Effect of Compression Wood on Leaching and Fixation of CCA-C Treated Red Pine

In this study, we investigated the effect of compression wood on the release rate of chromium, copper, and arsenic elements from red pine (Pinus resinosa Ait.) and the rate of fixation of hexavalent chromium in the wood. Wood blocks from red pine, some containing compression wood and some with normal wood, were treated with a 1.0% CCA-C solution and then allowed to fix at 23°C ± 2 (74°F ± 4) for 0, 6, 24, 48, 96, 192, and 336 h. After each fixation period, sets of blocks removed from the conditioning room were subjected to 336 h of leaching. The percentage of hexavalent chromium reduced to the trivalent state was determined for solution pressed from matched sets of blocks. The blocks containing compression wood released significantly less chromium and copper elements. For chromium, the biggest effect was seen after the 192- and 336-h fixation periods. In the normal wood blocks fixed for 336 h, the average chromium release rate after 6 h of leaching was almost five times greater than that of the compression wood blocks. Copper and arsenic release was also affected by compression wood, but for these two elements, the effect diminished during the later stages of fixation. A higher percentage of hexavalent chromium was reduced to trivalent chromium in compression wood compared with that in normal wood after most fixation periods, and this difference was significant after 0, 48, 96, and 192 h

Weatherability and Leach Resistance of Wood Impregnated with Nano-Zinc Oxide

Southern pine specimens vacuum-treated with nano-zinc oxide (nano-ZnO) dispersions were evaluated for leach resistance and UV protection. Virtually, no leaching occurred in any of the nano-ZnO–treated specimens in a laboratory leach test, even at the highest retention of 13 kg/m3. However, specimens treated with high concentrations of nano-ZnO showed 58–65% chemical depletion after 12 months of outdoor exposure. Protection from UV damage after 12 months exposure is visibly obvious on both exposed and unexposed surfaces compared to untreated controls. Graying was markedly diminished, although checking occurred in all specimens. Nano-zinc oxide treatment at a concentration of 2.5% or greater provided substantial resistance to water absorption following 12 months of outdoor exposure compared to untreated and unweathered southern pine. We conclude that nano-zinc oxide can be utilized in new wood preservative formulations to impart resistance to leaching, water absorption and UV damage of wood

Chemical and Biological Remediation of CCA-Treated Waste Wood

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。Since common disposal options such as landfill and incineration for chromated copper arsenate CCA-treated waste wood are becoming more unacceptable, there is a need to develop alternative technologies to use CCA-treated waste wood as a potential fiber source. Chemical and biological remediations of CCA-treated waste wood are thought to be environmentally acceptable. This paper reviews the ability of chemical and microbial processes to remove chromium, copper, and arsenic elements from CCA-treated waste wood. Some researchers have explored chemical extraction using various inorganic and organic acids. Depending on several parameters, such as concentration, time, temperature, pH, particle size, etc., chemical extraction was found to be effective in removing much of the CCA from treated wood or contaminated wastes. On the other hand, bioremediation using bacteria and fungi is another possible method for removal of heavy metals from treated wood since some bacteria and fungi are extremely tolerant to toxic metals. Some copper tolerant fungi can remove some of the arsenic and chromium as well as copper. In addition, some metal leaching bacteria can be used effectively to extract concentrated heavy metal ions from treated woo

BORON-BASED WOOD PRESERVATIVES AND THEIR USES

Wood is degraded biologically because organisms recognize the carbohydrate polymers in the cell wall of wood and have very specific enzyme systems capable of hydrolyzing these polymers into digestible units. Biodegradation of the cell wall matrix and the high molecular weight cellulose weakens the fiber cell. Wood cell wall components also undergo degradation through oxidation, hydrolysis, and dehydration reactions. The reason for fungi to attack wood is to obtain sufficient carbon and nitrogen for survival. Wood degrading fungi produce extracellular enzymes which are shown to have an important role in biochemical and chemical reactions involved in wood degradation. In addition to those enzymes, low molecular weight molecules such as organic acids facilitate lignin degradation

Heat Modification of Wood: Chemical Properties and Resistance to Mold and Decay Fungi

The resistance of heat modified sugi (Crvptomeria japonica D) sapwood against mold and decay fungi was evaluated under laboratory conditions Wood specimens were subjected to heat treatment at 180 C for 2 and 4 hours and at 220 C for 2 hours Changes in lignin and polysaccharide weight percent composition, solubility, and pH of heat-modified specimens were determined Treatment at 220 C for 2 hours decreased wood polysaccharide content Heat treatment slightly increased resistance against Rhizopus javanicus and Gliocladium (Trichoderma) wrens but not against Aspergillus rage, The highest temperature used increased resistance to decay by the white-rot fungus Trametes versicolor but mass losses with the brown-rot fungus Fomitopsis palustris were higher than those with T versicolo

Heat Modification of Wood: Chemical Properties and Resistance to Mold and Decay Fungi

The resistance of heat modified sugi (Crvptomeria japonica D) sapwood against mold and decay fungi was evaluated under laboratory conditions Wood specimens were subjected to heat treatment at 180 C for 2 and 4 hours and at 220 C for 2 hours Changes in lignin and polysaccharide weight percent composition, solubility, and pH of heat-modified specimens were determined Treatment at 220 C for 2 hours decreased wood polysaccharide content Heat treatment slightly increased resistance against Rhizopus javanicus and Gliocladium (Trichoderma) wrens but not against Aspergillus rage, The highest temperature used increased resistance to decay by the white-rot fungus Trametes versicolor but mass losses with the brown-rot fungus Fomitopsis palustris were higher than those with T versicolo

Anatomical structure and degradation characteristics of bioincised oriental spruce wood by Physisporinus vitreus

This study is a part of a Ph.D. study at Istanbul University-Cerrahpasa, Istanbul, Turkey, and financially supported by The Scientific and Technological Research Council of Turkey (TUBITAK) (Project No: 115O934) and The Coordination Unit for Scientific Research Projects (BAP), Istanbul University-Cerrahpasa (Project No: 24880).Even though oriental spruce (Picea orientalis L.), a common species in the East Black Sea Region of Turkey, is used in a wide range of applications, its wood has low permeability. This study investigated the degradation effects of the bioincising process to improve its treatability with wood preservatives on the microstructure of oriental spruce wood. Test samples were previously subjected to bioincising by Physisporinus vitreus fungus, and the bioincised samples were examined under both a light microscope and scanning electron microscope to observe the effects of the bioincising on the anatomical properties. Bordered pits on the longitudinal tracheid radial walls, piceoid-type cross-field pits, ray tracheid bordered pits, and ray tracheid cell walls in the earlywood and latewood regions within a growth ring were particularly subjected to anatomical evaluations. In the study, the degradation intensity in the samples after the bioincising was well correlated with the weight losses occurred. Splits and factures were determined on the tori of bordered pits on the tracheid cell walls while tears and cracks were present on the pit apertures. The results also show that P. vitreus, a Type I and II white rot fungus, may cause a Type I soft rot