Abstract:BackgroundAs a natural renewable biomass, the tea oil fruit hull (TOFH) mainly consists of lignocellulose, together with some bioactive substances. Our earlier work constructed a two-stage solvent-based process, including one aqueous ethanol organosolv extraction and an atmospheric glycerol organosolv (AGO) pretreatment, for bioprocessing of the TOFH into diverse bioproducts. However, the AGO pretreatment is not as selective as expected in removing the lignin from TOFH, resulting in the limited delignification… Show more
“…SB is comprised of all biomass refuse after sugarcane harvest, and is usually discarded or burned at the field [4]. Both of these ongoing practices represent environmentally imprudent or even harmful usage of a readily available biomass resource [3–5]. The results of previous studies on the biorefining of SB indicated SB as well-suited for the production of value-added products especially due to its high polysaccharide content.…”
Section: Introductionmentioning
confidence: 99%
“…This characteristic thus necessitates the implementation of economical pretreatment that deconstructs the lignocellulosic entanglement without inducing damaging its constituents. To date, the pretreatment technologies that have received the most attention include hydrothermal, steam explosion, diluted acid, and diluted alkaline pretreatment [5, 8, 9].…”
BackgroundObtaining high-value products from lignocellulosic biomass is central for the realization of industrial biorefinery. Acid pretreatment has been reported to yield xylooligosaccharides (XOS) and improve enzymatic hydrolysis. Moreover, xylose, an inevitable byproduct, can be upgraded to xylonic acid (XA). The aim of this study was to valorize sugarcane bagasse (SB) by starting with XA pretreatment for XOS and glucose production within a multi-product biorefinery framework.ResultsSB was primarily subjected to XA pretreatment to maximize the XOS yield by the response surface method (RSM). A maximum XOS yield of 44.5% was achieved by acid pretreatment using 0.64 M XA for 42 min at 154 °C. Furthermore, XA pretreatment can efficiently improve enzymatic digestibility, and achieved a 90.8% cellulose conversion. In addition, xylose, the inevitable byproduct of the acid-hydrolysis of xylan, can be completely converted to XA via bio-oxidation of Gluconobacter oxydans (G. oxydans). Subsequently, XA and XOS can be simultaneously separated by electrodialysis.ConclusionsXA pretreatment was explored and exhibited a promising ability to depolymerize xylan into XOS. Mass balance analysis showed that the maximum XOS and fermentable sugars yields reached 10.5 g and 30.9 g per 100 g raw SB, respectively. In summary, by concurrently producing XOS and fermentable sugars with high yields, SB was thus valorized as a promising feedstock of lignocellulosic biorefinery for value-added products.
“…SB is comprised of all biomass refuse after sugarcane harvest, and is usually discarded or burned at the field [4]. Both of these ongoing practices represent environmentally imprudent or even harmful usage of a readily available biomass resource [3–5]. The results of previous studies on the biorefining of SB indicated SB as well-suited for the production of value-added products especially due to its high polysaccharide content.…”
Section: Introductionmentioning
confidence: 99%
“…This characteristic thus necessitates the implementation of economical pretreatment that deconstructs the lignocellulosic entanglement without inducing damaging its constituents. To date, the pretreatment technologies that have received the most attention include hydrothermal, steam explosion, diluted acid, and diluted alkaline pretreatment [5, 8, 9].…”
BackgroundObtaining high-value products from lignocellulosic biomass is central for the realization of industrial biorefinery. Acid pretreatment has been reported to yield xylooligosaccharides (XOS) and improve enzymatic hydrolysis. Moreover, xylose, an inevitable byproduct, can be upgraded to xylonic acid (XA). The aim of this study was to valorize sugarcane bagasse (SB) by starting with XA pretreatment for XOS and glucose production within a multi-product biorefinery framework.ResultsSB was primarily subjected to XA pretreatment to maximize the XOS yield by the response surface method (RSM). A maximum XOS yield of 44.5% was achieved by acid pretreatment using 0.64 M XA for 42 min at 154 °C. Furthermore, XA pretreatment can efficiently improve enzymatic digestibility, and achieved a 90.8% cellulose conversion. In addition, xylose, the inevitable byproduct of the acid-hydrolysis of xylan, can be completely converted to XA via bio-oxidation of Gluconobacter oxydans (G. oxydans). Subsequently, XA and XOS can be simultaneously separated by electrodialysis.ConclusionsXA pretreatment was explored and exhibited a promising ability to depolymerize xylan into XOS. Mass balance analysis showed that the maximum XOS and fermentable sugars yields reached 10.5 g and 30.9 g per 100 g raw SB, respectively. In summary, by concurrently producing XOS and fermentable sugars with high yields, SB was thus valorized as a promising feedstock of lignocellulosic biorefinery for value-added products.
“…2,5,6 A previous study showed that CLSM can be used to determine the distribution of lignin on lignocellulosic biomass. 29 As shown in Figure 4, the feedstock possessed an intact web-like structure, while the ac-AGO pretreated substrate exhibited a significant breakage of the sclerenchyma and middle lamella of the plant cell walls, as well as an obvious separation of cell walls and middle lamella. The observations show that the ac-AGO pretreatment dissociated the natural cell structure of sugarcane bagasse, which is consistent with the above SEM images.…”
Conventional atmospheric glycerol
organosolv pretreatment is energy-intensive
with the requirement of long time and/or high temperature. Herein,
acid-catalyzed atmospheric glycerol organosolv (ac-AGO) pretreatment
was developed under a mild condition to modify the sugarcane bagasse
structure for improving enzymatic hydrolyzability. Using single factor
and central composite design experiments, ac-AGO pretreatment was
optimized at 200 °C for 15 min with 0.06% H2SO4 addition, wherein the hemicellulose and lignin removal rates
were 82 and 52%, respectively, with extremely high cellulose retention
of 98%. The ac-AGO-pretreated substrate exhibited good enzymatic hydrolyzability
at a modest cellulase loading, affording a 70% glucose yield after
72 h. Multiple analysis tools were used to correlate the hydrolyzability
of the substrate with its structural features. The results indicated
that the mild ac-AGO pretreatment can modify the lignocellulosic biomass
structure to achieve good hydrolyzability, mainly resulting in significant
hemicellulose removal.
“…When two-step pretreatments were implemented, the crystallite size increased gradually to 3.26 nm (Case 8) and 3.24 nm (Case 11), respectively. This phenomenon indicated that pretreatment did not disrupt the cellulose crystallinity and reduce the crystalline size, but increased it, due to the reformation or recrystallization of crystalline cellulose [ 27 ].…”
Section: Resultsmentioning
confidence: 99%
“…The glucose yield of the pretreated solid with the combinatorial pretreatment of NaOH and 60% ethanol (Case 3) was substantially enhanced by 41% and 205% compared to that of NaOH or 60% ethanol pretreated solids, respectively, which was in line with a previous report [ 1 ]. This phenomenon was ascribed to the higher removal of hemicellulose (22.6% of xylan) and lignin (17.9% of AIL), which destroyed the matrix structure and provided more cellulose for enzyme accessibility [ 16 , 27 ]. Fig.…”
BackgroundThe recalcitrant structure of lignocellulosic biomass made it challenging for their bioconversion into biofuels and biochemicals. Pretreatment was required to deconstruct the intact structure by the removal of hemicellulose/lignin, improving the cellulose accessibility of enzyme. Combinatorial pretreatments with liquid hot water/H2SO4 and ethanol/NaOH of sugarcane bagasse were developed to improve enzymatic hydrolysis under mild conditions.ResultsAfter one-step 60% ethanol containing 0.5% NaOH pretreatment with solid to liquid ratio of 1/10, the glucose yield after hydrolysis for 72 h with enzyme dosage of 20 FPU/g substrate was enhanced by 41% and 205% compared to that of NaOH or 60% ethanol pretreated solids, respectively. This improvement was correlated with the removal of hemicellulose and lignin. However, using combinatorial pretreatments with 1% H2SO4 followed by 60% ethanol containing 0.5% NaOH, the highest glucose yield with Tween 80 reached 76%, representing 84.5% of theoretical glucose in pretreated substrate. While retaining similar glucose yield, the addition of Tween 80 capacitated either a reduction of enzyme loading by 50% or shortening hydrolysis time to 24 h. However, the enhancement with the addition of Tween 80 decreased as hydrolysis time was extended.ConclusionsThis study demonstrated that a combinatorial pretreatment with 1% H2SO4 followed by 60% ethanol containing 0.5% NaOH had significant effects on improving the enzymatic hydrolysis of sugarcane bagasse. The addition of Tween 80 enabled reducing the enzyme loading or shortening the hydrolysis time. This study provided an economically feasible and mild process for the generation of glucose, which will be subsequently converted to bioethanol and biochemicals.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1313-7) contains supplementary material, which is available to authorized users.
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