Lignocellulosic Research Articles

Insights into lignin bioconversion: lignin-derived compounds treatment of a novel marine fungus K-2.

The potential for the efficient conversion of lignocellulosic biomass has been extensively explored to produce a wide range of bioproducts. Many approaches have been sought for the deep conversion of lignin to generate products that are toxin-free and beneficial for processing into high-value-added components. This study reported a fungus isolated from the deep sea with strong synthesis of multiple lignocellulases, conversion of lignin and guaiacol (0.1%) by 71.6% and 86.1% within 9 days at 30 °C respectively, and outstanding environmental adaptability (20-50 °C and pH 3-8). Metabolic pathway profiling showed that this fungus utilized lignin to rapidly activate multiple ring-opening reactions including the 2,3- and 3,4-cleavage pathways, with the 2,3-cleavage pathway predominating after 5 days. Conversion of metabolic intermediates confirmed the superb potential of this strain for lignin treatment. Meanwhile, its shikimic acid pathway was metabolically active under lignin. This further expands the potential to produce valuable bioproducts during lignin treatment, especially under ambient conditions, which can significantly enhance high-value precursor compound production. © 2024 Society of Chemical Industry.

KINETIC STUDY OF ESTERIFICATION CATALYZED WITH ALUMINUM SULFATE AIMED AT CONVERTING LEVULINIC ACID INTO METHYL LEVULINATE

Recycling lignocellulosic biomass is a sustainable alternative to the petrochemical industry since it allows the production of valuable, sustainable, and environmentally friendly chemical products, such as levulinic acid (LVA) and levulinate esters. Methyl levulinate (MLV), for example, has been assessed as a fuel additive with low toxicity, high lubricity, and flash point stability. In this respect, the present investigation details a kinetic study of methyl esterification catalyzed with aluminum sulfate aimed at converting levulinic acid into methyl levulinate. The reactions were carried out in a Parr Instruments stainless steel reactor to assess the effect of temperature (120, 140 and 160 °C) and reaction time (30, 60, 120 and 180 min) on LVA conversion into MLV, maintaining a constant LVA:methanol ratio of 1:8 and aluminum sulfate catalyst concentration of 0.04 mol.L-1. The maximum LVA-MLV conversion of 93.04 % was obtained at a temperature of 160 °C and reaction time of 60 minutes. The pseudo first-order kinetic model exhibited the best fit to the experimental data, with correlation coefficients (R²) greater than 0.96, and it was used to calculate activation energy, obtaining a value of 10.19 kcal.mol-1.

Selectivity control in catalytic glucose dehydration using iron- and tungsten-modified ZSM-5 catalysts

The conversion of lignocellulosic biomass into valuable chemicals and fuels has received considerable attention owing to the issues related to global warming. 5-Hydroxymethylfurfural (HMF) is a versatile lignocellulose-derived platform chemical used in a wide range of high-value bioproducts. However, the HMF production is completed with polymerization by which humins are inevitably formed as a by-product. Recently, the potential of humins for various applications has been explored. In this study, a series of ZSM-5 zeolite catalysts modified with iron (Fe) and tungsten (W) were used to selectively control glucose dehydration to HMF and humins. The zeolite catalysts possessing tunable bifunctional Brønsted–Lewis acid characteristics were prepared through pretreatment using a diluted nitric acid solution, followed by metal impregnation. The impregnation of Fe into ZSM-5 induced the formation of highly dispersed extraframework isolated Fe3+ ions and Fe2O3 species, which increased the content of Lewis acid sites. The W species added to ZSM-5 existed in the form of Si–OH–W linkages and polytungstates with moderate-to-strong Brønsted acidity. The selective synthesis of HMF was efficiently performed over the Fe-modified ZSM-5 catalysts. Furthermore, the W-modified catalysts exhibited potential application as novel catalysts for the selective production of humins. The controlled selectivity to each product depended on the acidic properties and Lewis/Brønsted acidity ratio of the catalysts as well as the transition metal-dependent characteristics of the Brønsted and Lewis acid sites.

XylR regulates genes at xyl cluster, involved in D-xylose catabolism in Herbaspirillum seropedicae Z69.

D-xylose, one of the most abundant sugars in lignocellulosic biomass, is not widely used to produce bioproducts with added value, in part due to the absence of industrial microorganisms able to metabolize it efficiently. Herbaspirillum seropedicae Z69 is a β-proteobacterium able to accumulate poly-3-hydroxybutyrate, a biodegradable thermoplastic biopolymer, with contents higher than 50%. It metabolizes D-xylose by non-phosphorylative pathways. In the genome of Z69, we found the genes xylFGH (ABC D-xylose transporter), xylB, xylD, and xylC (superior non-phosphorylative pathway), and the transcriptional regulator xylR, forming the xyl cluster. We constructed the knock-out mutant Z69ΔxylR that has a reduced growth in D-xylose and in D-glucose, compared with Z69. In addition, we analyzed the expression of xyl genes by RT-qPCR and promoter fusion. These results suggest that XylR activates the expression of genes at the xyl cluster in the presence of D-xylose. On the other hand, XylR does not regulate the expression of xylA, mhpD (lower non-phosphorylative pathways) and araB (L-arabinose dehydrogenase) genes. The participation of D-glucose in the regulation mechanism of these genes must still be elucidated. These results contribute to the development of new strains adapted to consume lignocellulosic sugars for the production of value-added bioproducts.

Hydrothermal alkaline treatment of lignocellulosic biomass for microcrystalline cellulose generation at subcritical water

Like lignocellulosic biomass, wood waste sawdust is rich in cellulose and can potentially be used as a source of microcrystalline cellulose (MCC) production via removal of hemicellulose and lignin constituents. Under hydrothermal alkaline treatment (100 to 140 °C), the breaking in the linkages of lignin and hemicellulose groups may happen, resulting in the solid residue, which is known as a cellulose-rich solid product. Results of FTIR analysis indicated that the removal of non-cellulosic constituents improved with increasing operating temperature and/or the prolonged treatment time. The XRD diffractogram pattern proved that improving the operating parameters (temperature and/or time) may also improve the crystallinity index of the solid product. On the contrary, the yield of the solid product decreases with increasing operating temperature and/or the prolonged treatment time.

Co-pyrolysis of biomass/polyurethane foam waste: Thermodynamic study using Aspen Plus

Due to the varieties and identical feature of solid waste, this research aims to consider the use of various feedstocks in pyrolysis process for liquid fuel production. The feedstock considered covers woody and non-woody biomass and plastic waste which are represented by sawdust (SD), palm leaf (PL) and polyurethane foam (PU) waste. In this research, both pure solid waste and the co-pyrolysis of biomass and plastic wastes were determined based on thermodynamics study. The model of pyrolysis process developed through Aspen Plus simulator was implemented to study the product yield, higher heating value (HHV) and energy consumption with a wider range of pyrolysis temperature and blending weight ratio. The simulation results clearly showed that the use of pure PU waste can provide the highest oil yield (∼44 wt%) which is corresponded to highest HHV (∼28 MJ/kg). The pyrolysis, operating at 400 °C, can provide the most significant quantity of oil. For the co-pyrolysis, the results revealed that more PU waste blended in both biomasses can improve both oil yield and HHV while the energy consumption is lower. From the simulation results, the optimal blending weight ratio of biomass and PU waste at 25:75 can provide suitable oil yield (∼43 wt%), HHV (∼26 MJ/kg) and energy consumption (243 kW).

Enhanced biomass densification pretreatment using binary chemicals for efficient lignocellulosic valorization

Many effective pretreatment methods (such as dilute acid, dilute alkali, ionic liquids, etc.) have been developed for lignocellulose upgrading, but several defaults of low working mass, high sugar loss and extra cost of solid-liquid separation and water washing hinder their large-scale application in industry. Besides, the valorization of lignin-rich residue from pretreated biomass after hydrolysis or fermentation greatly contributes to the economy and sustainability of lignocellulosic biorefinery, which is usually underestimated. This study developed a densification pretreatment with binary chemicals (densifying lignocellulosic biomass with sulfuric acid (SA) and metal salt (MS) followed by autoclave treatment ((DLCA(SA-MS)), which was conducted under mild condition (121 °C) with a biomass working mass as high as 400 kg/m3. The DLCA(SA-MS) biomass achieved over 95% sugar retention, 90% enzymatic sugar conversion and a high concentration of fermentable sugar (212.3 g/L) with superior fermentability. Furthermore, bio-adsorbent derived from DLCA(SA-MS) biomass residue was highly adsorptive and suitable for dyeing wastewater treatment, providing a feasible and eco-friendly method for lignin-rich residue valorization. These findings indicated that DLCA(SA-MS) pretreatment enables the full-component utilization of biomass and boosts the economic viability of lignocellulosic biorefinery.

Hydrothermal liquefaction of southern yellow pine with downstream processing for improved fuel grade chemicals production

The hydrothermal liquefaction (HTL) technique for liquefying lignocellulose biomass feedstock is often associated with low biocrude yield and poor fuel properties. This study examined the HTL of southern yellow pine sawdust and the hydrotreatment (HYD) of produced biocrudes in an effort to address these challenges. Pine HTL treatment was performed within water and water–ethanol mixed reaction medium at 250, 300, and 350℃ temperatures using metallic iron (Fe) as a catalyst. The rising reaction temperature in a water medium and increasing ethanol content in a mixed reaction medium were found to be effective in enhancing the biocrude yield from the non-catalytic pine HTL process. Maximum non-catalytic biocrude yield of 18 wt.% was produced in water at 350℃, whereas the ethanol and water (1:1 on mass basis) mixture generated the highest biocrude yield of 34 wt.% at 300℃ without any catalyst. The iron catalyst facilitated a maximum of 29 wt.% of biocrude yield as opposed to 18 wt.% without the catalyst at 350℃ in water. The use of an iron catalyst also raised the calorific value of produced biocrudes by 2.5–14 % within 250-350℃ in both water and water–ethanol media. The catalytic and non-catalytic biocrude products were chosen to undergo HYD treatment at 400 °C under high hydrogen pressure (initial 1000 psi) using an alumina-supported cobalt-molybdenum catalyst. The HYD treatment reduced the oxygen content of upgraded oils by 36–60 % compared to the parent HTL biocrudes with 35–37 MJ/kg calorific values. The simulated distillation detected the maximum gasoline range compounds in upgraded oil from catalyst and water–ethanol conditions, whereas the GC–MS analysis revealed the production of increased aromatic hydrocarbons in all upgraded HYD oils. This work has demonstrated the potential of ethanol and inexpensive iron catalyst in enhancing the biocrude production from pine, which could be upgraded to better fuel using the HYD process.

A comprehensive overview of lignocellulosic biomass exploiting for sustainable bioethanol production: recent advances and emerging challenges towards commercial implementation

A comprehensive overview of lignocellulosic biomass exploiting for sustainable bioethanol production: recent advances and emerging challenges towards commercial implementation

Catalytic pyrolysis of hydrolyzed lignin using HZSM-5/MCM-41 supported transition-metal to produce monocyclic aromatic hydrocarbons

Hydrolyzed lignin (HL), one kind of organic solid wastes, comes from the production of hydrolysis of lignocellulosic biomass for high-value chemicals, unsuitable treatment of which not only meaning the waste of resources but also resulting environmental pollution. The pyrolysis of HL has the problem of high oxygen-containing compounds and low hydrocarbons in the products. The HZSM-5/MCM-41 (HM) meso-microporous composite catalyst, containing nickel and molybdenum, was synthesized through impregnation to enhance the production of monocyclic aromatic hydrocarbons (MAHs) during the in-situ catalytic pyrolysis of hydrolyzed lignin. Different transition metals loaded on composite molecular sieves were prepared for comparison. The relationship between catalyst structure and pyrolysis efficiency was studied based on characterization techniques including SEM, BET, and XRD. This study investigated the catalytic properties of modified composite molecular sieves with Ni and Mo at different loaded ratios on the pyrolysis of hydrolyzed lignin. Results indicated that HM loaded with different metals had different catalytic pyrolysis selectivity. The relative yield of MAHs on 3 %Ni-HM was the highest, at 27.78 %, while that of phenolic on 5 %Mo-HM was 51.02 %. Thus, by modifying the co-loading ratios between Ni and Mo, the combined catalytic pyrolysis of hydrolyzed lignin was performed, achieving a 39.24 % yield of MAHs on the catalyst Mo1Ni2-HM, markedly surpassing the 17.69 % yield from unaltered HZSM-5/MCM-41. In addition, the improvement of active sites was caused by transition metals loaded and the synergistic effect between bimetals enhanced the catalytic activity and stability. HZSM-5/MCM-41 loaded with metal oxides promoted the depolymerization of macromolecules in the intermediate products of pyrolysis, and thus improved the relative yield of MAHs among pyrolysis products of hydrolyzed lignin.

Interactions between soil and other environmental variables modulate forest expansion and ecotone dynamics in humid savannas of Central Africa.

Forest expansion into savanna is a pervasive phenomenon in West and Central Africa, warranting comparative studies under diverse environmental conditions. We collected vegetation data from the woody and grassy components within 73 plots of 0.16 ha distributed along a successional gradient from humid savanna to forest in Central Africa. We associated spatially collocated edaphic parameters and fire frequency derived from remote sensing to investigate their combined influence on the vegetation. Soil texture was more influential in shaping savanna structure and species distribution than soil fertility, with clay-rich soils promoting higher grass productivity and fire frequency. Savanna featuring woody aboveground biomass surpassing 40 Mg ha-1 could escape the grass-fire feedback loop, by depressing grass biomass below 4 Mg ha-1. This thicker woody layer also favoured the establishment of fire-tolerant forest pioneers, which synergically contributed to the expansion of forests. Conversely, savannas below this fire suppression threshold sustained a balance between trees and grasses through the grass-fire feedback mechanism. This hysteresis loop, particularly pronounced on clayey soils, suggests that the contrast between grassy savanna and young forests might represent alternative ecosystem states, although savannas with low woody biomass remained vulnerable to forest edge encroachment.

One-step microwave pyrolysis-H3PO4 activation of woody biomass: Insight into the product characteristics and life cycle assessment

Microwave-assisted pyrolysis coupled with chemical activation was developed to prepare the woody biomass-derived activated carbon (AC) with desirable structural characteristics. In this study, sawdust powder was impregnated with phosphoric acid before being microwave-pyrolyzed to achieve AC. The utilization of microwave greatly enhanced the transformation of volatiles into gaseous components, and the yield of char increased when phosphoric acid accelerated the secondary polymerization of volatile matters. Microwave-induced activation may alter the interaction between activator and sawdust-derived organic species, enriching the categories of oily components. The char originating from microwave-activation treatment has a high graphitization degree, exhibiting superior thermal stability and hydrophilic property. Moreover, one-step microwave-activation approach increased specific surface area (978.2 m2g−1 versus 13.0 m2g−1 in conventional pyrolysis) and improved the formation of porous structure. The life cycle assessment analysis revealed that microwave-activation technique had a low environmental impact due to enhanced heating efficiency and reduced energy consumption.

Sustainable Approaches used in Pesticides contaminated Agricultural Waste Water Remediation

With the growing population of our global community and thereby increasing the demand for food has led the farmers to use more and more pesticides. Pesticides are chemical compounds used to kill pests. It is commonly used to control various agricultural pests that destroy crops and ultimately affect our agricultural productivity. Although the use of pesticides is a beneficial approach, but unfortunately it also has some drawbacks in terms of harming the environment and human health. Some pesticides pose significant hazards that ultimately affect human health systems. Contamination of agricultural land and agricultural wastewater by pesticides is a serious environmental problem and has a negative impact on biodiversity. Most synthetic pesticides are not readily biodegradable, they accumulate in the environment and cause soil contamination. To overcome the environmental burden of pesticide-contaminated sites, various sustainable approaches can be effectively used to detoxify contaminants or transform them into harmless secondary compounds. The current review focuses on the role of microorganisms and lignocellulosic biomass and plants in the degradation of agricultural pesticides under sustainable approaches.

Nanocellulose as Sustainable Eco-friendly Nanomaterials: Production, Characterization, and Applications

Nanocellulose is a biodegradable nanomaterial derived from lignocellulosic biomass through mechanical, chemical, or enzymatic defibrillation processes to convert wood fibers into nanofibrils. This material consists of a network of cellulosic fibrils with a wide range of diameters, offering unique properties suitable for various functional applications. Nanocellulose can act as a substrate or coating, serving as an eco-friendly alternative to synthetic plastics. Despite having good barrier properties and strong mechanical strength, nanocellulose films are still not as effective as synthetic plastics. They are used in creating barrier materials, flexible electronics, and coatings for paper products.

Insights into the pelletization behaviors of artificial lignocellulosic biomass based on cellulose, hemicellulose and lignin: A simplex lattice mixture design approach

The use of high quality densified pellet as an alternative to traditional fossil fuels is a promising avenue of research due to their interesting higher density, superior heating values, and enhanced combustion performance. However, little is known about the pelletization behaviors from the aspect of lignocellulosic biomass fundamental components (cellulose, hemicellulose and lignin) and their mixtures. This study presents an artificial biomass developed based on cellulose, hemicellulose and lignin using a simplex lattice design approach, aiming to understand the detailed role of major components and its effects on pellet quality. The correlation between the experimental data obtained from the simplex lattice design and the predicted response parameters were effectively explained by Scheffé's special cubic model, with a coefficient of determination beyond 90 %. Parameter estimates showed a significant synergetic effect of each components for density and Meyer hardness. Results revealed that xylan may be softened like lignin and thereby potentially act as binder. The use of a high cellulose concentration resulted in enhanced pellet strength by acting as a supporting skeleton. Xylan and cellulose played a major role in the thermal degradation of densified pellets. Based on the results obtained, the optimal components composition was determined to be 34.5 % lignin, 36.3 % cellulose, and 29.2 % xylan. Under this, the pellet exhibited the best density and Meyer hardness beyond 1500 kg/m3 and 80 N/mm2, respectively. The results provide a foundation for future efforts to be able to predict pellet properties from the perspective of biomass composition.

Structural and molecular modifications of woody biomass under minimal torrefaction conditions toward making durable pellets

Extensive research has been published on pelletizing severely torrefied biomass with the aid of binders, but limited studies have investigated the structural modifications of biomass during mild torrefaction. This study investigates the effects of several combinations of minimal torrefaction temperatures (230°C and 250°C) and relatively short durations (10, 15, and 30 minutes) on the thermophysical and molecular structure of the model woody biomass loblolly pine (Pinus Taeda) residues. The low severity treated biomass is compared with the untreated biomass and the biomass torrefied at 270°C for 30 minutes. Structural characterization methods include laser diffraction for particle size distribution and Brunauer-Emmett-Teller (BET) analysis to evaluate specific surface area. Additionally, FTIR, XRD, and TGA are used to assess changes in crystallinity and thermochemical composition. The woody residue torrefied at 250°C for 10 minutes exhibited a higher BET surface area (4.7 m²/g) than torrefied at 250°C for 15 minutes (3.5 m²/g). At a constant temperature of 250°C, the crystallinity index increases with the treatment duration, emphasizing the effect of time on retaining more hydroxyl groups that may act as binders for pelletization. This study demonstrates that minimizing the combination of torrefaction time and temperature can help control the degree of biomass molecular structure degradation thus minimizing overall mass loss, offering potential applications in the emerging biocarbon pellet industry.

Unlocking Nature’s Potential: Modelling Acacia melanoxylon as a Renewable Resource for Bio-Oil Production through Thermochemical Liquefaction

This study is focused on the modelling of the production of bio-oil by thermochemical liquefaction. Species Acacia melanoxylon was used as the source of biomass, the standard chemical 2-Ethylhexanol (2-EHEX) was used as solvent, p-Toluenesulfonic acid (pTSA) was used as the catalyst, and acetone was used for the washing process. This procedure consisted of a moderate acid-catalysed liquefaction process and was applied at 3 different temperatures to determine the proper model: 100, 135, and 170 °C, and at 30-, 115-, and 200-min periods with 0.5%, 5.25%, and 10% (m/m) catalyst concentrations of overall mass. Optimized results showed a bio-oil yield of 83.29% and an HHV of 34.31 MJ/kg. A central composite face-centred (CCF) design was applied to the liquefaction reaction optimization. Reaction time, reaction temperature, as well as catalyst concentration, were chosen as independent variables. The resulting model exhibited very good results, with a highly adjusted R-squared (1.000). The liquefied products and biochar samples were characterized by Fourier-transformed infrared (FTIR) and thermogravimetric analysis (TGA); scanning electron microscopy (SEM) was also performed. The results show that invasive species such as acacia may have very good potential to generate biofuels and utilize lignocellulosic biomass in different ways. Additionally, using acacia as feedstock for bio-oil liquefaction will allow the valorisation of woody biomass and prevent forest fires as well. Besides, this process may provide a chance to control the invasive species in the forests, reduce the effect of forest fires, and produce bio-oil as a renewable energy.

Altered Lignin Accumulation in Sorghum Mutated in Silicon Uptake Transporter SbLsi1.

Sorghum [Sorghum bicolor (L.) Moench] has been receiving attention as a feedstock for lignocellulose biomass energy. During the combustion process, the ash containing silicon (Si) can be produced, which causes problems in furnace maintenance. Hence, lowering Si content in the plants is crucial. Nevertheless, limiting Si supply to crops is difficult in practice because Si is abundant in soil. Previously, a Si uptake transporter (SbLsi1) has been identified, and the Si-depleted mutant has also been generated in the model sorghum variety BTx623. In this study, we aim to investigate the change induced by the mutation of SbLsi1 on the accumulation and the structure of lignin in cell walls. Through chemical and NMR analyses, we demonstrated that the lsi1 mutation resulted in a significant increase in lignin accumulation levels as well as a significant reduction in Si content. At least some of the modification was induced by transcriptional changes, as suggested by the upregulation of phenylpropanoid biosynthesis-related genes in the mutant plants. These findings derived from the model variety would be useful for the future development of practical cultivars with high biomass and less Si content for bioenergy applications.

Layer Characteristics on Quartz and Feldspar Bed Particles in an Industrial-Scale Fast Pyrolysis Process of Woody Biomass

Layer Characteristics on Quartz and Feldspar Bed Particles in an Industrial-Scale Fast Pyrolysis Process of Woody Biomass

Quantification of biomass availability for wood harvesting and storage in the continental United States with a carbon cycle model

BackgroundWood Harvesting and Storage (WHS) is a form of Biomass Carbon Removal and Storage (BiCRS) that utilizes a combined natural and engineered process to harvest woody biomass and put it into long term storage, most frequently in the form of subterranean burial. This paper aims to quantify the availability of woody biomass for the purposes of WHS in the continental United States using a carbon cycle modeling approach. Using a regional version of the VEGAS terrestrial carbon cycle model at 10 km resolution, this paper calculates the annual woody net primary production in the continental United States. It then applies a series of constraints to exclude woody biomass that is unavailable for WHS. These constraints include fine woody biomass, current land use, current wood utilization, land conservation, and topographical limitations. These results were then split into state by state and regional totals.ResultsIn total, the model projects the continental United States could produce 1,274 MtCO2e (CO2 equivalent) worth of coarse woody biomass annually in a scenario with no anthropogenic land use or constraints. In a scenario with anthropogenic land use and constraints on wood availability, the model projects that 415 MtCO2e of coarse woody biomass is available for WHS annually. This is enough to offset 8.5% of the United States’ 2020 greenhouse gas emissions. Of this potential, 20 MtCO2e is from the Pacific region, 77 MtCO2e is from the Western Interior, 91 MtCO2e is from the Northeast region, and 228 MtCO2e is from the Southeast region.ConclusionThere is enough coarse woody biomass available in the continental United States to make WHS a viable form of carbon removal and storage in the country. There is coarse woody biomass available across the continental United States. All four primary regions analyzed have enough coarse woody biomass available to justify investment in WHS projects.