[Show abstract][Hide abstract] 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/P(o) 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.
[Show abstract][Hide abstract] ABSTRACT: Lignin, an abundant, naturally occurring biopolymer, is often considered “waste” and used as a simple fuel source in the paper-making process. However, lignin has emerged as a promising renewable resource for engineering materials, such as carbon fibers. Unfortunately, the molecular architecture of lignin (in vivo and extracted) is still elusive, with numerous conflicting reports in the literature, and knowledge of this structure is extremely important, not only for materials technologies, but also for production of biofuels such as cellulosic ethanol due to biomass recalcitrance. As such, the molecular structures of solvent-extracted (sulfur-free) lignins, which have been modified using various acyl chlorides, have been probed using small-angle X-ray (SAXS) and neutron (SANS) scattering in tetrahydrofuran (THF) solution along with hydrodynamic characterization using dilute solution viscometry and gel permeation chromatography (GPC) in THF. Mass spectrometry shows an absolute molecular weight ≈18–30 kDa (≈80–140 monomers), while GPC shows a relative molecular weight 3 kDa. A linear styrene oligomer (2.5 kDa) was also analyzed in THF using SANS. Results clearly show that lignin molecular architectures are somewhat rigid and complex, ranging from nanogels to hyperbranched macromolecules, not linear oligomers or physical assemblies of oligomers, which is consistent with previously proposed delignification (extraction) mechanisms. Future characterization using the methods discussed here can be used to guide extraction processes as well as genetic engineering technologies to convert lignin into value added materials with the potential for high positive impact on global sustainability.
[Show abstract][Hide abstract] ABSTRACT: Hygroscopicity, low durability, and low thermal resistance are disadvantages of lignocellulosic materials that also plague wood–plastic composites (WPCs). Hemicellulose is the most hydrophilic wood polymer and is currently considered as a sugar source for the bioethanol industry. The objective of this research is to extract hemicellulose from woody materials and enhance the properties of WPC by diminishing the hydrophilic character of wood. Hemicellulose of Southern Yellow Pine was extracted by hot-water at three different temperatures: 140, 155, and 170 °C. Wood flour was compounded with polypropylene in an extruder, both with and without a coupling agent. Injection molding was used to make tensile test samples. The thermal stability of wood flour was found to have increased after extraction. Extraction of hemicellulose improved the tensile strength and water resistance of composites, which may indicate a decrease in the hygroscopicity of wood flour, better compatibility, and interfacial bonding of the filler and matrix.
Composites Part A Applied Science and Manufacturing 04/2012; 43(4):686–694. · 2.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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 all biochars by two broad bands at 1587 and 1350 cm–1. These two broad peaks were deconvoluted into pseudo-subpeaks, which revealed that the number of aromatic rings linearly increased with the pyrolysis temperature. Cross-linkages between aromatic rings were also found to increase with thermal treatment, and switchgrass biochars contained a higher number of aromatic rings and cross-linkages than pine wood biochars, which was consistent with turbostratic carbon crystallites in the X-ray diffraction (XRD) pattern.
[Show abstract][Hide abstract] ABSTRACT: Abstract
Hemicellulose is the most hydrophilic
polymer of wood, and as a polysaccharide
, it has potential applications in conversion to biofuels. The objective of this study was to enhance properties of flakeboard by extracting hemicellulose. Hotwater pretreatment
was performed to extract hemicellulose under different temperatures (140[degrees]C, 155[degrees]C, and 170[degrees]C) and times (30 and 60 min). The flakes were blended with 5 percent liquid phenol-formaldehyde resin and 1 percent wax emulsion. The mat was pressed at 200[degrees]C for 5 minutes. The physical and mechanical properties and the susceptibility of flakeboard to mold were studied. Panels made from the hemicellulose-extracted flakes showed remarkable decreases in water absorption and thickness swelling without a decrease in mechanical properties. Resistance of the panels to the mold growth also increased with increasing mass loss due to extraction. The most severe condition of extraction (170[degrees]C, 60 min), in addition to having the lowest water absorption and thickness swelling, showed the highest mold resistance.
[Show abstract][Hide abstract] ABSTRACT: Hot-water pretreatment was performed on wood strands to investigate effects of the extraction of hemicellulose under different
temperature (140, 155, and 170°C) and time durations (30 and 60min) conditions. Hydrolysate was analyzed by means of high-performance
liquid chromatography. Chemical changes in the surface of wood strands were studied by infrared spectroscopy. The effects
of hemicellulose extraction on the wettability of wood strands were studied by measuring the contact angle and surface free
energy. The mechanical properties of wood cell walls before and after treatment were studied by nanoindentation. Among the
extracted monosaccharides, mannose was found in the highest concentration. The mechanical properties of cell walls showed
little decrease after extraction. The chemical changes in the surface of the wood strands reduced wettability of wood surface
by water and produced hydrophobic characteristics after extraction.
KeywordsHot-water extraction–High-performance liquid chromatography–Infrared spectroscopy–Wettability–Nanoindentation
[Show abstract][Hide abstract] ABSTRACT: To take advantage of the unique characteristics of the wood flour by combining them with plastic in
conventional panel pressing methods, awet process was developed to make composites using polypropylene
and steam-exploded (SE) flour from small-diameter loblolly pine. Wet-laid wood flour/polymer composites
were fabricated using astandard TAPPI handsheet method followed by compression molding. The variables
that may affect the product properties were investigated using an orthogonal test design. The results revealed
that the modulus of elasticity (MOE) of composites increased, while modulus of rupture (MOR) decreased with
increasing SE wood flour content. Both MOE and MOR of the composites increased with maleic anhydride grafted
polypropylene content. Dynamic mechanical analyzer and differential scanning calorimetry measurement gave
insight into the structure of these composites, and scanning electron microscope was used to characterize
the interfacial adhesion.
Um die besonderen Eigenschaften von Holzmehl in Kombination mit Kunststoff bei konventionellen Plattenpressverfahren
voll auszunutzen, wurde ein Nassverfahren zur Herstellung von Verbundwerkstoffen aus Polypropylen und im
Dampfdruckverfahren erzeugtem Holzmehl aus Weihrauchkieferschwachholz entwickelt. Holzmehl-Polypropylen-Verbundstoffe
wurden nach einem TAPPI-Standardverfahren im Nassverfahren aufgebracht und anschließend verpresst.
Die Variablen, die die Produkteigenschaften beeinflussen können, wurden mittels eines orthogonalen
Versuchsdesigns untersucht. Die Ergebnisse zeigten, dass der E-Modul der Verbundwerkstoffe mit zunehmendem
Holzmehlanteil zunahm, während die Biegefestigkeit abnahm. Mit steigendem Gehalt an Maleinsäureanhydrid
gepfropftem Polypropylen stieg sowohl der E-Modul als auch die Biegefestigkeit der Werkstoffe. Dynamisch-mechanische
Analysen und Differenzialrasterkalorimeter-Messungen gaben einen Einblick in die Struktur dieser Verbundwerkstoffe.
Mittels eines Rasterelektronenmikroskops wurde die Haftung zwischen dem Holz und der Kunststoffmatrix untersucht.
Holz als Roh- und Werkstoff 01/2009; 67(4):449-455. · 0.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Laser-induced breakdown spectroscopy (LIBS) is being proposed more and more as a high-throughput technology to assess the elemental composition of materials. When a specific element is of interest, semiquantification is possible by building a calibration model using the emission line intensity of this element for known samples. However, a unique element has usually more than one emission line, and there are many examples where several emission lines used in combination give dramatically better results than any of the individual variables used alone. With a multivariate approach, models can be constructed that take into account all the emission lines related to a specific element; therefore more robust models can be developed. In this work, chemometric methods such as principal component analysis and partial least squares are proposed to resolve and extract useful information from the LIBS spectral data collected on biological materials.
[Show abstract][Hide abstract] ABSTRACT: Research has already shown that extraction of valuable hemicellulose-rich streams is a viable option for revenue generation in the pulp and paper industries. Applying this value prior to pulping concept to the composite panel industry is a natural extension. If an extraction of hemicellulose is accomplished under the right conditions, a non-trivial amount of chemicals can be generated while leaving the woody substrate structurally intact for production to traditional products, such as oriented strand board (OSB). This research studied the effects of hemicellulose removal by hot water extraction on softwood OSB wood flakes and focused on changes that occurred in the physical and chemical properties of the wood flakes and liquid hydrolysates during extraction. Three reaction temperatures (120, 140, 160°C) and three isothermal hold times (20, 40, 60 min) were investigated. Results indicated that the extraction of hemicellulose in quantifiable levels begins at 120°C and 40 min and cellulose extraction begins at 140°C, 40 min. The level of extraction of lignocellulosic materials, the decrease of wood flake thickness, and the acidity of the recovered hydrolysates all increase with increases in extraction severity. The most promising results in regards to industrial implementation of hemicellulose extraction occur at a temperature of 140°C.
CLEAN - Soil Air Water 07/2008; 36(8):674 - 681. · 2.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fourier transform infrared (FTIR) spectroscopic imaging was used to study the initial diffusion of different solvents in cellulose
acetate butyrate (CAB) films containing different amounts of acetyl and butyryl substituents. Different solvents and solvent/non-solvent
mixtures were also studied. The FTIR imaging system allowed acquisition of sequential images of the CAB films as solvent penetration
proceeded without disturbing the system. The interface between the non-swollen polymer and the initial swelling front could
be identified using multivariate data analysis tools. For a series of ketone solvents the initial diffusion coefficients and
diffusion rates could be quantified and were found to be related to the polar and hydrogen interaction parameters in the Hansen
solubility parameters of the solvents. For the solvent/non-solvent system the initial diffusion rate decreased less than linearly
with the weight-percent of non-solvent present in the solution, which probably was due to the swelling characteristic of the
non-solvent. For a given solvent, increasing the butyryl content of the CAB increased the initial diffusion rate. Increasing
the butyryl content from 17wt.% butyryl to 37wt.% butyryl produced a considerably larger increase in initial diffusion rate
compared to an increase in butyryl content from 37wt.% to 50wt.% butyryl.
[Show abstract][Hide abstract] ABSTRACT: Optimal locations for biomass facilities that use mill residues are identified for 13 southern U.S. states. The Biomass Site Assessment Tool (BioSAT) model is used to identify the top 20 locations for 13 southern U.S. states. The trucking cost model of BioSAT is used with Timber Mart South 2009 price data to estimate the total cost, average cost, and marginal costs for biomass facilities that use mill residues for up to 1.5 million dry tons of annual consumption. Demand locations are based on the U.S. Census Bureau zip code tabulation areas (ZCTA). There are 9,353 zip code tabulation areas (ZCTA) in the 13-state study region. Demand point location based on a ZCTA offers an improvement in truck cost estimates when compared to demand point location based on a county centroid. The top 20 ZCTAs in the study region are located in south Mississippi, southeast Georgia, southeast Oklahoma, southwest Alabama, and east Texas. Costs in these areas range from $25 to $38 per dry ton for up to 1.5 million annual dry tons. Additional research on BioSAT is forthcoming for 33 eastern U.S. states. These studies will include more types of woody and agricultural biomass (e.g., logging residues, pulpwood, corn stover, etc.). Additional cost models for transportation such as truck combinations with rail and barge will be components of BioSAT.
In: McWilliams, Will: Moisen, Gretchen, Czaplewski, Ray, comps. 2008. 2008 Forest Inventory and Analysis (FIA) Symposium Park City, UT. Proc. RMRS-P-56CD. Fort Collins, CO: USDA, Forest Service, Rocky Mountain Research Station. 01/2008;