Research Articles

Fly ash was collected as a byproduct from the processing of southern pine wood chips in a pilot-scale biomass gasifier. General properties of the fly ash were determined to assess its applicability as a soil amendment. Its alkaline pH (9.5) and high concentrations of Ca, K, and Mg suggest that it could be used as both a liming agent and a fertilizer. The concentrations of most heavy metals in all ash samples in this study were lower than the ecological soil screening levels used as a guideline. A sequential extraction analysis was used to evaluate the bioavailability of selected nutrient elements and pollutant heavy metals in the fly ash. Most nutrient elements were present in exchangeable/acid extractable and easily reducible fractions. The heavy metals were generally less bioavailable, thus ameliorating concerns for land application of fly ash, with or without prior combustion. Comparison of sequential extraction test results for all of the ashes indicated that the conditions experienced during gasification, such as high processing temperatures, impacted both the total heavy metal concentrations and their potential bioavailabilities.

Preliminary tests of a new hydrogen peroxide bleaching procedure for mechanical pulps were performed in a bleaching medium comprised of water and an alcohol, which is characterized by good miscibility with water, poor solvency for hemicelluloses, and good solvency for lignin. As compared with a conventional bleaching method, this modified process is aimed at reducing the removal of hemicelluloses while moderately increasing the dissolution of lignin. Results showed that an aspen CTMP pulp can be bleached to a target brightness with less bleaching chemicals and/or with a higher pulp yield. The laboratory studies demonstrate that this new bleaching process offers substantially enhanced efficiency and selectivity over the conventional peroxide bleaching. Overall, the brightness increased by about 5 ISO units for a given peroxide consumption and the yield increased by 2 to 3 percent at the same target brightness.

Trees in two provenance-progeny experimental sites of Pinus brutia Ten. were sampled to study variation in wood density and its components among and within six populations and to estimate heritability of wood density and ring components. Wood increment cores (12 mm thick) were collected from 29-year-old trees at breast height. A total of 1023 wood strips were scanned with the X-ray densitometry technique. There were significant differences among populations and among families (within populations) in all the characters studied. Murtbeli (M) population from the middle altitude (486 m asl) had the highest values in both ring-area-weighted density and late wood proportion (500 ± 2.7 kg/ m3 and 49 ± 0.3 %, respectively), whereas Hacibekar (H) population from the highest altitude (1032 m asl) exhibited the lowest values (468 ± 3.0 kg/ m3, 42 ± 0.3 %). Relatively high heritability values (hi2 between 0.45 and 0.74; hhs2 between 0.68 and 0.80) for investigated characters (except latewood density) suggest that these characteristics are under moderate to strong genetic control, and thus, by selecting populations (and families within populations) having high wood density, genetic improvement can be achieved in P. brutia. Correlations between wood density and other growth traits have indicated that simultaneous selection of desired genotypes for most of the wood density components is possible for the species. Latewood percentage and earlywood density present an optimal target for selection to improve wood density.

Experimental binderless particleboards were made from various sizes of Rhizophora spp. particles. The experimental samples were made by cold pressing the particles to a target density of 1 gm/cm3. The internal bond strength and dimensional stability of the disks were evaluated based on Japanese standards. The experimental results showed that the internal bond strength and dimensional stability of the samples were enhanced as the particle size decreased. The microstructure of samples was investigated by field emission scanning electron microscopy (FE-SEM coupled with energy dispersive X-ray analysis (EDXA). An X-ray diffraction (XRD) procedure was used to study the crystalline structure of binderless particleboard samples. .

A novel reaction route was proposed from 5-hydroxymethylfuran-2- carbaldehyde (HMFCA) to 2-hydroxy-5-methylene-2,5-dihydro-furan-2-carbaldehyde (HMDFC) on the basis of the mechanism previously offered by Horvat, to account for the formation mechanism of levulinic acid. The probabilities of the two mechanisms were compared by Gaussian 03 software. It was found that the conversion from HMFCA to HMDFC in the newly deduced mechanism has a lower net energy requirement than that in the original mechanism, and thus should be more preferable. The mechanism indicates that HMFCA is initially protonized by H+ addition at the position 5 of the furan ring, and then combines with OH-, thereby completing the hydration process after isomerization. Finally, an H2O molecule is released, forming the intended intermediate product of HMDFC.

This study described a process of making ultra-low density fiberboard (ULDF) and investigated the properties of samples of ultra-low density fibreboard made from wood fiber using a liquid frothing approach. The fiberboard had a density of 56.3 kg/m3 and a layered cross-linked interior structure. Density profiles showed a relatively high density in the surface layers and low density in the core layer. The results showed that the fiberboard had an internal bond strength of 0.15 MPa, a modulus of rupture of 0.70 MPa, a modulus of elasticity of 8.91 MPa, and a compressive strength of 0.17 MPa at 10% deformation. Thickness swelling after 24 hours water immersion was 0.57%. It had a low thermal conductivity of 0.035 W/mK, and a high sound reduction coefficient of 0.67. Resin was uniformly distributed on the fiber surface. The fiberboard can be used as buffer material for packaging and insulation material for building.

Effects were studied of 200 ppm nano-silver suspension on physical and mechanical properties of particleboard made on an industrial scale at the Iran-Choob Factory. Nano-silver suspension was added to the mat at two levels of 100 and 150 milli-liters/kg dry weight wood particles and compared with control boards; all the other manufacturing variables remained constant. Results showed that hot-pressing time was reduced by 10.9% and 10.1% when 100 and 150 mL of nano-silver were used, respectively. Also, both levels of nano-silver consumption had improving effects on physical and mechanical properties, although in some cases not statistically significant. It can be concluded that heat-transfer property of nano-silver particles in the mat can be used to reduce the hot-press time as the bottle-neck of nearly all wood-composite factories, as well as to reduce the heat gradient and consequently to improve physical and mechanical properties of composite-boards.

The unknown nature of the future requires us to question our decisions and seek reliable methods. The artificial neural networks approach, which is one of the methods used to best predict the future and one that is important for decision making has been thought of, particularly in recent years, as a method with a high level of validity in the fields of economy and financial prediction. The Istanbul Stock Exchange (ISE), at which millions of national and international investors operate, is among the developed stock exchanges of the world. The ISE has the attributes of being appropriate for making predictions regarding financial returns, without any sector differentiation, as a whole. In this study, it was aimed to predict monthly stock yields of 14 different paper companies dealing with the ISE (Istanbul Stock Exchange) by using artificial neural network. Four different variables (the gold price, ISE daily trading volume, exchange rate purchase-sale average, and monthly deposit interest rates by utilizing) and 127 months data were used. Results show that the monthly stock yields of the paper sector can be predicted correctly to account for 95% of the variability of data with the artificial neural network model, and the average absolute percentage failure value was 6.85%.

Ni/CeO2-ZrO2 catalysts were prepared via co-precipitation and characterized by N2 adsorption–desorption, XRD, SEM, and TPR techniques. The effects of reaction temperature, carbon-equivalent space velocity (GC1HSV), and steam-to-carbon ratio (S/C) on the performance of the catalysts for ethanol steam reforming (ESR) were investigated. It was found that the best catalytic performance was obtained over the Ni/Ce0.75Zr0.25 catalyst with GC1HSV=345 h-1 and S/C=9.2. Under these conditions, H2 selectivity reached its highest value of 98% at T=725 °C, and carbon conversion reached 100% at T=825 °C. The performances of Ni/Ce0.75Zr0.25 and Ni/Ce0.5Zr0.5 were also compared at S/C ranging from 2.5 to 9.2. The results showed a higher carbon conversion for the Ni/Ce0.75Zr0.25 catalyst than for Ni/Ce0.5Zr0.5.

Two different agricultural wastes, sunflower stalk and tobacco stalk, were evaluated for the production of xylose, which can be used as a raw material and converted to xylitol, a highly valued product. The objective of the study was to determine the effects of H2SO4 concentration, temperature, and reaction time on the production of sugars (xylose, glucose, and arabinose), and on the reaction by-products (furfural and acetic acid) from sunflower stalk and tobacco stalk and to compare the hydrolysis conditions of these wastes. Since both agricultural wastes had different structures, they had different responses to experimental conditions. Response surface methodology (RSM) was used to optimize the hydrolysis process in order to obtain high xylose yield and selectivity. The optimum reaction temperature, reaction time and acid concentration were 120 oC, 30 min and 4% of acid concentration for sunflower stalk and 133 oC, 27 min and 4.9% of acid concentration for tobacco stalk.