1,721,039 research outputs found
The Content and Mobility of Copper, Chromium and Arsenic in the Soil of a Wood-Preserving Plant Using CCA
No full textRemoval of copper, chromium, and arsenic from CCA-C treated wood by EDTA extraction
No full textEthylenediaminetetracetic acid (EDTA) is one of the most common chelators used to bind the metal ions in extremely stable complexes in heavy metal contaminated soils and thus to remediate such substrates. EDTA forms water soluble complexes with many metal ions and it is used to release the various metals. In this study, EDTA extraction of copper, chromium, and arsenic from chromated copper arsenate (CCA-C) treated wood was evaluated using batch leaching experiments. CCA-treated wood samples were extracted with eight different concentrations of EDTA for 4, 8, 18, and 24 h at room temperature. Exposing CCA-treated chips and sawdust to EDTA extraction enhanced removal of CCA components compared with extraction by deionized water. Grinding CCA-treated wood chips into 40-mesh sawdust provided greater access to and removal of CCA components. Extraction with 1% EDTA solution for 24 h removed 60% copper, 13% chromium, and 25% arsenic from treated chips. EDTA extraction of treated sawdust samples resulted in 93% copper, 36% chromium, and 38% arsenic removal. CCA leaching from treated wood blocks was also evaluated according to modified AWPA E11-99 standard test method of determining the leachability of wood preservatives. Leaching of CCA components from treated wood blocks with 1% EDTA solution for 14 days caused more copper leaching compared to leaching with deionized water. Leaching with 1% EDTA for 14 days removed 53 % copper from the blocks whereas 14% copper was leached from the blocks with deionized water. The results suggest that EDTA extraction removes significant quantities of copper from CCA-treated wood. Thus, EDTA could be important in the remediation of wood waste treated with the newest formulations of organometatic copper compounds and other water-borne wood preservatives containing copper. (C) 2002 Elsevier Ltd. All rights reserved
Combined effect of boron compounds and heat treatments on wood properties: Boron release and decay and termite resistance
No full textThe decay and termite resistance of boric acid (BA)- and di-sodium octoborate tetrahydrate (DOT)-treated sugi sapwood was tested in the context of additional heat treatments at two temperature levels. Heat treatments had no effect on boron release and almost all boron was leached from specimens during a 10-day weathering period. Decay tests with the brown-rot fungus Fomitopsis palustris and the white-rot fungus Trametes versicolor and a 3-week termite resistance test with the subterranean termite Coptotermes formosanus were performed. Heat treatments did not increase the decay resistance of either BA- or DOT-treated specimens against the brown-rot fungus. However, the decay resistance of BA-treated specimens against the same fungus increased after heat treatment at 220 degrees C for 2 h. Heat treatments at 180 degrees C for 4 h and 220 degrees C for 2 h also resulted in increased decay resistance of DOT-treated specimens against T. versicolor. Increased resistance against termite attack was observed only in DOT-treated specimens heated at 180 degrees C for 4 h or at 220 degrees C for 2 h. Accordingly, a synergistic effect between heat and DOT treatments was observed for resistance against white- rot decay and termites
Brief Introduction of a Research Project on the Wood Materials from an Ancient Byzantine Port Unearthed During Drilling for Underground Rail Tunnel in Istanbul
No full textEffects of incising on treatability and leachability of CCA-C-treated eastern hemlock
No full textIncising is used to increase exposed wood surface and improve uptake and penetration of preservative during pressure treatment of refractory species. However, incising may also cause increased leaching of preservative when the wood is placed in service. This study compared the rate of leaching from unincised eastern hemlock to that of wood that had been incised to two depths and with two density patterns. Incising greatly increased both the penetration and retention of preservative in the incised wood compared to unincised wood. Doubling the depth of the incisions further improved retention and penetration, but doubling the density of the incisions appeared to benefit primarily the uniformity of preservative penetration. Incising did not increase the percentage of copper, chromium, or arsenic that leached from the wood. This study indicates that the benefits of incising can be obtained without the risk of increased leaching
Leachability of boron from wood treated with natural and semi-synthetic polymers and calcium precipitating agent
No full textEffect of compression wood on leaching and fixation of CCA-C treated red pine
No full textIn 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 degreesC +/- 2 (74 degreesF +/- 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
Decay and termite resistance of medium density fiberboard (MDF) made from different wood species
No full textMedium density fiberboard (MDF) production worldwide is increasing due to the development of new manufacturing technologies. As a result, MDF products are increasingly utilized in traditional wood applications that require fungal and insect resistance. This study evaluated the ability of white and brown rot fungi and termites to decompose MDF consisting of different wood species by measuring weight loss. Furnish in the boards was prepared from heart and sapwood portions of pine (Pinus nigra Arnold var. pallasiana), beech (Fagus orientalis Lipsky), and European oak (Quercus robur L.) species. Fungal decay resistance tests were performed according to ASTM D 2017-81 standard method using two brown-rot fungi, Gloeophyllum trabeum (Pers. ex Fr.) Murr. (Mad 617), Postia placenta (Fries) M. Larsen et Lombard (Mad 698), and one white-rot fungus, Trametes versicolor (L. ex Ft.) Pilat (Mad 697). MDF and wood specimens were also bioassayed against the eastern subterranean termite, Reticulitermes flavipes (Kollar) in order to determine termite resistance of the specimens. MDF specimens containing oak and mixed furnish demonstrated increased durability against decay fungi. Only pine, oak, and mixed MDF specimens met the 25% or less weight loss limit to be classified resistant according to ASTM D 2017-81 standard method. Overall, MDF specimens made from oak showed better performance than oak solid wood specimens. Accelerated aging according to ASTM D 1037-96a standard method before fungal bioassay decreased fungal resistance of the specimens. In contrast to the fungal bioassay, MDF specimens made from beech and mixed furnish showed decreased weight losses from termite attack after 4 weeks. However, none of the MDF specimens were resistant to termite attack. In severe conditions, the MDFs may require the incorporation of chemical biocides prior to board production for increasing the resistance of MDF to termite attack. (C) 2002 Elsevier Science Ltd. All rights reserved
Development and application of colorimetric microassay for determining boron-containing compounds
No full textThis paper describes the development of a microassay for boron and the application of this microassay for evaluating leachability of boron by post-treatment of southern pine with the calcium precipitating agent NHA (N'N-napthaloylhydroxylamine). The microassay method for quantitative estimation of boron content in treated wood and leachates is a microadaptation of the colorimetric azomethine-H method. The primary advantages of this microassay method are that it uses fewer reagents, uses smaller sample volumes, and conserves time for analysis when a large number of tests are required. Wood blocks were treated with boric acid, disodium octaborate tetrahydrate (DOT), and NHA solutions at several concentrations. Boron leaching performance was evaluated on the blocks using AWPA E 11-97 standard method. Blocks treated sequentially with DOT and then with 0.5 or 1.0 percent NHA solutions showed similar to30% less boron leaching, whereas similar treatment with boric acid and 0.1% NHA solutions did not enhance boron retention compared with the blocks treated with only boric acid. We conclude that precipitation of NHA at higher concentrations decreases or limits boron leaching
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