Volume 6 Issue 4

The goal of this study was to survey the feasibility of the biosorption of Reactive Black 5 (RB5) from aqueous solutions using biomass prepared from potato peel waste. Adsorption isotherms were constructed, and the kinetics of dye adsorption were studied. Langmuir and Freundlich isotherms were constructed, and pseudo-first order, pseudo-second order, and modified pseudo-first order kinetic models were studied. Maximum adsorption (85.5%) was observed at a pH of 3, and uptake decreased with increasing pH. The biosorption of RB5 increased with increasing contact time and reached equilibrium after two hours. RB5 removal efficiency decreased with an increase in the initial dye concentration, but the uptake of dye increased. Adsorption data conformed to the Langmuir isotherm model and pseudo-first order kinetics.

Biomass pretreatment by autohydrolysis uses hot-water to extract soluble components from wood prior to converting the woody residuals into paper, wood products, or fuel, etc. Mixed hardwood chips were autohydrolyzed in hot-water at 150, 160, 170, and 180 ºC, for 1 and 2 h. The tradeoff between fermentable sugar yield and caloric value of the residual solids was studied for a process that will be referred to as “value prior to combustion”. The extracted liquid was treated with dilute sulfuric acid to break down sugar oligomers into fermentable monomers. Material balances were performed around autohydrolysis to evaluate the role of temperature and residence time on sugar production and residual solid heating value. The composition (sugars and byproducts) of the extracted liquid was determined. As the autohydrolysis temperature increased, the material balance became less precise, presumably due to more volatile byproducts being formed that were not quantified. More hemicelluloses were extracted from the wood by the hot water extraction process under higher temperature and longer residence time, but a greater degree of sugar degradation was also observed. After hot-water extraction the heating value of the solid residues was higher than the original wood. The total energy content of the residual solid after extraction ranged from 74 to 95% of the original energy content of the feed.

The Young’s modulus and the in-plane shear modulus of medium-density fiberboard (MDF) were obtained by conducting a flexural vibration test under the free-free condition based on Timoshenko’s vibration theory using specimens with various depth/length ratios and performing a subsequent numerical analysis. The results obtained by the experiment and numerical analysis revealed that the Young’s modulus was independent of the specimen configuration. In contrast, the in-plane shear modulus was significantly dependent on the specimen configuration and could not be measured properly based on Timoshenko’s theory when the specimen had a small depth/length ratio. The numerical analysis also revealed that the Poisson’s ratio has a significant influence on the measurement of shear modulus as well as the specimen configuration. A statistical analysis on the results experimentally obtained suggested that the length of the specimen must be less than 7.5 times the depth to measure the in-plane shear modulus appropriately.

Experimental eight-ply laminated veneer lumbers (LVLs) from rotary peeled I-214 (Populus x Euramericana) and I-77/51 (Populus deltoides)fast growing hybrid poplar clones were successfully manufactured using three different press durations (18, 24, and 30 min) with a melamine urea formaldehyde (MUF) adhesive. The effect of press durations on LVLs’ selected physical, mechanical, and combustibility characteristics were determined. The results showed that press duration affected dimensional stability (thickness swelling and water absorption), modulus of rupture, and/or compression strength parallel to grain, depending on the clone types. Improvement in dimensional stability and some mechanical properties of LVLs can be achieved by proper curing of the MUF adhesive. On the other hand, the press durations did not affect oven-dry densities, modulus of elasticity, and the combustibility (weight loss after completion of the test). For improved physical and mechanical properties, up to a 30 min press duration can be recommended. This is necessary for LVLs when they are to be used under conditions where water and/or high humidity is present.

In this study we analyze changes in United States imports of wood furniture over the 39-year period from 1972 to 2010. In 1972, Canada and the former Yugoslavia were the most important sources of imported wood furniture, and Europe accounted for nearly 60 percent of total imports. Shipments of low-cost wood furniture from Taiwan started to increase in the 1970s, and by 1978, Taiwan was the most important source of imported wood furniture. Overall, low-cost sources in Asia displaced Europe in 1987. Taiwan continued to be the most important source until 1994. Canada became the most important source of imported wood furniture from 1994 to 2000 as the Canadian dollar declined in value against the United States dollar. In 2001, China became the most important source of wood furniture imports. More recently furniture imports from an emerging source, Vietnam, have increased dramatically. One reason why Asian manufacturers have been so successful in the U.S. market has been that furniture consumers were influenced mainly by price. By contrast, success in some segments of the U.S.-based furniture industry indicates that models enabling consumers to make styling and pricing decisions also can be competitive.

In this study the effect of different levels of dissolved oxygen tension (d.o.t) on the production of three main components of extracellular cellulases (FPase, CMCase and β-glucosidase) at a fixed agitation speed by Aspergillus terreus was investigated. Growth of A. terreus and cellulase production were modeled based on logistic and Luedeking-Piret equations. The results from the model fit well with the experimental data, confirming that the models were appropriate for describing and representing growth and cellulase production at various d.o.t levels. The models showed that the production of FPase and CMCase were growth-associated processes. Cell growth and cellulase production were approximately two-fold higher in a stirred tank bioreactor compared with a shake-flask culture. At a d.o.t of 55% air saturation, cell growth and cellulase production were higher than at low d.o.t (40% air saturation) or high d.o.t (80% air saturation). The highest activities of FPase (2.33 U ml-1), CMCase (51.10 U ml-1), and β-glucosidase (16.18 U ml-1) were obtained at a d.o.t of 55% air saturation, yielding overall productivities of 19.40, 425.00, and 67.40 U l.h-1, respectively.

This study evaluates the use of steam explosion (SE) as a pre-treatment of Eucalyptus globulus chips, aimed at making this wood suitable as feedstock in biorefineries or alternative processes such as biopulping. Several SE treatments were applied, modifying the following variables: previous hydration of the chips, number of SE cycles, and duration of the first cycle. Chemical composition and structural properties were analyzed after all treatments. Our results show that acetone and hot water extractives contents increased between 1.0% and 6.2% and between 3.6% and 7.1%, respectively, depending on SE operational conditions. Holocellulose content was also observed to decrease (9.4 to 15.6%), while the Klason lignin underwent a slight solubilization. Furthermore, greater water retention capacity and new bigger sized pores were found in the exploded samples. It is reasonable to expect that these changes would facilitate the subsequent implementation of chemical or biological treatments of the cellulose fraction in the biorefinery design.

In previous studies we found significant differences in the suberin content with respect to the bark layer of Quercus suber samples. In this study the monomer composition of suberin from the two bark layers (i.e., back and cork) of three provenances (Extremadura, Castile-la Mancha, and Portugal) was investigated using pyrolysis in the presence of tetramethylammonium hydroxide (TMAH) with gas chromatography-mass spectrometry (GC/MS). The major compounds released were octadec-9-enedioic acid, docosanedioic acid, and 9,10-epoxyocta-decanedioic acid with mean values of 17%, 14.5%, and 11%, respectively. The former is more abundant in back than in cork, and the latter in cork than in back with mean differences, in terms of percentages, between the back and cork of 4.3 ± 0.81 and 2.2 ± 0.52, respectively.

A novel class of hydrogel was prepared by graft copolymerization of acetic acid lignin (AAL) and N-isopropylacrylamide (NIPAAm) in the presence of N,N'-Methylenebisacrylamide (MBAAm) as the crosslinker and H2O2 as the initiator. The impact of AAL content on the hydrogel properties were investigated in terms of their swelling behavior, thermal behavior, and interior morphology. The data showed that these newly synthesized hydrogels were temperature-sensitive. Differential scanning calorimetry (DSC) curves demonstrated that the lower critical solution temperature (LCST) of the lignin-based hydrogels was approximately 31°C. The thermogravimetric analysis (TGA) data revealed that the temperature of rapid decomposition of all the hydrogel samples was within a narrow range of 400 to 410°C. Furthermore, the scanning electron microscopy (SEM) images showed that the pore size of the hydrogel increased with increasing the AAL content.

Norway spruce specimens 50x30x30mm with initially determined ultrasonic characteristics in the longitudinal, radial, and tangential directions were subjected to bio-attacks with the brown-rot fungi Serpula lacrymans, Coniophora puteana,or Gloeophyllum trabeum, and the white-rot fungus Trametes versicolor, respectively. Bio-attacks lasted 4, 8, 12, or 16 weeks. Decreases of the ultrasonic wave velocities (Dc) and the dynamic modulus of elasticity (DMOEd) depended more or less closely on the enlarged degrees of rot in the spruce wood, and as the dynamic modulus of elasticity decreased approx. 1.7 to 2.3 times more than corresponding weights (Dm from 2.01 to 42.35%) or 2.1-3.4 times more than corresponding densities (Dr from 2.42 to 26.63%). Two sample t-test analyses of slopes “a” in the linear regressions Dc or DMOEd = a.(Dm) or a.(Dr) showed that drops of the ultrasonic and elastic characteristics of wood having the brown rot were not influenced by the fungus species. On the other hand, the velocity of ultrasonic waves in the longitudinal direction and the dynamic modulus of elasticity appeared to be suitable for distinguishing the brown rot from the white rot at known decreases of wood density. The anatomical direction of wood was a significant factor only for the white rot, when approx. 2-times higher decrease of the ultrasonic wave velocities was determined in the radial and tangential directions compared to the longitudinal one.