Abstract:Pre-pulping extraction is a means of deriving a hemicellulose-rich process stream from the front end of a kraft pulp mill. When the extraction is carried out using green liquor, pulp quality and quantity can be retained while still releasing hemicelluloses and acetic acid (HAc) for recovery as bioprocessing feedstock or chemical products. The HAc that is present in the wood extraction is inhibitory to microorganisms and can hinder fermentation. HAc is also a commodity chemical that may provide sufficient value… Show more
“…During the HPAC pretreatment, the AC was consumed and peroxyacetic acid was formed. Pressure shift distillation coupled with a separation process was capable to separate AC and peroxyacetic acid in HPAC pretreatment liquor [51, 52]. The two-step pretreatment of AC and HPAC provided a preferable feature to prepare XOS and monosaccharides from poplar with relatively mild conditions, showing great potential application in industrial production of XOS, biofuels, and biochemicals from biomass.Fig.…”
Background
Populus
(poplar) tree species including hybrid varieties are considered as promising biomass feedstock for biofuels and biochemicals production due to their fast growing, short vegetative cycle, and widely distribution. In this work, poplar was pretreated with acetic acid (AC) to produce xylooligosaccharides (XOS), and hydrogen peroxide–acetic acid (HPAC) was used to remove residual lignin in AC-pretreated poplar for enzymatic hydrolysis. The aim of this work is to produce XOS and monosaccharides from poplar by a two-step pretreatment method.
Results
The optimal conditions for the AC pretreatment were 170 °C, 5% AC, and 30 min, giving a XOS yield of 55.8%. The optimal HPAC pretreatment conditions were 60 °C, 2 h, and 80% HPAC, resulting in 92.7% delignification and 87.8% cellulose retention in the AC-pretreated poplar. The two step-treated poplar presented 86.6% glucose yield and 89.0% xylose yield by enzymatic hydrolysis with a cellulases loading of 7.2 m/g dry mass. Very high glucose (93.8%) and xylose (94.6%) yields were obtained with 14.3 mg cellulases/g dry mass. Both Tween 80 and β-glucosidase enhanced glucose yield of HPAC-pretreated poplar by alleviating the accumulation of cellobiose. Under the optimal conditions, 6.9 g XOS, 40.3 g glucose, and 8.9 g xylose were produced from 100 g poplar.
Conclusions
The AC and HPAC pretreatment of poplar represented an efficient strategy to produce XOS and fermentable sugars with high yields. This two-step pretreatment was a recyclable benign and advantageous scheme for biorefinery of the poplar into XOS and monosaccharides.
Electronic supplementary material
The online version of this article (10.1186/s13068-019-1423-x) contains supplementary material, which is available to authorized users.
“…During the HPAC pretreatment, the AC was consumed and peroxyacetic acid was formed. Pressure shift distillation coupled with a separation process was capable to separate AC and peroxyacetic acid in HPAC pretreatment liquor [51, 52]. The two-step pretreatment of AC and HPAC provided a preferable feature to prepare XOS and monosaccharides from poplar with relatively mild conditions, showing great potential application in industrial production of XOS, biofuels, and biochemicals from biomass.Fig.…”
Background
Populus
(poplar) tree species including hybrid varieties are considered as promising biomass feedstock for biofuels and biochemicals production due to their fast growing, short vegetative cycle, and widely distribution. In this work, poplar was pretreated with acetic acid (AC) to produce xylooligosaccharides (XOS), and hydrogen peroxide–acetic acid (HPAC) was used to remove residual lignin in AC-pretreated poplar for enzymatic hydrolysis. The aim of this work is to produce XOS and monosaccharides from poplar by a two-step pretreatment method.
Results
The optimal conditions for the AC pretreatment were 170 °C, 5% AC, and 30 min, giving a XOS yield of 55.8%. The optimal HPAC pretreatment conditions were 60 °C, 2 h, and 80% HPAC, resulting in 92.7% delignification and 87.8% cellulose retention in the AC-pretreated poplar. The two step-treated poplar presented 86.6% glucose yield and 89.0% xylose yield by enzymatic hydrolysis with a cellulases loading of 7.2 m/g dry mass. Very high glucose (93.8%) and xylose (94.6%) yields were obtained with 14.3 mg cellulases/g dry mass. Both Tween 80 and β-glucosidase enhanced glucose yield of HPAC-pretreated poplar by alleviating the accumulation of cellobiose. Under the optimal conditions, 6.9 g XOS, 40.3 g glucose, and 8.9 g xylose were produced from 100 g poplar.
Conclusions
The AC and HPAC pretreatment of poplar represented an efficient strategy to produce XOS and fermentable sugars with high yields. This two-step pretreatment was a recyclable benign and advantageous scheme for biorefinery of the poplar into XOS and monosaccharides.
Electronic supplementary material
The online version of this article (10.1186/s13068-019-1423-x) contains supplementary material, which is available to authorized users.
“…Therefore, the HPAA–SH process had a great potential to decrease the cost of monosaccharides production from poplar. To reduce the cost of the HPAA–SH pretreatment, pressure shift distillation can be employed to separate acetic acid and the peracetic acid formed in HPAA solution [ 45 , 46 ]. Furthermore, the HPAA solution can be reused in the next pretreatment to reduce the cost.…”
Background
Hydrogen peroxide–acetic acid (HPAA) is widely used in pretreatment of lignocellulose because it has a good capability in selective delignification. However, high concentration (more than 60%) of HPAA increases the cost of pretreatment and the risk of explosion. In this work, alkaline post-incubation was employed to decrease the HPAA loading and improve the saccharification of poplar.
Results
Pretreatment with 100% HPAA removed 91.0% lignin and retained 89.9% glucan in poplar. After poplar was pretreated by 100% HPAA at 60 °C for 2 h, the glucan conversion in enzymatic hydrolysis by cellulase increased to 90.1%. Alkaline incubation reduced the total lignin, surface lignin, and acetyl group of HPAA-pretreated poplar. More than 92% acetyl groups of HPAA-pretreated poplar were removed by alkaline incubation with 1.0% NaOH at 50 °C for 1 h. After incubation of 60% HPAA-pretreated poplar with 1.0% NaOH, the glucan conversion enhanced to 95.0%. About 40% HPAA loading in pretreatment was reduced by alkaline incubation without the decrease of glucose yield.
Conclusions
Alkaline post-incubation had strong ability on the deacetylation and delignification of HPAA-pretreated poplar, exhibiting a strong promotion on the enzymatic hydrolysis yield. This report represented alkaline incubation reduced the HPAA loading, improved pretreatment safety, exhibiting excellent potential application in saccharification of poplar.
“…Therefore, the HPAA-SH process had a great potential to decrease the cost of monosaccharides production from poplar. To reduce the cost of the HPAA-SH pretreatment, pressure shift distillation can be employed to separate acetic acid and the peracetic acid formed in HPAA solution [45,46]. Sodium hydroxide solution in alkaline post-incubation can be reused in next process.…”
Background: Hydrogen peroxide-acetic acid (HPAA) is widely used in pretreatment of lignocellulose because it has a good capability in selective delignification. However, high concentration (more than 60%) of HPAA increases the cost of pretreatment and the risk of explosion. In this work, alkaline post-incubation was employed to decrease the HPAA loading and improve the saccharification of poplar. Results: Pretreatment with 100% HPAA removed 91.0% lignin and retained 89.9% glucan in poplar. After poplar was pretreated by 100% HPAA at 60 °C for 2 h, the glucan conversion in enzymatic hydrolysis by cellulase increased to 90.1%. The total lignin, surface lignin, and acetyl group of HPAA-pretreated poplar were removed by alkaline incubation. More than 92% acetyl groups of HPAA-pretreated poplar were removed by 1.0% NaOH. After incubation of 60% HPAA-pretreated poplar with 1.0% NaOH, the glucan conversion enhanced to 95.0%. About 40% HPAA loading in pretreatment was reduced by alkaline incubation without the decrease of glucose yield. Conclusions: Alkaline post-incubation has strong ability on the deacetylation and delignification of HPAA-pretreated poplar, exhibiting a strong promotion on the enzymatic hydrolysis yield. This report represented alkaline incubation reduced the HPAA loading, improved pretreatment safety, exhibiting excellent potential application in saccharification of poplar.
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