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This work investigated the integration of a two-stage hydrothermal treatment for production of xylooligosaccharides (XOS), a high-value product, into the isolation process of cellulose nanofibrils (CNF) from sugarcane bagasse. Under optimized conditions, the first stage yielded a XOS-rich, high purity hydrolysate and in the second stage only a xylose-rich hydrolysate could be obtained at high purity. The resulting solid cellulosic fraction was delignified and bleached to obtain a cellulose-rich pulp, which was mechanically defibrillated by disc ultra-refining to CNF. Except for the viscosity, the sugarcane CNF showed properties (i.e., thermal stability, crystallinity and diameter size) comparable or superior to the CNF prepared from commercial bleached eucalyptus Kraft pulp. In conclusion, the integration of the two-stage hydrothermal treatment is an efficient and promising strategy to obtain hemicellulose-derived high-value co-products in the process of isolating CNF. In addition, lignin was also recovered as a co-product with yield comparable to other biomass fractionation approaches., (Copyright © 2020 Elsevier B.V. All rights reserved.)

This work evaluated sugarcane bagasse pretreatment with wood-decay fungi, producing varied patterns of biodegradation. The overall mass balance of sugars released after pretreatment and enzymatic hydrolysis indicated that a selective white-rot was necessary to provide glucose yields similar to the ones observed from leading physico-chemical pretreatment technologies. The selective white-rot Ceriporiopsis subvermispora was selective for lignin degradation in the lignocellulosic material, preserved most of the glucan fraction, and increased the cellulose digestibility of biotreated material. Glucose mass balances indicated that of the potential glucose of untreated bagasse, 47% was recovered as sugar-rich syrup after C. subvermispora biotreatment for 60days followed by enzymatic digestion of the pretreated material., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

This study investigated the recovery of H2 and CH4 from bagasse bioethanol fermentation residues (bagasse BEFR) using a two-stage bioprocess. In the hydrogen fermentation bioreactor (HFB), carbohydrate removal efficiency was maintained at 82-93% and the highest hydrogen yield was 8.24mL/gCOD at volumetric loading rate (VLR) of 80kgCOD/m(3)/day. The results indicated a positive correlation between hydrogen yield and butyrate-to-acetate ratio, which might be due to the mechanisms of lactate/acetate utilization for hydrogen production and acetogenesis occurring in the HFB. Remaining volatile fatty acids and alcohols in the HFB effluent were further utilized for methane production in methane fermentation bioreactor (MFB), in which the highest methane yield of 345.2mL/gCOD was attained at VLR of 2.5kgCOD/m(3)/day. Overall, the two-stage bioprocess achieved a maximum COD removal of 81% from bagasse BEFR, and converted 0.3% and 72.8% of COD in the forms of H2 and CH4, respectively., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

This study is aimed to examine the inhibition of soluble fraction (SF) and enzymatic residual fraction (ERF) in dry dilute acid (DDA), ethylenediamine (EDA) and steam explosion (SE) pretreated corn stover (CS) on the enzymatic digestibility of cellulose. SF of DDA, EDA and SE pretreated CS has high xylose, soluble lignin and xylo-oligomer content, respectively. SF of EDA pretreated CS leads to the highest inhibition, followed by SE and DDA pretreated CS. Inhibition of ERF of DDA and SE pretreated CS is higher than that of EDA pretreated CS. The inhibition degree (A0/A) of SF is 1.76 and 1.21 times to that of ERF for EDA and SE pretreated CS, respectively. The inhibition degree of ERF is 1.05 times to that of SF in DDA pretreated CS. The quantitative analysis shows that SF of EDA pretreated CS, SF and ERF of SE pretreated CS cause significant inhibition during enzymatic hydrolysis., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Viscosity trends in alkali-pretreated sugarcane bagasse (SCB) slurries undergoing high solids fed-batch enzymatic hydrolysis were measured for a range of solids loading from 15% to 36%. Solids liquefaction times were related to system viscosity changes. The viscosity decreased quickly for low solids loading, and increased with increasing solids content. Fed-batch hydrolysis was initiated with 15% solids loading, and an additional 8%, 7% and 6% were successively added after the system viscosity decreased to stable values to achieve a final solids content of 36%. Two enzyme-adding modes with 8.5FPU/g solid were investigated. The batch mode with all enzyme being added at the beginning of the reaction produced the highest yields, with approximately 231.7g/L total sugars and 134.9g/L glucose being obtained after 96h with nearly 60% of the final glucan conversion rate. This finding indicates that under the right conditions, the fed-batch strategy might be a plausible way to produce high sugars under high solids., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The effect of combinations and ratios between different enzymes has been investigated in order to assess the optimal conditions for hydrolysis of cashew apple bagasse pretreated with alkaline hydrogen peroxide (the solids named CAB-AHP). The separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes were evaluated in the ethanol production. The enzymatic hydrolysis conducted with cellulase complex and β-glucosidase in a ratio of 0.61:0.39, enzyme loading of 30FPU/g(CAB-AHP) and 66CBU/g(CAB-AHP), respectively, using 4% cellulose from CAB-AHP, turned out to be the most effective conditions, with glucose and xylose yields of 511.68 mg/g(CAB-AHP) and 237.8 mg/g(CAB-AHP), respectively. Fermentation of the pure hydrolysate by Kluyveromyces marxianus ATCC 36907 led to an ethanol yield of 61.8kg/ton(CAB), corresponding to 15 g/L ethanol and productivity of 3.75 g/( Lh). The ethanol production obtained for SSF process using K. marxianus ATCC 36907 was 18 g/L corresponding to 80% yield and 74.2kg/ton(CAB)., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Corncob residue is a cellulose-rich byproduct obtained from industrial xylose production via dilute acid hydrolysis processes. Enzymatic hydrolysis of cellulose in acid hydrolysis residue of corncob (AHRC) is often less efficient without further pretreatment. In this work, the process characteristics of acid impregnated steam explosion were studied in conjunction with a dilute acid process, and their effects on physiochemical changes and enzymatic saccharification of corncob residue were compared. With the acid impregnated steam explosion process, both higher xylose recovery and higher cellulose conversion were obtained. The maximum conversion of cellulose in acid impregnated steam explosion residue of corncob (ASERC) reached 85.3%, which was 1.6 times higher than that of AHRC. Biomass compositional analysis showed similar cellulose and lignin content in ASERC and AHRC. XRD analysis demonstrated comparable crystallinity of ASERC and AHRC. The improved enzymatic hydrolysis efficiency was attributed to higher porosity in ASERC, measured by mercury porosimetry., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Fed-batch enzymatic hydrolysis process from alkali-pretreated sugarcane bagasse was investigated to increase solids loading, produce high-concentration fermentable sugar and finally to reduce the cost of the production process. The optimal initial solids loading, feeding time and quantities were examined. The hydrolysis system was initiated with 12% (w/v) solids loading in flasks, where 7% fresh solids were fed consecutively at 6h, 12h, 24h to get a final solids loading of 33%. All the requested cellulase loading (10 FPU/g substrate) was added completely at the beginning of hydrolysis reaction. After 120 h of hydrolysis, the maximal concentrations of cellobiose, glucose and xylose obtained were 9.376 g/L, 129.50 g/L, 56.03 g/L, respectively. The final total glucan conversion rate attained to 60% from this fed-batch process., (Copyright © 2014. Published by Elsevier Ltd.)

To release sugars effectively from sweet sorghum bagasse (SSB), a cellulose solvent and organic solvent-based lignocellulose fractionation pretreatment approach was studied using response surface methodology (RSM). Based on RSM's central composite design, a batch experimental matrix was set up to determine the effects of reaction time (20-60 min) and temperature (40-60 °C) on delignification, total reducing sugar yield, glucan digestibility, and overall glucose yields following a pretreatment-hydrolysis process. The optimum pretreatment conditions of 50 °C and 40 min led to 51.4% delignification, 86% overall glucose yield, and 61% overall xylose yield. An effort has also been made to obtain predictive models to illustrate the correlation between independent and dependent variables using RSM. The significance of the correlations and adequacy of these models were statistically tested for the selected objective functions. The optimum pretreatment condition predicted by the model was 49.1 °C and 39.2 min which matched the experimental data well. Results from this study can be applied to large scale biorefineries using sugars released from SSB for producing various biofuels., (© 2013 American Institute of Chemical Engineers.)

Alkaline oxidation pretreatment was developed for spruce, birch and sugar cane bagasse. The reaction was carried out in alkaline water solution under 10 bar oxygen pressure and at mild reaction temperature of 120-140°C. Most of the lignin was solubilised by the alkaline oxidation pretreatment and an easily hydrolysable carbohydrate fraction was obtained. After 72 h hydrolysis with a 10 FPU/g enzyme dosage, glucose yields of 80%, 91%, and 97%, for spruce, birch and bagasse, respectively, were achieved. The enzyme dosage could be decreased to 4 FPU/g without a major effect in terms of the hydrolysis performance. Compared to steam explosion alkaline oxidation was found to be significantly better in the conditions tested, especially for the pretreatment of spruce. In hydrolysis and fermentation at 12% d.m. consistency an ethanol yield of 80% could be obtained with both bagasse and spruce in 1-3 days., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Ozonolysis was studied separately and in combination with wet disk milling (WDM) for the pretreatment of sugarcane bagasse and straw, with the aim of improving their enzymatic saccharification. The glucose yields for ozonolysis followed by WDM were 89.7% for bagasse and 63.1% for straw, whereas the use of WDM followed by ozonolysis resulted in glucose yields of 81.1% for bagasse and 92.4% for straw, with shorter WDM time. This last procedure allowed a substantial decrease in energy consumption in comparison to the use of WDM alone or of ozonolysis followed by WDM. Higher overall saccharification yields with shorter milling times were observed when ozonolysis was carried out before WDM. This effect might be related to the higher specific surface area. Additionally, a finer morphology was observed by the association of the two treatments in comparison to the sole use of ozonolysis or WDM., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The chemical composition, hydrolysis products, and kinetics during liquid hot water pretreatment of sweet sorghum bagasse (SSB) and eucalyptus wood chips (EWC) were investigated. Under optimal conditions, a total xylose recovery of 79.6% and 55.6% for SSB and of 74.9% and 84.4% for EWC was achieved after pretreatments in a step-change flow rate reactor (184 °C, 20 ml/min, 8 min, and 10 ml/min, 10 min) and batch stirred reactor (184 °C, 5%w/v, 18 min), respectively. More than 90% of the xylose was recovered as oligomers from SSB, independent of the type of reactor employed. The activation energies of xylan decomposition of SSB in the step-change flow rate reactor was 6.5-fold greater than that of EWC in the batch stirred reactor due to accumulation of acidic products. These findings show that sugar recovery is dependent on the reactor configuration for specific substrates., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

In this study, sugarcane bagasse was pretreated by six ionic liquids (ILs) using a bagasse/IL ratio of 1:20 (wt%). The solubilization of bagasse in the ILs was followed by water precipitation. On using 1-ethyl-3-methylimidazolium acetate [Emim] [Ac] at 120 °C for 120 min, 20.7% of the bagasse components remained dissolved and enzymatic saccharification experiments resulted on 80% glucose yield within 6h, which evolved to over 90% within 24 h. Moreover, FE-SEM analysis of the precipitated material indicated a drastic lignin extraction and the exposure of nanoscopic cellulose microfibrils with widths of less than 100 nm. The specific surface area (SSA) of the pretreated bagasse (131.84 m2/g) was found to be 100 times that of untreated bagasse. The ability of [Emim] [Ac] to simultaneously increase the SSA and to decrease the biomass crystallinity is responsible for the improved bagasse enzymatic saccharification rates and yields obtained in this work., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A combination of a twin-screw extrusion and an acid-catalyzed hot water extraction process performed at a bench-scale was used to prepare high monomeric xylose hydrolysate for cellulosic production. The influences of the screw speed (30-150 rpm), barrel temperature (80-160 °C) and corresponding specific mechanical energy of the extruder on the structural properties of the pretreated rice straw, sugar concentration and conversion were investigated. The optimal condition for the extrusion step was determined to be 40 rpm with 3% H2SO4 at 120 °C; the optimal condition for the extraction step was determined to be 130 °C for 20 min. After the pretreatment at the optimal condition, 83.7% of the xylan was converted to monomeric xylose, and the concentration reached levels of 53.7 g/L. Finally, after the subsequent enzymatic hydrolysis, an 80% yield of the total saccharification was obtained., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Experiments based on a 2(3) central composite full factorial design were carried out in 200-ml stainless-steel containers to study the pretreatment, with dilute sulfuric acid, of a sugarcane bagasse sample obtained from a local sugar-alcohol mill. The independent variables selected for study were temperature, varied from 112.5°C to 157.5°C, residence time, varied from 5.0 to 35.0 min, and sulfuric acid concentration, varied from 0.0% to 3.0% (w/v). Bagasse loading of 15% (w/w) was used in all experiments. Statistical analysis of the experimental results showed that all three independent variables significantly influenced the response variables, namely the bagasse solubilization, efficiency of xylose recovery in the hemicellulosic hydrolysate, efficiency of cellulose enzymatic saccharification, and percentages of cellulose, hemicellulose, and lignin in the pretreated solids. Temperature was the factor that influenced the response variables the most, followed by acid concentration and residence time, in that order. Although harsher pretreatment conditions promoted almost complete removal of the hemicellulosic fraction, the amount of xylose recovered in the hemicellulosic hydrolysate did not exceed 61.8% of the maximum theoretical value. Cellulose enzymatic saccharification was favored by more efficient removal of hemicellulose during the pretreatment. However, detoxification of the hemicellulosic hydrolysate was necessary for better bioconversion of the sugars to ethanol.

This study aims to establish an efficient pretreatment process using cellulose-dissolution solvents to enhance the enzymatic saccharification. LiOH/urea, LiCl/DMAc, concentrated phosphoric acid, ionic liquid (1-butyl-3-methylimidazolium chloride; [BMIM]Cl) and N-methyl-morpholine-N-oxide (NMMO) were selected as the cellulose dissolution agents. Except the cellulosic sample regenerated from LiCl/DMAc system, all the other treated samples exhibited lower cellulose crystallinity and degree of polymerization (DP), and consequently, exhibited a significant enhancement on enzymatic hydrolysis kinetic. Ionic liquid pretreatment offered unique advantages in the hydrolysis rate in the first 10h, probably due to the extensively structural transformation of cellulose from the crystalline to the amorphous region. Meanwhile, the regenerated cellulose from concentrated phosphoric acid almost completely consisted of cellulose II, and achieved the highest saccharification yield., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Sugarcane bagasse was pretreated with diluted sulfuric acid to obtain sugarcane bagasse hemicellulosic hydrolysate (SBHH). Experiments were conducted in laboratory and semi-pilot reactors to optimize the xylose recovery and to reduce the generation of sugar degradation products, as furfural and 5-hydroxymethylfurfural (HMF). The hydrolysis scale-up procedure was based on the H-Factor, that combines temperature and residence time and employs the Arrhenius equation to model the sulfuric acid concentration (100 mg(acid)/g(dm)) and activation energy (109 kJ/mol). This procedure allowed the mathematical estimation of the results through simulation of the conditions prevailing in the reactors with different designs. The SBHH obtained from different reactors but under the same H-Factor of 5.45+/-0.15 reached similar xylose yield (approximately 74%) and low concentration of sugar degradation products, as furfural (0.082 g/L) and HMF (0.0071 g/L). Also, the highest lignin degradation products (phenolic compounds) were rho-coumarilic acid (0.15 g/L) followed by ferulic acid (0.12 g/L) and gallic acid (0.035 g/L). The highest concentration of ions referred to S (3433.6 mg/L), Fe (554.4 mg/L), K (103.9 mg/L). The H-Factor could be used without dramatically altering the xylose and HMF/furfural levels. Therefore, we could assume that H-Factor was directly useful in the scale-up of the hemicellulosic hydrolysate production.

This work aims at the valorization of sugarcane bagasse by extracting xylose which is destined to the production of xylitol after purification and hydrogenation. Our approach consists in applying the principle of biorefinery to sugarcane bagasse because of its hemicellulose composition (particularly rich in xylan: (92%)). Optimizing of the thermal treatment was investigated. A treatment at 170 degrees C for 2 h was found optimal, with higher solubilzation of hemicellulose than that at 150 degrees C and lower degradation of sugar monomers than 190 degrees C. Recovery of xylose was high and the purity of xylose solution (78%) allows expecting an easy purification and separation of xylose before hydrogenation. Analysis of thermal hydrolyzates shows the presence of xylan oligomers and polymers with large distribution of DPs. This fraction should be submitted to enzymatic treatment to recover more xylose monomer.

The use of cellulosic biosludges generated in a Kraft pulp mill was investigated as substrate for lactic acid production by simultaneous saccharification and fermentation (SSF). The effect of the operation mode (batch or fedbatch), the initial liquid to solid ratio (12 or 30 g/g) and the nutrient supplementation (MRS components or none) on several parameters including lactic acid concentration, volumetric productivity and product yields, were evaluated. When the operation was carried out in fedbatch mode with nutrient supplementation and using a LSR(0)=12 g/g, a broth containing 42 g/L was obtained after 48 h with a volumetric productivity of 0.87 g/L h and a product yield of 37.8 g lactic acid/100 g biosludges. In a similar experiment carried out without nutrient supplementation, a lactic acid concentration of 39.4 g/L was obtained after 48 h with a volumetric productivity of 0.82 g/L h and a product yield of 35.5 g L-lactic acid/100 g biosludges.

Poplar wood was treated with peracetic acid, KOH, and ball milling to produce 147 model lignocelluloses with a broad spectrum of lignin contents, acetyl contents, and crystallinity indices (CrIs), respectively. An empirical model was identified that describes the roles of these three properties in enzymatic hydrolysis. Lignin content and CrI have the greatest impact on biomass digestibility, whereas acetyl content has a minor impact. The digestibility of several lime-treated biomass samples agreed with the empirical model. Lime treatment removes all acetyl groups and a moderate amount of lignin and increases CrI slightly; lignin removal is the dominant benefit from lime treatment.

An ammonia pressurization/depressurization process was investigated to evaluate the potential of producing reducing sugars from dwarf elephant grass, a warm-season forage. Moisture, temperature, and ammonia loading affected sugar yield (p < 0.0001). At optimal conditions, ammonia processing solubilized 50.9% of the hemicellulose and raised the sugar yield (percentage of theoretical) from 18 to 83%. Glucose and xylose production were increased 3.2- and 8.2-fold, respectively. The mild processing conditions of the ammonia treatment (90-100 degrees C, 5 min), the low enzyme loading (2 international filter paper units/g), and the short hydrolysis time (24 h), greatly enhance the potential of using forages to produce sugars valuable for several applications.

1. O-Acetylated polysaccharides were obtained from green wood of both sweet chestnut and wych elm by treatment of the residue remaining after dimethyl sulphoxide extraction with water at 98 degrees . This gives a mixture of polysaccharides containing xylose, galactose, glucose and uronic acids. Analysis of these and their fractionated products suggest that only xylans in green sweet chestnut and green wych elm are O-acetylated. 2. The isolated O-acetylated xylans are not representative of the total O-acetylated xylans occurring in sweet chestnut and wych elm. 3. Application of the method developed by Bouveng for the location of O-acetyl groups to all four O-acetylated xylans obtained in this series of investigations by dimethyl sulphoxide extraction showed that those from sweet chestnut and wych elm, under the same conditions of incubation, lost: 74.2 and 43.4% of acetyl groups respectively, at C-2; 58.0 and 28.5% of acetyl groups respectively at C-3; 41.8 and 82.2% of acetyl groups respectively at C-2 and C-3. 4. A consideration of electronic and steric factors indicates that there does not appear to be a purely chemical reason for the difference in loss of O-acetyl groups between sweet chestnut and wych elm. It is suggested that the location of O-acetylated xylans in the wood cell walls and the presence of extractive may play some part in this difference.