Component Of Lignocellulosic Biomass Research Articles

Lignin Degradation by Klebsiella aerogenes TL3 under Anaerobic Conditions.

Lignin, the largest non-carbohydrate component of lignocellulosic biomass, is also a recalcitrant component of the plant cell wall. While the aerobic degradation mechanism of lignin has been well-documented, the anaerobic degradation mechanism is still largely elusive. In this work, a versatile facultative anaerobic lignin-degrading bacterium, Klebsiella aerogenes TL3, was isolated from a termite gut, and was found to metabolize a variety of carbon sources and produce a single kind or multiple kinds of acids. The percent degradation of alkali lignin reached 14.8% under anaerobic conditions, and could reach 17.4% in the presence of glucose within 72 h. Based on the results of infrared spectroscopy and 2D nuclear magnetic resonance analysis, it can be inferred that the anaerobic degradation of lignin may undergo the cleavage of the C-O bond (β-O-4), as well as the C-C bond (β-5 and β-β), and involve the oxidation of the side chain, demethylation, and the destruction of the aromatic ring skeleton. Although the anaerobic degradation of lignin by TL3 was slightly weaker than that under aerobic conditions, it could be further enhanced by adding glucose as an electron donor. These results may shed new light on the mechanisms of anaerobic lignin degradation.

Perspective on Lignin Conversion Strategies That Enable Next Generation Biorefineries.

The valorization of lignin, a currently underutilized component of lignocellulosic biomass, has attracted attention to promote a stable and circular bioeconomy. Successful approaches including thermochemical, biological, and catalytic lignin depolymerization have been demonstrated, enabling opportunities for lignino-refineries and lignocellulosic biorefineries. Although significant progress in lignin valorization has been made, this review describes unexplored opportunities in chemical and biological routes for lignin depolymerization and thereby contributes to economically and environmentally sustainable lignin-utilizing biorefineries. This review also highlights the integration of chemical and biological lignin depolymerization and identifies research gaps while also recommending future directions for scaling processes to establish a lignino-chemical industry.

Process simulation of flax straw pyrolysis with kinetic reaction Model: Experimental validation and exergy analysis

Pyrolysis, a viable method for converting organic material into value-added products, has significant potential to reduce environmental footprints. In this study, slow and fast pyrolysis of flax straw biomass was modeled in an Aspen Plus. This was followed by validation of the product yields (biochar, bio-oil, and gas) with our earlier experimental data with slow pyrolysis. The Aspen Plus model incorporated a kinetic reaction model based on the three main components of lignocellulosic biomass: cellulose, hemicellulose, and lignin. The kinetic reaction model includes 21 reactions representing the volatilization, degradation, and decomposition processes inherent in biomass pyrolysis. The Aspen Plus confirmed the consistency of the findings by validating the biogas yield (which ranged from 21.4 wt% to 38.6 wt%), biochar (29.5 wt% to 42.8 wt%), and bio-oil (35.8 wt% to 40.3 wt%). The robustness of the model was verified by experimental data using controlled pyrolysis tests of flax straw feedstock at different temperatures, showing strong agreement. The kinetic reaction model is adaptable for predicting pyrolysis yields for various lignocellulosic biomass feedstocks under typical pyrolysis conditions. Furthermore, energy and exergy analyses were briefly assessed using the product yields, pyrolysis temperature, and heating values of the products at slow and fast pyrolysis conditions. The conventional exergy analysis showed an exergy efficiency of 87–95 % with varying temperatures from 400 to 600 °C for slow pyrolysis, with the highest efficiency obtained at 500 °C. Fast pyrolysis has resulted in a higher exergy efficiency than slow pyrolysis, ranging from 89 % to 98 %.

Enhancement of cellulolytic enzyme production from intrageneric protoplast fusion of Aspergillus species and evaluating the hydrolysate scavenging activity

BackgroundLignocellulosic biomass provides a great starting point for the production of energy, chemicals, and fuels. The major component of lignocellulosic biomass is cellulose, the employment of highly effective enzymatic cocktails, which can be produced by a variety of microorganisms including species of the genus Aspergillus, is necessary for its utilization in a more productive manner. In this regard, molecular biology techniques should be utilized to promote the economics of enzyme production, whereas strategies like protoplast fusion could be employed to improve the efficacy of the hydrolytic process.ResultsThe current study focuses on cellulase production in Aspergillus species using intrageneric protoplast fusion, statistical optimization of growth parameters, and determination of antioxidant activity of fermentation hydrolysate. Protoplast fusion was conducted between A. flavus X A. terreus (PFFT), A. nidulans X A. tamarii (PFNT) and A. oryzae X A. tubingensis (PFOT), and the resultant fusant PFNT revealed higher activity level compared with the other fusants. Thus, this study aimed to optimize lignocellulosic wastes-based medium for cellulase production by Aspergillus spp. fusant (PFNT) and studying the antioxidant effect of fermentation hydrolysate. The experimental strategy Plackett-Burman (PBD) was used to assess how culture conditions affected cellulase output, the best level of the three major variables namely, SCB, pH, and incubation temperature were then determined using Box-Behnken design (BBD). Consequently, by utilizing an optimized medium instead of a basal medium, cellulase activity increased from 3.11 U/ml to 7.689 U/ml CMCase. The following medium composition was thought to be ideal based on this optimization: sugarcane bagasse (SCB), 6.82 gm; wheat bran (WB), 4; Moisture, 80%; pH, 4; inoculum size, (3 × 106 spores/ml); and incubation Temp. 31.8 °C for 4 days and the fermentation hydrolysate has 28.13% scavenging activities.ConclusionThe results obtained in this study demonstrated the significant activity of the selected fusant and the higher sugar yield from cellulose hydrolysis over its parental strains, suggesting the possibility of enhancing cellulase activity by protoplast fusion using an experimental strategy and the fermentation hydrolysate showed antioxidant activity.

Cellulolytic and Ethanologenic Evaluation of Heterotermes indicola's Gut-Associated Bacterial Isolates.

Cellulose is the basic component of lignocellulosic biomass (LCB) making it a suitable substrate for bioethanol fermentation. Cellulolytic and ethanologenic bacteria possess cellulases that convert cellulose to glucose, which in turn yields ethanol subsequently. Heterotermes indicola is a subterranean termite that causes destructive damage by consuming wooden structures of infrastructure, LCB products, etc. Prospectively, the study envisioned the screening of cellulolytic and ethanologenic bacteria from the termite gut. Twenty six bacterial strains (H1-H26) based on varied colonial morphologies were isolated. Bacterial cellulolytic activity was tested biochemically. Marked gas production in the form of bubbles (0.1-4 cm) in Durham tubes was observed in H3, H7, H13, H15, H17, H21, and H22. Sugar degradation of all isolates was indicated by pink to maroon color development with the tetrazolium salt. Hallow zones (0.42-11 mm) by Congo red staining was exhibited by all strains except H2, H7, H8, and H19. Among the 26 bacterial isolates, 12 strains were identified as efficient cellulolytic bacteria. CMCase activity and ethanol titer of all isolates varied from 1.30 ± 0.03 (H13) to 1.83 ± 0.01 (H21) umol/mL/min and 2.36 ± 0.01 (H25) to 7.00 ± 0.01 (H21) g/L, respectively. Likewise, isolate H21 exhibited an ethanol yield of 0.40 ± 0.10 g/g with 78.38 ± 2.05% fermentation efficiency. Molecular characterization of four strains, Staphylococcus sp. H13, Acinetobacter baumanni H17, Acinetobacter sp. H21, and Acinetobacter nosocomialis H22, were based on the maximum cellulolytic index and the ethanol yield. H. indicola harbor promising and novel bacteria with a natural cellulolytic tendency for efficient bioconversion of LCB to value-added products. Hence, the selected cellulolytic bacteria can become an excellent addition for use in enzyme purification, composting, and production of biofuel at large.

Effect of lignocellulosic biomass components on the extracellular electron transfer of biochar-based microbe-electrode in microbial electrochemical systems

Biomass-derived carbon-based electrodes with good biocompatibility, sustainability, and low cost are competitive in microbial electrochemical systems. Unfortunately, biomass composition is complex, and biochar performance is dependent on the kind of biomass, making quantitative function control difficult. Three-dimensional (3D) lignocellulosic carbon-based electrodes were generated in this study by varying the ratios of three natural biopolymers (cellulose, lignin, and hemicellulose). The biopolymer contents significantly impacted the material's physicochemical and electrochemical properties. Only the proper ratio of these natural polymers can ensure the 3D structure's integrity and mechanical strength after carbonization. The greater the cellulose content and the lower the hemicellulose (xylan) content, the lower the ohmic and charge transfer resistance. The maximum power density (Pmax) of the microbial fuel cells equipped with the biopolymer-based anode ranged between 4.5 and 4.8 W m−2, setting a new record for biocarbon electrodes. The highest Pmax was observed when the cellulose, lignin, and xylan ratios were 1:3:2 (4.80 ± 0.04 W m−2). The Pmax correlates with cellulose content more than lignin and xylan and with material capacitance more than with other parameters. High cellulose content facilitates electron transfer but reduces the capacitance of carbon-based electrodes. The material's electron transfer resistance and capacitance contribute to the opposite of the Pmax. So, the interaction with multiple properties influences the electrode performance. This research revealed the effects of natural biopolymer compositions on electrode performance, which was helpful for quantitatively modifying functional carbon-based materials.

Ab Initio and Kinetic Modeling of β-d-Xylopyranose under Fast Pyrolysis Conditions.

Lignocellulosic biomass is an abundant renewable resource that can be upgraded to chemical and fuel products through a range of thermal conversion processes. Fast pyrolysis is a promising technology that uses high temperatures and fast heating rates to convert lignocellulose into bio-oils in high yields in the absence of oxygen. Hemicellulose is one of the three major components of lignocellulosic biomass and is a highly branched heteropolymer structure made of pentose, hexose sugars, and sugar acids. In this study, β-d-xylopyranose is proposed as a model structural motif for the essential chemical structure of hemicellulose. The gas-phase pyrolytic reactivity of β-d-xylopyranose is thoroughly investigated using computational strategies rooted in quantum chemistry. In particular, its thermal degradation potential energy surfaces are computed employing Minnesota global hybrid functional M06-2X in conjunction with the 6-311++G(d,p) Pople basis set. Electronic energies are further refined by performing DLPNO-CCSD(T)-F12 single-point calculations on top of M06-2X geometries using the cc-pVTZ-F12 basis set. Conformational analysis for minima and transition states is performed with state-of-the-art semiempirical quantum chemical methods coupled with metadynamics simulations. Key thermodynamic quantities (free energies, barrier heights, enthalpies of formation, and heat capacities) are computed. Rate coefficients for the initial steps of thermal decomposition are computed by means of reaction rate theory. For the first time, a detailed elementary reaction kinetic model for β-d-xylopyranose is developed by utilizing the thermodynamic and kinetic information acquired from the aforementioned calculations. This model specifically targets the initial stages of β-d-xylopyranose pyrolysis in the high-pressure limit, aiming to gain a deeper understanding of its reaction kinetics. This approach establishes a systematic strategy for exploring reactive pathways, evaluating competing parallel reactions, and selectively accepting or discarding pathways based on the analysis. The findings suggest that acyclic d-xylose plays a significant role as an intermediary in the production of key pyrolytic compounds during the pyrolysis of xylose. These compounds include furfural, anhydro-d-xylopyranose, glycolaldehyde, and dihydrofuran-3(2H)-one.

Hydrophobicity and mechanical properties of purified lignin nanoparticles reinforced marine‐derived biopolymer composites

AbstractLignin has been considered the main aromatic renewable biopolymer. Besides its availability in large quantities as a major and low‐cost side product of several industries as a polysaccharide component of lignocellulosic biomass for industrial applications, it remains underutilized and as such, lignin valorization is highly desirable. This study was focused on the fabrication, purification, and characterization of lignin nanoparticles (LNPs) from black liquor of oil palm (Elaeis guineensis) empty fruit bunch (EFB). The functional properties of the LNPs investigated include the morphology, particle size, zeta potential distribution, elemental composition, functional groups, and gas chromatography–mass spectrometry (GC–MS). The purified LNPs provided smaller particle sizes ranging from 32 to 62 nm while the unpurified sample sizes range between 53 and 88 nm. The zeta potential value of purified LNPs displays relatively good stability to the unpurified LNPs despite the consistency in their particle size spreading as observed from the TEM micrograph. The results of the GC–MS analysis signify that the purification procedure affects the compounds in the LNPs. The kappa‐carrageenan (KC) biopolymers reinforced with purified LNPs provided more organized surfaces than the biopolymers reinforced with unpurified LNPs, leading to enhanced hydrophobicity and mechanical properties of the bionanocomposites. This study shows the potential applications of valorized lignin from oil palm residue as a reinforcement agent in renewable packaging.Highlights Lignin nanoparticles (LNPs) were yielded from empty fruit bunch black liquor. Syringyl to guaiacyl ratio of LNPs was increased from 0.83 to 1.26. Biopolymers were prepared by incorporating LNPs into the kappa‐carrageenan. Biopolymer with 4% purified LNPs had an optimum contact angle of 106.83°. The optimized biopolymer showed an optimum tensile strength of 38.42 MPa.

Interaction among lignocellulosic biomass components in thermochemical processes

This research aims to evaluate the thermal behavior of main components of biomass (hemicellulose, cellulose and lignin) in order to identify their synergistic effect in thermochemical processes. These components were isolated from sugarcane bagasse and straw using different chemical treatments and their chemical and physical-chemical characterizations were performed. Results showed that chemical treatments were adequate for cellulose and lignin isolation, although it was verified that more adequate methodologies must be sought for hemicellulose isolation. The thermogravimetric analysis of each sample and their mixtures in inert (N2) and oxidant (synthetic air) atmospheres allowed investigating the synergism among the components. It was observed that the synergistic effect was more pronounced in DTG curves in an oxidizing atmosphere. There was a weak interaction effect between cellulose and hemicellulose, but hemicellulose allowed reducing cellulose decomposition rate. Moreover, the mixture between hemicellulose and lignin showed a synergistic effect on lignin, which promoted an increase in hemicellulose decomposition rate, while hemicellulose anticipated the main event of lignin decomposition in an oxidizing atmosphere. It was found that lignin had a positive effect on cellulose decomposition in an oxidizing atmosphere, thus inhibiting its decomposition, while cellulose promoted an increase in lignin decomposition rate in its final event. Ultimately, results for the synergistic effect allowed detecting other components besides isolated elements in the biomass structure in smaller amounts, which nevertheless affect the behavior of its thermal decomposition.

Ultrasound-Assisted Cold Alkaline Extraction: Increasing Hemicellulose Extraction and Energy Production from Populus Wood

Alkaline pretreatments are considered highly effective for the separation of the different components of lignocellulosic biomass. However, cold alkaline extraction (CAE) exhibits minimal modification/degradation of hemicellulosic fraction and successfully accomplishes efficient delignification. In this research, the fast-growing clone AF2 of Populus x euramericana wood was utilized as the raw material and subjected to ultrasound-assisted CAE. The objective of incorporating ultrasound into cold alkaline extraction is to increase the yield of a hemicellulosic-rich liquid phase that can be used to produce high-value products such as furfural or xylitol. Simultaneously, it aims to obtain a solid phase with a higher calorific value compared to the raw material. The results, obtained from a central composite factorial design, demonstrated that the CAE process for 90 min at a sodium hydroxide concentration of 100 g L−1, a temperature of 30 °C, and with ultrasound assistance maximized hemicellulose extraction in the liquid phase (60.8% was extracted) and improved the heating value of solid phase.

Composition and Antimicrobial Activity of Different Plant Parts of <em>Parthenium hysterophorus</em> L.

This study was aimed to determine the lignocellulosic biomass in different parts of Parthenium hysterophorus and evaluate its antimicrobial activity against selected microbial plant pathogens. Compositional analyses were conducted on live whole plants and their leaves, stems, flowers, and roots. The lignocellulosic biomass components were estimated gravimetrically as a percentage of dry weight, using the standard equation, while reducing sugar was quantified using a glucose standard curve. Significant differences (p < 0.05) in cellulose content were observed among different plant parts, with the highest dry weight percentage in the whole mature plant (48±0.33), followed by the stem (45±0.21), whole young plant (41±0.10), root (21±0.00), leaf (28±0.01), and inflorescence (21±0.14). Additionally, reducing sugar content in mg/mL was significantly higher in the stem (1.94±0.01) and root (1.17±0.00), followed by the mature whole plant (0.95±0.20), leaf-stem mixture (0.93±0.11), inflorescence (0.67±0.02), young whole plant (0.23±0.19), and leaf (0.17±0.01). The stem and root extracts from mature plants inhibited soil-borne plant pathogenic bacteria Pseudomonas sp. and Ralstonia sp. respectively. The leaf and inflorescence extracts of P. hysterophorus showed inhibitory effects only against Pseudomonas sp., not Ralstonia sp. Furthermore, the mature Parthenium plant extract inhibited all tested soil-borne fungi, with significantly higher inhibition percentages observed for Scelerotium sp. (81.93%) and Colletotrichum sp. (45.45%) compared to Fusarium sp. and Pythium sp. Significantly higher cellulose and lignin contents in the whole mature P. hysterophorus plant, along with its antimicrobial activity against major soil-borne plant pathogenic microbes was prominent than the individual plant parts and the young immature plant.

NAD-Regenerating Biocathode Applied to Electroenzymatic Conversion of Lignin

Non-renewable and limited fossil resources (i.e. petroleum, coal, and natural gas) have been used over the last years for the production of energy, commodity chemicals, and polymer materials. Nonetheless, the extraction and consumption of these resources leads to deleterious and irreversible environmental impacts. As a sustainable alternative, lignin, one of the major components of lignocellulosic biomass, represents the most promising renewable raw material to produce aromatic-based chemicals and high value-added products. However, the use of lignin as a source of valuable molecules similar to the petroleum-derived chemicals is hindered due to its recalcitrance and structural heterogeneity. Biological approaches have been studied to develop selective and ecofriendly pathways for lignin valorization. It has been reported that some microorganisms can cleave selectively β-ether bonds representing more than a half of lignin bonding pattern.[1] The etherolytic pathway of the soil probacterium Sphingobium paucimobilis, which involves NAD-dependent dehydrogenases and β-etherases, has been well characterized for this purpose.[2] Here we focus on the design of a bioanode combining NAD-regenerating properties and the immobilization of lignin degrading enzymatic cascade to cleave such bonds. We explored the possibility of combing in situ electrochemical regeneration of NAD+ cofactor with a surface immobilized biocatalysts on a single interface. First, we have demonstrated that the electrodes based on multiwalled carbon nanotubes modified with toluidine blue are capable to regenerate NAD+ cofactor at low potential from its reduced form. This process is essential for dehydrogenases activities. Secondly, we used cross-linked hydrogel of pyrene-modified linear poly(ethyleneimine) to entrap the enzymes on the electrode surface.[3] The obtained bioanode modified with NAD-regenerating catalyst and the multi-enzymatic cascade of Lig enzymes was tested in the presence of guaiacylglycerol-β-guaiacylether (GGE), a lignin dimer substrate with β-ether bond, to produce γ-hydroxypropiovanillone (HPV). We believe that such electrochemical systems employing the enzymatic cascade acting like a metabolic funnel with the simultaneous regeneration of the cofactor would permit to refine the heterogeneous mixture of aromatics from lignin depolymerization products into a uniform distribution of value-added compounds.[1] Renewable Sustainable Energy Rev., 2022, 157, 112025.[2] Catal. Sci. Technol., 2016,6, 2195-2205.[3] Chem. Sci., 2018,9, 5172-5177. Figure 1

Modeling pyrolysis kinetics of extracted biomass components with the bio-chemical percolation devolatilization model

Within the pyrolysis modeling of biomass, the solid is typically interpreted as a mixture of cellulose, hemicellulose, and lignin, where the components react independently before the products are linearly superimposed. This assumption applies to the bio-chemical percolation devolatilization model (Bio-CPD), which, as a network model, represents the physicochemical processes very realistically. A literature review regarding available structural and kinetic parameters for the Bio-CPD model revealed four hits. To investigate and evaluate the model predictivity, experiments from extracted lignocellulosic biomass components pyrolyzed separately in a fluidized bed reactor are used as reference data. Using single-component data simplifies the reaction chemistry by minimizing interactions between the components and best approximates the model assumptions. The comparison between experimentally obtained total volatile release rates and model predictions revealed the parameter set from Vizzini et al. (2008) for cellulose and the one from Sheng and Azevedo (2002) for hemicellulose as best-suitable candidates to predict the pyrolysis behavior for the boundary conditions of the fluidized bed reactor. For lignin, instead, the Genetti correlation (Genetti, Fletcher, and Pugmire, 1999) to estimate structural parameters based on the ultimate and proximate analysis led to better results than all other sets. Further, the analysis of light gas and tar fractions showed a high relevance to model secondary tar cracking reactions in the fluidized bed reactor system.

Kinetic modelling of the hydrothermal carbonisation of the macromolecular components in lignocellulosic biomass

Hydrothermal carbonisation (HTC) can play a significant role in the valorisation of lignocellulosic biomass to increase the share of renewable sources in the energy system. However, due to the complexity and the variety of biomass, literature lacks HTC kinetic models with predictive capabilities for specific classes of biomass.This study developed and tested three comprehensive kinetic models for the hydrothermal carbonisation of the macromolecular components in lignocellulosic biomass: cellulose, hemicellulose and lignin. The kinetic models were developed to accurately predict the carbon concentrations in the hydrochar, gas and liquid residuals. The estimated kinetic parameters were presented for each reaction and compared to those reported in the literature. The model validations were carried out by processing a total of 106 experimental data points in a wide range of operating conditions. The kinetic models were able to accurately predict the carbon content in all the HTC product phases.

Production of phenolic compounds from argan shell waste by reductive catalytic fractionation

AbstractFor efficient utilization of lignocellulosic biomass components, reductive catalytic fractionation appears as a promising biorefinery strategy. In this work, this concept of biomass valorization was used to study the potential of an unexplored feedstock, argan shells. This material was processed in a non-catalytic route and over a Pd/C catalyst in two different reaction media. The effects of the treatment temperature (250, 275, and 300 °C), as well as the catalyst loading (catalyst/argan shells mass ratio of 0.05 and 0.1 g/g), were also studied. The main product (lignin-derived oil) was thoroughly characterized using GC/MS/FID, SEC, and NMR. The highest monomer yields of 48–49 wt% based on the lignin content were obtained for n-butanol/water reaction medium at 300 °C using a Pd/C catalyst load of 0.1 g/g and for methanol reaction medium at 275 °C and 0.05 g/g. Significantly lower monomeric phenol yields were obtained in the non-catalytic route (4–19 wt% for n-butanol/water and 9–16 wt% for methanol). The main phenolic monomers in the catalytic pathway were 4-n-propanolguaiacol, 4-n-propanolsyringol, and 4-alkyl guaiacols and syringols, with some differences in the selectivities from one solvent to another. Graphical Abstract

Functional Lignin‐based Polymers: Isolation, Synthetic Methods and High‐valued Applications

AbstractAs a major component of lignocellulosic biomass, lignin has lots of fascinating properties, such as regeneration, biocompatibility, antioxidant, hydrophilicity, unique aromatic structure, and various functional groups, which make them become interesting natural polymer raw material, and attracted more and more attention. In particular, the rich functional groups of lignin can be easily functionalized through various synthesis methods, which can endow lignin‐based polymers with new structure and function. These functional lignin‐based polymers are widely used in environmental remediation, smart hydrogel materials, catalysis, biomedical, etc. However, its various sources and types, the complex structure, relatively weak chemical reactivity, the unstable processing property, and few high value‐added products limited their practical applications. With the development of lignin varieties, modified reagent, synthesis methods, and polymerization process, many works had been published for the synthesis and application of lignin‐based polymers. In this review, the lignin isolation, modification strategies, polymerization method and process, and the promising applications were summarized and analyzed in recent years. Specially, the recent advances in the preparation of high excellent adsorbents from deconstructed lignin products are highlighted from the synthesis methods and adsorption mechanism perspective. Finally, we discussed these challenges in the green and controllable synthesis of lignin‐based polymers, and prospected their functional applications.

Two-step valorization of invasive species Rosa rubiginosa L. husk waste through eco-friendly optimized pectin extraction and subsequent pyrolysis

This research studied chemical and thermal treatments of rosehip husk (RH), from invasive species in Patagonia Rosa rubiginosa, which is considered a main waste in the seed-oil extraction industry, to obtain added-value products by optimizing an eco-friendly pectin extraction, followed by pyrolysis of the remaining solid (RHW). The aim was to valorize the rosehip husk of an invasive species by finding the optimal conditions for pectin extraction (maximum yield and minimum CO2 emissions) and assessing the pyrolysis process together with the products obtained, finding the temperature of maximum production of each species in the gaseous product. By applying multi-objective optimization, it was found that the optimal yield was 17.83 % with 456.7 g of CO2 emitted for kg of pectin at temperature T = 79.6 ºC, time t = 30 min, and pH = 2.3. By TGA, 6 processes were identified in the pyrolysis of RHW: moisture evaporation and 5 consecutive reactions which were related to lignocellulosic biomass components decomposition. The kinetic parameters of each reaction were obtained by isoconversional method (activation energy), compensation effect method (pre-exponential factor), and master-plots method (conversion function). The pyrolysis gaseous products of energetic interest identified were CH4, H2, and C2H4, with maximum production at 630, 700, 850 ºC respectively. The main compounds found by GC-MS were diacetone alcohol, mesityl oxide, butylated hydroxytoluene, among others. The ash was analyzed by XRD and showed a high Ca concentration (46.9 %) with presence of Ca(OH)2, MgO, KCaPO4, and K4Ca(PO4)2.

Development of a global kinetic model based on chemical compositions of lignocellulosic biomass for predicting product yields from hydrothermal liquefaction

This study aimed to develop a global kinetic model to predict product yields from hydrothermal liquefaction (HTL) of lignocellulosic biomass based on its chemical compositions (contents of cellulose, hemicellulose, and lignin). HTL experiments were carried out with biomass model compounds (cellulose, xylan, and lignin) and lignocellulosic biomass (bamboo, cornstalk, and pinewood) at various temperatures (225–300 °C) and reaction times (10–60 min) with K2CO3 catalyst. Out of the three major components of lignocellulosic biomass, lignin was found to be the main contributor to bio-oil formation. A universal reaction network was proposed, and a kinetic model was developed based on the experimental results obtained from HTL of biomass model compounds. The kinetic parameters were determined by the lease-squares method using a MATLAB optimization function. Assuming no interactions among the components (cellulose, hemicellulose, and lignin) of lignocellulosic biomass during HTL, a global kinetic model was developed based on the chemical compositions of lignocellulosic biomass and the kinetic parameters obtained from the model compound. The developed model was validated with our experimental results from HTL of bamboo, cornstalk, and pinewood and the publicly available HTL data in literature obtained with lignocellulosic biomass feedstocks.

Improvement of enzymatic saccharification by simultaneous pulping of sugarcane bagasse and washing of its cellulose fibers in a batch reactor.

A modification of the conventional batch organosolv process is proposed in a way where the solid biomass remains inside a basket, physically separated from the liquid phase, with the vapor promoting the fractionation of the biomass and the extracted compounds and fragments being washed down to the liquid phase. The modified organosolv process applied to sugarcane bagasse (SB-M) delivers a rich cellulosic solid phase that after enzymatic hydrolysis leads to a hydrolyzed with approximately 100gL-1 of glucose. At the same enzymatic hydrolysis conditions, the conventional organosolv process (SB-C) delivers a hydrolyzed with 80gL-1 of glucose, while the autohydrolysis process (SB-A) leads to 55gL-1 of glucose. These different results are related to the cellulose content: SB-M (70%), SB-C (57%), e SB-A (44%), as well the reduced lignin content in the SB-M. The novelty of this study is the confirmation that it is possible to degrade lignin from sugarcane bagasse and simultaneously remove its fragments from the cellulose fibers in a batch reactor containing an internal basket. This study describes a simple and rapid protocol for the isolation of the main components of lignocellulosic biomass (cellulose, hemicellulose, and lignin), which may lead to the study of new catalysts for the chemical transformation of these components separately or simultaneously to the step of pretreatment.

Synergistic interactions and co-pyrolysis characteristics of lignocellulosic biomass components and plastic using a fast heating concentrating photothermal TGA system

Co-pyrolysis of lignocellulosic biomass (LCB) with plastic has gained significant attention recently. Studying the pyrolysis kinetic behavior of LCB and plastic is beneficial for developing a framework for designing and improving biofuel production. The co-pyrolysis behavior, synergistic interactions and kinetic triplet parameters of the three main LCB components, i.e., cellulose, hemicellulose and lignin, and two plastics (polyethylene terephthalate [PET] and polyvinyl chloride [PVC]) were evaluated using a fast heating concentrating photothermal TGA system. The maximum decrease in mass loss rate with increasing heating rates was observed for cellulose with PET (1.23–0.94%/°C) and with PVC (1.05–0.62%/°C). The mechanism of synergistic interaction between hemicellulose and PET proceeded with polymer degradation and conversions of monomer units into excess volatiles in the higher heating rate regime. Distributed Activation Energy Model [DAEM] and Coats-Redfern [CR]) were used to calculate the kinetic parameters. DAEM results confirmed that mixed samples required lower activation energy to start the reaction. Using the CR method, the first degradation phase showed the best synergistic effect for lowering the PET and PVC activation energy, particularly with hemicellulose and lignin.