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Oral drug delivery is a common route for management of inflammatory bowel disease (IBD) but suffers from low bioavailability and systemic side effects during passage through the alimentary canal. Here, we present a therapeutic nano reagent of a ferulic acid-derived lignin nanoparticle (FALNP). We showed that FALNP with favorable antioxidant activity can regulate IBD. More importantly, the intestinal pH-responsive degradability of FALNP allows it to withstand the harsh gastric acid environment, bypass physiological barriers, and target the intestine for gastrointestinal delivery.

Thioacidolysis is widely used for lignin structural characterization by cleaving β-aryl ethers to release syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) monomers followed by GC analysis. However, the traditional thioacidolysis method requires tedious extraction steps with chlorinated solvent underlying harmful to health, limiting its efficiency and application. Herein, an improved thioacidolysis method with high sensitivity for the quantitation of lignin-derived monomers was developed. The improved protocol used a quick, streamlined procedure to recover the monomeric products using ethyl acetate as extracting solvent and MS detector in multi-reaction monitoring mode to enhance its ability to detect extremely low concentration (0.1 ppb with signal-to-noise higher than 2) of monomeric products. Additionally, a fast GC program was established to speed up the GC quantitation. Several representative lignocellulose samples, including gymnosperm, angiosperm, and poaceae, were used to test this tailored method. The results demonstrated that the ratios of lignin monomer compositions determined by this method were consistent with that of traditional procedure despite the slightly higher monomer yields measured. More importantly, this method uses non-chlorinated solvent for microscale extraction and requires no evaporation step for workup, which is a green and efficient way for the quantification of lignin monomer compositions.

Fluorescent cellulose films with high strength, transparency and UV resistance were prepared. Such extraordinary properties allow application prospects in UV protection, anti-counterfeiting and remote LED devices.

Although measuring lignin contents is a routine operation for biomass compositional analysis in process development aiming at efficient utilization of woody biomass, it is still a challenging task requiring many steps, hazardous reagents, heating, and a significant time. A facile spectroscopic method, our CASA (Cysteine–Assisted Sulfuric Acid) method, was developed to quantify the lignin content of lignocellulosic biomass, based on an extraordinary system in which biomass samples are fully dissolved in 72% H2SO4 containing cysteine at 24 °C in 60 min. Using synthetic lignins, the lignin absorptivities were determined to be 17.25 g−1 L cm−1 for softwood lignin and 11.23 g−1 L cm−1 for hardwood lignin and monocot lignin. Seven softwoods, six hardwoods, and six monocots were tested using the CASA method. A high coefficient of determination (R2 = 0.95) was found between the CASA results and the acid-insoluble lignin contents, and an even better R2 (0.98) was obtained when the CASA data were correlated with the total lignin contents.

Soda process is one of the most important pulping processes in paper industry producing large quantities of alkali lignins that can afford plenty of biofuels, aromatic chemicals and materials. However, the structural and size-related heterogeneities and complexities hinder the development in these directions. Herein, we report new insights into the structure of alkali lignin, through investigating the formation and transformation of enol ether and arylglycerol structures that are significant responsible for the structural transformation from native lignin to alkali lignin. Four-type enol ethers composed of G/S units in hardwood alkali lignin were identified by 2D HSQC NMR. A series of alkali lignins prepared by alkali treatment of eucalyptus cellulolytic enzyme lignin under various temperatures were analyzed by 2D HSQC NMR, 31P NMR and gel permeation chromatography (GPC). Upon these analyses and related model compound studies, it was found that the arylglycerols formed from native β-O-4 linkages tends to be oxidized with the further degradation of aryl ether bonds, and that the enol ether linkages are facile to be hydrolyzed or oxidized in the air. These insights improve the mechanistic understanding for the structural evolution and the diversity of alkali lignins and will aid the development of further lignin valorization strategies.

Lignin-containing cellulose nanofibrils (LCNFs) with tunable lignin contents from sugarcane bagasse were directly prepared by low-temperature soda‑oxygen pulping combined with simple mechanical treatment. The residual lignin structure, morphology and physical dimensions of LCNFs, and properties of the relevant cellulose nanopapers (CNPs) were investigated. In situ 2D Heteronuclear Single Quantum Coherence (HSQC) NMR spectra showed β-O-4 linkages, ferulate, and para-coumarate were well preserved in the LCNFs. Compared with the cellulose nanofibrils (CNFs), LCNFs displayed a more uniform size and narrow diameter distribution. The corresponding CNPs exhibited outstanding mechanical properties (tensile strength reached 152.9 MPa), and excellent combined optical properties both in the UV blocking and visible light transparency. Moreover, the water contact angles (50.0-80.2°) of LCNFs were much higher than that of CNFs (21.7°). Direct preparation of LCNFs under mild condition would unlock the full potential of cellulosic materials and provide enhanced opportunities for cellulose to fabricate multi-functional and high-value materials.

Lignin condensation reactions are hard to avoid or control during separation, which is a deterrent to lignin isolation and post-conversation, especially for the full utilization of lignocelluloses. Selective protection of β-aryl ether linkages in the isolation process is crucial to lignin valorization. Herein, a two-step acid/alkali separation method assisted with l-cysteine for

Lignin is a renewable and the most abundant aromatic source that can be used for extensive chemicals and materials. Although approximately 50 million tons of lignin are produced annually as a by-product of the pulp and paper industry, it is currently underutilized. It is important to know the structural features of technical lignin when considering its application. In this work, we have demonstrated the formation of low-molecular-weight constituents from hardwood (Eucalyptus) lignin, which produces much more low-molecular-weight constituents than softwood (spruce) lignin, after a chemical pulping process, and analyzed the micromolecular compositions in the alkali lignin after fractionation by dichloromethane (DCM) extraction. By applying analytical methods (gel-permeation chromatography, 2D NMR and GC-MS) with the aid of evidence from authenticated compounds, a great treasure trove of lignin-derived phenolic compounds from Eucalyptus alkali lignin were disclosed. Except for some common monomeric products, as many as 15 new lignin-derived monomers and dimers including syringaglycerol, diarylmethane, 1,2-diarylethanes, 1,2-diarylethenes, (arylvinyl ether)-linked arylglycerol dimers and isomeric syringaresinols were identified in the DCM-soluble fraction. Regarding the formation and evolution of the Cα-condensed β-aryl ether structure, a novel route that is potentially responsible for the high content of β-1 diarylethenes and diarylethanes in the lignin low-molecular-weight fraction, in addition to the β-1 (spirodienone) pathway, was proposed. This work not only provides novel insights into the chemical transformation of S–G lignin during the alkali pulping process, but also discovered lignin-derived phenolic monomers and dimers that can potentially be used as raw materials in the chemical or pharmaceutical industries.

In this study, experiments and molecular dynamics simulations were combined to get insights into the role of solvent during the process of xylose conversion under catalyst-free conditions. Solvents used for furfural production were comparatively discussed, including traditional and emerging biomass-derived solvents – water, dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), isopropanol (ISO), γ-butyrolactone (GBL) and γ-valerolactone (GVL). The degradation behavior of solvents, the solubility and α/β ratio of xylose, the distribution of the solvent around xylose/furfural and the hydrogen bonding between them were also studied. The results showed that in pure solvents, the different hydrogen bonding between xylose and the solvent resulted in different products. Water was a favourable solvent for xylose to form furfural among these pure solvents because less formic acid was produced from xylose in water under catalyst-free conditions. Furfural could be produced in mixed solvents if there was more water around xylose, which was similar to the case in pure water. Otherwise, the situation in mixed solvents was similar to that in the corresponding pure organic solvents. GBL and GVL, as green solvents, had weaker affinities with xylose than DMSO, DMF and ISO, but were intensively attracted by furfural, thus they could provide protective shells for furfural, which played a positive role during the production of furfural. The highest furfural yield of 46.4% was achieved in GBL–H2O at 180 °C – 150 min in the absence of catalysts.

Elucidating the structural characteristics and changes of lignin during biorefining is considerably important for lignin valorization. To examine the structural transformations of lignin under deep...

Using originally isolated xylan-type hemicelluloses for material application suffers from poor mechanical properties including low tensile strength and brittleness. The subsequent chemical modifications of hemicelluloses are facing the problems of high costs and toxic chemicals. Consequently, this study tried to investigate the factors affecting the film-forming properties of the originally isolated xylan-hemicelluloses and promoting their material properties from the extraction step. Two different extraction methods, a one-step alkali or alkaline peroxide solution method and a two-step alkali extraction-delignification method were used to extract the hemicellulose with different chemical structures from sugarcane bagasse. For the two-step alkali extraction-delignification method, hemicelluloses were first extracted by alkali solution and then delignified by dioxane/water, hydrogen peroxide solution or sodium hypochlorite solution. The lignin contents of all the extracted hemicelluloses ranged from 1.6%–9.5%, of which the lowest value was obtained through delignification by sodium hypochlorite. The number average molecular weight ranged from 8200 to 26800, while the xylan/arabinan ratio ranged from 5.0 to 9.1. The hemicelluloses were characterized and processed into films. Tensile strength of films could be considerably improved up to ˜52% when using sodium hypochlorite solution as the delignification agents and the lignin content was greatly reduced for the hemicellulose fraction. Statistical models were generated between film mechanical properties and hemicellulose structural characteristics. The models predicted that hemicellulose with higher molecular weight, more linear structure and lower lignin content would result in better mechanical properties.

Phenolation is a commonly used method to improve the reactivity of lignin for various applications. In this study, resinol lignin models (syringaresinol and pinoresinol) and eucalyptus alkali lignin were treated under acid-catalyzed phenolation conditions to investigate the products derived from resinol (β-β) structures of lignins. The phenolation products were characterized by means of GC-MS and NMR spectroscopy following separation using flash chromatography and thin-layer chromatography. A series of new naphthalene products were identified from phenolation of syringaresinol, and the corresponding guaiacyl analogs were also identified by GC-MS. The C1-Cα bond of these resinol compounds was cleaved to release syringol or guaiacol during phenolation. In addition, diphenylmethane products formed from phenol or phenol and syringol/guaiacol were found in the phenolation products. Comparatively, more naphthalene products were obtained by phenolation from syringaresinol than those obtained from pinoresinol. HSQC NMR characterization of the phenolated alkali lignin revealed that naphthalene structures formed in the phenolated lignin.

Technical lignins, mostly generated as byproducts from the pulping industry, are highly abundant aromatic sources. However, they are underutilized due to their complexity, as well as structural alt...

Understanding the chemical structure of lignin in willow bark is an indispensable step to design how to separate its fiber bundles. The whole cell wall and enzyme lignin preparations sequentially isolated from ball-milled bark, inner bark, and wood were comparatively investigated by nuclear magnetic resonance (NMR) spectroscopy and three classical degradative methods, i.e., alkaline nitrobenzene oxidation, derivatization followed by reductive cleavage, and analytical thioacidolysis. All results demonstrated that the guaiacyl (G) units were predominant in the willow bark lignin over syringyl (S) and minor p-hydroxyphenyl (H) units. Moreover, the monomer yields and S/G ratio rose progressively from bark to inner bark and wood, indicating that lignin may be more condensed in bark than in other tissues. Additionally, major interunit linkage substructures (β-aryl ethers, phenylcoumarans, and resinols) together with cinnamyl alcohol end groups were relatively quantitated by two-dimensional NMR spectroscopy. Bark and inner bark were rich in pectins and proteins, which were present in large quantities and also in the enzyme lignin preparations.

As a highly abundant natural and renewable aromatic polymer, lignin has been proven to be a good UV-absorber and natural broad-spectrum sun blocker. The structure-activity relationship of lignin under UV radiation remains unclear due to lignin’s complexity and heterogeneity. Here we report the structure influence of lignin on its anti-UV radiation properties of sun protection factor (SPF), UV absorbance, and antioxidant activity by using different lignin model compounds, including β–O–4, β–β, and β–5 dimers, etc., representing the structures of both native lignins and technical lignins. Meanwhile, UV protection properties of six lignin preparations, including cellulolytic enzyme lignin (CEL), organosolv lignin (OL), and kraft lignin (KL) of pinus kesiya and eucalyptus, were also evaluated for better comparison. SPF values of sunscreen preparations were increased but varied with the same addition of each single model compound into the pure cream or commercial sunscreen. In particular, the SPF value of the sunscreen has been greatly enhanced by the addition of a certain molar concentration of a single model compound (0.0558 mmol, around 2 wt%) into the low SPF commercial sunscreen, which was attributed to the synergistic effects of lignin models and inherent sunscreen agent. By comparing, lignin models containing β–O–4 linkage displayed the least desirable UV protection properties in this work, and side-chain difference, especially the existence of conjugate structure and carboxylic groups, would significantly impact the lignin model compounds’ UV performance. Additionally, the antioxidant activities and UV absorbance of different model compounds and lignin preparations are closely related to their structures. These insights revealed the structure-activity relationship of lignin under UV radiation and will provide a theoretical basis for optimizing lignins or lignin derivatives as the sun-screening agents in sunscreens.

Poacic acid, a decarboxylated product from 8–5-diferulic acid that is commonly found in monocot lignocellulosic hydrolysates, has been identified as a natural antifungal agent against economically significant fungi and oomycete plant pathogens. Starting from commercially available or monocot-derivable ferulic acid, a three-step synthetic procedure has been developed for the production of poacic acid needed for field testing in a controlled agricultural setting. First, ferulic acid was esterified to produce ethyl ferulate in 92% yield. Second, peroxidase-catalyzed free radical dehydrodimerization of ethyl ferulate produced crude diferulates, mainly 8–5-diferulate, in 91% yield. Finally, crystalline poacic acid was obtained in 25% yield via alkaline hydrolysis of the crude diferulates after purification by flash-column chromatography. This new procedure offers two key improvements relevant to large-scale production: 1) bubbling air through the reaction mixture in the second step to remove acetone greatly improves the recovery efficiency of the crude diferulates; and 2) telescoping minor impurities directly into the alkaline hydrolysis step eliminates the need for additional column purifications, thus reducing the overall cost of production and removing a major impediment to process scale-up.

γ-valerolactone (GVL)/H2O/acid solvent mixtures has been used in chemical pretreatment of lignocellulosic biomass, it was claimed that GVL lignins were structurally close to proto (native) lignins, or having low molecular weight with narrow polydispersity, however, the structural changes of GVL lignins have not been investigated. In this study, β-O-4 (β-aryl ether, GG), β-5 (phenylcoumaran), and β-β (resinol) lignin model compounds were treated by an acidic GVL-H2O solvent system, a promising pretreatment of lignocellulose for biomass utilization, to investigate the structural changes possibly related to the lignin involved. NMR characterization of the products isolated from the treated GG indicated that a phenyl dihydrobenzofuran, having typical C-H correlations at δC/δH 50.74/4.50 and 93.49/4.60 ppm in its HSQC spectrum, was produced from GG. In the pretreatment, the released formaldehyde from GG reacted fast with GG to form a novel 1,3-dioxane intermediate whose characteristic HSQC signals were: δC/δH 94.15–94.48/4.81–5.18 ppm and 80.82–83.34/4.50–4.94 ppm. The β-5 model, dihydrodehydrodiconiferyl alcohol, was converted into phenylcoumarone and stilbene having benzaldehyde that resulted from the allyl alcohol side chain. The β-β model, syringaresinol, was isomerized to form a mixture of syringaresinol, epi-, and dia-syringaresinol although being degraded slightly.

During the lignification of grass cell walls, ferulate acts like a nucleation site that can cross couple with monolignols, i.e. coniferyl alcohol and sinapyl alcohol, to form dimeric products. Here we investigated in detail the ferulate-sinapyl alcohol cross-coupling products in an effort on better understanding the nature and scope of lignin-ferulate interactions. In a biomimetic oxidative system, sinapyl alcohol (SA) reacted with ethyl ferulate (FA), a simplified model for feruloyl polysaccharides in plants, to give a mixture of dozens of dimeric products. We delineated the structure of each product by GC-MS and NMR characterizations. It was found that sinapyl alcohol readily reacts with ethyl ferulate producing various cross-coupled dimers including SA-(β–5)-FA (compound 6), SA-(β–8)-FA (both ester and lactones, compounds 7 and 9), and SA-(β–O–4)-FA (compound 8) cross-coupled products in addition to homo-coupled products from ethyl ferulate or sinapyl alcohol. SA-(β–O–4)-FA 8 was identified for the first time in a vitro free radical biomimetic system and the homo-coupled SA-(β–O–4)-SA 3 from sinapyl alcohol was accurately quantified as less than 5%, while the half-open syringaresinol 5 was discovered when dimerization of SA was catalyzed by peroxidase in a biomimetic buffer system. Moreover, one new compound 18 formed by the cross-coupled linkage SA-(β–5)-FA (de-protonated) was identified by GC-MS and NMR, and one possible FA-(8–β)-SA dimer 19* was proposed.

Lignin structural studies play an essential role both in understanding the development of plant cell walls and for valorizing lignocellulosics as renewable biomaterials. Dimeric products released by selectively cleaving β–aryl ether linkages between lignin units reflect the distribution of recalcitrant lignin units, but have been neither absolutely defined nor quantitatively determined. Here, 12 guaiacyl‐type thioacidolysis dimers were identified and quantified using newly synthesized standards. One product previously attributed to deriving from β–1‐coupled units was established as resulting from β–5 units, correcting an analytical quandary. Another longstanding dilemma, that no β–β dimers were recognized in thioacidolysis products from gymnosperms, was resolved with the discovery of two such authenticated compounds. Individual GC response factors for each standard compound allowed rigorous quantification of dimeric products released from softwood lignins, affording insight into the various interunit‐linkage distributions in lignins and thereby guiding the valorization of lignocellulosics.

Thioacidolysis is a method used to measure the relative content of lignin monomers bound by β‐O‐4 linkages. Current thioacidolysis methods are low‐throughput as they require tedious steps for reaction product concentration prior to analysis using standard GC methods. A quantitative thioacidolysis method that is accessible with general laboratory equipment and uses a non‐chlorinated organic solvent and is tailored for higher‐throughput analysis is reported. The method utilizes lignin arylglycerol monomer standards for calibration, requires 1–2 mg of biomass per assay and has been quantified using fast‐GC techniques including a Low Thermal Mass Modular Accelerated Column Heater (LTM MACH). Cumbersome steps, including standard purification, sample concentrating and drying have been eliminated to help aid in consecutive day‐to‐day analyses needed to sustain a high sample throughput for large screening experiments without the loss of quantitation accuracy. The method reported in this manuscript has been quantitatively validated against a commonly used thioacidolysis method and across two different research sites with three common biomass varieties to represent hardwoods, softwoods, and grasses.

Wet-storage is the most common way to maintain sugarcane bagasse in the paper-making industry, although there were few studies on the structural alteration of lignins caused by a wet-storage system. Lignin preparations isolated from wet-stored bagasse in a laboratory simulated wet storage system, corresponding pulps, and spent liquors of soda-oxygen pulping were characterized by various analytical techniques, including elemental analysis (EA), gel permeation chromatography (GPC), and heteronuclear single-quantum coherence (HSQC) NMR spectroscopy. The characteristics of these lignins were compared with those of lignin preparations isolated from fresh sugarcane bagasse samples. Eleven percent decrease of p-coumarate (p-CA) in the lignins from wet-stored raw materials were observed. p-Coumarate and tricin were completely removed during the pulping process. Results from this study suggested that syringyl units were more easily degraded and dissolved under low temperature soda-oxygen pulping conditions. Wet-st...

The structural homogeneity and acid stability of linear C-lignins allow their deconstruction to useful monomers in high yield., Lignin, a major component of lignocellulosic biomass, is crucial to plant growth and development but is a major impediment to efficient biomass utilization in various processes. Valorizing lignin is increasingly realized as being essential. However, rapid condensation of lignin during acidic extraction leads to the formation of recalcitrant condensed units that, along with similar units and structural heterogeneity in native lignin, drastically limits product yield and selectivity. Catechyl lignin (C-lignin), which is essentially a benzodioxane homopolymer without condensed units, might represent an ideal lignin for valorization, as it circumvents these issues. We discovered that C-lignin is highly acid-resistant. Hydrogenolysis of C-lignin resulted in the cleavage of all benzodioxane structures to produce catechyl-type monomers in near-quantitative yield with a selectivity of 90% to a single monomer.

Plant biologists are seeking new approaches for modifying lignin to improve the digestion and utilization of structural polysaccharides in crop cultivars for the production of biofuels, biochemicals, and livestock. To identify promising targets for lignin bioengineering, we artificially lignified maize (Zea mays L.) cell walls with normal monolignols plus 21 structurally diverse alternative monomers to assess their suitability for lignification and for improving fiber digestibility. Lignin formation and structure were assessed by mass balance, Klason lignin, acetyl bromide lignin, gel-state 2D-NMR and thioacidolysis procedures, and digestibility was evaluated with rumen microflora and from glucose production by fungal enzymes following mild acid or base pretreatments. Highly acidic or hydrophilic monomers proved unsuitable for lignin modification because they severely depressed cell wall lignification. By contrast, monomers designed to moderately alter hydrophobicity or introduce cleavable acetal, amide, or ester functionalities into the polymer often readily formed lignin, but most failed to improve digestibility, even after chemical pretreatment. Fortunately, several types of phenylpropanoid derivatives containing multiple ester-linked catechol or pyrogallol units were identified as desirable genetic engineering targets because they readily formed wall-bound polymers and improved digestibility, presumably by blocking cross-linking of lignin to structural polysaccharides and promoting lignin fragmentation during mild acidic and especially alkaline pretreatment.

Tricin [5,7-dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-chromen-4-one] is a flavone that has been found to be incorporated in grass lignin polymers via 4′–O–β coupling. Herein, we investigated the tricin-lignin structure using nuclear magnetic resonance (NMR) methods by comparing the 1H–13C heteronuclear correlation (HSQC) NMR spectra of the isolated lignin with a series of dimeric and trimeric tricin-4′–O–β-ether model compounds. Results showed that the tricin moiety significantly affects the chemical shift of the Cβ/Hβ of 4′–O–β unit, producing peaks at around δC/δH 82.5–83.5/4.15–4.45, that differ from the Cβ/Hβ correlations from normal 4–O–β units formed solely by monolignols, and that have to date been unassigned., The authors thank the China Scholarship Council, State Education Department, for supporting living expenses for Wu Lan’s Program in the Department of Biological System Engineering, University of Wisconsin, Madison. W.L., F.Y., F.L., and J.R. (John Ralph) were funded by the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-FC02-07ER64494 and DE-SC0018409). J.R. (Jorge Rencoret) and J.C.d.R. were funded by the Spanish Projects CTQ2014-60764-JIN and AGL2017-83036-R (co-financed by FEDER funds).

&gamma, valerolactone (GVL)/H2O/acid solvent mixtures has been used in chemical pretreatment of lignocellulosic biomass, it was claimed that GVL lignins were structurally close to proto (native) lignins, or having low molecular weight with narrow polydispersity, however, the structural changes of GVL lignins have not been investigated. In this study, &beta, O-4 (&beta, aryl ether, GG), &beta, 5 (phenylcoumaran), and &beta, &beta, (resinol) lignin model compounds were treated by an acidic GVL-H2O solvent system, a promising pretreatment of lignocellulose for biomass utilization, to investigate the structural changes possibly related to the lignin involved. NMR characterization of the products isolated from the treated GG indicated that a phenyl dihydrobenzofuran, having typical C-H correlations at &delta, C/&delta, H 50.74/4.50 and 93.49/4.60 ppm in its HSQC spectrum, was produced from GG. In the pretreatment, the released formaldehyde from GG reacted fast with GG to form a novel 1,3-dioxane intermediate whose characteristic HSQC signals were: &delta, H 94.15&ndash, 94.48/4.81&ndash, 5.18 ppm and 80.82&ndash, 83.34/4.50&ndash, 4.94 ppm. The &beta, 5 model, dihydrodehydrodiconiferyl alcohol, was converted into phenylcoumarone and stilbene having benzaldehyde that resulted from the allyl alcohol side chain. The &beta, model, syringaresinol, was isomerized to form a mixture of syringaresinol, epi-, and dia-syringaresinol although being degraded slightly.

Analytical thioacidolysis releases diagnostic monomers from lignins by selectively cleaving alkyl aryl ether bonds. High yielding syntheses of the three thioacidolysis monomers were developed, and the compounds were used as standards for gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC-FID) quantitation of monomers released from lignocellulosics. First, syringyl, guaiacyl, and p-hydroxyphenyl glycerols were synthesized from the corresponding ethyl cinnamates and used as thioacidolysis substrates to prepare the monomers in high yields. These monomers were then used as standard compounds to measure their GC-MS and GC-FID response factors against two internal standards, 4,4'-ethylenebisphenol and tetracosane. For quantitation, it was shown that 4,4'-ethylenebisphenol is the better internal standard for GC-MS, whereas tetracosane remains the choice for GC-FID. When the obtained response factors were applied, the thioacidolysis monomer yields from white spruce, loblolly pine, poplar, bamboo, and sugar cane bagasse were determined by GC-MS. The obtained results were consistent with those reported in the literature.

Ultrasound-assisted dissolution of cellulose was performed in ionic liquid 1-butyl-3-methylimidazolium chloride ([C 4 mim]Cl). The dissolution process was monitored with polarizing microscope. The effects of parameters including ultrasonic power and irradiation time on cellulose dissolution time were investigated. The dissolution time required for complete dissolution decreased from 190 min without assistance to 60 min irradiated with 30 W ultrasound for 20 min. The regenerated cellulose samples were characterized with FT-IR, solid-state CP/MAS 13 C NMR, wide-angle X-ray diffraction and thermal analysis. The results showed that most crystalline structure of cellulose was destroyed to amorphous structure, and the remained crystalline structure of cellulose was converted to cellulose II from cellulose I in native cellulose. After dissolution and regeneration in ionic liquid, the thermal stability of cellulose decreased and the pyrolysis residues increased.

In present study, succinoylation of sugarcane bagasse cellulose was performed with succinic anhydride (SA) using iodine as a catalyst in solvent system containing ionic liquid (IL), 1-butyl-3-methylimidazolium chloride ([C 4 mim]Cl), and dimethylsulfoxide (DMSO). The results showed that all succinylated cellulosic derivatives had the degree of substitution (DS) in the range of 0.56–1.54, which noticeably increased compared with the products without any catalysts, indicating that iodine was an effective catalyst for cellulose succinoylation in ionic liquids. The succinylated cellulosic derivatives were also characterized with FT-IR and solid-state CP/MAS 13 C NMR spectroscopies. The results indicated that the iodine-catalyzed succinoylation efficiency increased, and the reaction of hydroxyl groups at C-6, C-2 and C-3 positions in cellulose occurred. The thermal stability of the succinylated cellulose was found to decrease upon chemical modification.

The homogeneous chemical modification of cellulose with succinic anhydride was investigated in a solvent system containing 1-butyl-3-methylimidazolium chloride ionic liquid and dimethylsulfoxide using N-bromosuccinimide (NBS) as a catalyst. The results showed that the degree of substitution of the succinylated cellulosic samples, in the range of 0.24-2.31, noticeably increased as compared with the products without any catalysts, indicating that NBS was a novel efficient catalyst for cellulose succinoylation in ionic liquids. Fourier transform infrared and solid-state cross-polarization/magic angle spinning (13)C NMR spectroscopies also provided evidence of succinoylation reaction. The results indicated that the reaction of hydroxyl groups at C-6, C-2, and C-3 positions in cellulose occurred. The thermal stability of the succinylated cellulose was found to decrease upon chemical modification.

Wood shortages, environmental pollution and high energy consumption remain major obstacles hindering the development of today’s pulp and paper industry. Energy-saving and environmental friendly pulping processes are still needed, especially for non-woody materials. In this study, soda-oxygen pulping of bagasse was investigated and a successful soda-oxygen pulping process for bagasse at 100 °C was established. The pulping parameters of choice were under active alkali charge of 23%, maximum cooking temperature 100 °C, time hold at maximum temperature 180 min, initial pressure of oxygen 0.6 MPa, MgSO4 charge 0.5%, and de-pithed bagasse consistency 12%. Properties of the resultant pulp were screened yield 60.9%, Kappa number 14, viscosity 766 dm3/kg, and brightness 63.7% ISO. Similar pulps were also obtained at 110 °C or 105 °C with a cooking time of 90 min. Compared with pulps obtained at higher temperatures (115–125 °C), this pulp had higher screened yield, brightness, and acceptable viscosity, while the delignification degree was moderate. These results indicated that soda-oxygen pulping at 100 °C, the lowest cooking temperature reported so far for soda-oxygen pulping, is a suitable process for making chemical pulp from bagasse. Pulping at lower temperature and using oxygen make it an environmental friendly and energy-saving pulping process.

Cellulose, the most widespread natural polymers, can be used as a green source for fabricating biodegradable and biocompatible materials with attractive properties by chemical modification or mixing with other components (Potthast et al., 2006). Effective utilization of cellulose not only mitigates the fossil resources crisis but also protects the environment of the Earth. However, cellulose is extraordinarily difficult to be dissolved due to its considerable hydrogen bonds and partially crystalline structure.