Lignin Samples Research Articles

H2O2 generated through ORR on cathode in a protic ionic liquid and its utilization in lignin valorization

The quantitative study of lignin valorization by H 2 O 2 generated through ORR process on the cathode in [Et 3 NH][HSO 4 ] was performed, that is approximately 20 molecules of H 2 O 2 were needed to produce one molecule of vanillin from lignin depolymerization. • H 2 O 2 generated through ORR process on cathode in electrolyte of [Et 3 NH][HSO 4 ]. • Application of H 2 O 2 electro-generated in situ to lignin valorization. • About 2 molecules of H 2 O 2 needed for breaking one α-O-4 ether bond in PBP molecule. • About 19.4 molecules of H 2 O 2 required for producing one molecule of vanillin from lignin. Lignin valorization to obtain small aromatic compounds requires selective oxidation to break the linkage bonds among the C9 units in lignin molecules. It has been reported that hydrogen peroxide (H 2 O 2 ) generated through the oxygen reduction reaction (ORR) on the cathode could be an appropriate oxidizing reagent to depolymerize lignin, but the current efficiency was still unsatisfactory. In this study, a protic ionic liquid [Et 3 NH][HSO 4 ] is used as electrolyte instead of aqueous solution, and the generation rate of H 2 O 2 is determined as 0.0563 mmol cm −2 min −1 and the current efficiency of 79.7 % by the Ti-TPyP colorimetric method. Then using p -benzylethoxyphenol (PBP) as a lignin model compound, it is figured out that approximately-two molecules of H 2 O 2 are consumed for breaking one α-O-4 ether bond. Finally, in the electrolysis of an actual lignin sample, it is evaluated that about 19.4 molecules of H 2 O 2 are needed for producing one molecule of vanillin when taking vanillin as a representative degradation product of lignin.

Primary release and transformation of inorganic and organic sodium during fast pyrolysis of sodium-loaded lignin

This study employs a wire-mesh reactor (WMR) to understand the primary release and transformation of inorganic and organic sodium during fast pyrolysis of various sodium-loaded lignin samples at 300–800 °C. Due to the minimization of volatile-char interactions in WMR, the overall sodium release during lignin pyrolysis is relatively low, i.e., ∼9–11% and ∼7–14% for the inorganic and inorganic sodium loaded lignin, respectively. The presence of the inorganic sodium in the condensed volatiles (so-called oil) clearly indicates the important role of thermal ejection in the release of the inorganic sodium, since sodium salts are unlikely to evaporate under current conditions. While the release of the organic sodium into oil can be due to both thermal ejection of aerosols and evaporation of low carboxylates. Despite the low sodium release, significant transformation of the inorganic and organic sodium can take place during lignin pyrolysis. For the inorganic sodium loaded lignin, the inorganic sodium decreases continuously from ∼67% at 300 °C to ∼42% at 800 °C, accompanied by a steady increase in the organic sodium (i.e., the ion-exchangeable sodium) from ∼17% at 300 °C to ∼37% at 800 °C. While for the organic sodium loaded lignin, its transformation into the inorganic sodium is faster at higher temperatures, leading to a large increase in the inorganic sodium (i.e., carbonates) from ∼9% at 300 °C to ∼48% at 800 °C, as well as a reduction in the organic sodium from ∼79% at 300 °C to ∼28% at 800 °C. The data generated in this study will be important to understand the catalytic mechanism of sodium during thermochemical processing of alkali lignin for the production of bioenergy and biofuels.

The effects of pH on the precipitation of rice straw lignin from An Giang, Vietnam

This research aimed to extract lignin from rice straw and reveal the pH value of diluted acid at which the most effective yield of lignin was precipitated. In this study, rice straw obtained from local fields in the An Giang province of Vietnam and sodium hydroxide 2 M was employed to extract lignin from rice straw. Hydrochloric acid was used to adjust the sample pH values to be in the range of 1.5-3.5. Fourier-transform infrared spectroscopy (FTIR) analysis was used to characterize the functional groups of the lignin materials. Thermogravimetric analysis (TGA) analysis was employed to supply information on the thermal decomposition of the lignin samples. Herein, the results showed that lignin precipitated at different pH values affected its thermal properties. At 700oC, the yield of the remaining lignin components were 56% at pH 2.0, but the weight loss of lignin samples precipitated at pH 3.5 dropped to 85% because many non-lignin substances existed in the samples. The yield of the crude lignin samples obtained were 16.51, 17.66, 15.27, 14.33 and 13.26% for pH of 1.5, 2.0, 2.5, 3.0 and 3.5 respectively. The crystallite regions played an important role in the lignin structures. The spectrum peaks at pH 1.5, 2.0 and 2.5 were broader than the peaks at pH 3.0 and 3.5. The results demonstrated the highest percentage of lignin precipitate was collected at pH 2.0.

Tandem strategy of photocatalytic preoxidation-ultrasonic cavitation depolymerization for lignin valorization

Tandem strategy for lignin utilization with photocatalytic preoxidation and ultrasonic cavitation depolymerization was proposed. Cornstalk residual lignin from industrial bioethanol process was first photocatalytically preoxidized under visible light by g-C3N4 and WO3/g-C3N4/h-BN (WCB) photocatalysts respectively, then obtained lignin samples were characterized to confirm the preoxidation with raw lignin as a blank. During photocatalytic preoxidation, benzyl hydroxyls in lignin was transformed to carbonyls, but a certain degree of lignin degradation and condensation was observed. In comparison, WCB-catalyzed photopreoxidation was more effective. Thereafter, lignin depolymerization was achieved by ultrasonic cavitation-assisted ethanololysis under optimal conditions. Compared with the mere ultrasonic cavitation depolymerization of pristine lignin, WCB-induced photocatalytic preoxidation improved the conversion rate by 14%, the light-oil yield by 26%, and the phenolic monomer yield by 35%. In general, the reported tandem method worked very well for the enhancement of lignin depolymerization and provided a new idea for the development of lignin valorization.

Enhancing the Efficacy of the Subcritical Water-Based Alkali Lignin Depolymerization by Optimizing the Reaction Conditions and Using Heterogeneous Catalysts

The catalytic depolymerization of alkali lignin into phenolic monomers was studied using subcritical water. In this study, subcritical water was used as the greener solvent with heterogeneous catalysts. The goal of this study was to screen for the best catalyst for the depolymerization, to optimize the reaction conditions, and to increase the yield of the phenolic monomers. The depolymerization reactions were performed at 200 and 240 °C for 5, 10, and 15 min, using subcritical water as the solvent with different catalysts. The treatment of the lignin sample with Ni-Graphene catalyst in subcritical water at 240 °C for 10 min resulted in the highest total yield of phenolic monomers, which was 41.16 ± 0.27 mg/g of alkali lignin. The catalysts also resulted the highest yield for each of the phenolic monomers guaiacol (G), vanillin (G), and homovanillic acid (G) compared to other catalysts studied. The optimized method proved to be an excellent approach to depolymerize alkali lignin.

Pyrolysis characteristics, gas products, volatiles, and thermo–kinetics of industrial lignin via TG/DTG–FTIR/MS and in–situ Py–PI–TOF/MS

The lignosulfonates and de–alkalized lignin pyrolysis characteristics were evaluated by using TG/DTG–FTIR/MS and in–situ Py–PI–TOF/MS. TG/DTG experiments showed that lignin sample pyrolysis proceeded in three stages from 303.15 to 1173.15 K, and the thermographs shifted to higher temperatures with increasing heating rate. Gases MS analysis showed that the pyrolysis of sodium lignosulfonate produced more CH4 and CO2 than the pyrolysis products of calcium lignosulfonate and de–alkalized lignin. The escape temperature of volatile matter in the lignin samples were basically consistent with the order of its organic content, but there were obvious differences in product composition. The escape peak temperature of olefins, aromatics, monophenols, and bisphenols showed a decline trend with the increase of substituent carbon number. The sample pyrolysis thermo–kinetics was estimated by Coats–Redfern, FWO, KAS, and integral Master–plots methods. The activation energies were 66.74–678.20 kJ mol−1 (calcium lignosulfonate) > 32.24–598.38 kJ mol−1 (sodium lignosulfonate) > 44.27–265.69 kJ mol−1 (de–alkalized lignin). The most potential kinetic models were not all consistent with the standard curves for the stages of sample pyrolysis. This study provides theoretical and practical guidance for solving the engineering problems of lignin wastes pyrolysis in papermaking wastewater.

ФОРМУВАННЯ ЯКОСТІ ВЕГЕТАТИВНОЇ МАСИ ЕНЕРГЕТИЧНИХ КУЛЬТУР РІЗНОЇ ТРИВАЛОСТІ ВЕГЕТАЦІЇ

The research results show that in the samples of switchgrass plants with different vegetation periods the dry matter content varied from 52.40% in the leaves of the 3rd year of vegetation to 77.15% in the leaves of plants of the 8th year of vegetation. In the leaves of miscanthus, the dry matter content varied from 59.35 to 62.30% depending on the duration of the growing season. This figure for energy willow was in the range of 61.23–66.12%. There is a general trend in the content of raw ash in various plant organs: more in the leaves and less in the stem in all variants of the studied plants. Thus, the ash content in switchgrass plants ranged from 1.2% in the stems of plants of the 8th year of vegetation to 4.5% in the leaves of plants of the 10th year of vegetation. The ash content in miscanthus plants ranged from 1.6% to 3.0%, and in willow samples - in the range of 1.9–3.5%. The accumulation of hemicellulose in bioenergetics plants occurs gradually during the growing season. In particular, a slightly higher content of hemicellulose was observing in the stems of bioenergetics plants, less in the leaves. Thus, in switchgrass plants the highest content of hemicellulose was in the stem – 22.65%, and in the leaves 22.75%. In miscanthus plants, the hemicellulose content in the stem ranged from 21.51 to 22.55%, and in the leaves from 21.49 to 22.30%. With regard to energy willow, the distribution of hemicellulose in the plant varied like switchgrass – less in the leaves and more in the stems. The accumulation and distribution of cellulose in bioenergetics plants was similar to hemicelluloses, the leaves were smaller comparing to the stems. In switchgrass plants, the highest cellulose content was in the stems – 42.03–45.49%, and in the leaves – 42.08–45.33%, depending on the duration of the growing season. The distribution of cellulose in switchgrass and energy willow plants changed similarly. Young plants have little lignin, but with age its amount in the tissues increases significantly. Plants accumulate the most lignin in the spring and less in the fall. The accumulation of lignin in samples of bioenergetics plants was different. Its greater content was in the leaves, and less in the stems. Thus, the plants of switchgrass had the highest amount of lignin in the leaves – 18.59% (plants of the 10th year of vegetation), the lowest in the leaves – 15.92% (plants of the 3rd year of vegetation), and in the stems, respectively, 18.02 and 15.90%.

Pretreatment of lignin by electrochemical hydrogenation to enhance the olefins and aromatic products during rapid pyrolysis

Lignin is one of the most promising biopolymers for producing hydrocarbons and aromatic compounds in nature. Electrochemical conversion of lignin is regarded as an attractive technology for producing various aromatic chemicals which are generally derived from fossil fuels. The author reports an electrochemical approach for hydrogenating alkaline lignin (AL), which uses relatively low-cost Ni foam as a working electrode under alkali electrolyte. The primary factors (such as power input, reactor type, temperature, reaction time, catalysts, and electrode substrates) of electrochemical hydrogenation were used to control the products' yield and features. The redox characteristics of the reaction system were directly compared with the cyclic voltammetry measurement under different parameters. After electrochemical hydrogenation (ECH), rapid pyrolysis was conducted on HAL samples to investigate the influence of electrochemical reactions on lignin. The maximum olefins and aromatics yield from HAL was increased to more than three times AL, accounting for 2.22 wt% and 4.07 wt%, respectively. Then, thermogravimetric analysis (TGA), elemental analysis (EA), Fourier-transform infrared spectroscopy (FTIR), and heteronuclear single quantum coherence (HSQC) NMR were employed to characterize hydrogenated lignin samples (HAL), as well as gas chromatography–mass spectrometry (GC-MS) was conducted to investigate the oil-phase products. This work focused on this electrochemical hydrogenation coupled with rapid pyrolysis process to give a possibility that converting lignin into not only liquid oil products, but solid hydrogenated lignin can be used to produce more olefins and aromatics in rapid pyrolysis, and presented the advantages and disadvantages of this two-stage process finally.

Impact of temperature and residence time on the hydrothermal carbonization of organosolv lignin

Herein, we have investigated how pure lignin extracted from birch and spruce via a hybrid organosolv/steam explosion method reacts under hydrothermal carbonization (HTC) to produce hydrochar, a product that has found applications in environmental remediation, energy storage and catalysis. We subjected thirteen lignin samples obtained from birch and spruce under different extraction conditions to HTC at 260 ℃ for four hours. The yield of hydrochar varied between the different extraction conditions and source, although no clear correlation between extraction conditions and yield could be observed. For instance, lignin from birch pretreated in 60%v/v ethanol for 15 min resulted in a hydrochar yield of 39 wt%. Increasing the time to 30 and 60 resulted in a hydrochar yield of 27 wt% and 23 wt%, respectively. This suggested that small changes in the organosolv reaction conditions might produce highly structurally different lignin, resulting in the difference in HTC yield. Thus, we chose a subset of four lignin samples to investigate in-depth, subjecting these samples to a range of hydrothermal reaction temperatures and residence times. Solid State NMR and FTIR analysis indicated that the most significant structural changes occurred below 230 ℃ resulting in the breaking of C-O- linkages. Increasing the temperature or time had minimal impact, with no further C-O- linkages broken and no changes to the ring structure of C-C groups. Size exclusion chromatography indicated that the degree of micro and macromolecules in the liquid product varied significantly with lignin source and HTC reaction conditions. Overall, this study demonstrated that lignin has a large reaction range where it produces a very chemically similar solid product, with the only major difference being the yield of material. This is important for industry, as it indicates that a similar solid product can be easily achieved independently of extraction conditions allowing the HTC reaction to be tuned towards extracting the maximum benefit from products contained in the liquid.

Influence of thermochemical activation of wood on the physicochemical properties of lignin

The wood matrix is a lignin–carbohydrate nanobiocomposite, thermodynamically quasi-equilibrium heterogeneous system of biopolymers. Changing its thermodynamic equilibrium due to directed chemical and (or) physical impacts opens up new approaches to the study of plant objects. Thermochemical activation, including treatments in sub- (steam explosion) and supercritical conditions (supercritical fluid extraction) having similar mechanisms of action, is one such method. The effect of steam explosion is determined by two components — chemical (the catalytic effect of formed acetic and formic acid) and physical (a sharp adiabatic expansion). The main components of supercritical treatment are increased temperature and pressure in the CO2 medium with cosolvents. The chemical component of this treatment is due to the addition of chemical reagents. Such treatments lead to a change in the thermodynamic state and capillary-porous structure of the lignin–carbohydrate matrix, an increase in its heterogeneity, and the yield of extracted lignin preparations. Lignin is the most reactive component of the wood matrix, and these processes result in changes in its functional nature and reaction properties. Thus, the lignin sample extracted after steam explosion had the greatest increase in the content of phenolic hydroxyl (by 39 rel.%) and carboxyl (by 57 rel.%) groups. Change in the functional composition of lignin leads to a change in its redox state, characterized by the oxidative potential and free energy of oxidation. It was shown that lignin after steam explosion had the highest oxidative potential and the lowest value of the oxidation energy, which indicated the greatest change in its reactivity in redox interactions.

Cooperative catalytic effects between aqueous acidic ionic liquid solutions and polyoxometalate-ionic liquid in the oxidative depolymerization of alkali lignin

The oxidative depolymerization of alkali lignin can be achieved by using Keggin structure polyoxometalate-ionic liquid (POM-IL) as catalyst under aerobic conditions. The effects of catalysts such as [HC4im]3PMo12O40, [HC4im]5PV2Mo10O40, [HC2im]5PV2Mo10O40, and [HC4im]4SiMo12O40 (abbreviated as POM-IL1, POM-IL2, POM-IL3, and POM-IL4, respectively), the acidity of aqueous IL solutions on lignin conversion, and aromatic product distribution were investigated. Under optimized conditions, phenolic products (mainly m (p)-cresol, veratrole, vanillin) had the highest yield and the selectivity was as high as 75.0% using POM-IL1 as the catalyst. POM-IL2 and POM-IL3 were used as the catalysts, the highest conversion of 76.0% of lignin was achieved, and the overall yield of ketone products were higher on lignin samples, in which the main products include acetovanillone, 3-methoxyphenol, and 4-methylcatechol, and the highest selectivity of ketone products was 76.8%. The results show that the lignin fragments could be successfully oxidized into platform compounds in aqueous acidic ILs (AILs) solutions catalyzed by Keggin structure POM-IL. In addition, the role of AILs and POM-ILs in the oxidative depolymerization of alkaline lignin was analyzed, and the possible reaction mechanism between AIL-water/POM-IL/lignin system was speculated.

The Consistency of Yields and Chemical Composition of HTL Bio-Oils from Lignins Produced by Different Preprocessing Technologies

This work evaluates the effect of feedstock type and composition on the conversion of lignin to liquid by solvolysis with formic acid as hydrogen donor (LtL), by analyzing the yields and molecular composition of the liquid products and interpreting them in terms of both the type and the preprocessing of the lignocellulosic biomass using chemometric data analysis. Lignin samples of different types and purities from softwood, hardwood, and grasses (rice straw and corn stover) have been converted to bio-oil, and the molecular composition analyzed and quantified using GC-MS. LtL solvolysis was found to be a robust method for lignin conversion in terms of converting all samples into bio-oils rich in phenolic compounds regardless of the purity of the lignin sample. The bio-oil yields ranged from 24–94 wt.% relative to lignin input and could be modelled well as a function of the elemental composition of the feedstock. On a molecular basis, the softwood-derived bio-oil contained the most guaiacol-derivatives, and syringol was correlated to hardwood. However, the connection between compounds in the bio-oil and lignin origin was less pronounced than the effects of the methods for biomass fractionation, showing that the pretreatment of the biomass dominates both the yield and molecular composition of the bio-oil and must be addressed as a primary concern when utilization of lignin in a biorefinery is planned.

Different Kraft lignin sources for electrospun nanostructures production: Influence of chemical structure and composition

This work focuses on the structural features and physicochemical properties of different Kraft lignins and how they can influence the electrospinning process to obtain nanostructures. Structural features of Kraft lignins were characterized by nuclear magnetic resonance, size exclusion chromatography, fourier-transform infrared spectroscopy, and thermal analysis, whereas chemical composition was analyzed by standard method. The addition of cellulose acetate (CA) improves the electrospinning process of Kraft lignins (KL). Thus, solutions of KL/CA at 30 wt% with a KL:CA weight ratio of 70:30 were prepared and then physicochemical and rheologically characterized. The morphology of electrospun nanostructures depends on the intrinsic properties of the solutions and the chemical structure and composition of Kraft lignins. Then, surface tension, electrical conductivity and viscosity of eucalypt/CA and poplar/CA solutions were suitable to obtain electrospun nanostructures based on uniform cross-linked nanofibers with a few beaded fibers. It could be related with the higher purity and higher linear structure, phenolic content and S/G ratios of lignin samples. However, the higher values of electrical conductivity and viscosity of OTP/CA solutions resulted in electrospun nanostructure with micro-sized particles connected by thin fibers, due to a lower purity, S/G ratio and phenolic content and higher branched structure in OTP lignin.

Kraft lignin-derived carbon sheets produced by molten salt-assisted thermal treatment – Graphitization behavior of the sheet structures

The synthesis of high-value carbon materials from lignin-based feedstocks to variable applications has been under intensive research. Production of well ordered crystalline carbon as 2H-graphite has been challenging due to the generally poor graphitizability of lignins. Herein, we produced kraft-lignin-derived carbon materials and studied their graphitization behavior. We show that the use of a LiCl-KCl molten salt mixture promoted the formation of sheet-like carbon structures. Furthermore, these structures indicated improved crystallinity after annealing at 700 °C. This was not observed in the case of kraft-lignin annealed without the presence of a salt mixture. These structures were further thermally post-treated at 1900 °C and 2400 °C in an argon atmosphere by induction annealing to study their graphitization tendency. The high-temperature treatment further emphasized the crystalline structure difference between the LiCl-KCl salt-treated and non-LiCl-KCl-treated kraft lignin samples.

Green materials from added-lignin thermoformed pulps

In this article, added-lignin thermoformed pulps (ALTP) were explored as a new alternative for green materials. Technical lignin was added to mechanical pulp and subsequently thermoformed, yielding a biobased material with lignin contents above natural levels. This material was tested for its mechanical properties, water-uptake, and density. In addition, FTIR and TGA-DSC were used to characterize the lignin samples, i.e., Soda, Kraft, and hydrolysis lignin, as well as lignosulfonates. The material properties were significantly changed at 20 – 40 wt% added-lignin per dry fiber. Lignin addition increased density and reduced water-uptake and wettability. The effect on mechanical properties could vary, however, pure lignin had a more beneficial effect than hydrolysis lignin containing residual cellulose. Higher stiffness was observed for the pure lignin samples at constant or decreasing tensile strength. In conclusion, ALTP is a promising material for developing new pulp products and plastics-replacements, where the ratio and type of added-lignin may be used to fine-tune the desired characteristics.

Mild, Electroreductive Lignin Cleavage: Optimizing the Depolymerization of Authentic Lignins

Among candidate strategies to depolymerize lignin, electroreduction has promise as a mild, environmentally friendly, low-cost method to cleave lignin’s most common linkage, the β-O-4 bond. Much of the prior work on lignin electrolysis has focused on anodic (oxidative) approaches, while most available electroreduction studies have studied lignin model compounds rather than authentic lignin. Here, after optimizing with a model system, we investigated the room-temperature electroreductive cleavage of four common lignin samples from different pretreatment approaches, including Kraft, Soda, GVL, and Cu-AHP lignin. This mild electrolysis process resulted in the solubilization of 45% of the GVL lignin and 60% of the Cu-AHP lignin, affording approximately 17.6 and 19.4 wt % of monomeric materials, respectively. The present work is an encouraging first step toward an electroreductive strategy for lignin depolymerization and upgrading.

Characterization of lignin from sugarcane bagasse by Raman spectroscopy and FTIR

Background: The structural information of the lignin samples obtained using various extraction methods have been investigated by FTIR and Raman spectroscopy .In the present work, information regarding the changes in lignin caused by different extraction processes has been reported. The present manuscript appraised various prominent and seclusion methods currently being surveyed in favour of sugarcane bagasse lignin extraction (Saccharum officinarum). Methods: The methods used were acid hydrolysis, alkaline pulping, extraction by dioxane and HCL, alkaline KOH. Significant findings: The Raman spectra of lignin calliberated at 532 nm resulted the decrease in the intensity band at 1200 cm-1.

Structural characteristics of eucalyptus lignin regulated through alkali cooking process

Understanding the basic chemical structure of lignin macromolecules can facilitate the development of lignin-based materials. In this study, the lignin structure was regulated through different alkali cooking conditions. The acid precipitated lignin from the spent cooking liquor was purified and fractionated with different organic solvents. The lignin samples with different structures were obtained by regulating the cooking time. The structural characteristics of the lignin preparations were systematically investigated. The results revealed that the structure of lignin was regulated by the heating time and the residence time during the cooking process. Non-condensed lignin was achieved after a specific cooking condition; it had higher molecular weight (9686 g/mol), more β-O-4 linkages (25.3/100Ar), but lower phenolic hydroxyl content (1.51 mmol/g) than the counterpart pulping with longer time duration. The non-condensed lignin also had excellent thermal stability. Compared with industrial lignin, the lignin with non-condensed structure can be modified to obtain phenolic resin materials with better performance. The non-condensed structure with the specific characteristics can broaden the valorization of lignin for producing biochemical and biomaterials.

Combination of green solvents for efficient sugarcane bagasse fractionation

This work addresses an unprecedented combination of solvents (choline chloride and oxalic acid deep eutectic solvent, carbon dioxide, and ethanol) that were used to fractionate sugarcane bagasse into three main fractions: 1) glucan rich fibers, 2) dissolved hemicellulose sugars and co-products, and 3) precipitated lignin. To maximize the lignin removal, a two-level three-variable design of experiments assessed the effects of solids loading, DES to biomass mass ratio, and the amount of CO2. Following, kinetic were carried out in temperatures varying from 130 to 190 °C, using anhydrous and hydrated ethanol to improve hemicellulose hydrolysis and delignification. At the best condition, delignification extent as high as 90% were obtained after reaction times of 30 min. These results were accompanied by glucan contents of approximately 85 wt% and by over 80% of fibers' glucan maintenance. Also, over 60% of the hemicellulose sugars were dissolved in a liquid fraction. Finally, the third fraction was composed of the precipitated lignin with negligible carbohydrate contents. Lignin samples presented low apparent average molecular masses, and FT-IR spectra demonstrated the presence of bands typical of lignin samples from herbaceous crops. In general, this work attested to the technical feasibility of using green solvents for the efficient fractionation of sugarcane bagasse into streams that could be exploited to produce fuels, chemicals, and biomaterials.

Oxidation of partially decomposed wood: Experimental investigation and kinetic analysis

The purpose of this article is to study experimentally the oxidation process of wood of different degrees of thermal conversion. We compared experimental data of thermogravimetric analysis in the oxidizing environment of raw wood, cellulose, lignin, and wood samples of different degrees of thermal conversion. Thermally treated wood samples were obtained by heating raw pine wood in an inert atmosphere to a given temperature (250, 300, 350, 400, 500 °C), followed by rapid quenching in water. All obtained samples were studied by the thermal analysis combined with mass spectrometry (TGA-MS) in inert and oxidizing environments; technical (moisture content, ash content, volatile yield, or W, A, V) and elemental analysis (C, H, O) data were obtained. We propose a new method for kinetic analysis of biomass decomposition: the change in the leading decomposition mechanisms is monitored by the change in the composition of the detected products. Differences between the thermochemical behavior of biomass, its individual components (cellulose and lignin), and their thermal degradation products are discussed.