Pyrolysis of lignin extracted from prairie cordgrass,aspen, and Kraft lignin by Py-GC/MS and TGA/FTIR

A study is undertaken to assess the effectiveness of lignin extracted from prairie cordgrass as a pyrolysis feedstock. The effects of variability of lignin source on fast and slow pyrolysis products are also investigated. To accomplish these goals, Py-GC/MS and TGA/FTIR are employed in the pyrolysis of three types of lignin: prairie cordgrass (PCG) lignin extracted from prairie cordgrass, aspen lignin extracted from aspen trees (hardwood), and synthetic Kraft lignin. Fast pyrolysis results from Py-GC/MS show that for PCG lignin, only ten of the detected compounds have relative peak area percentiles that exceed 2% and make up over 52% of the total area. For aspen lignin, excluding butanol that is used in the extraction process, only eight compounds are found to have relative peak areas exceeding 2% that make up over 52% of the total area. For Kraft lignin, only eight compounds exceeding 2% are found to make up more than 45% of the total area. Both techniques, Py-GC/MS and TGA/FTIR, indicate that PCG lignin releases more alkyls than aspen and Kraft lignin. TGA/FTIR results indicate that PCG lignin also releases by far the most light volatile products (<200 °C) while producing the least amount of char among the three types of lignin studied. These characteristics make PCG lignin a good choice in producing good quality bio-oil and thus decreasing upgrade requirements. Py-GC/MS results conclude that aspen lignin produces significantly more pyrolytic products than PCG lignin. This is indicative of the potential of aspen lignin to result in higher conversion rates of bio-oil than the other two lignins.     

Eco-friendly composite resins based on renewable biomass resources: Polyfurfuryl alcohol/lignin thermosets

The properties of an innovative polyfurfuryl alcohol (PFA)/lignin combined matrix have been investigated. Furfuryl alcohol (FA) and lignin are, respectively, monomeric and polymeric precursors issued from biomass feedstock. In the present work, a plasticized lignin (PL) has been blended during polymerization of FA into PFA. Two kinds of samples were prepared at different FA/lignin ratio. Structural investigations were made on resins by ¹³C NMR while the thermo-mechanical performances of the combined materials were studied using thermogravimetric (TGA) and dynamic mechanical analysis (DMA). TGA results have permitted us to determine the thermal stability and the composition of the cured material on the basis of the ash content. According with these results, it was found that the lignin ratio in the cured material is more important than in the initial threshold. The TGA reveals that the PFA/PL thermo-oxidative degradation occurs at higher temperature compared to the natural (PL) component system, together with a lower rate of decomposition. This underlines a good interpenetration of lignin within the furanic matrix. The morphologies of the combined PFA/lignin systems, controlled by scanning electron microscopy (SEM), reveal a monophasic structure. These observations are in good agreement with the presence of a unique relaxation peak as shown in the DMA results.     

Residual lignin inhibits thermal degradation of cellulosic fiber sheets

The market for cellulosic fiber based food packaging applications is growing together with the importance of improving the thermal durability of these fibers. To shed light on this, we investigated the role of residual lignin in pulp on the thermal stability of refined pulp sheets. The unbleached, oxygen delignified, and fully bleached pulp sheets were studied after four separate refining degrees. Comparison by Gurley air resistance, Bendtsen porosity, and the oxygen transmission rate tests showed that lignin containing sheets had better air and oxygen barrier properties than fully bleached sheets. Sheet density and light scattering coefficient measurements further confirmed that the lignin containing pulps underwent more intense fibrillation upon refining that changed the barrier properties of the sheets. Thermal treatments (at 225 °C, 20 and 60 min, in water vapor atmospheres of 1 and 75 v/v %) were applied to determine the thermal durability of the sheets. The results revealed that the residual lignin in pulps improved the thermal stability of the pulp sheets in the hot humid conditions. This effect was systematically studied by tensile strength, brightness, and light absorption coefficient measurements. The intrinsic viscosity results support the findings and suggest that lignin is able to hinder the thermal degradation of pulp polysaccharides. In spite of the fact that lignin is known to enhance the thermal yellowing of paper, no significant discoloration of the pulp sheets containing residual lignin was observed in the hot humid conditions (75 v/v %). Our results support the idea of lignin strengthening the thermal durability of paper.     

Mathematical Tool from Corn Stover TGA to Determine Its Composition

Corn stover was treated by steam explosion process at four different temperatures. A fraction of the four exploded matters was extracted by water. The eight samples (four from steam explosion and four from water extraction of exploded matters) were analysed by wet chemical way to quantify the amount of cellulose, hemicellulose and lignin. Thermogravimetric analysis in air atmosphere was executed on the eight samples. A mathematical tool was developed, using TGA data, to determine the composition of corn stover in terms of cellulose, hemicellulose and lignin. It uses the biomass degradation temperature as multiple linear function of the cellulose, hemicellulose and lignin content of the biomass with interactive terms. The mathematical tool predicted cellulose, hemicellulose and lignin contents with average absolute errors of 1.69, 5.59 and 0.74?%, respectively, compared to the wet chemical method.     

The Cellulase-Mediated Saccharification on Wood Derived from Transgenic Low-Lignin Lines of Black Cottonwood (Populus trichocarpa)

Downregulated lignin transgenic black cottonwood (Populus trichocarpa) was used to elucidate the effect of lignin and xylan content on enzymatic saccharification. The lignin contents of three transgenic samples (4CL1-1, 4CL1-4, and CH8-1-4) were 19.3, 16.7, and 15.0?%, respectively, as compared with the wild type (21.3?%). The four pretreatments were dilute acid (0.1?% sulfuric acid, 185?°C, 30?min), green liquor (6?% total titratable alkali, 25?% sulfidity based on TTA, 185?°C, and 15?min.), autohydrolysis (185?°C, 30?min), and ozone delignification (25?°C, 30?min). Following the pretreatment, enzymatic saccharification was carried out using an enzyme charge of 5?FPU/g of substrates. The removal of lignin and hemicellulose varies with both the types of pretreatments and the lignin content of the transgenic trees. Due to the greatest removal of lignin, green liquor induced the highest sugar production and saccharification efficiency, followed by acid, ozone, and autohydrolysis in descending order. The results indicated that lignin is the main recalcitrance of biomass degradation. At a given lignin content, pretreatment with ozone delignification had lower saccharification efficiency than the other pretreatment methods due to higher xylan content.     

Enhanced deconstruction and dissolution of lignocellulosic biomass in ionic liquid at high water content by lithium chloride

Fabricating an aqueous ionic liquid (IL) for deconstruction and dissolution of lignocellulose is attractive because addition of water could reduce the cost and viscosity of the solvent and improve the biomass processing, but the solvating power of the IL is usually depressed in the presence of water. In the present study, an aqueous IL consisting of 1-butyl-3-methylimidazolium chloride (BmimCl), water, and lithium chloride was fabricated for efficient deconstruction and dissolution of lignocellulose (bamboo). The dissolution of cell wall components (cellulose, lignin, and hemicelluloses) in the aqueous IL was investigated. The results indicated that the presence of water significantly reduced the solvating power of BmimCl; For example, 11.5 % water decreased the dissolution of bamboo in BmimCl from ~97 to ~53 %. Dissolution of cellulose and lignin was specifically depressed. However, addition of lithium chloride was able to improve the tolerance of BmimCl to water and enhance the deconstruction and dissolution of biomass in BmimCl with high water content. It was found that approximately 80 % bamboo could be dissolved in solvent consisting of 45 wt% BmimCl and 55 wt% LiCl·2H₂O (25 wt% overall water content in the solvent). In particular, lignin and hemicelluloses were selectively dissolved by 96 and 92 %, respectively. The undissolved residue was predominantly composed of cellulose (~86 %) with a small amount of lignin (<5 %). BmimCl-LiCl-H₂O is a promising and effective solvent system with low cost and viscosity for biomass processing.     

Effect of Two-Step Formosolv Fractionation on the Structural Properties and Antioxidant Activity of Lignin

The formosolv fractionation process has been demonstrated to be an effective approach toward lignin recovery as an antioxidant from lignocellulosic biomass. In this study, four lignin fractions, FL-88%, FSL-70%, FIL-70% and FL-EtAc, were isolated from Phragmites australis biomass through two-step formosolv fractionation (88% formic acid delignification followed by 70% aqueous formic acid fractionation). To better understand the structural properties of the lignin obtained from this fractionation process, four isolated lignins were successfully characterized by gel permeation chromatography (GPC), Fourier transform infrared (FT-IR), two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (2D-HSQC NMR) spectroscopy, thermogravimetric analysis (TGA) and gas chromatograph-mass spectroscopy (GC/MS). It was found that lignin depolymerization via β-O-4 cleavage occurred via a formylation, elimination and hydrolysis mechanism, accompanied by a competitive condensation reaction. Noteworthily, two-step formosolv fractionation can produce specific lignin fractions with different ABTS and DPPH radical scavenging activities. The FL-EtAc fraction with low molecular weight (M_w = 2748 Da) and good homogeneity (PDI = 1.5) showed excellent antioxidant activity, compared with the other three isolated lignin fractions, even equal to that of commercial antioxidant BHT at the same concentration of 2.0 mg·mL⁻¹. These findings are of great help for specific lignin from biomass as a natural antioxidant in the future.     

Preparation and Characterization of Biobased Lignin-Co-Polyester/Amide Thermoplastics

More than 23 million tonnes of lignin are produced annually in the US from wood pulping and 98% of this lignin is burnt. Therefore, creating products from lignin, such as plastics, offers an approach for obtaining sustainable materials in a circular economy. Lignin-based copolymers were synthesized using a single pot, solvent free, melt condensation reaction. The synthesis occurred in two stages. In the first stage, a biobased prepolymer consisting of butanediol (BD, 0.8–1 molar content) and a diacid (succinic (SA), adipic (AA) and suberic acids (SuA), with varying amounts of diaminobutane (DAB, 0–0.2 molar content) was heated under vacuum and monitored by Fourier transform infra-red (FTIR) spectroscopy and electrospray ionization-mass spectrometry (ESI-MS). In the second stage, prepolymer was mixed with a softwood kraft lignin (0–50 wt.%) and further reacted under vacuum at elevated temperature. Progression of the polymerization reaction was monitored using FTIR spectroscopy. The lignin-copolyester/amide properties were characterized using tensile testing, X-ray diffraction (XRD), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Lignin co-polymer tensile (strength 0.1–2.1 MPa and modulus 2 to 338 MPa) properties were found to be influenced by the diacid chain length, lignin, and DAB contents. The lignin-copolymers were shown to be semi-crystalline polymer and have thermoplastic behavior. The SA based copolyesters/amides were relatively stiff and brittle materials while the AA based copolyesters/amides were flexible and the SuA based copolyesters/amides fell in-between. Additionally, > 30 wt.% lignin the lignin- copolyesters/amides did not exhibit melt behavior. Lignin-co-polyester/amides can be generated using green synthesis methods from biobased building blocks. The lignin- copolyesters/amides properties could be tuned based on the lignin content, DAB content and diacid chain length. This approach shows that undervalued lignin can be used in as a macromonomer in producing thermoplastic materials.     

Enzymatic Conversion of Different Qualities of Refined Softwood Hemicellulose Recovered from Spent Sulfite Liquor

Spent sulfite liquor (SSL) from softwood processing is rich in hemicellulose (acetyl galactoglucomannan, AcGGM), lignin, and lignin-derived compounds. We investigated the effect of sequential AcGGM purification on the enzymatic bioconversion of AcGGM. SSL was processed through three consecutive purification steps (membrane filtration, precipitation, and adsorption) to obtain AcGGM with increasing purity. Significant reduction (~99%) in lignin content and modest loss (~18%) of polysaccharides was observed during purification from the least pure preparation (UFR), obtained by membrane filtration, compared to the purest preparation (AD), obtained by adsorption. AcGGM (~14.5 kDa) was the major polysaccharide in the preparations; its enzymatic hydrolysis was assessed by reducing sugar and high-performance anion-exchange chromatography analysis. The hydrolysis of the UFR preparation with Viscozyme L or Trichoderma reesei β-mannanase TrMan5A (1 mg/mL) resulted in less than ~50% bioconversion of AcGGM. The AcGGM in the AD preparation was hydrolyzed to a higher degree (~67% with TrMan5A and 80% with Viscozyme L) and showed the highest conversion rate. This indicates that SSL contains enzyme-inhibitory compounds (e.g., lignin and lignin-derived compounds such as lignosulfonates) which were successfully removed.     

Wastewater treatment containing methylene blue dye as pollutant using adsorption by chitosan lignin membrane: Development of membrane,characterization and kinetics of adsorption

An influential subject of research is the use of lignin for effective removal of hazardous dyes from wastewater effluents utilizing green techniques. Lignin makes up to 10–25% of lignocellulosic biomass. In this study, a solvent evaporation approach was employed to construct a novel chitosan lignin membrane, which was then used to remove the methylene blue (MB) dye from water. The physicochemical, thermal, and morphological attributes were characterized by SEM, XRD, FTIR ATR, and TGA DSC. With higher lignin content in the membrane, its tensile strength was reduced. The dye was removed 95% of the time by the membrane, and the adsorption followed the Langmuir isotherm. The membranes could be recycled up to five times.     

聚苯胺-木质素纳米复合物的制备及对银离子的吸附还原性能

以酶解木质素为分散剂、苯胺为单体,采用原位聚合法制备聚苯胺-酶解木质素(PANI-Lignin)纳米复合物.采用红外光谱、紫外-可见光谱、场发射扫描电子显微镜、透射电子显微镜、热重分析和宽角X射线衍射研究了PANI-Lignin纳米复合物的结构和性能.同时,采用静态吸附法研究了PANI-Lignin纳米复合物对银离子的吸附性能.研究结果表明,酶解木质素的添加量对PANI-Lignin纳米复合物的结构和性能有很大影响.酶解木质素添加量为10 wt%时,PANI-Lignin复合物为粒径约为70 nm的纳米粒子.随着酶解木质素添加量由0增加到30 wt%,PANI-Lignin纳米复合物对银离子的吸附容量和吸附率是先增加后减少.当酶解木质素添加量为10 wt%时,PANI-Lignin纳米复合物的银离子吸附容量达到最大值,为565.4 mg/g.对吸附后产物的分析可知,吸附后有长达1 cm,宽为0.220～4.38μm,厚为219～311 nm的纳米带状单质银生成,说明该PANI-Lignin复合物具有较强的反应性银离子吸附能力.     

Examination of the lignin content in a softwood and a hardwood decayed by a brown‐rot fungus with the acetyl bromide method and Fourier transform infrared spectroscopy

Fourier transform infrared (FTIR) spectroscopy was used to examine lignin modification in Pinus sylvestris L. (Scots pine) and Fagus sylvatica L. (beech) decayed to different weight losses by the brown‐rot fungus Coniophora puteana. Samples of different weight losses, ranging from 3 to 64% for beech and 15 to 62% for pine, were analyzed along with undecayed controls. The ratios of the heights of the lignin/carbohydrate FTIR peaks were determined, and the lignin contents of the blocks were measured with the acetyl bromide method. The ratios of the reference peaks for lignin against polysaccharide (i.e., cellulose and hemicellulose) peaks were compared with the lignin content of the wood determined by the acetyl bromide method. A good correlation was obtained for ratios of some of the lignin/carbohydrate reference peaks (lignin peaks at 1505 and 1330 cm^?1 for beech and at 1511 and 1225 cm^?1 for pine against polysaccharide peaks at 1734, 1375, and 1158 cm^?1) against the lignin content for both wood species decayed to different levels. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2340–2346, 2004     

生物质主要组分低温热解研究

利用热重分析仪和裂解气质联用仪进行生物质主要组分低温热解特性研究。热重实验结果表明,生物质主要组分的热稳定性为：纤维素>木质素>半纤维素。半纤维素主要热解温度在210℃～320℃,而纤维素和木质素的主要热解温度分别在310℃～390℃和200℃～550℃。裂解气质联用实验考察不同温度对生物质主要组分低温热解产物的影响。半纤维素热解产物主要有乙酸、1-羟基-丙酮和1-羟基-2-丁酮,纤维素热解产物主要包括左旋葡聚糖和脱水纤维二糖,而木质素热解产物主要是邻甲氧基苯酚。     

Spruce Bark-Extracted Lignin and Tannin-Based Bioresin-Adhesives: Effect of Curing Temperatures on the Thermal Properties of the Resins

In this study, formaldehyde-free bioresin adhesives were synthesised from lignin and tannin, which were obtained from softwood bark. The extraction was done via organosolv treatment and hot water extraction, respectively. A non-volatile, non-toxic aldehyde, glyoxal, was used as a substitute for formaldehyde in order to modify the chemical structure of both the lignin and tannin. The glyoxal modification reaction was confirmed by ATR–FTIR spectroscopy. Three different resin formulations were prepared using modified lignin along with the modified tannin. The thermal properties of the modified lignin, tannin, and the bioresins were assessed by DSC and TGA. When the bioresins were cured at a high temperature (200 °C) by compression moulding, they exhibited higher thermal stability as well as an enhanced degree of cross-linking compared to the low temperature-cured bioresins. The thermal properties of the resins were strongly affected by the compositions of the resins as well as the curing temperatures.     

Effect of Ceria Addition to Na2O-ZrO2 Catalytic Mixtures on Lignin Waste Ex-Situ Pyrolysis

Waste lignin is a potential source of renewable fuels and other chemical precursors under catalytic pyrolysis. For this purpose, four mixed metal oxide catalytic mixtures (Cat) derived from Na₂CO₃, CeO₂ and ZrO₂ were synthesised in varying compositions and utilised in a fixed bed reactor for catalytic vapour upgrading of Etek lignin pyrolysis products at 600 °C. The catalytic mixtures were analysed and characterised using XRD analysis, whilst pyrolysis products were analysed for distribution of products using FTIR, GC-MS and EA. Substantial phenolic content (20 wt%) was obtained when using equimolar catalytic mixture A (Cat_A), however the majority of these phenols were guaiacol derivatives, suggesting the catalytic mixture employed did not favour deep demethoxylation. Despite this, addition of 40–50% ceria to NaZrO₂ resulted in a remarkable reduction of coke to 4 wt%, compared to ~9 wt% of NaZrO₂. CeO₂ content higher than 50% favoured the increase in conversion of the holo-cellulose fraction, enriching the bio-oil in aldehydes, ketones and cyclopentanones. Of the catalytic mixtures studied, equimolar metal oxides content (Cat_A) appears to showcase the optimal characteristics for phenolics production and coking reduction.     

Synthesis of polyurea nanocomposite from industrial waste lignin: Classical curing of isocyanate by lignin-polyamine

Polyurea is an important class of polymer obtained through curing of the isocyanate and polyamine. Here lignin amine processed successive three-step reactions for the synthesis of nanostructure polyurea composite. Further the competence nature is found out by combining different lignin-polyamine with various di-isocyanate. In the first step, lignin was reacted with tosyl-chloride which modified the hydroxy function of lignin as a good leaving group. This reaction for tosylated lignin (Lignin-OTs) has 80% yield. Further lignin-OTs was reacted with four different polyamines replaced tosyl functional group by amine gives aminated lignin. Eventually, a classical reaction of aminated lignin and three different di-isocyanate yield a polyurea composite. A series of changes from lignin to its tosylation eventually to polyurea composite was pursued by the change in the functional group of lignin. The tosylated lignin was confirmed by IR absorption of the C-O peak at 1190 and 1365 cm^?1 and invisible peak absorption at 3500 cm^?1. The aminated lignin was confirmed by IR absorption at 3120 and 3430 cm^?1 for –NH. Thermal gravimetric analysis (TGA) and differential scanning colorimetry (DSC) were used to determine the product's thermal characteristics. Complete structural morphology of nanostructure lignin-polyurea composite was investigated by X-ray diffraction, FE-SEM and EDX.     

Formation and characterization of mechanochemically generated free lignin radicals from olive seeds

In this study, formation and quantification of mechanochemically generated free radicals of lignin were evaluated after the extraction of lignin from olive seeds and detailed lignin characterization was performed. Lignin was extracted from crushed olive seeds as an insoluble solid using Klason method. Isolated lignin was mechanochemically grinded under cryo conditions using Cryomill and particlesizes were determined by using Zeta Sizer, structural changes were followed by XRD and FTIR-ATR; thermal stabilities were tracked by TGA and DSC. In order to enable solubility demanding studies (such as ¹H‑NMR and GPC), acylation of lignin was accomplished. ESR measurements were completed to prove the nature of the radicals. Free radicals cavenging activity of olive seed lignin was determined and quantified using 2-diphenyl-1-picrylhydrazyl (DPPH) method. Number of created mechanoradicals (per gram of olive seed lignin) was calculated from the corresponding UV‑Vis spectra. Finally, morphological changes of the lignin over cryomilling was evaluated using SEM.     

Testing new graphene oxide-coated glazing for papyrus manuscripts in museums: Part I

The display of papyrus and paper (as cellulosic materials) in the Egyptian museums is always critical due to the traditional placement of display of sensitive materials between two plates of glass, acrylic, or other types of glazing materials. The sensitivity of the glazing materials to abrasion, ultraviolet rays, dust adhesion, and high light reflectivity are considered concerning issues to conservators, curators, and visitors. In this paper, thin protective coatings of graphene oxide (GO) were synthesized by modified Hummers' method and deposited on selected museums' glazing materials (glass and acrylic) using spin coating. Multi-analytical techniques were employed to assess the applicability of GO-coated glazing including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FTIR), microhardness testing, NIR VIS, and UV spectrophotometer and static potential measurements. The results showed that the glass glazing hardness was increased by ~10% due to the deposition of the GO coating. Moreover, according to glazing type, the reflectance values of the GO-coated glazing samples, compared with the uncoated samples, confirmed that the thin film of GO improved the UV rays blocking. As is evident in the GO-coated glass where approximately 27% of UV rays have been blocked, likewise, 19% of UV rays were blocked in GO-coated acrylic (TRU VUE). Considering VIS and NIR reflection spectra of GO-coated plexiglass, a higher reflectance is presented by 29%. Furthermore, the static potential measurements showed an energy decline in GO-coated glazing compared with the uncoated samples.     

Preparation,characterization and antimicrobial application of hybrid cellulose-lignin beads

In the present study, cellulose-lignin beads were prepared using pretreated dissolving grade-pulp and extracted from birch wood hydrotropic lignin as starting materials. The preparation involved dissolution of both polymers in environmentally friendly 7% NaOH/12% urea aqueous solution, shaping the solution into beads and subsequent regeneration. Lignin content in the beads varied from 0 to 40%. The beads were characterized using FTIR, scanning electron and confocal fluorescence microscopy. Porosity, swelling behavior and leaching of lignin from the beads in water were studied as well. The antibacterial properties of the beads and original hydrotropic lignin were tested using Escherichia coli (XL-1 Blue) and Staphylococcus aureus (ATCC 25923). The obtained beads in a never-dried state were highly porous spherical particles with evenly distributed lignin in them. Their shape, structure and properties were influenced by the lignin content. The beads did not show antibacterial activity against gram-negative E. coli. On the other hand, never-dried cellulose-lignin beads inhibited growth of gram-positive S. aureus, and the inhibition efficiency increased with the lignin content. The half inhibitory concentration for never-dried beads with 40% of lignin was 1.06 mg (dry weight) per 1 mL of broth determined after incubation for 24 h at 37 °C and at initial concentration of S. aureus of 6.48 log(CFU/mL). In contrast to cellulose-lignin beads, pure cellulose beads did not inhibit growth of S aureus. The results demonstrated that hydrotropic birch lignin can be used for the preparation of composite cellulose-lignin beads. Such beads show a great potential for antibacterial applications against S. aureus.     

Pretreatment of sugarcane bagasse by acidified aqueous polyol solutions

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.