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1.
Oxidative Lime Pretreatment of Alamo Switchgrass 总被引:1,自引:0,他引:1
Previous studies have shown that oxidative lime pretreatment is an effective delignification method that improves the enzymatic
digestibility of many biomass feedstocks. The purpose of this work is to determine the recommended oxidative lime pretreatment
conditions (reaction temperature, time, pressure, and lime loading) for Alamo switchgrass (Panicum virgatum). Enzymatic hydrolysis of glucan and xylan was used to determine the performance of the 52 studied pretreatment conditions.
The recommended condition (110°C, 6.89 bar O2, 240 min, 0.248 g Ca(OH)2/g biomass) achieved glucan and xylan overall yields (grams of sugar hydrolyzed/100 g sugar in raw biomass, 15 filter paper
units (FPU)/g raw glucan) of 85.9 and 52.2, respectively. In addition, some glucan oligomers (2.6 g glucan recovered/100 g
glucan in raw biomass) and significant levels of xylan oligomers (26.0 g xylan recovered/100 g xylan in raw biomass) were
recovered from the pretreatment liquor. Combining a decrystallization technique (ball milling) with oxidative lime pretreatment
further improved the overall glucan yield to 90.0 (7 FPU/g raw glucan). 相似文献
2.
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 degrees C for 6-24 h. The optimum treatment conditions were found to be 15 wt% of NH(3), 60 degrees 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. 相似文献
3.
Oxidative lime pretreatment increases the enzymatic digestibility of lignocellulosic biomass primarily by removing lignin.
In this study, recommended pretreatment conditions (reaction temperature, oxygen pressure, lime loading, and time) were determined
for Dacotah switchgrass. Glucan and xylan overall hydrolysis yields (72 h, 15 FPU/g raw glucan) were measured for 105 different
reaction conditions involving three different reactor configurations (very short term, short term, and long term). The short-term
reactor was the most productive. At the recommended pretreatment condition (120 °C, 6.89 bar O2, 240 min), it achieved an overall glucan hydrolysis yield of 85.2 g glucan hydrolyzed/100 g raw glucan and an overall xylan
yield of 50.1 g xylan hydrolyzed/100 g raw xylan. At this condition, glucan oligomers (1.80 g glucan recovered/100 g glucan
in raw biomass) and xylan oligomers (25.20 g xylan recovered/100 g xylan in raw biomass) were recovered from the pretreatment
liquor, which compensate for low pretreatment yields. 相似文献
4.
Chen Y Sharma-Shivappa RR Keshwani D Chen C 《Applied biochemistry and biotechnology》2007,142(3):276-290
Production of bioethanol from agricultural residues and hays (wheat, barley, and triticale straws, and barley, triticale, pearl millet, and sweet sorghum hays) through a series of chemical pretreatment, enzymatic hydrolysis, and fermentation processes was investigated in this study. Composition analysis suggested that the agricultural straws and hays studied contained approximately 28.62-38.58% glucan, 11.19-20.78% xylan, and 22.01-27.57% lignin, making them good candidates for bioethanol production. Chemical pretreatment with sulfuric acid or sodium hydroxide at concentrations of 0.5, 1.0, and 2.0% indicated that concentration and treatment agent play a significant role during pretreatment. After 2.0% sulfuric acid pretreatment at 121 degrees C/15 psi for 60 min, 78.10-81.27% of the xylan in untreated feedstocks was solubilized, while 75.09-84.52% of the lignin was reduced after 2.0% sodium hydroxide pretreatment under similar conditions. Enzymatic hydrolysis of chemically pretreated (2.0% NaOH or H2SO4) solids with Celluclast 1.5 L-Novozym 188 (cellobiase) enzyme combination resulted in equal or higher glucan and xylan conversion than with Spezyme(R) CP- xylanase combination. The glucan and xylan conversions during hydrolysis with Celluclast 1.5 L-cellobiase at 40 FPU/g glucan were 78.09 to 100.36% and 74.03 to 84.89%, respectively. Increasing the enzyme loading from 40 to 60 FPU/g glucan did not significantly increase sugar yield. The ethanol yield after fermentation of the hydrolyzate from different feedstocks with Saccharomyces cerevisiae ranged from 0.27 to 0.34 g/g glucose or 52.00-65.82% of the theoretical maximum ethanol yield. 相似文献
5.
Sweet sorghum bagasse (SSB) was steam pretreated in the conditions of 190 °C for 5 min to assess its amenability to the pretreatment and enzymatic hydrolysis. Results showed that pretreatment conditions were robust enough to pretreat SSB with maximum of 87% glucan and 72% xylan recovery. Subsequent enzymatic hydrolysis showed that the pretreated SSB at 2% substrate consistency resulted in maximum of 70% glucan-glucose conversion. Increasing substrate consistency from 2% to 16% led to a significant reduction in glucan conversion. However, the decrease ratio of glucan-glucose conversion was the minimum when the consistency increased from 2% to 12%. When the pretreated SSB consistency of 12% was applied for hydrolysis, increase in cellulase loading from 7.5 up to 20 filter paper units (FPU)/g glucan resulted only in 14% increase in glucan-glucose conversion compared to 20% increase with cellulase loading varying from 2.5 to 7.5 FPU/g glucan. More than 10 cellobiase units (CBU)/g glucan β-glucosidase supplementation had no noticeable improvement on glucan-glucose conversion. Additionally, supplementation of xylanase was found to significantly increase glucan-glucose conversion from 50% to 80% with the substrate consistency of 12%, when the cellulase and β-glucosidase loadings were at relatively low enzyme loadings (7.5 FPU/g and 10 CBU/g glucan). It appeared that residual xylan played a critical role in hindering the ease of hydrolysis of SSB. A proper xylanase addition was suggested to achieve a high hydrolysis yield at relatively high substrate consistency with relatively low enzyme loadings. 相似文献
6.
Dilute-acid pretreatment liquor (PL) produced at NREL through a continuous screw-driven reactor was analyzed for sugars and other potential inhibitory components. Their inhibitory effects on enzymatic hydrolysis of Solka Floc were investigated. When the PL was mixed into the enzymatic hydrolysis reactor at 1:1 volume ratio, the glucan and xylan digestibility decreased by 63% and 90%, respectively. The tolerance level of the enzyme for each inhibitor was determined. Of the identified degradation components, acetic acid was found to be the strongest inhibitor for cellulase activity, as it decreased the glucan yield by 10% at 1 g/L. Among the sugars, cellobiose and glucose were found to be strong inhibitors to glucan hydrolysis, whereas xylose is a strong inhibitor to xylan hydrolysis. Xylo-oligomers inhibit xylan digestibility more strongly than the glucan digestibility. Inhibition by the PL was higher than that of the simulated mixture of the identifiable components. This indicates that some of the unidentified degradation components, originated mostly from lignin, are potent inhibitors to the cellulase enzyme. When the PL was added to a simultaneous saccharification and co-fermentation using Escherichia coli KO11, the bioprocess was severely inhibited showing no ethanol formation or cell growth. 相似文献
7.
A pretreatment method using aqueous ammonia was investigated with the intent of minimizing the liquid throughput. This process
uses a flow-through packed column reactor (or percolation reactor). In comparison to the ammonia recycle percolation (ARP)
process developed previously in our laboratory, this process significantly reduces the liquid throughput to one reactor void
volume in packed bed (2.0–4.7 mL of liquid/g of corn stover) and, thus, is termed low-liquid ARP (LLARP). In addition to attaining
short residence time and reduced energy input, this process achieves 59–70% of lignin removal and 48–57% of xylan retention.
With optimum operation of the LLARP to corn stover, enzymatic digestibilities of 95, 90 and 86% were achieved with 60, 15,
and 7.5 filter paper units/g of glucan, respectively. In the simultaneous saccharification and fermentation test of the LLARP
samples using Saccharomyces cerevisiae (NREL-D5A), an ethanol yield of 84% of the theoretical maximum was achieved with 6% (w/v) glucan loading. In the simultaneous saccharification
and cofermentation (SSCF) test using recombinant Escherichia coli (KO11), both the glucan and xylan in the solid were effectively utilized, giving an overall ethanol yield of 109% of the
theoretical maximum based on glucan, a clear indication that the xylan content was converted into ethanol. The xylooligomers
existing in the LLARP effluent were not effectively hydrolyzed by cellulase enzyme, achieving only 60% of digestibility. SSCF
of the treated corn stover was severely hampered when the substrate was supplemented with the LLARP effluent, giving only
56% the overall yield of ethanol. The effluent appears to significantly inhibit cellulase and microbial activities. 相似文献
8.
Oxidative lime pretreatment of high-lignin biomass 总被引:1,自引:0,他引:1
Lime (Ca[OH]2) and oxygen (O2) were used to enhance the enzymatic digestibility of two kinds of high-lignin biomass: poplar wood and newspaper. The recommended
pretreatment conditions for poplar wood are 150°C, 6 h, 0.1 g of Ca(OH)2/g of dry biomass, 9 mL of water/g of dry biomass, 14.0 bar absolute oxygen, and a particle size of −10 mesh. Under these
conditions, the 3-d reducing sugar yield of poplar wood using a cellulase loading of 5 filter paper units (FPU)/g of raw dry
biomass increased from 62 to 565 mg of eq. glucose/g of raw dry biomass, and the 3-d total sugar (glucose + xylose) conversion
increased from 6 to 77% of raw total sugars. At high cellulase loadings (e.g., 75 FPU/g of raw dry biomass), the 3-d total
sugar conversion reached 97%. In a trial run with newspaper, using conditions of 140°C, 3 h, 0.3 g of Ca(OH)2/g of dry biomass, 16 mL of water/g of dry biomass, and 7.1 bar absolute oxygen, the 3-d reducing sugar yield using a cellulase
loading of 5 FPU/g of raw dry biomass increased from 240 to 565 mg of eq. glucose/g of raw dry biomass. A material balance
study on poplar wood shows that oxidative lime pretreatment solubilized 38% of total biomass, including 78% of lignin and
49% of xylan; no glucan was removed. Ash increased because calcium was incorporated into biomass during the pretreatment.
After oxidative lime pretreatment, about 21% of added lime could be recovered by CO2 carbonation. 相似文献
9.
Sugar cane bagasse consists of hemicellulose (24%) and cellulose (38%), and bioconversion of both fractions to ethanol should
be considered for a viable process. We have evaluated the hydrolysis of pretreated bagasse with combinations of cellulase,
β-glucosidase, and hemicellulase. Ground bagasse was pretreated either by the AFEX process (2NH3: 1 biomass, 100 °C, 30 min) or with NH4OH (0.5 g NH4OH of a 28% [v/v] per gram dry biomass; 160 °C, 60 min), and composition analysis showed that the glucan and xylan fractions remained largely
intact. The enzyme activities of four commercial xylanase preparations and supernatants of four laboratory-grown fungi were
determined and evaluated for their ability to boost xylan hydrolysis when added to cellulase and β-glucosidase (10 filter
paper units [FPU]: 20 cellobiase units [CBU]/g glucan). At 1% glucan loading, the commercial enzyme preparations (added at
10% or 50% levels of total protein in the enzyme preparations) boosted xylan and glucan hydrolysis in both pretreated bagasse
samples. Xylanase addition at 10% protein level also improved hydrolysis of xylan and glucan fractions up to 10% glucan loading
(28% solids loading). Significant xylanase activity in enzyme cocktails appears to be required for improving hydrolysis of
both glucan and xylan fractions of ammonia pretreated sugar cane bagasse. 相似文献
10.
Ammonia fiber explosion treatment of corn stover 总被引:1,自引:0,他引:1
Farzaneh Teymouri Lizbeth Laureano-Pérez Hasan Alizadeh Bruce E. Dale 《Applied biochemistry and biotechnology》2004,115(1-3):951-963
Optimizing process conditions and parameters such as ammonia loading, moisture content of biomass, temperature, and residence
time is necessary for maximum effectiveness of the ammonia fiber explosion process. Approximate optimal pretreatment conditions
for corn stover were found to be temperature of 90°C, ammonia: dry corn stover mass ratio of 1∶1, moisture content of corn
stover of 60% (dry weight basis), and residence time (holding at target temperature), of 5 min. Approximately 98% of the theoretical
glucose yield was obtained during enzymatic hydrolysis of the optimal treated corn stover using 60 filter paper units (FPU)
of cellulase enzyme/g of glucan (equal to 22 FPU/g of dry corn stover). The ethanol yield from this sample was increased up
to 2.2 times over that of untreated sample. Lowering enzyme loading to 15 and 7.5 FPU/g of glucan did not significantly affect
the glucose yield compared with 60 FPU, and any differences between effects at different enzyme levels decreased as the treatment
temperature increased. 相似文献
11.
Lime pretreatment of crop residues bagasse and wheat straw 总被引:9,自引:0,他引:9
Vincent S. Chang Murlidhar Nagwani Mark T. Holtzapple 《Applied biochemistry and biotechnology》1998,74(3):135-159
Lime (calcium hydroxide) was used as a pretreatment agent to enhance the enzymatic digestibility of two common crop residues:
bagasse and wheat straw. A systematic study of pretreatment conditions suggested that for short pretreatment times (1–3 h),
high temperatures (85-135°C) were required to achieve high sugar yields, whereas for long pretreatment times (e.g., 24 h),
low temperatures (50–65°C) were effective. The recommended lime loading is 0.1 g Ca(OH)2/g dry biomass. Water loading had little effect on the digestibility. Under the recommended conditions, the 3-d reducing sugar
yield of the pretreated bagasse increased from 153 to 659 mg Eq glucose/g dry biomass, and that of the pretreated wheat straw
increased from 65 to 650 mg Eq glucose/g dry biomass. A material balance study on bagasse showed that the biomass yield after
lime pretreatment is 93.6%. No glucan or xylan was removed from bagasse by the pretreatment, whereas 14% of lignin became
solubilized. A lime recovery study showed that 86% of added calcium was removed from the pretreated bagasse by ten washings
and could be recovered by carbonating the wash water with CO2 at pH 9.5. 相似文献
12.
Current technology for conversion of biomass to ethanol is an enzyme-based biochemical process. In bioethanol production,
achieving high sugar yield at high solid loading in enzymatic hydrolysis step is important from both technical and economic
viewpoints. Enzymatic hydrolysis of cellulosic substrates is affected by many parameters, including an unexplained behavior
that the glucan digestibility of substrates by cellulase decreased under high solid loadings. A comprehensive study was conducted
to investigate this phenomenon by using Spezyme CP and Avicel as model cellulase and cellulose substrate, respectively. The
hydrolytic properties of the cellulase under different substrate concentrations at a fixed enzyme-to-substrate ratio were
characterized. The results indicate that decreased sugar yield is neither due to the loss of enzyme activity at a high substrate
concentration nor due to the higher end-product inhibition. The cellulase adsorption kinetics and isotherm studies indicated
that a decline in the binding capacity of cellulase may explain the long-observed but little-understood phenomenon of a lower
substrate digestibility with increased substrate concentration. The mechanism how the enzyme adsorption properties changed
at high substrate concentration was also discussed in the context of exploring the improvement of the cellulase-binding capacity
at high substrate loading. 相似文献
13.
Chang Geun Yoo Nhuan P. Nghiem Kevin B. Hicks Tae Hyun Kim 《Applied biochemistry and biotechnology》2013,169(8):2430-2441
Soaking in aqueous ammonia (SAA) pretreatment was investigated to improve enzymatic digestibility and consequently to increase total fermentable sugar production from barley straw. Various effects of pretreatment process parameters, such as reaction temperature, reaction time, solid:liquid ratio, and ammonia concentration, were evaluated, and the optimum conditions for two of the most important factors, reaction temperature and time were determined using response surface methodology. Optimized reaction conditions were 77.6 °C treatment temperature, 12.1 h. treatment time, 15 wt.% ammonia concentration, and 1:8 solid-to-liquid ratio, which gave a sugar recovery yield of 71.5 % (percent of theoretical sugar recovered from the untreated barley straw) with enzyme loading of 15 FPU/g-glucan. In the optimization of the SAA pretreatment process, ammonia concentration, reaction temperature, and reaction time were determined to be the most significant factors correlated to subsequent enzyme digestibility. Based on tested conditions exhibiting high sugar recovery yields of >60 %, it appeared that reaction temperature affected total fermentable sugar production more significantly than reaction time. 相似文献
14.
Zheng Y Pan Z Zhang R Wang D Jenkins B 《Applied biochemistry and biotechnology》2008,146(1-3):231-248
Our previous research has shown that saline Creeping Wild Ryegrass (CWR), Leymus triticoides, has a great potential to be used for bioethanol production because of its high fermentable sugar yield, up to 85% cellulose
conversion of pretreated CWR. However, the high cost of enzyme is still one of the obstacles making large-scale lignocellulosic
bioethanol production economically difficult. It is desirable to use reduced enzyme loading to produce fermentable sugars
with high yield and low cost. To reduce the enzyme loading, the effect of addition of non-ionic surfactants and non-catalytic
protein on the enzymatic hydrolysis of pretreated CWR was investigated in this study. Tween 20, Tween 80, and bovine serum
albumin (BSA) were used as additives to improve the enzymatic hydrolysis of dilute sulfuric-acid-pretreated CWR. Under the
loading of 0.1 g additives/g dry solid, Tween 20 was the most effective additive, followed by Tween 80 and BSA. With the addition
of Tween 20 mixed with cellulase loading of 15 FPU/g cellulose, the cellulose conversion increased 14% (from 75 to 89%), which
was similar to that with cellulase loading of 30 FPU/g cellulose and without additive addition. The results of cellulase and
BSA adsorption on the Avicel PH101, pretreated CWR, and lignaceous residue of pretreated CWR support the theory that the primary
mechanism behind the additives is prevention of non-productive adsorption of enzymes on lignaceous material of pretreated
CWR. The addition of additives could be a promising technology to improve the enzymatic hydrolysis by reducing the enzyme
activity loss caused by non-productive adsorption. 相似文献
15.
Pretreatment based on aqueous ammonia was investigated under two different modes of operation: soaking in aqueous ammonia
and ammonia recycle percolation. These processes were applied to three different feedstocks with varied composition: corn
stover, high lignin (HL), and low lignin (LL) hybrid poplars. One of the important features of ammonia-based pretreatment
is that most of the hemicellulose is retained after treatment, which simplifies the overall bioconversion process and enhances
the conversion efficiency. The pretreatment processes were optimized for these feedstocks, taking carbohydrate retention as
well as sugar yield in consideration. The data indicate that hybrid poplar is more difficult to treat than corn stover, thus,
requires more severe conditions. On the other hand, hybrid poplar has a beneficial property that it retains most of the hemicellulose
after pretreatment. To enhance the digestibility of ammonia-treated poplars, xylanase was supplemented during enzymatic hydrolysis.
Because of high retention of hemicellulose in treated hybrid poplar, xylanase supplementation significantly improved xylan
as well as glucan digestibility. Of the three feedstocks, best results and highest improvement by xylanase addition was observed
with LL hybrid poplar, showing 90% of overall sugar yield. 相似文献
16.
Hot water and aqueous ammonia fractionation of corn stover were used to separate hemicellulose and lignin and improve enzymatic
digestibility of cellulose. A two-stage approach was used: The first stage was designed to recover soluble lignin using aqueous
ammonia at low temperature, while the second stage was designed to recover xylan using hot water at high temperature. Specifically,
the first stage employed a batch reaction using 15 wt.% ammonia at 60 °C, in a 1:10 solid:liquid ratio for 8 h, while the
second stage employed a percolation reaction using hot water, 190–210 °C, at a 20 ml/min flow rate for 10 min. After fractionation,
the remaining solids were nearly pure cellulose. The two-stage fractionation process achieved 68% lignin purity with 47% lignin
recovery in the first stage, and 78% xylan purity, with 65% xylan recovery in the second stage. Two-stage treatment enhanced
the enzymatic hydrolysis of remaining cellulose to 96% with 15 FPU/g of glucan using commercial cellulase enzymes. Enzyme
hydrolyses were nearly completed within 12–24 h with the remaining solids fraction. 相似文献
17.
Nonisothermal simultaneous saccharification and fermentation for direct conversion of lignocellulosic biomass to ethanol 总被引:1,自引:0,他引:1
The enzymatic reaction in the simultaneous saccharification and fermentation (SSF) is operated at a temperature much lower
than its optimum level. This forces the enzyme activity to be far below its potential, consequently raising the enzyme requirement.
To alleviate this problem, a nonisothermal simultaneous saccharification and fermentation process (NSSF) was investigated.
The NSSF is devised so that saccharification and fermentation occur simultaneously, yet in two separate reactors that are
maintained at different temperatures. Lignocellulosic biomass is retained inside a column reactor and hydrolyzed at the optimum
temperature for the enzymatic reaction (50°C). The effluent from the column reactor is recirculated through a fermenter, which
runs at its optimum temperature (20-30°C). The cellulase enzyme activity is increased by a factor of 2-3 when the hydrolysis
temperature is raised from 30 to 50°C. The NSSF process has improved the enzymatic reaction in the SSF to the extent that
it reduces the overall enzyme requirement by 30-40%. The effect of temperature on β-glucosidase activity was the most significant
among the individual cellulase compounds. Both ethanol yield and productivity in the NSSF are substantially higher than those
in the SSF at the enzyme loading of 5 IFPU/g glucan. With 10 IFPU/g glucan, improvement in productivity was more discernible
for the NSSF. The terminal yield attainable in 4 d with the SSF was reachable in 40 h with the NSSF. 相似文献
18.
Fengxue Xin Anli Geng Ming Li Chen Ming Jun Marcus Gum 《Applied biochemistry and biotechnology》2010,162(4):1052-1064
Fermentation of enzymatic hydrolysate of waste newspaper was investigated for cellulosic ethanol production in this study. Various nonionic and ionic surfactants were applied for waste newspaper pretreatment to increase the enzymatic digestibility. The surfactant-pretreated newspaper was enzymatically digested in 0.05 M sodium citrate buffer (pH 4.8) with varying solid content, filter paper unit loading (FPU/g newspaper), and ratio of filter paper unit/β-glucosidase unit (FPU/CBU). Newspaper pretreated with the anionic surfactant sodium dodecyl sulphate (SDS) demonstrated the highest sugar yield. The addition of Tween-80 in the enzymatic hydrolysis process enhanced the enzymatic digestibility of newspaper pretreated with all of the surfactants. Enzymatic hydrolysis of SDS-pretreated newspaper with 15% solid content, 15 FPU/g newspaper, and FPU/CBU of 1:4 resulted in a newspaper hydrolysate conditioning 29.07 g/L glucose and 4.08 g/L xylose after 72 h of incubation at 50 °C. The fermentation of the enzymatic hydrolysate with Saccharomyces cerevisiae, Pichia stipitis, and their co-culture produced 14.29, 13.45, and 14.03 g/L of ethanol, respectively. Their corresponding ethanol yields were 0.43, 0.41, and 0.42 g/g. 相似文献
19.
Pretreatment of corn stover with dilute sulfuric acid at moderate temperature was investigated, and glucan digestibility by Cellic CTec2 and Celluclast on the pretreated biomass was compared. Pretreatments were carried out from 60 to 180 min at the temperature from 105 to 135 °C, with acid concentrations ranging from 0.5 to 2 % (w/v). Significant portion of xylan was removed during pretreatment, and the glucan digestibility by CTec2 was significantly better than that by Celluclast in all cases. Analysis showed that glucan digestibility by both two enzymes correlated directly with the extent of xylan removal in pretreatment. Confidence interval was built to give a more precise range of glucan conversion and to test the significant difference among pretreatment conditions. Response surface model was built to obtain the optimal pretreatment condition to achieve high glucan conversion after enzymatic hydrolysis. Considering the cost and energy savings, the optimal pretreatment condition of 1.75 % acid for 160 min at 135 °C was determined, and glucan conversion can achieve the range from 72.86 to 76.69 % at 95 % confidence level after enzymatic hydrolysis, making total glucan recovery up to the range from 89.42 to 93.25 %. 相似文献
20.
Zhanying Zhang Ian M. O’Hara William O. S. Doherty 《Cellulose (London, England)》2013,20(6):3179-3190
Pretreatments of sugarcane bagasse by three high boiling-point polyol solutions were compared in acid-catalysed processes. Pretreatments by ethylene glycol (EG) and propylene glycol solutions containing 1.2 % H2SO4 and 10 % water at 130 °C for 30 min removed 89 % lignin from bagasse resulting in a glucan digestibility of 95 % with a cellulase loading of ~20 FPU/g glucan. Pretreatment by glycerol solution under the same conditions removed 57 % lignin with a glucan digestibility of 77 %. Further investigations with EG solutions showed that increases in acid content, pretreatment temperature and time, and decrease in water content improved pretreatment effectiveness. A good linear correlation of glucan digestibility with delignification was observed with R2 = 0.984. Bagasse samples pretreated with EG solutions were characterised by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction, which confirmed that improved glucan enzymatic digestibility is mainly due to delignification and defibrillation of bagasse. Pretreatment by acidified EG solutions likely led to the formation of EG-glycosides. Up to 36 % of the total lignin was recovered from pretreatment hydrolysate, which may improve the pretreatment efficiency of recycled EG solution. 相似文献