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Ionic liquids (ILs) can be used to sustainably convert lignocellulosic feedstocks into renewable bio-based materials and chemicals. To improve the prospects of commercialization, it is essential to investigate the fate of lignocellulosic biomass during IL-based processing and develop tools for designing and optimizing this "green" technology. In situ characterization during pretreatment and dissolution processes have shown that ILs reduced the inherent recalcitrance of lignocellulosic biomass via swelling of cellulose bundles and formation of fissures in the secondary cell wall layers. It subsequently enhanced the penetration of ILs into the plant cell wall leading to depolymerization and solubilization of matrix polysaccharides, mainly hemicellulose via deacetylation. Lignin also underwent dehydration or reduction reactions, depending on the IL type, with different mechanisms leading to the cleavage of inter-unit linkages. Following this process, the accessibility to cellulose microfibrils increased and induced delamination. Complementary X-ray diffraction analyses have elucidated that ILs also reduced cellulose crystallinity and altered cellulose polymorphs. High throughput in situ analyses, namely bright-field optical microscopy, nuclear magnetic resonance and Fourier transform infrared spectroscopies, have aided in monitoring the degree of swelling and chemical structural changes in lignocellulosic biomass during IL-based processing. Development of novel in situ analytical tools like IL-based gel permeation chromatography and rheometry will further shed light on molecular level changes in lignocellulose. Thus, an overall understanding of physico-chemical changes underwent by lignocellulosic biomass will help develop tools for monitoring and improving IL-based engineering of renewable materials and chemicals. [ABSTRACT FROM AUTHOR]

The objective of this research was to investigate the presence of residual lignin in cellulose fibers on the efficiency and energy consumption during nanofibers processing. Four kinds of lignin-containing cellulose nanofibers (LCNFs) from switchgrass, yellow poplar, hybrid poplar, and pine, respectively, were isolated via organosolv fractionation coupling mechanical grinding. Nanofibrils were observed after organosolv fractionation. The details of their morphological features, chemical structures, water retention value (WRV), and thermal degradation characteristics were revealed and compared. Mean diameters of nanofibers separated from switchgrass, yellow poplar, hybrid poplar, and pine were 27.9 nm, 25.4 nm, 24.6 nm, and 21.5 nm, respectively. The presence of lignin for the four types of LCNFs led to a decrease in energy consumption and an increase in WRV, among which pine nanofibers show the best with an average energy consumption of 0.511 kWh/kg and a WRV of 537%. It was also demonstrated that increasing lignin content for LCNFs could contribute to the sample's thermal stability. In conclusion, exact benefits of residual lignin for nanofiber will facilitate its preparation process and extend its application. [ABSTRACT FROM AUTHOR]

Sciadopitys verticillata (Sv) produces a white, sticky, latex-like resin with antimicrobial properties. The aims of this research were to evaluate the effects of this resin (Sv resin) on bacterial populations and to determine the impact of its primary volatile components on bioactivity. The impact of sample treatment on chemical composition of Sv resin was analyzed using Fourier transform infrared spectroscopy (FTIR) coupled with principal component analysis. The presence and concentration of volatiles in lyophilized resin were determined using gas chromatography/mass spectrometry (GC/MS). Changes in bacterial population counts due to treatment with resin or its primary volatile components were monitored. Autoclaving of the samples did not affect the FTIR spectra of Sv resin; however, lyophilization altered spectra, mainly in the CH and C=O regions. Three primary bioactive compounds that constituted >90% of volatiles (1R-α-pinene, tricyclene, and β-pinene) were identified in Sv resin. Autoclaved resin impacted bacterial growth. The resin was stimulatory for some plant and foodborne pathogens (Pseudomonas fluorescens, P. syringae, and Xanthomonas perforans) and antimicrobial for others (Escherichia coli, Bacillus cereus, Agrobacterium tumefaciens, and Erwinia amylovora). Treatment with either 1R-α-pinene or β-pinene reduced B. cereus population growth less than did autoclaved resin. The complex resin likely contains additional antimicrobial compounds that act synergistically to inhibit bacterial growth. [ABSTRACT FROM AUTHOR]

Development of commercially relevant bioenergy switchgrass cultivars requires reducing recalcitrance for bioprocessing without compromising biomass yield. Low-lignin transgenic switchgrass has been produced via down-regulation of caffeic acid O-methyltransferase (COMT), a lignin biosynthetic enzyme, or by over-expression of the MYB4 transcription factor, a repressor of the lignin biosynthetic pathway. The aim of this study was to evaluate parents and selected hybrids obtained from COMT and MYB4 hybrid families under field conditions for agronomic performance and biomass quality. Plant height, width, number of tillers, dry weight, cell wall composition including lignin content, and sugar release were measured after the establishment year (2014) and the second growing season (2015). For COMT hybrids, biomass yield of the transgenic hybrids was similar to or greater than the wild-type parents selected for high biomass. Lignin content of COMT transgenic hybrids was reduced by 10%, S/G ratio decreased by 27%, and sugar release increased between 20% and 44% compared to their wild-type parents. These results indicate that hybridization of COMT with a high-yielding locally selected genotype resulted in both improved agronomic performance and enhanced biomass quality in the offspring. On the other hand, the MYB transgenic hybrid showed a 10% reduction in biomass yield compared with its wild-type parent in year 1, but not in year 2. The lignin S/G ratio was not reduced in MYB transgenic hybrids, nor was sugar release increased. These data indicate that the MYB transgene may not be suitable for an agronomic setting. More testing is needed of transgenic and wild-type, high-biomass selections for use as breeding parents. These results show that combining low-lignin transgenic switchgrass with a breeding and selection program for biomass yield will allow for the deployment of effective transgenes in high-yielding genetic backgrounds. [ABSTRACT FROM AUTHOR]

Materials generated from renewable resources are promising and attractive substitutes for petroleum-based materials. Recently, regeneration of cellulose fibers using ionic liquids (ILs) as green solvents has been a topic of interest to both industrial and academic sectors. However, extraction of cellulose from lignocellulosic biomass requires numerous energy intensive processing steps. Additionally, the deconstruction and removal of lignin and hemicellulose components from lignocellulosic biomass usually involve corrosive pretreatment and the solvation of specific biomass components. Instead, utilization of the whole biomass—particularly woody residues—to manufacture high-performance materials offers an attractive value-proposition. In this study, we demonstrated fiber regeneration of whole hybrid poplar (HP) biomass by a sustainable method. We developed an environmentally friendly approach by partially auto-hydrolyzing the biomass with water before its dissolution in 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) ionic liquid, for large-scale, roll-to-roll production of fibers by solution spinning. We report, for the first time, a fundamental understanding of the inter- and intramolecular interactions in HP biomass–IL solutions, as well as their corresponding spinnability, structural reformation, and mechanical performance of the regenerated fibers. Particularly, the molecular alignment, recrystallization, and crystallinity of the spun fibers were correlated to the chain entanglement, molecular relaxation, and rheological properties of the HP biomass–IL solutions. A window of entangled concentration (4–6.5 wt%) of biomass in the IL was determined to be favorable for fiber spinning. [ABSTRACT FROM AUTHOR]

Catalytic pyrolysis may serve as an alternative production strategy to petroleum-derived fuels and chemicals. Furthermore, red mud, a toxic industrial bauxite byproduct, could serve as a sustainable catalyst and overcome the need for more robust catalysts. To test this, in situ catalytic pyrolysis was run on a semi-pilot scale reactor with various ratios of red mud and switchgrass (Panicum virgatum). Authors hypothesized that the coking process would render red mud environmentally friendly, improve soil quality, and yield for bioenergy crop production, like biochar. Therefore, this work investigated red mud's capability to enhance bio-oil quality, as well as, how the modified biochar produced from in situ pyrolysis affected switchgrass seedling vigor, and root/shoot mass. The results indicated that red mud was effective at increasing soil pH and biochar and bio-oil yields, while reducing the total acid number in bio-oil. While a high loading of reacted red mud had a negative impact on plant yield, the addition of uncatalyzed biochar to pure red mud considerably improved the seedling yield in marginal soils. These results suggest that this technology has potential for valorizing a waste stream and creating a soil amendment from red mud that closes nutrient and bioenergy production cycles while potentially reducing soil pollution. [ABSTRACT FROM AUTHOR]

The recalcitrance bottleneck of lignocellulosic materials presents a major challenge for biorefineries, including second-generation biofuel production. Because of their abundance in the northern hemisphere, softwoods, such as Norway spruce, are of major interest as a potential feedstock for biorefineries. In nature, softwoods are primarily degraded by basidiomycetous fungi causing brown rot. These fungi employ a non-enzymatic oxidative system to depolymerize wood cell wall components prior to depolymerization by a limited set of hydrolytic and oxidative enzymes. Here, it is shown that Norway spruce pretreated with two species of brown-rot fungi yielded more than 250% increase in glucose release when treated with a commercial enzyme cocktail and that there is a good correlation between mass loss and the degree of digestibility. A series of experiments was performed aimed at mimicking the brown-rot pretreatment, using a modified version of the Fenton reaction. A small increase in digestibility after pretreatment was shown where the aim was to generate reactive oxygen species within the wood cell wall matrix. Further experiments were performed to assess the possibility of performing pretreatment and saccharification in a single system, and the results indicated the need for a complete separation of oxidative pretreatment and saccharification. A more severe pretreatment was also completed, which interestingly did not yield a more digestible material. It was concluded that a biomimicking approach to pretreatment of softwoods using brown-rot fungal mechanisms is possible, but that there are additional factors of the system that need to be known and optimized before serious advances can be made to compete with already existing pretreatment methods. [ABSTRACT FROM AUTHOR]

Abstract A statistical response surface methodology (RSM) using a central composite design (CCD) model was applied to identify the optimum thermal desorption conditions for maximum recovery of preservative from copper naphthenate (CuNap) treated wood and subsequent production of a high quality pyrolytic vapor from the thermally treated wood. From the designed experiment, 94% of the total preservative present in the ties was desorbed at temperatures higher than 250 °C and residence times longer than 30 min. Elevating the temperature from 215 °C to 285 °C for 45 min residence time generated a weight loss of 12–36 wt%, an increase in higher heating value (HHV) from 20.1 to 21.9 MJ/kg, and a reduction of energy yield from 90.4 to 71.5% of the resulting thermally treated biomass. Pyrolysis at 450 °C of this material produced a vapor rich in sugars- and lignin-derived compounds. The predicted optimum conditions in terms of a maximum preservative recovery, minimum energy yield loss of the wood, and production of thermally treated biomass that generates a high proportion of sugars- and lignin-derived compounds during pyrolysis were found to be 265 °C and 51 min. Under these optimum conditions, the predicted maximum preservative recovery was 95% while the predicted thermally treated solid retained 77% of the original energy yield and produced high portions of levoglucosan and lignin-derived compounds during subsequent pyrolysis, similar to torrefied wood. Highlights • Used railroad wood ties were thermally treated for preservative recovery. • A response surface methodology identified optimum thermal treatment conditions. • A thermal treatment of wood ties recovered 95% preservative at 265 °C and 51 min. • Preservative-free woods contained 21.9 MJ/kg HHV and 77% energy yield. • Pyrolysis of thermally treated wood improved levoglucosan and phenolics yields. [ABSTRACT FROM AUTHOR]

Abstract: In the USA, over 21 million wood railroad ties are produced per year to replace approximately 20 million used ties that have provided primary service in railroad tracks over 40 years. Traditionally, used ties have been processed for energy recovery, typically as boiler fuel. However, recent US Environmental Protection Agency (US EPA) regulations and the low cost of natural gas is leading to preservative‐treated ties being used increasingly as landfill. This study evaluated the economic viability of a process that aims to recover the preservatives from used ties and subsequently convert the extracted wood ties to hydrocarbon fuels (gasoline and diesel blendstocks) using an integrated biorefinery concept. This techno‐economic analysis considered three plants, geographically spread across the USA to minimize transportation costs, with a capacity of 1769 dry tons per day based on a yearly available used railroad‐tie inventory estimated at 2.33 million tons. Under the baseline case scenario, the process produces 237 tons per day of recovered creosote and 69 293 and 74 922 gal per day of gasoline and diesel, respectively. The total capital investment for an nth plant is estimated at $380 million. The minimum fuel selling price (MFSP) is determined to be $2.52 per gasoline gallon equivalent (GGE) at a 10% required internal rate of return in 2016 US dollars, with a simple payback period of 9 years after tax and a market price of recovered creosote of $2.80/gal. The sensitivity analysis reveals that plant size, internal rate of return, and feedstock cost have the most impact on the MFSP. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Composites of electrocatalytically active transition-metal compounds present an intriguing opportunity toward enhanced activity and stability. To identify potentially scalable pairs of a catalytically active family of compounds, we demonstrate that phosphides of iron, nickel, and cobalt can be deposited on molybdenum carbide to generate nanocrystalline heterostructures. Composites synthesized via solvothermal decomposition of metal acetylacetonate salts in the presence of highly dispersed carbide nanoparticles show hydrogen evolution activities comparable to those of state-of-the-art non-noble metal catalysts. Investigation of the spent catalyst using high resolution microscopy and elemental analysis reveals that formation of carbide-phosphide composite prevents catalyst dissolution in acid electrolyte. Lattice mismatch between the two constituent electrocatalysts can be used to rationally improve electrochemical stability. Among the composites of iron, nickel, and cobalt phosphide, iron phosphide displays the lowest degree of lattice mismatch with molybdenum carbide and shows optimal electrochemical stability. Turnover rates of the composites are higher than that of the carbide substrate and compare favorably to other electrocatalysts based on earth-abundant elements. Our findings will inspire further investigation into composite nanocrystalline electrocatalysts that use molybdenum carbide as a stable catalyst support. [ABSTRACT FROM AUTHOR]

Phosphides and carbides are among the most promising families of materials based on earth-abundant elements for renewable energy conversion and storage technologies such as electrochemical water splitting, batteries, and capacitors. Nickel phosphide and molybdenum carbide in particular have been extensively investigated for electrochemical water splitting. However, a composite of the two compounds has not been explored. Here, we demonstrate preferential deposition of nickel phosphide on molybdenum carbide in the presence of carbon by using a hydrothermal synthesis method. We employ the hydrogen evolution reaction in acid and base to analyze the catalytic activity of phosphide-deposited carbide. The composite material also shows superior electrochemical stability in comparison to unsupported phosphide. We anticipate that the enhanced electrochemical activity and stability of carbide deposited with phosphide will stimulate investigations into the preparation of other carbide-phosphide composite materials. [ABSTRACT FROM AUTHOR]

Nanoparticles are a new frontier to valorize underutilized and abundant lignin generated by biorefineries. Typical chemical processes to synthesize lignin micro- and nano-particles (LMNPs) use large quantity of organic solvents and therefore, could adversely impact the environment. Hence, we have employed an eco-friendly mechanical approach, i.e. , ultrafine friction grinding (UFG), to produce "green" LMNPs with controlled size and micromorphology. Specifically, we investigated the effect of processing temperature, at 0, 25 and 70 °C, on lignin nanosizing. Our results showed that low temperature (0 °C) significantly favored the size reduction of lignin where we achieved a median particle size of ∼100 nm after 12 grinding passes. At 70 °C, LMNPs reached a size equilibrium of ∼160 nm within four passes but did not decrease in size upon subsequent grinding. Moreover, analysis of the LMNPs by SEM showed that samples produced at 0 °C mostly had irregular flat shapes with sharp angles, such as stars and polyhedrons, with a glabrous surface, whereas, samples produced at 25 and 70 °C featured spheres and rods with nanoscopic pores on the surface. Physico-chemical properties of LMNPs, such as molecular weight and thermal degradation, did not change significantly compared to the original lignin, however, samples generated at 0 °C exhibited significantly fewer inter-unit linkages than those generated at 70 °C. Our study thus shows that varying the grinding temperature facilitates the customization of LMNP micromorphology. Furthermore, the proposed method for LMNP manufacturing is simple and eco-friendly, and presents a viable approach for lignin valorization. [Display omitted] • Modulating grinding temperature facilitates efficient lignin nanosizing. • At 70 °C very few grinding passes were required to achieve size equilibrium. • The smallest particle size of 100 nm was achieved by processing lignin at 0 °C. • Lignin formed flat polyhedral or spherical nanoparticles at different temperatures. • Grinding causes minimal physico-chemical changes in lignin especially at 70 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • A renewable adhesive was developed from hardwood lignin biomass for joining steel substrates. • Lignin content in the compositions were varied, to alter toughness, stiffness, and surface energy. • Highest adhesive strength of 13.1 MPa was measured for an optimal composition. • This study demonstrates the viability of lignin as a valuable building block for adhesives. Adhesive bonding of metals has become increasingly relevant in recent years due to the demand for reducing weight and improving performance in structural applications such as automobiles and aerospace. We developed renewable thermoplastic adhesives from technical organosolv lignin isolated from hardwood biomass and acrylonitrile butadiene co-polymer rubber (NBR) for joining steel substrates. NBR33, NBR41 and NBR51 with acrylonitrile molar ratios of 33, 41 and 51%, respectively, were blended with lignin to form two-phase thermoplastic adhesives, and their adhesion, viscoelastic and surface properties were measured. Lignin content in the compositions were varied, ranging from 40% to 80% (w/w), to alter toughness, stiffness, and surface energy characteristics of the material. Better interaction or reactivity between the lignin and NBR phases was observed with greater nitrile content in NBR, leading to greater modulus and stiffness of the adhesive. Simultaneously, increasing the proportion of lignin reduced toughness and improved stiffness, with the highest adhesive strength of 13.1 MPa measured in a 60% lignin loading ratio with NBR51. Surface energy measurements revealed that total surface energy (sum of polar and dispersive surface energy) raised with lignin loading, suggesting that both surface energy and matrix strength play a critical role in the adhesive properties of the synthesized materials. A finite element-based cohesive zone model (CZM) was developed and implemented to study the failure strength of the adhesively bonded joint. This study demonstrates the viability of lignin as a valuable building block for adhesives, not only due to its inherent chemical structure and rigidity, but also for its surface energy characteristics. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the efficiency of an ionic liquid (IL) 1-butyl-3-methylimidazolium acetate ([C 4 mim][OAc]) pretreatment (110 °C for 30 min) in comparison to high severity autohydrolysis pretreatment in terms of delignification, cellulose crystallinity and enzymatic digestibility. The increase in severity of autohydrolysis pretreatment had positive effect on glucan digestibility, but was limited by the crystallinity of cellulose. [C 4 mim][OAc] pretreated sugarcane bagasse exhibited a substantial decrease in lignin content, reduced cellulose crystallinity, and enhanced glucan and xylan digestibility. Glucan and xylan digestibility was determined as 97.4% and 98.6% from [C 4 mim][OAc] pretreated bagasse, and 62.1% and 57.5% from the bagasse autohydrolyzed at 205 °C for 6 min, respectively. The results indicated the improved digestibility and hydrolysis rates after [C 4 mim][OAc] pretreatment when compared against a comparable autohydrolyzed biomass. [ABSTRACT FROM AUTHOR]

Inorganic elements present in lignocellulosic biomass and introduced during harvesting and handling of the feedstock negatively affect biomass conversion to fuels and products. In particular, alkali and alkaline earth metals act as catalysts during thermochemical conversion, contribute to reactor degradation, and decrease the yield and quality of the reaction products. In this study, we investigated an approach to reduce ash content of switchgrass. Several reagents (chelating agents ethylenediaminetetraacetic acid (EDTA) and citric acid, as well as acetic acid, sulfuric acid, and water) under various extraction times (5, 10, 15, and 20 min) were tested using a microwave-assisted extraction method. After the extraction, mass loss, total ash, individual inorganics, and concentration of sugars in the hydrolyzates were measured. EDTA afforded the highest inorganics removal, with near complete extraction of alkali and alkaline earth metals K, Ca, and Mg, and high removal of S and Si. Citric acid and sulfuric acid removed similarly high amounts of K, Ca, and Mg as EDTA, but less Mg, P, S, and Fe. Additionally, extraction with water resulted in near complete removal of K; however, more modest removal of other inorganics was observed compared to other treatments. The mass loss was significantly higher in the sulfuric acid extractions due to hydrolysis of the structural carbohydrates, while EDTA resulted in little carbohydrate degradation due to the more neutral pH conditions. This study illustrated the benefits of extracting with chelating agents, as opposed to mineral acids, to remove inorganics and improve biomass quality. [ABSTRACT FROM AUTHOR]

In recent years, bioenergy has become a promising renewable energy source that can potentially reduce the greenhouse emissions and generate economic growth in rural areas. Gaining understanding and controlling biomass chemical composition contributes to an efficient biofuel generation. This paper presents a principal component analysis (PCA) that shows the influence and relevance of selected controllable factors over the chemical composition of switchgrass and, therefore, in the generation of biofuels. The study introduces the following factors: (1) storage days; (2) particle size; (3) wrap type; and (4) weight of the bale. Results show that all the aforementioned factors have an influence in the chemical composition. The number of days that bales have been stored was the most significant factor regarding changes in chemical components due to its effect over principal components 1 and 2 (PC1 and PC2, approximately 80% of the total variance). The storage days are followed by the particle size, the weight of the bale and the type of wrap utilized to enclose the bale. An increment in the number of days (from 75-150 days to 225 days) in storage decreases the percentage of carbohydrates by -1.03% while content of ash increases by 6.56%. [ABSTRACT FROM AUTHOR]

Lignins from various poplar genotypes were isolated by using organosolv fractionation and subjected to rheological treatment at various temperatures. Physicochemical characterization of the lignin variants shows a broad distribution of glass transition temperatures, melt viscosity, and pyrolysis char residues. Rheological treatment at 170 °C induces lignin repolymerization accompanied with an increase in condensed linkages, molecular weights, and viscosities. In contrast, rheology testing at 190 °C results in the decrease in lignin aliphatic and phenolic hydroxyl groups, β-O-aryl ether linkages, molecular weights, and viscosity values. Lignin under air cooling generates more oxygenated and condensed compounds, but lower amounts of ether linkages than lignin cooled under nitrogen. Lignin with a lower syringyl/guaiacyl ratio tends to form more cross-linkages along with higher viscosity values, higher molecular weight and larger amounts of condensed bonds. [ABSTRACT FROM AUTHOR]

Used creosote-treated wood ties were thermally treated between 250 and 350 °C to recover preservative and upgrade the wood to provide an improved quality biomass for thermochemical processes. With thermal treatments ranging from 250 to 300 °C, the amounts of creosote, mostly consisting of polycyclic aromatic hydrocarbons (PAHs), recovered were from 47 to 79% of total creosote present in the used ties. Thermal treatment at 350 °C recovered 97% of total PAH compounds. Larger amounts of PAHs with higher molecular weights (HMWs) and lower vapor pressures (LVP) were recovered at elevated temperatures. Temperature above 300 °C decomposed the wood matrix, with a mass loss ranging between 50 and 63 wt% and produced large amounts of light organics, anhydrosugars, and phenolic compounds that would contaminate the recovered creosote. Our study concluded that thermal treatment ranging between 275 and 300 °C would be preferred to recover preservative for recycling and improve the wood quality, i.e., high carbon content and caloric value, and low hazardous pollutants (creosote residues) for thermochemical processes such as pyrolysis or gasification. These findings suggest that the proposed approach could be a commercially viable and environmentally beneficial alternative to landfill for used railroad ties. [ABSTRACT FROM AUTHOR]

As interest in soil organic carbon (SOC) dynamics increases, so do needs for rapid, accurate, and inexpensive methods for quantifying SOC. Objectives were to i) evaluate near infrared reflectance (NIR) spectroscopy potential to determine SOC and soil organic matter (SOM) in soils from across Tennessee, USA; and ii) evaluate potential upper limits of SOC from forest, pasture, no-tillage, and conventional tilled sites. Samples were analyzed via dry-combustion (SOC), Walkley–Black chemical SOM, and NIR. In addition, the sample particle size was classified to give five surface roughness levels to determine effects of particle size on NIR. Partial least squares regression was used to develop a model for predicting SOC as measured by NIR by comparing against SOM and SOC. Both NIR and SOM correlated well (R2 > 0.9) with SOC (combustion). NIR is therefore considered a sufficiently accurate method for quantifying SOC in soils of Tennessee, with pasture and forested systems having the greatest accumulations.AbbreviationsSOC, soil organic carbon; NIR, Near Infrared Reflectance Spectroscopy; MTREC, Middle Tennessee Research and Education Center; RECM, Research and Education Center at Milan; PREC, Plateau Research and Education Center; PLS, Partial least squares. [ABSTRACT FROM AUTHOR]

A two-step thermal process, an initial thermal treatment at mild temperature followed by a fast pyrolysis step, was investigated to recover wood preservatives and produce preservatives-free wood for production of high quality bio-oil from used creosote-treated railroad ties. During the initial thermal treatment at temperature of 280 °C for 10–30 min, the treated wood ties underwent a 20–25% weight loss with energy yield (77–83%). Energy yield at 280 °C was lower than that at 200 and 250 °C (92–97%) but higher than that at the 300 °C (64–74%). Recovery level of creosote at 280 °C was comparable to that at 300 °C. Fast pyrolysis at 450 °C of the 280 °C-treated wood ties produced high amount of levoglucosan and phenolic compounds with a traceable amount (1.7–1.9% of the total peak area) of creosote compounds. [ABSTRACT FROM AUTHOR]

Abstract: Switchgrass (Panicum virgatum) is a perennial grass that has emerged as an ideal candidate for production of biofuel and value-added co-products. One of the primary requirements for the successful manufacturing of these switchgrass-derived bioproducts is to produce a consistent feedstock with reliable and adequate amounts of the substrate constituent needed. For example, the biofuels industry requires a fast-growing energy crop with higher cellulose content and lower inhibitors found in secondary constituents. Other industries would profit from higher lignin content for products such as carbon fibers, or higher water and ethanol-soluble extracts containing compounds of interest. Two switchgrass field plots in eastern Tennessee were monitored over a period of six months, including before and after traditional harvesting times for the biorefinery. Characterization of the biomass and its constituents, such as water and ethanol extracts, cellulose, hemicelluloses, lignin, and ash, was performed to examine chemical changes in switchgrass that occurred prior to, during, and after traditional harvesting times used in a biorefinery setting. Total carbohydrate (65.6–66.7 wt%) and lignin (21.7–23.2 wt%) content was found to peak in January. Extractives content was at a maximum in early harvests at 15.9–16.6 wt% and decreased to 5.5–5.8 wt% in February. An inverse relationship exists between the extractives and lignin content (R 2 = 0.94). Nonstructural soluble sugars peaked in early October with 5.1 wt% of the switchgrass composition. Remobilization efficiencies of K, Mg, P, and Fe increased with time, indicating conservation of soil nutrients if harvests were completed in late winter. [Copyright &y& Elsevier]

Abstract: Surface properties of switchgrass-derived biochars produced at fast pyrolysis temperatures of 450, 600 and 800°C were characterized at different solution pHs in order to determine the structural and chemical changes of artificially-weathered biochars when incorporated into soil. As biochars were acidified from pH 7 to 3, crystalline minerals dissolved slowly releasing nutrients; however, residual minerals were still detected in biochars produced at higher pyrolysis temperatures after pH treatment. Moreover, the amount of exchangeable bases and other inorganic compounds released from the biochars increased when pH decreased. As minerals dissolved from the biochars, total surface area and pore volume were found to increase. Surface functional groups and water vapor adsorption capacity at 0.8 P/Po also increased, whereas the potential CEC of biochars decreased due to the replacement of exchangeable sites by hydrogen ion. Therefore, during the aging process, it is predicted that soil-incorporated biochars will slowly release nutrients with changes in surface functionality and porosity, which are expected to enhance water holding capacity of soil and provide a beneficial habitat for microbial colonization. [Copyright &y& Elsevier]

This study analyzes the effects of N fertilizer application rates on profitability of growing switchgrass and using the feedstock in a pyrolysis biorefinery facility to create a source of sustainable aviation fuel (SAF) supply in Tennessee. Switchgrass (Panicum virgatum L.) is a perennial bunchgrass native to North America with traits suitable for biofuel and co-product production. Previous chemical analysis has shown that ash content in switchgrass is related to the amount of nitrogen applied to the field, while at the biorefinery level, the percentage ash content reduces the biorefinery fuel output. To obtain optimal nitrogen (N) application rates for the switchgrass producers and the biorefinery, a two-part analysis is employed. First, a partial budgeting profitability analysis is conducted for this cropping enterprise at the farm-gate level without considering downstream implications of biomass quality, i.e., ash content. Second, the effects of higher ash content as a percentage of the feedstock on biorefinery output are analyzed. Results show farm-gate profit is maximized when N fertilizer is applied at 111 kg/ha, while as a result of increased production levels and decreased percentage ash content, biorefinery profit is maximized when N is applied at 157 kg/ha. Lower ash could lead to premium prices paid to switchgrass producers if higher quality feedstock were to be demanded as part of an integrated biofuel industry. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass is an alternative source of energy that can reduce our dependency on fossil fuels and limit greenhouse gas emissions. Several techno-economic analyses have consistently shown that all the steps in biomass-to-bioproduct processes needs improvement. Simultaneous assessment of genotypes for multiple productivity characteristics and integrating information across production stages has seldom been the focus of research efforts. To address this gap, we first determined the agronomic performance of 10 poplar genotypes. Differences between genotypes in height, diameter at breast height (DBH), tree mass and yield were consistently observed. Correlation analyses revealed that height and DBH are positively correlated with tree mass and yield, whereas bark content is negatively correlated with tree mass, yield and disease incidence. Four highest-yielding genotypes were subjected to proximate, ultimate, targeted chemical analyses, along with assessment of sugar production by acid hydrolysis and enzymatic saccharification. Despite having only marginal changes in overall chemistry, the genotypes showed differential conversion efficiencies of enzymatic saccharification. Interestingly, the genotype that showed highest cellulose conversion efficiency had the lowest estimated sugar yields due to its low biomass yield, whereas the genotype with lowest conversion efficiency had the highest estimated sugar yields. These results show the importance of integrating information across the stages of biomass production and bioconversion. These results also demonstrate the complexity of biomass feedstock production and the need for future studies to assess whether these tradeoffs can be genetically separated to guide the selection of genotypes that can maximize the overall biomass feedstock production efficiency. [ABSTRACT FROM AUTHOR]

Correction for 'Understanding the in situ state of lignocellulosic biomass during ionic liquids-based engineering of renewable materials and chemicals' by Kalavathy Rajan et al., Green Chem., 2020, 22, 6748–6766, DOI: 10.1039/D0GC02582H. [ABSTRACT FROM AUTHOR]

• Third growth cycle provided higher total switchgrass extractives and total phenolics. • Early harvest generated biomass with higher total phenolics and increased anti-oxidant activity. • Switchgrass cultivar 'EG1102' displayed higher DPPH radical scavenging activity. • Switchgrass IC 50 was inversely correlated to free sugars content. • Switchgrass IC 50 was positively correlated to flavonols and caffeic acid content. Optimum utilization of lignocellulosic bioenergy feedstock, such as switchgrass, via recovery of value-added phytochemicals and reduction of waste streams will increase the economic feasibility as well as the sustainability of integrated biorefineries. Switchgrass contains significant amount of overlooked non-structural components, i.e. extractives, which encompasses phenolic derivatives with potential antimicrobial and antioxidant properties. As a perennial crop, it is essential to assess the natural variability of switchgrass extractives content and composition in order to determine the feasibility of its extraction and utilization. In this study, three switchgrass cultivars were harvested from four commercial farms in their second and third growing seasons. Their respective extractive fractions were characterized for the presence of free sugars, total phenolics (TPC), hydroxycinnamic acid (HCAs) derivatives, total flavonols, and other important phytochemicals. Biomass harvested in the third growing season displayed greater amounts of TPC, HCAs, and total flavonols. Environmental conditions such as total precipitation, and cultural practices including harvest time, played important roles in the accumulation of TPC. The switchgrass extractives also exhibited DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity with a positive correlation between inhibiting concentration (IC 50) value and total flavonols content. [ABSTRACT FROM AUTHOR]

Background: Lignocellulosic biomass requires either pretreatment and/or fractionation to recover its individual components for further use as intermediate building blocks for producing fuels, chemicals, and products. Numerous ionic liquids (ILs) have been investigated for biomass pretreatment or fractionation due to their ability to activate lignocellulosic biomass, thereby reducing biomass recalcitrance with minimal impact on its structural components. In this work, we studied and compared 1-allyl-3-methylimidazolium formate ([AMIM][HCOO]) to the commonly used 1-ethyl-3-methylimidazolium acetate ([EMIM][CH3COO]) for its potential to activate hybrid poplar biomass and enable high cellulose and hemicellulose enzymatic conversion. Although [EMIM][CH3COO] has been widely used for activation, [AMIM][HCOO] was recently identified to achieve higher biomass solubility, with an increase of 40% over [EMIM][CH3COO]. Results: Since IL activation is essentially an early stage of IL dissolution, we assessed the recalcitrance of [EMIM][CH3COO] and [AMIM][HCOO]-activated biomass through a suite of analytical tools. More specifically, Fourier transform infrared spectroscopy and X-ray diffraction showed that activation using [AMIM][HCOO] does not deacetylate hybrid poplar as readily as [EMIM][CH3COO] and preserves the crystallinity of the cellulose fraction, respectively. This was supported by scanning electron microscopy and enzymatic saccharification experiments in which [EMIM][CH3COO]-activated biomass yielded almost twice the cellulose and hemicellulose conversion as compared to [AMIM][HCOO]-activated biomass. Conclusion: We conclude that the IL [AMIM][HCOO] is better suited for biomass dissolution and direct product formation, whereas [EMIM][CH3COO] remains the better IL for biomass activation and fractionation. [ABSTRACT FROM AUTHOR]

As a crucial strategy towards a sustainable chemical industry, the direct synthesis of dimethyl carbonate (DMC) from renewable carbon dioxide (CO 2 ) and methanol (MeOH) is studied using CeO 2 nanoparticles modified with 1-butyl-3-methylimidazolium hydrogen carbonate ([BMIm][HCO 3 ]) devoid of stoichiometric dehydrating agents. The synthesized CeO 2 @[BMIm][HCO 3 ] catalyst having high thermal stability harnesses the unique physicochemical properties of CeO 2 and the ionic liquid to exhibit a DMC yield of 10.4 % and a methanol conversion of 16.1 % at optimal conditions (pressure of CO 2 =5 MPa; temperature=130 °C). The catalytic behavior of CeO 2 @[BMIm][HCO 3 ] studied with a detailed XRD, XPS, CO 2 and NH 3 -TPD, Raman spectroscopy, TGA, FTIR, SEM and TEM suggests that the synergy between the two catalytic components originating from an increased surface oxygen vacancies boosts the overall catalytic performance. After several recycling tests, the catalyst demonstrated no significant reduction in DMC yield and methanol conversion. This platform is an attractive approach to synthesize thermally stable nanoparticle@ionic liquid that retains and merges the physical attributes of both materials for producing useful bulk chemicals from readily available chemical resources., (© 2024 Wiley-VCH GmbH.)

Firefighters are exposed to occupational hazards and have a higher prevalence of health issues. The gut microbiota plays a crucial role in the immune, endocrine, and neural systems, and disruptions in its composition can impact health outcomes. This pilot study aimed to investigate the potential association between occupational factors, changes in gut microbiota, and the development of adverse health outcomes in firefighters. To test this hypothesis, we recruited 15 firefighters and age/sex-matched controls to investigate the relationship between occupational environment and gut microbiota. Firefighters exhibit lower intestinal bacterial alpha diversity and a higher presence of pathogenic bacteria than the control. Moreover, unique gut bacterial taxa were observed in firefighters with high post-traumatic stress disorder (PTSD) scores, which could contribute to immune dysregulation and higher susceptibility to pathogen colonization. These preliminary findings suggest that occupational factors, including exposure to traumatic stressors and chemicals, may influence firefighters' health by modulating their gut microbiota. The observed changes in gut microbiota composition and the potential link to occupational hazards highlight the need for further research in larger sample-size studies. Understanding the role of gut microbiota in firefighter health may have implications for preventive measures and interventions to mitigate occupational health risks and improve overall well-being.

Ionic liquids (ILs) have been widely investigated for the pretreatment and deconstruction of lignocellulosic feedstocks. However, the modes of interaction between IL-anions and cations, and plant cell wall polymers, namely, cellulose, hemicellulose, and lignin, as well as the resulting ultrastructural changes are still unclear. In this study, we investigated the atomic level and suprastructural interactions of microcrystalline cellulose, birchwood xylan, and organosolv lignin with 1,3-dialkylimidazolium ILs having varying sizes of carboxylate anions. Analysis by 13 C NMR spectroscopy indicated that cellulose and lignin exhibited stronger hydrogen bonding with acetate ions than with formate ions, as evidenced by greater chemical shift changes. Small-angle X-ray scattering analysis showed that while both cellulose and xylan adopted a single-stranded conformation in acetate-ILs, twice as many acetate ions were bound to one anhydroglucose unit than to an anhydroxylose unit. We also determined that a minimum of seven representative carbohydrate units must interact with an anion for that IL to effectively dissolve cellulose or xylan. Lignin is associated as groups of four polymer molecules in formate-ILs and dispersed as single molecules in acetate-ILs, which indicates that it is highly soluble in the latter. In summary, our study demonstrated that 1,3-dialkylimidazolium acetates displayed stronger binding interactions with cellulose and lignin, as compared to formates, and thus have superior potential to fractionate these polymers from lignocellulosic feedstocks.

Hemicellulose, a structural polysaccharide and often underutilized co-product stream of biorefineries, could be used to produce prebiotic ingredients with novel functionalities. Since hot water pre-extraction is a cost-effective strategy for integrated biorefineries to partially fractionate hemicellulose and improve feedstock quality and performance for downstream operations, the approach was applied to process switchgrass (SG), hybrid poplar (HP), and southern pine (SP) biomass at 160°C for 60 min. As a result, different hemicellulose-rich fractions were generated and the chemical characterization studies showed that they were composed of 76-91% of glucan, xylan, galactan, arabinan, and mannan oligosaccharides. The hot water extracts also contained minor concentrations of monomeric sugars (≤18%), phenolic components (≤1%), and other degradation products (≤3%), but were tested for probiotic activity without any purification. When subjected to batch fermentations by individual cultures of Lactobacillus casei , Bifidobacterium bifidum , and Bacteroides fragilis , the hemicellulosic hydrolysates elicited varied responses. SG hydrolysates induced the highest cell count in L. casei at 8.6 log 10 cells/ml, whereas the highest cell counts for B. fragilis and B. bifidum were obtained with southern pine (5.8 log 10 cells/ml) and HP hydrolysates (6.4 log 10 cells/ml), respectively. The observed differences were attributed to the preferential consumption of mannooligosaccharides in SP hydrolysates by B. fragilis . Lactobacillus casei preferentially consumed xylooligosaccharides in the switchgrass and southern pine hydrolysates, whereas B. bifidum consumed galactose in the hybrid poplar hydrolysates. Thus, this study (1) reveals the potential to produce prebiotic ingredients from biorefinery-relevant lignocellulosic biomass, and (2) demonstrates how the chemical composition of hemicellulose-derived sources could regulate the viability and selective proliferation of probiotic microorganisms., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Rajan, D’Souza, Kim, Choi, Elder, Carrier and Labbé.)

The wide-scale production of renewable fuels from lignocellulosic feedstocks continues to be hampered by the natural recalcitrance of biomass. Therefore, there is a need to develop robust and reliable methods to characterize and quantify components that contribute to this recalcitrance. In this study, we utilized a method that incorporates pyrolysis with successive gas chromatography and mass spectrometry (Py-GC/MS) to assess lignification in cell suspension cultures. This method was compared with other standard techniques such as acid-catalyzed hydrolysis, acetyl bromide lignin determination, and nitrobenzene oxidation for quantification of cell wall bound phenolic compounds. We found that Py-GC/MS can be conducted with about 250 µg of tissue sample and provides biologically relevant data, which constitutes a substantial advantage when compared to the 50-300 mg of tissue needed for the other methods. We show that when combined with multivariate statistical analyses, Py-GC/MS can distinguish cell wall components of switchgrass ( Panicum virgatum ) suspension cultures before and after inducing lignification. The deposition of lignin precursors on uninduced cell walls included predominantly guaiacyl-based units, 71% ferulic acid, and 5.3% p-coumaric acid. Formation of the primary and partial secondary cell wall was supported by the respective ~15× and ~1.7× increases in syringyl-based and guaiacyl-based precursors, respectively, in the induced cells. Ferulic acid was decreased by half after induction. These results provide the proof-of-concept for quick and reliable cell wall compositional analyses using Py-GC/MS and could be targeted for either translational genomics or for fundamental studies focused on understanding the molecular and physiological mechanisms regulating plant cell wall production and biomass recalcitrance., (Copyright © 2020 Kline, Voothuluru, Lenaghan, Burris, Soliman, Tetard, Stewart, Rials and Labbé.)

Huanglongbing (HLB), also known as citrus greening, is a bacterial disease that poses a devastating threat to the citrus industry worldwide. To manage this disease efficiently, we developed and characterized a ternary aqueous solution (TSOL) that contains zinc nitrate, urea, and hydrogen peroxide. We report that TSOL exhibits better antimicrobial activity than commercial bactericides for growers. X-ray fluorescence analysis demonstrates that zinc is delivered to citrus leaves, where the bacteria reside. FTIR and Raman spectroscopy, molecular dynamics simulations, and density functional theory calculations elucidate the solution structure of TSOL and reveal a water-mediated interaction between Zn 2+ and H 2 O 2 , which may facilitate the generation of highly reactive hydroxyl radicals contributing to superior antimicrobial activity of TSOL. Our results not only suggest TSOL as a potent antimicrobial agent to suppress bacterial growth in HLB-infected trees, but also provide a structure-property relationship that explains the superior performance of TSOL.

Switchgrass ( Panicum virgatum L.) is a leading lignocellulosic bioenergy feedstock. Cellulose is a major component of the plant cell walls and the primary substrate for saccharification. Accessibility of cellulose to enzymatic breakdown into fermentable sugars is limited by the presence of lignin in the plant cell wall. In this study, putatively novel switchgrass secondary cell wall cellulose synthase PvCesA4 and primary cell wall PvCesA6 genes were identified and their functional role in cellulose synthesis and cell wall composition was examined by overexpression and knockdown of the individual genes in switchgrass. The endogenous expression of PvCesA4 and PvCesA6 genes varied among including roots, leaves, stem, and reproductive tissues. Increasing or decreasing PvCesA4 and PvCesA6 expression to extreme levels in the transgenic lines resulted in decreased biomass production. PvCesA6 -overexpressing lines had reduced lignin content and syringyl/guaiacyl lignin monomer ratio accompanied by increased sugar release efficiency, suggesting an impact of PvCesA6 expression levels on lignin biosynthesis. Cellulose content and cellulose crystallinity were decreased, while xylan content was increased in PvCesA4 and PvCesA6 overexpression or knockdown lines. The increase in xylan content suggests that the amount of non-cellulosic cell wall polysaccharide was modified in these plants. Taken together, the results show that the manipulation of the cellulose synthase genes alters the cell wall composition and availability of cellulose as a bioprocessing substrate.

Synthesizing lignin-based copolymers would valorize a major coproduct stream from pulp and paper mills and biorefineries as well as reduce the dependence on petrochemical-based consumer goods. In this study, we used organosolv lignin isolated from hybrid poplar ( Populus trichocarpa × P. deltoides) to generate lignin-containing methacrylate hydrogels. The copolymer hydrogels were synthesized by first grafting 2-hydroxyethyl methacrylate (HEMA) onto lignin (OSLH) via esterification and then by free radical polymerization of OSLH with excess HEMA. The copolymer hydrogels were prepared with different stoichiometric ratios of OSLH (e.g., 0, 10, 20, and 40 wt %) with respect to HEMA. Copolymerization with OSLH led to an increase in cross-linking density, which in turn enhanced the hydrogel's material properties; we report up to 39% improvement in water retention, 20% increase in thermostability, and up to a 3 order increase in magnitude of the storage modulus ( G'). The copolymer's properties, such as water retention and glass transition temperature, could be tuned by altering the percent functionalization of lignin OH groups and the ratio of OSLH to HEMA.

The ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([EMIM]Acetate) has been widely used for biomass processing, i.e., to pretreat, activate, or fractionate lignocellulosic biomass to produce soluble sugars and lignin. However, this IL does not achieve high biomass solubility, therefore minimizing the efficiency of biomass processing. In this study, [EMIM]Acetate and three other ILs composed of different 3-methylimidazolium cations and carboxylate anions ([EMIM]Formate, 1-allyl-3-methylimidazolium ([AMIM]) formate, and [AMIM]Acetate) were analyzed to relate their physicochemical properties to their biomass solubility performance. While all four ILs are able to dissolve hybrid poplar under fairly mild process conditions (80 °C and 100 RPM stirring), [AMIM]Formate and [AMIM]Acetate have particularly increased biomass solubility of 40 and 32%, respectively, relative to [EMIM]Acetate. Molecular dynamics simulations suggest that strong interactions between IL and specific plant biopolymers may contribute to this enhanced solubilization, as the calculated second virial coefficients between ILs and hemicellullose are most favorable for [AMIM]Formate, matching the trend of the experimental solubility measurements. The simulations also reveal that the interactions between the ILs and hemicellulose are an important factor in determining the overall biomass solubility, whereas lignin-IL interactions were not found to vary significantly, consistent with literature. The combined experimental and simulation studies identify [AMIM]Formate as an efficient biomass solvent and explain its efficacy, suggesting a new approach to rationally select ionic liquid solvents for lignocellulosic deconstruction.

The production of renewable chemicals and biofuels must be cost- and performance- competitive with petroleum-derived equivalents to be widely accepted by markets and society. We propose a biomass conversion strategy that maximizes the conversion of lignocellulosic biomass (up to 80% of the biomass to useful products) into high-value products that can be commercialized, providing the opportunity for successful translation to an economically viable commercial process. Our fractionation method preserves the value of all three primary components: (i) cellulose, which is converted into dissolving pulp for fibers and chemicals production; (ii) hemicellulose, which is converted into furfural (a building block chemical); and (iii) lignin, which is converted into carbon products (carbon foam, fibers, or battery anodes), together producing revenues of more than $500 per dry metric ton of biomass. Once de-risked, our technology can be extended to produce other renewable chemicals and biofuels.

Ionic liquids (ILs) are benign solvents that are highly effective for biomass pretreatment. However, their applications for scale-up biorefinery are limited due to multiple expensive IL recovery and separation steps that are required. To overcome this limitation, it is very critical to develop a compatible enzymatic and microbial biocatalyst system to carry the simultaneous saccharification and fermentation in IL environments (SSF-IL). While enzymatic biocatalysts have been demonstrated to be compatible with various IL environments, it is challenging to develop microbial biocatalysts that can thrive and perform efficient biotransformation under the same conditions (pH and temperature). In this study, we harnessed the robust metabolism of Yarrowia lipolytica as a microbial platform highly compatible with the IL environments such as 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]). We optimized the enzymatic and microbial biocatalyst system using commercial cellulases and demonstrated the capability of Y. lipolytica to convert cellulose into high-value organics such as α-ketoglutaric acid (KGA) in the SSF-IL process at relatively low temperature 28 °C and high pH 6.3. We showed that SSF-IL not only enhanced the enzymatic saccharification but also produced KGA up to 92% of the maximum theoretical yield.

The anatomical and chemical characteristics of sweetgum were studied after 11 years of elevated CO2 (544 ppm, ambient at 391 ppm) exposure. Anatomically, branch xylem cells were larger for elevated CO2 trees, and the cell wall thickness was thinner. Chemically, elevated CO2 exposure did not impact the structural components of the stem wood, but non-structural components were significantly affected. Principal component analysis (PCA) was employed to detect differences between the CO2 treatments by considering numerous structural and chemical variables, as well as tree size, and data from previously published sources (i.e., root biomass, production and turnover). The PCA results indicated a clear separation between trees exposed to ambient and elevated CO2 conditions. Correlation loadings plots of the PCA revealed that stem structural components, ash, Ca, Mg, total phenolics, root biomass, production and turnover were the major responses that contribute to the separation between the elevated and ambient CO2 treated trees., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Fractionation of lignocellulosic biomass is an attractive solution to develop an economically viable biorefinery by providing a saccharide fraction to produce fuels and a lignin stream that can be converted into high value products such as carbon fibers. In this study, the analysis of ionic liquid-activated biomass demonstrates that in addition of decreasing crystallinity, the selected ILs (1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium acetate) deacetylate Yellow poplar under mild conditions (dissolution at 60-80 °C), and lower the degradation temperature of each biomass polymeric component, thereby reducing the recalcitrance of biomass. Among the three tested ILs, 1-ethyl-3-methylimidazolium acetate performed the best, providing a strong linear relationship between the level of deacetylation and the rate of enzymatic saccharification for Yellow poplar., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Bamboo has wide range of moisture content, low bulk energy density and is difficult to transport, handle, store and feed into existing combustion and gasification systems. Because of its important fuel characteristics such as low ash content, alkali index and heating value, bamboo is a promising energy crop for the future. The aim of this study was to evaluate the effects of torrefaction on the main energy properties of Bambusa vulgaris. Three different torrefaction temperatures were employed: 220, 250 and 280°C. The elemental characteristics of lignite and coal were compared to the torrefied bamboo. The characteristics of the biomass fuels tend toward those of low rank coals. Principal component analysis of FTIR data showed a clear separation between the samples by thermal treatment. The loadings plot indicated that the bamboo samples underwent chemical changes related to carbonyl groups, mostly present in hemicelluloses, and to aromatic groups present in lignin., (Copyright © 2011 Elsevier Ltd. All rights reserved.)