress, and was highest for chopped Corn Stover. Also, chopped Corn Stover exhibited the highest angle of internal friction, unconfined yield strength, major consolidation strength, and cohesive strength, all of which indicated increased challenges in handling chopped Corn Stover. The measured angle of internal friction and cohesive strength indicated that chopped biomass cannot be handled by gravity alone. The measured angle of internal friction and cohesive strength were 43° and 0.75 kPa for chopped switchgrass; 44° and 0.49 kPa for chopped wheat straw; and 48° and 0.82 kPa for chopped Corn Stover. Unconfined yield strength and major consolidation strength used for characterization of bulk flow materials and design of hopper dimensions were 3.4 and 10.4 kPa for chopped switchgrass; 2.3 and 9.6 kPa for chopped wheat straw and 4.2 and 11.8 kPa for chopped Corn Stover. These results are useful for the development of efficient handling, storage, and transportation systems for biomass in biorefineries.
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specific energy requirement for compacting Corn Stover
Bioresource Technology, 2006Co-Authors: Sudhagar Mani, Shahab SokhansanjAbstract:Abstract Corn Stover is a major crop residue for biomass conversion to produce chemicals and fuels. One of the problems associated with the supply of Corn Stover to conversion plants is the delivery of feedstock at a low cost. Corn Stover has low bulk density and it is difficult to handle. In this study, chopped Corn Stover samples were compacted in a piston cylinder under three pressure levels (5, 10, 15 MPa) and at three moisture content levels (5%, 10%, 15% (wb)) to produce briquettes. The total energy requirement to compress and extrude briquette ranged from 12 to 30 MJ/t. The briquette density ranged from 650 to 950 kg/m 3 increasing with pressure. Moisture content had also a significant effect on briquette density, durability and stability. Low moisture Stover (5–10%) resulted in denser, more stable and more durable briquettes than high moisture Stover (15%).
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variation in Corn Stover composition and energy content with crop maturity
Biomass & Bioenergy, 2005Co-Authors: L O Pordesimo, Shahab Sokhansanj, Bonnie R. Hames, W C EdensAbstract:Abstract How to harvest and process Corn Stover to maximize its quality as a fuel or industrial feedstock and minimize material losses are compelling issues in the industrial utilization of Corn Stover. The objectives of this investigation were to evaluate the variation in the chemical composition and energy content of aboveground components of the Corn plant over time and to evaluate how composition changes after grain physiological maturity is reached and the plants are weathered while undergoing further field drying. Above ground biomass distribution and composition of two almost identical Corn cultivars (Pioneer 32K61 and 32K64 Bt) were studied from an estimated 2 weeks before Corn kernel physiological maturity until 4 weeks after the grain had already reached a moisture content suitable for combine harvesting. Compositional analysis of Corn Stover fractions gathered over the course of maturation, senescence, and weathering using NIR spectroscopy showed (1) a rapid drop in soluble glucan, (2) increase in lignin, and (3) increase in xylan. By day 151 after planting, about when grain from surrounding non-test plots was harvested at about 15.5% moisture, composition of the different fractions remained fairly constant. Since product yield in fermentation-based biomass conversion processes is proportional to the structural carbohydrate content of the feedstock, timing of Stover collection and the proportion of anatomical fractions collected affect the quality of Corn Stover as fermentation feedstock. Since the energy content of Corn Stover anatomical fractions is shown to remain fairly constant over time and from one plant to another (16.7–20.9 kJ g−1), insofar as combustion processes are concerned, it apparently makes little difference which part of the plant is used, or at what time the material is harvested.
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distribution of aboveground biomass in Corn Stover
Biomass & Bioenergy, 2004Co-Authors: L O Pordesimo, W C Edens, Shahab SokhansanjAbstract:Corn Stover can be a principal feedstock for bioenergy and industrial applications because of its abundance and its current underutilization. Development of strategies/systems for the postharvest handling of Corn Stover involves quantifying what Corn Stover biomass is available over time after grain physiological maturity has been reached. It also involves understanding how the biomass is distributed in the different aboveground components of the Corn plant. The objectives of this preliminary investigation were to measure the allocation of biomass to aboveground components of the Corn plant over time and to develop relationships for estimating total aboveground Corn plant biomass through simple Corn plant dimensional measurements. Aboveground biomass distribution for two Corn cultivars (Pioneer 32K61 and 32K64 Bt) was studied in standing plants from roughly 1 week before grain physiological maturity until 4 weeks after grain harvest from other plots in the field. Over the monitoring period, the amount of dry matter in Stover averaged 50% of the total aboveground dry plant mass with stalks comprising 50% of the Stover dry matter at the time grain was harvested. This study indicated that the more conservative 0.8:1 Stover:grain fresh weight ratio, rather than the 1:1 widely used, may be more realistic at the grain harvest moisture range of 18–31% w.b. Such precondition has not been clearly emphasized in the literature. Regression equations involving stalk diameter and plant height for DeKalb 626 derived to estimate fresh green weight and dry matter of the Corn plant above the ground had a maximum R2 of 0.75.
Mark T Holtzapple - One of the best experts on this subject based on the ideXlab platform.
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delignification kinetics of Corn Stover in lime pretreatment
Bioresource Technology, 2006Co-Authors: Sehoon Kim, Mark T HoltzappleAbstract:Corn Stover was pretreated with excess calcium hydroxide (0.5 g Ca(OH)(2)/g raw biomass) in non-oxidative and oxidative conditions at 25, 35, 45, and 55 degrees C. The delignification kinetic model of Corn Stover used three first-order reactions with following forms: W(L) = 0.09 x exp(-infinity x t) + 0.28 x exp(-k(2) x t) + 0.63 x exp(-k(3) x t) in non-oxidative pretreatment; W(L) = 0.16 x exp(-infinity x t) + 0.27 x exp(-k(2) x t) + 0.57 x exp(-k(3) x t) in oxidative pretreatment. The first term corresponds to the initial phase, which is essentially infinite at the time scale of the reaction (weeks). The second and third terms correspond to the bulk and residual phases of delignification. The activation energies for delignification in the oxidative lime pretreatment reactions were estimated as 50.15 and 54.21 kJ/mol in the bulk and residual phases, respectively, which are similar to the Kraft delignification of bagasse, but much less than in Kraft delignification of wood.
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effect of structural features on enzyme digestibility of Corn Stover
Bioresource Technology, 2006Co-Authors: Mark T HoltzappleAbstract:Abstract Corn Stover was pretreated with excess calcium hydroxide (0.5 g Ca(OH) 2 /g raw biomass) in non-oxidative and oxidative conditions at 25, 35, 45, and 55 °C. The enzymatic digestibility of lime-treated Corn Stover was affected by the change of structural features (acetylation, lignification, and crystallization) resulting from the treatment. Extensive delignification required oxidative treatment and additional consumption of lime (up to 0.17 g Ca(OH) 2 /g biomass). Deacetylation reached a plateau within 1 week and there were no significant differences between non-oxidative and oxidative conditions at 55 °C; both conditions removed approximately 90% of the acetyl groups in 1 week at all temperatures studied. Delignification highly depended on temperature and the presence of oxygen. Lignin and hemicellulose were selectively removed (or solubilized), but cellulose was not affected by lime pretreatment in mild temperatures (25–55 °C), even though Corn Stover was contacted with alkali for a long time, 16 weeks. The degree of crystallinity slightly increased from 43% to 60% with delignification because amorphous components (lignin, hemicellulose) were removed. However, the increased crystallinity did not negatively affect the 3-d sugar yield of enzymatic hydrolysis. Oxidative lime pretreatment lowered the acetyl and lignin contents to obtain high digestibility, regardless of crystallinity. The non-linear models for 3-d hydrolysis yields of glucan ( Y g ), xylan ( Y x ), and holocellulose ( Y gx ) were empirically established as a function of the residual lignin ( L ) for the Corn Stover pretreated with lime and air.
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effect of structural features on enzyme digestibility of Corn Stover
Bioresource Technology, 2006Co-Authors: Sehoon Kim, Mark T HoltzappleAbstract:Corn Stover was pretreated with excess calcium hydroxide (0.5 g Ca(OH)2/g raw biomass) in non-oxidative and oxidative conditions at 25, 35, 45, and 55 degrees C. The enzymatic digestibility of lime-treated Corn Stover was affected by the change of structural features (acetylation, lignification, and crystallization) resulting from the treatment. Extensive delignification required oxidative treatment and additional consumption of lime (up to 0.17 g Ca(OH)2/g biomass). Deacetylation reached a plateau within 1 week and there were no significant differences between non-oxidative and oxidative conditions at 55 degrees C; both conditions removed approximately 90% of the acetyl groups in 1 week at all temperatures studied. Delignification highly depended on temperature and the presence of oxygen. Lignin and hemicellulose were selectively removed (or solubilized), but cellulose was not affected by lime pretreatment in mild temperatures (25-55 degrees C), even though Corn Stover was contacted with alkali for a long time, 16 weeks. The degree of crystallinity slightly increased from 43% to 60% with delignification because amorphous components (lignin, hemicellulose) were removed. However, the increased crystallinity did not negatively affect the 3-d sugar yield of enzymatic hydrolysis. Oxidative lime pretreatment lowered the acetyl and lignin contents to obtain high digestibility, regardless of crystallinity. The non-linear models for 3-d hydrolysis yields of glucan (Y(g)), xylan (Y(x)), and holocellulose (Y(gx)) were empirically established as a function of the residual lignin (L) for the Corn Stover pretreated with lime and air.
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lime pretreatment and enzymatic hydrolysis of Corn Stover
Bioresource Technology, 2005Co-Authors: Sehoon Kim, Mark T HoltzappleAbstract:Abstract Corn Stover was pretreated with an excess of calcium hydroxide (0.5 g Ca(OH) 2 /g raw biomass) in non-oxidative and oxidative conditions at 25, 35, 45, and 55 °C. The optimal condition is 55 °C for 4 weeks with aeration. Glucan (91.3%) and xylan (51.8%) were converted to glucose and xylose respectively, when the treated Corn Stover was enzymatically hydrolyzed with 15 FPU/g cellulose. Only 0.073 g Ca(OH) 2 was consumed per g of raw Corn Stover. Of the initial lignin, 87.5% was maximally removed. Almost all acetyl groups were removed. After 4 weeks at 55 °C with aeration, some cellulose and hemicellulose were solubilized as monomers and oligomers in the pretreatment liquor. When considering the dissolved fragments of glucan and xylan in the pretreatment liquor, the overall yields of glucose and xylose were 93.2% and 79.5% at 15 FPU/g cellulose. The pretreatment liquor has no inhibitory effect on ethanol fermentation.
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using lime pretreatment to facilitate the enzymic hydrolysis of Corn Stover
Biomass & Bioenergy, 2000Co-Authors: William E Kaar, Mark T HoltzappleAbstract:Abstract Corn Stover is an abundant, potential fermentation substrate. The most efficient means to produce fermentable sugars from Corn Stover is by enzymic hydrolysis, which is facilitated by thermochemical pretreatment of the Corn Stover. Pretreatment with slake lime (calcium hydroxide) increased the enzymic hydrolysis of Corn Stover nine times compared to untreated Corn Stover. The recommended pretreatment conditions are: lime loading 0.075 g Ca(OH)2 (g dry biomass)−1; water loading 5 g H2O (g dry biomass)−1; and heating for 4 h at 120°C. The recommended enzyme loading for the enzymic saccharification of pretreated Corn Stover is 10 FPU (g dry biomass)−1 and the recommended hydrolysis temperature is 40°C. The enzymic conversion of the Corn Stover to monosaccharides, when pretreated and saccharified as prescribed for 72 h, was about 60% cellulose, 47% xylan, and 53% total available polysaccharide. Increasing the enzyme loading to 25 FPU (g dry biomass)−1 and the hydrolysis time to 7 days produced conversions of 88.0, 87.7, and 92.1% for the glucan, xylan and arabinan, respectively. These high conversions indicate that pretreatment with lime can lead to Corn Stover polysaccharide conversions approaching 100%; the success of the saccharification after lime pretreatment depends on the enzyme loading.
Y Y Lee - One of the best experts on this subject based on the ideXlab platform.
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pretreatment of Corn Stover by soaking in aqueous ammonia at moderate temperatures
Applied Biochemistry and Biotechnology, 2007Co-Authors: Tea Hyun Kim, Y Y LeeAbstract:Soaking in aqueous ammonia at moderate temperatures was investigated as a method of pretreatment for enzymatic hydrolysis as well as simultaneous saccharification and cofermentation (SSCF) of Corn Stover. The method involves batch treatment of the feedstock with aqueous ammonia (15–30 wt%) at 40–90°C for 6–24 h. The optimum treatment conditions were found to be 15 wt% of NH3, 60°C, 1∶6 of solid-to-liquid ratio, and 12 h of treatment time. The treated Corn Stover retained 100% glucan and 85% of xylan, but removed 62% of lignin. The enzymatic digestibility of the glucan content increased from 17 to 85% with 15 FPU/g-glucan enzyme loading, whereas the digestibility of the xylan content increased to 78%. The treated Corn Stover was also subjected to SSCF test using Spezyme-CP and recombinant Escherichia coli (KO11). The SSCF of the soaking in aqueous ammonia treated Corn Stover resulted in an ethanol concentration of 19.2 g/L from 3% (w/v) glucan loading, which corresponds to 77% of the maximum theoretical yield based on glucan and xylan.
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pretreatment and fractionation of Corn Stover by ammonia recycle percolation process
Bioresource Technology, 2005Co-Authors: Tae Hyu Kim, Y Y LeeAbstract:Corn Stover was pretreated with aqueous ammonia in a flow-through column reactor, a process termed as Ammonia Recycle Percolation (ARP). The aqueous ammonia causes swelling and efficient delignification of biomass at high temperatures. The ARP process solubilizes about half of xylan, but retains more than 92% of the cellulose content. Enzymatic digestibility of ARP-treated Corn Stover is 93% with 10 FPU/g-glucan enzyme loading. The SEM pictures and FTIR spectra confirm swelling and delignification effects of the ARP process. The X-ray crystallography data indicate that the basic crystalline structure of the cellulosic component of Corn Stover is not altered by the ARP treatment. Low-liquid ARP can reduce the liquid throughput and residence time to 3.3 mL/g-biomass and 10-12 min, without adversely affecting the overall effectiveness. The low-water ARP achieved 73.4% delignification and 88.5% digestibility with 15 FPU/g-glucan. The ethanol yield from the SSF of low-liquid ARP-treated Corn Stover using Saccharomyces cerevisiae reached 84% of the theoretical maximum. Successive operation of a hot-water treatment and the ARP was applied as a method of biomass fractionation. The two-stage process separated xylan in the first stage (84%) and lignin in the second stage (75%), resulting treated solid that contains 79% glucan.
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pretreatment of Corn Stover by soaking in aqueous ammonia
Applied Biochemistry and Biotechnology, 2005Co-Authors: Tae Hyu Kim, Y Y LeeAbstract:Soaking in aqueous ammonia (SAA) was investigated as a pretreatment method for Corn Stover. In this method, the feedstock was soaked in aqueous ammonia over an extended period (10–60 d) at room temperature. It was done without agitation at atmospheric pressure. SAA treatment removed 55–74% of the lignin, but retained nearly 100% of the glucan and 85% of the xylan. The xylan remaining in the Corn Stover after SAA treatment was hydrolyzed along with the glucan by xylanase present in the Spezyme CP enzyme. In the simultaneous saccharification and fermentation (SSF) test of SAA-treated Corn Stover, using S. cerevisiae (D5A), an ethanol yield of 73% of theoretical maximum was obtained on the basis of the glucan content in the treated Corn Stover. The accumulation of xylose in the SSF appears to inhibit the cellulase activity on glucan hydrolysis, which limits the yield of ethanol. In the simultaneous saccharification and co-fermentation (SSCF) test, using recombinant E. coli (KO11), both the glucan and xylose were effectively utilized, resulting in on overall ethanol yield of 77% based on the glucan and xylan content of the substrate. When the SSCF process is used, the fact that the xylan fraction is retained during pretreatment is a desirable feature since the overall bioconversion can be carried out in a single step without separate recovery of xylose from the pretreatment liquid.
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pretreatment of Corn Stover by aqueous ammonia
Bioresource Technology, 2003Co-Authors: Tae Hyu Kim, Jun Seok Kim, Changshi Sunwoo, Y Y LeeAbstract:Corn Stover was pretreated with aqueous ammonia in a flow-through column reactor, a process termed ammonia recycled percolation (ARP). This method was highly effective in delignifying of the biomass, reducing the lignin content by 70-85%. Most lignin removal occurred within the first 20 min of the process. Lignin removal by ARP was further confirmed by FTIR analysis and lignin staining. The ARP process solubilized 40-60% of the hemicellulose but left the cellulose intact. The solubilized carbohydrate existed in oligomeric form. Carbohydrate decomposition during the pretreatment was insignificant. Corn Stover treated for 90 min exhibited enzymatic digestibility of 99% with 60 FPU/g of glucan enzyme loading, and 92.5% with 10 FPU/g of glucan. The digestibility of ARP treated Corn Stover was substantially higher than that of alpha-cellulose. The enzymatic digestibility was related with the removal of lignin and hemicellulose, perhaps due to increased surface area and porosity. The SEM pictures indicated that the biomass structure was deformed and its fibers exposed by the pretreatment. The crystallinity index increased with pretreatment reflecting removal of the amorphous portion of biomass. The crystalline structure of the cellulose in the biomass, however, was not changed by the ARP treatment.
Nehru Chevanan - One of the best experts on this subject based on the ideXlab platform.
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bulk density and compaction behavior of knife mill chopped switchgrass wheat straw and Corn Stover
Bioresource Technology, 2010Co-Authors: Nehru Chevanan, Alvin R Womac, Venkata S P Bitra, C Igathinathane, Yuechuan T Yang, Petre I Miu, Shahab SokhansanjAbstract:Abstract Bulk density of comminuted biomass significantly increased by vibration during handling and transportation, and by normal pressure during storage. Compaction characteristics affecting the bulk density of switchgrass, wheat straw, and Corn Stover chopped in a knife mill at different operating conditions and using four different classifying screens were studied. Mean loose-filled bulk densities were 67.5 ± 18.4 kg/m3 for switchgrass, 36.1 ± 8.6 kg/m3 for wheat straw, and 52.1 ± 10.8 kg/m3 for Corn Stover. Mean tapped bulk densities were 81.8 ± 26.2 kg/m3 for switchgrass, 42.8 ± 11.7 kg/m3 for wheat straw, and 58.9 ± 13.4 kg/m3 for Corn Stover. Percentage changes in compressibility due to variation in particle size obtained from a knife mill ranged from 64.3 to 173.6 for chopped switchgrass, 22.2–51.5 for chopped wheat straw and 42.1–117.7 for chopped Corn Stover within the tested consolidation pressure range of 5–120 kPa. Pressure and volume relationship of chopped biomass during compression with application of normal pressure can be characterized by the Walker model and Kawakita and Ludde model. Parameter of Walker model was correlated to the compressibility with Pearson correlation coefficient greater than 0.9. Relationship between volume reduction in chopped biomass with respect to number of tappings studied using Sone’s model indicated that infinite compressibility was highest for chopped switchgrass followed by chopped wheat straw and Corn Stover. Degree of difficulty in packing measured using the parameters of Sone’s model indicated that the chopped wheat straw particles compacted very rapidly by tapping compared to chopped switchgrass and Corn Stover. These results are very useful for solving obstacles in handling bulk biomass supply logistics issues for a biorefinery.
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flowability parameters for chopped switchgrass wheat straw and Corn Stover
Powder Technology, 2009Co-Authors: Nehru Chevanan, Alvin R Womac, Venkata S P Bitra, D C Yoder, Shahab SokhansanjAbstract:Abstract A direct shear cell to measure the shear strength and flow properties of chopped switchgrass, wheat straw, and Corn Stover was designed, fabricated, and tested. Yield loci (r2 = 0.99) determined at preconsolidation pressures of 3.80 kPa and 5.02 kPa indicated that chopped biomass followed Mohr–Coulomb failure. Normal stress significantly affected the displacement required for shear failure, as well as the friction coefficient values for all three chopped biomass types. Displacement at shear failure ranged from 30 to 80 mm, and depended on preconsolidation pressure, normal stress, and particle size. Friction coefficient was inversely related to normal stress, and was highest for chopped Corn Stover. Also, chopped Corn Stover exhibited the highest angle of internal friction, unconfined yield strength, major consolidation strength, and cohesive strength, all of which indicated increased challenges in handling chopped Corn Stover. The measured angle of internal friction and cohesive strength indicated that chopped biomass cannot be handled by gravity alone. The measured angle of internal friction and cohesive strength were 43° and 0.75 kPa for chopped switchgrass; 44° and 0.49 kPa for chopped wheat straw; and 48° and 0.82 kPa for chopped Corn Stover. Unconfined yield strength and major consolidation strength used for characterization of bulk flow materials and design of hopper dimensions were 3.4 and 10.4 kPa for chopped switchgrass; 2.3 and 9.6 kPa for chopped wheat straw and 4.2 and 11.8 kPa for chopped Corn Stover. These results are useful for the development of efficient handling, storage, and transportation systems for biomass in biorefineries.
Michael A. Cotta - One of the best experts on this subject based on the ideXlab platform.
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response surface optimization of Corn Stover pretreatment using dilute phosphoric acid for enzymatic hydrolysis and ethanol production
Bioresource Technology, 2013Co-Authors: Ayse Avci, Badal C Saha, Bruce S Dien, Gregory J Kennedy, Michael A. CottaAbstract:Abstract Dilute H 3 PO 4 (0.0–2.0%, v/v) was used to pretreat Corn Stover (10%, w/w) for conversion to ethanol. Pretreatment conditions were optimized for temperature, acid loading, and time using central composite design. Optimal pretreatment conditions were chosen to promote sugar yields following enzymatic digestion while minimizing formation of furans, which are potent inhibitors of fermentation. The maximum glucose yield (85%) was obtained after enzymatic hydrolysis of Corn Stover pretreated with 0.5% (v/v) acid at 180 °C for 15 min while highest yield for xylose (91.4%) was observed from Corn Stover pretreated with 1% (v/v) acid at 160 °C for 10 min. About 26.4 ± 0.1 g ethanol was produced per L by recombinant Escherichia coli strain FBR5 from 55.1 ± 1.0 g sugars generated from enzymatically hydrolyzed Corn Stover (10%, w/w) pretreated under a balanced optimized condition (161.81 °C, 0.78% acid, 9.78 min) where only 0.4 ± 0.0 g furfural and 0.1 ± 0.0 hydroxylmethyl furfural were produced.
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hydrothermal pretreatment and enzymatic saccharification of Corn Stover for efficient ethanol production
Industrial Crops and Products, 2013Co-Authors: Badal C Saha, Michael A. Cotta, Tsuyoshi Yoshida, Kenji SonomotoAbstract:Abstract Corn Stover used in this study contained 37.0 ± 0.4% cellulose, 31.3 ± 0.6% hemicellulose and 17.8 ± 0.2% lignin on dry basis. Hydrothermal pretreatment and enzymatic saccharification were evaluated for conversion of Corn Stover cellulose and hemicellulose to fermentable sugars. Under the optimum conditions of hydrothermal pretreatment of Corn Stover (10%, w/v; 200 °C; 5 min) and enzymatic saccharification (45 °C, pH 5.0, 72 h), a total of 550 ± 5 mg of fermentable sugars was obtained per g Corn Stover which is equivalent to 72% of theoretical sugar yield. The Corn Stover hydrolyzate was fermented without any detoxification by recombinant Escherichia coli strain FBR 5 at pH 6.5 and 37 °C for 74 h to produce 20.9 ± 0.5 g ethanol from 42.8 ± 1.7 g sugars per L with a yield of 0.49 g ethanol per g available sugars and 0.27 g ethanol per g Corn Stover which is equivalent to 68.7% of theoretical ethanol yield from Corn Stover. This is the first report on the production of ethanol from hydrothermally pretreated Corn Stover by the recombinant bacterium.