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In this study, we propose a complete biomass fractionation strategy where all three major biopolymers, namely, cellulose, hemicellulose, and lignin, are separated with higher efficiency and purity....

Biomass processing industries and modern society are both interested in environmentally friendly plant-based polymers, such as lignin, to replace petrochemical derivatives. In this study, an n-buta...

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 Zn2+ and H2O2, 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.

Development of cross-linked, soft polymeric materials from biomass has been a focus of research. The aqueous phase of biomass pyrolysis oil (bio-oil) has been used as a precursor for monomer synthe...

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 sorption/desorption of gallic acid, a simple phenolic compound, was studied experimentally in a batch system. The motivation for this project was to provide insight into the recovery of phenolic compounds from switchgrass. Recovery of phenolic compounds could enhance the sustainability and economics of biorefining facilities. The sorption/desorption of gallic acid was shown to be qualitatively similar to that of phenolics extracted from switchgrass; so more extensive studies were made using gallic acid as a surrogate for the complex mixtures of phenolic compounds leached from switchgrass. The kinetics indicate that an approximation of equilibrium was reached within 48 h. Activated carbon was demonstrated to sorb gallic acid and phenolics from water and aqueous switchgrass leachate. The loading capacity of activated carbon for the gallic acid–water-activated carbon system increased with temperature for 20 to 60 °C. Ethanol was shown to be a preferable elution agent for desorbing gallic acid from activa...

A two-step thermochemical process combining a thermal desorption at 250–300 °C and a pyrolysis at 500 °C of used creosote-treated wooden railroad ties was carried out to recover preservative and produce a high quality bio-oil and biochar. Under optimal temperature between 280 and 300 °C, high preservative removal efficiency (70–74%) was achieved with a high proportion of polycyclic aromatic hydrocarbons (PAHs, 80–82%) and a large portion of the original wood mass (67–70%) was retained. This thermally treated biomass had higher heating value (HHV; 19.9–20 MJ/kg) than the starting material. The physical properties of the preservative, such as viscosity and density, and its toxic threshold against a common decay basidiomycete fungus were similar to those of commercially available P2-creosote. Pyrolysis of the thermally treated ties produced bio-oils with lower water content and total acid numbers, and a higher amount of lignin-derived compounds than that of untreated ties. Biochars derived from the thermally...

Reforming whole lignocellulosic biomass into value-added materials has yet to be achieved mainly due to the infusible nature of biomass and its recalcitrance to dissolve in common organic solvents. Recently, the solubility of biomass in ionic liquids (ILs) has been explored to develop all-lignocellulosic materials; however, efficient dissolution and therefore production of value-added materials with desired mechanical properties remain a challenge. This article presents an approach to producing high-performance lignocellulosic films from hybrid poplar wood. An autohydrolysis step that removes ≤50% of the hemicellulose fraction is performed to enhance biomass solvation in 1-ethyl-3-methyl imidazolium acetate ([C2mim][OAc]). The resulting biomass–IL solution is then cast into free-standing films using different coagulating solvents, yet preserving the polymeric nature of the biomass constituents. Methanol coagulated films exhibit a cocontinuous 3D-network structure with dispersed domains of less than 100 nm...

© 2017 American Chemical Society. We have prepared composite materials of hexagonal nickel phosphide and molybdenum carbide (Mo2C) utilizing a simple and scalable two-stage synthesis method composed of carbothermic reduction followed by hydrothermal incubation. We observe the monophasic hexagonal phosphide Ni2P in the composite at low phosphide-to-carbide (P:C) ratios. Upon an increase in the proportion of P:C, the carbide surface becomes saturated, and we detect the emergence of a second hexagonal nickel phosphide phase (Ni5P4) upon annealing. We demonstrate that vapor-phase upgrading (VPU) of whole biomass via catalytic fast pyrolysis is achievable using the composite material as a catalyst, and we monitor the resulting product slates using pyrolysis-gas chromatography/mass spectrometry. Our analysis of the product vapors indicates that variation of the P:C molar ratio in the composite material affords product slates of varying complexity and composition, which is indicated by the number of products and their relative proportions in the product slate. Our results demonstrate that targeted vapor product composition can be obtained, which can potentially be utilized for tuning of the composition of the bio-oil downstream.

© 2019 American Chemical Society. Mixed-metal oxides possess a wide range of tunability and show promise for catalytic stabilization of biomass pyrolysis products. For materials derived from layered double hydroxides, understanding the effect of divalent cation species and divalent/trivalent cation stoichiometric ratio on catalytic behavior is critical to their successful implementation. In this study, four mixed-metal oxide catalysts consisting of Al, Zn, and Mg in different stoichiometric ratios were synthesized and tested for ex-situ catalytic fast pyrolysis (CFP) using pine wood as feedstock. The catalytic activity and deactivation behavior of these catalysts were monitored in real-time using a lab-scale pyrolysis reactor and fixed catalyst bed coupled with a molecular beam mass spectrometer (MBMS), and data were analyzed by multivariate statistical approaches. In the comparison between Mg-Al and Zn-Al catalyst materials, we demonstrated that the Mg-Al materials possessed greater quantities of basic sites, which we attributed to their higher surface areas, and they produced upgraded pyrolysis vapors which contained less acids and more deoxygenated aromatic hydrocarbons such as toluene and xylene. However, detrimental impacts on carbon yields were realized via decarbonylation and decarboxylation reactions and coke formation. Given that the primary goals of catalytic upgrading of bio-oil are deoxygenation, reduction of acidity, and high carbon yield, these results highlight both promising catalytic effects of mixed-metal oxide materials and opportunities for improvement.

We present an investigation related to catalytic upgrading of cellulose pyrolysis vapors using mixed-metal oxide catalysts derived from layered double hydroxide precursors. We performed principal component analysis on the pyrolysis-gas chromatography/mass spectrometry data to elucidate changes in the product slate between noncatalytic fast pyrolysis, catalytic pyrolysis using the oxides of magnesium, aluminum, and zinc, and catalytic pyrolysis using our synthesized mixed-metal oxides containing the same cations. Our investigations demonstrate that the mixed-metal species behave differently than even a physical mixture of their monometal counterparts, and that they are capable of producing more furanic compounds by fast pyrolysis of cellulose. We also demonstrate that the metal ratio and identity in these catalysts impart different selectivities to the resulting product slates. Taken together, these data establish the utility of the mixed-metal oxide catalysts in producing a liquid product with low oxygen ...

© 2017 American Chemical Society. Removal of copper naphthenate (CN) from used wooden railroad ties was investigated to improve the commercial viability of this biomass as a fuel source and avoid alternative disposal methods such as landfilling. Bench-scale thermal desorption of organic preservative components from CN-impregnated ties was followed by extraction of the copper fraction with ethylenediaminetetraacetic acid, 1-hydroxy ethylidene-1,1-diphosphonic acid, or 2,6-pyridine dicarboxylic acid (PDA). Naphthenic acid (NA) and carrier oil were recovered at desorption temperatures between 225 and 300 °C and could potentially be recycled to treat new ties. The thermal treatment also mimicked torrefaction, improving the biomass properties for use as a thermochemical conversion feedstock. Chelation with PDA, a biodegradable chelating agent, after desorption had the highest extraction efficiency of copper and other naturally present inorganics, extracting 100% of the copper from both the raw and 225 °C-treated samples. Optimized desorbed material showed a 64% decrease in ash content when extracted with PDA; however, extraction efficiency decreased as desorption temperature increased, indicating that thermal treatment caused the inorganics to be less extractable. We concluded that the optimum desorption conditions were between 250 and 275 °C for 45 min followed by extraction with PDA when considering both NA removal and inorganic extraction efficiency.

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.

The pyrolysis vapor produced from pine wood using an intermediate pyrolysis auger reactor (72 s of solid residence time at 500, 525, and 550 °C) was condensed by three different temperature-profiled condensers. The first condenser had a surface temperature of 60–85 °C and a vapor temperature of 126–193 °C, whereas the second condenser had a surface temperature of 40–60 °C and a vapor temperature of 107–126 °C. The surface temperature of the third water-cooled condenser was ≤25 °C, and the vapor temperature was ∼33–99 °C. The water content was very low (11.1–13.9 wt %) in the bio-oil generated by the first condenser; however, it significantly increased in the bio-oil from the second (28.3–39.2 wt %) and third condensers (52.0–64.0 wt %), which led to the bio-oils with lower viscosities and densities. As the pyrolysis temperature increased, the water-insoluble fraction of the bio-oil was the highest (44–47 wt %) in the first condenser and was significantly lower in the second and third condensers (17–27 wt ...

Switchgrass- and pine wood-derived biochars produced by fast pyrolysis were characterized to estimate the degree of thermochemical transformation and to assess their potential use as a soil amendment and to sequester carbon. The feedstocks were pyrolyzed to biochars in an auger reactor at 450, 600, and 800 °C with a residence time of 30 s. Ash contents of switchgrass and pine wood biochars varied from 13 to 22% and from 1.3 to 5.2%, respectively. Nutrients, such as N, P, K, S, Mg, and Ca, in switchgrass biochars ranged from 0.16 to 1.77%. Under combustion conditions, switchgrass chars were decomposed at lower temperatures than pine wood biochars because of the structural differences between the two feedstocks. Principal component analysis of the Fourier transform infrared (FTIR) spectra allowed for the discrimination of all biochars by significant contributions of cellulose-derived functionality at low pyrolysis temperatures, while the same analysis of the Raman spectra presented apparent separation of al...

In this work, the effect of temperature on charcoal structure and chemical composition is investigated for four tree species. Wood charcoal carbonized at various temperatures is analyzed by mid infrared spectroscopy coupled with multivariate analysis and by thermogravimetric analysis to characterize the chemical composition during the carbonization process. The multivariate models of charcoal were able to distinguish between species and wood thermal treatments, revealing that the characteristics of the wood charcoal depend not only on the wood species, but also on the carbonization temperature. This work demonstrates the potential of mid infrared spectroscopy in the whiskey industry, from the identification and classification of the wood species for the mellowing process to the chemical characterization of the barrels after the toasting and charring process.