Bark Particles Research Articles

Flash pyrolysis of tar from the pyrolysis of pine bark

A mixture of tar vapours and other gases was obtained by introducing size-separated bark particles into a reactor at 650°C. This mixture was then directed through a second reactor, the temperature of which could be changed. For each temperature, the flow-rate of the mixture was varied from low to high values up to the disappearance of tar at the outlet. Three types of reaction were carried out: (1) second reactor empty, (2) second reactor filled with sand and (3) second reactor filled with dolomite (decarbonated or carbonated). Assuming that tar pyrolysis is a first order reaction, in each instance a curve was constructed of the time necessary for complete pyrolysis of tar versus the reactor temperature. The activation energies were also determined (21.5 kcal mole −1 for the homogeneous reaction, 18.4 kcal mole −1 for the reaction catalysed with sand and 11 kcal mole −1 for the reaction catalysed with dolomite). From these curves, the catalytic efficiencies of sand and decarbonated and carbonated dolomite were evaluated. The gas composition was always measured, which enabled curves to be constructed of the gas calorific value versus the pyrolysis temperature, showing that the use of decarbonated dolomite can increase the calorific value of the gases to a significant extent.

Internal Porosity, Water Availability, and Root Penetration of Pine Bark Particles

Abstract Internal porosity, availability of internally adsorbed water, and root growth within a pine bark particle were studied. Internal pore spaces comprised about 43% to 44% of the volume of a pine bark particle. Scanning electron microscopy (SEM) of Coleus blumei Benth. and Vaccinium ashei Reade showed roots anchored on the exterior surface and developing within the bark particle. Seedling development (Raphanus sativus L.) in water-saturated pieces indicated that internally adsorbed water was available provided that roots developed within the bark particle. The quantity of available water remains to be determined.

Ammonium Adsorption on a Pine-bark Growing Medium

Abstract Pine bark was shown to adsorb 1.5 mg of N/g of bark when NH4 solutions were leached through the bark. Increasing pH of bark increased adsorbed NH4. At pH 3.3, only NH4 was adsorbed to bark particles when a fertilizer solution containing NH4, Ca, K, and Mg was applied. However, adsorption of NH4 and other cations increased as pH was increased from 3.8 to 5.8. These data indicate that 2 types of sites exist for the adsorption of NH4 to pine bark. One site is effective at lower pH; the other is active as pH increases. Daily application of 2.5 cm of water containing 50 ppm NH4 required 20 days for equilibration to occur so as to satisfy all binding sites. Thus, incorporation of NH4 into a pine-bark medium prior to planting may be advisable to prevent low N levels from occurring in the container solution due to NH4 binding when plants are first planted and fertilized.

An experimental laboratory fixed bed study on the atmospheric pressure gasification of poplar bark with steam

AbstractAn experimental study has been made of the gasification of poplar bark particles exposed to a helium/water vapor atmosphere in a fixed‐bed reactor at 873–973 K. with and without silica catalyst. The effect of temperature on gas yields, calorific value and carbon conversion was evaluated for the pyrolytic conversion and steam‐char gasification stages. The kinetics of the production of various gases in catalytic steam‐char reaction has been studied.

Electron microprobe analysis of calcium solution penetration into milled pine bark particles

Abstract Pine bark (Pinus taeda L. and P. elliottii Engelm.) pieces, 2.5 to 5.0 cm diameter, submerged in water became saturated more rapidly in a vacuum than at atmospheric pressure. A test was conducted to determine the extent of Ca solution penetration into smaller milled particles and the effect physical structure of particles has on this process. Particles 2.0–2.8 mm diameter were submerged in a solution of 1000 ppm Ca as Ca(OH)2, placed in desiccators and evacuated to 150 mm Hg of tension. At intervals of 24, 48 and 96 hours samples were removed, freeze‐dried, and cut tangentially to expose the internal phloem. Electron microprobe x‐ray analysis initially showed different Ca concentration in peripheral and central zones and indicated that Ca solution had penetrated the particle and saturation was completed within 96 hours. The progression of Ca penetration was uniform from all edges and indicated that the varied structure of bark tissues did not impede water penetration.

Influence of Initial Moisture Content on the Wettability of a Milled Pine Bark Medium1

Abstract Water absorption curves were developed for air dry peat-vermiculite and pine bark media. Data indicated 70-78% of moisture saturation was attained within 5 days with a peatvermiculite medium while 48 days were required to achieve 58-70% saturation with a milled pine bark medium. Increased water absorption of pine bark after 10 days of wetting suggested that a threshold moisture level within the bark particles is necessary if water uptake is to be enhanced. The threshold moisture content was established at 35% (wet wt basis).

THE SITE OF PHEROMONE PRODUCTION IN TRYPODENDRON LINEATUM (COLEOPTERA: SCOLYTIDAE): BIO-ASSAY AND HISTOLOGICAL STUDIES OF THE HINDGUT

AbstractBio-assay showed that the pheromone of attractive female Trypodendron lineatum (Oliv.) must be produced in the posterior part of the ileum. Histological studies revealed a layer of secretory cells in the rear part of the ileum and the rectal valve which occur only in feeding adults. The attractive material is produced only when bark and wood particles are present at the site of pheromone production, and the actual production is initiated probably by activity of a female hormone or enzyme.

Comparative Rates of Decomposition in Soil of Wood and Bark Particles of Several Species of Pines

AbstractThe finely‐ground woods and barks of 9 species of pine were allowed to decompose in soils in the presence and absence of additional nitrogen for periods of 63 to 800 days. Carbon dioxide evolution was measured at frequent intervals. The pine species studied were white, shortleaf, loblolly, slash, longleaf, ponderosa, western white, lodgepole, and sugar. An average of 16.2% of the wood carbon was oxidized in 60 days in the absence of extra nitrogen and 16.9% in its presence. The corresponding values for the barks were 8.7 and 8.6. The wood species showed variations in CO2 evolution during the 60‐day period, ranging from 8% for sugar pine to 51% for shortleaf pine. The variations for the barks were between 3.0% for white pine and 23.3% for lodgepole pine. Most of the pine woods decomposed somewhat more rapidly than did the other softwoods previously studied, but not nearly so rapidly as did the hardwoods. The pine barks are oxidized at about the same slow rate as are the other softwood barks.

Comparative Rates of Decomposition in Soil of Wood and Bark Particles of Several Hardwood Species

AbstractThe decomposition rates of the finely‐ground woods and barks of 9 species of hardwoods were determined in the laboratory at two nitrogen levels. Carbon dioxide was measured at frequent intervals during periods varying from 72 to 580 days. The following species were studied: black oak, white oak, red oak, post oak, hickory, red gum, yellow poplar, chestnut, and black walnut. During the first 60 days an average of 30.3% of the wood carbon was released as CO2 in the absence of fertilizer nitrogen, and 45.1% was released in its presence; the corresponding values for the barks were 22.4 and 24.5%. The variations in the rates of CO2 release from the woods were not great, but hickory and black walnut barks decomposed much slower than the other barks. The hardwoods were attacked much more readily than most of the softwoods used in an earlier study, and consequently more nitrogen was required by the microorganisms that decomposed them. There were no indications that any of these wood products was toxic to the decay organisms.

Comparative Rates of Decomposition in Soil of Wood and Bark Particles of Several Softwood Species

AbstractThe rates of decomposition of 10 kinds of finely‐ground woods and the corresponding barks at two nitrogen levels were determined in the laboratory by measuring CO2 evolution over periods varying from 53 to 800 days. The following species were studied: California incense cedar, cypress, redwood, western larch, eastern hemlock, red fir, white fir, Douglas‐fir, red cedar, and Engleman spruce. The woods and barks of all of these species were considerably more resistant to biological attack than is shortleaf pine sawdust. California incense cedar, cypress, redwood, eastern hemlock, and red cedar, were decomposed to the extent of < 7% during a 2‐month period. The comparative resistance of woods and barks to decay varied for individual species but the average values for the 10 species were similar. Due to the slow rates of decomposition, the soil was able to furnish adequate available nitrogen for maximum rates of decomposition for all of the wood products, and supplemental nitrogen was not needed.