S. Nami Kartal

Removal of copper, chromium, and arsenic from CCA-C treated wood by EDTA extraction ☆

Ethylenediaminetetracetic 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 organometalic copper compounds and other water-borne wood preservatives containing copper.

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.

Decay and termite resistance of medium density fiberboard (MDF) made from different wood species

Medium 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.

Bioremediation of CCA-treated wood by brown-rot fungi Fomitopsis palustris, Coniophora puteana, and Laetiporus sulphureus

This study evaluated oxalic acid accumulation and bioremediation of chromated copper arsenate (CCA)-treated wood by three brown-rot fungi Fomitopsis palustris, Coniophora puteana, and Laetiporus sulphureus. The fungi were first cultivated in a fermentation broth to accumulate oxalic acid. Bioremediation of CCA-treated wood was then carried out by leaching of heavy metals with oxalic acid over a 10-day fermentation period. Higher amounts of oxalic acid were produced by F. palustris and L. sulphureus compared with C. puteana. After 10-day fermentation, oxalic acid accumulation reached 4.2 g/l and 3.2 g/l for these fungi, respectively. Fomitopsis palustris and L. sulphureus exposed to CCA-treated sawdust for 10 days showed a decrease in arsenic of 100% and 85%, respectively; however, C. puteana remediation removed only 18% arsenic from CCA-treated sawdust. Likewise, chromium removal in F. palustris and L. sulphureus remediation processes was higher than those for C. puteana. This was attributed to low oxalic acid accumulation. These results suggest that F. palustris and L. sulphureus remediation processes can remove inorganic metal compounds via oxalic acid production by increasing the acidity of the substrate and increasing the solubility of the metals.

Effect of essential oil compounds and plant extracts on decay and termite resistance of wood

Essential oils and their derivatives have a long history of safe usage as antimicrobial agents in food industry. In this study various essential oils and extracts from plants were screened for their ability to inhibit wood decay and termite attack in laboratory decay and termite resistance tests using treated wood specimens. In the laboratory decay resistance tests, wood specimens treated with essential oil compounds were subjected to brown-rot fungus, Tyromyces palustris, and white-rot fungus, Trametes versicolor for three months. The specimens were also subjected to termite attack by subterranean termites, Coptotermes formosanus for three weeks in laboratory conditions. The formulation with cinnamaldehyde (DF3) was found to be effective against both the brown-rot and white-rot fungi used in the study. However, the formulation with cinnamic acid (DF8) was able to protect wood specimens against only the white rot fungus and about 50% mass loss occurred in the specimens subjected to the brown-rot fungus. The mass losses in the wood specimens treated with cassia oil containing formulation (DF4) showed that cassia oil was effective against both fungi. The wood tar oil and dodecanal compounds also inhibited fungal decay in the specimens. The wood specimens treated with the formulations used in termite resistance tests were more resistant against the termites when compared to specimens treated with the formulations in decay resistance tests. Even after severe weathering process, treated wood specimens showed resistance against the subterranean termites. Results suggest that essential oils and plant extracts might be important to develop new wood preservatives that are less harmful to the environment and humans than recently available ones. Zusammenfassung In der Nahrungsmittelindustrie werden ätherische Öle und deren Derivate bereits seit langem als sichere antimikrobielle Mittel eingesetzt. In dieser Studie wurde in Laborprüfungen anhand behandelter Holzproben untersucht, inwieweit sich verschiedene ätherische Öle und Pflanzenextrakte zur Hemmung von Holzfäule und Termitenbefall eignen. In Laborprüfungen zur Fäuleresistenz wurden die Holzproben mit ätherischen Ölen behandelt und für drei Monate dem Braunfäulepilz Tyromyces palustris sowie dem Weissfäulepilz Trametes versicolor ausgesetzt. Die Holzproben wurden ebenfalls einem dreiwöchigen Termitenbefall unter Laborbedingungen ausgesetzt. Dabei wurden die Bodentermiten Coptotermes formosanus verwendet. Die Rezeptur mit Zimtaldehyd (DF3) erwies sich sowohl gegen Braun- als auch gegen Weissfäulepilze als wirksam. Dagegen bot die Rezeptur mit Zimtsäure (DF8) nur einen Schutz gegen Weissfäulepilze. Bei Braunfäulepilzen ausgesetzten Proben war ein Masseverlust von 50% zu verzeichnen. Die Masseverluste in den Holzproben, die mit Rezepturen, die Kassiaöl (DF4) enthielten, behandelt wurden, zeigten, dass Kassiaöl gegen beide Pilze wirksam ist. Holzteeröl und Dodecanal-Verbindungen hemmten ebenfalls den Pilzbefall in den Proben. Die Holzproben, die mit den in Termitenresistenzversuchen verwendeten Rezepturen behandelt wurden, zeigten sich gegen Termitenbefall resistenter als Proben, die mit den in Fäuleresistenzversuchen verwendeten Rezepturen behandelt wurden. Sogar nach starker Bewitterung erwiesen sich die behandelten Proben als resistent gegen Bodentermiten. Die Ergebnisse zeigen, dass ätherische Öle und Pflanzenextrakte bei der Entwicklung neuer Holzschutzmittel, die für die Umwelt und den Menschen weniger schädlich als die bereits erhältlichen Mittel sind, eine wichtige Rolle spielen können.

Laboratory evaluation of boron-containing quaternary ammonia compound, didecyl dimethyl ammonium tetrafluoroborate (DBF) for control of decay and termite attack and fungal staining of wood

This study evaluates the decay and termite resistance of wood treated with didecyl dimethyl ammonium tetrafluoroborate (DBF), a recently developed quaternary ammonia compound containing boron. Laboratory decay resistance tests were performed using brown-rot fungus, Fomitopsis palustris and white-rot fungus, Trametes versicolor. Treated wood specimens were also subjected a 3-week-termite resistance test using subterranean termites, Coptotermes formosanus. Decay resistance tests showed that wood specimens treated with 0.5 and 1.0% DBF solutions were well protected against both fungi even after a 10-day severe leaching process, suggesting the adequate fixation of DBF in wood. DBF treatment at 0.1% concentration was efficient against subterranean termites, Coptotermes formosanus Shiraki based on mass losses in both leached and unleached wood specimens. The ability of DBF to inhibit discolorations by selected mold and stain fungi was also screened in laboratory conditions. DBF at the highest concentration level (1%) provided limited protection against mold and staining fungi tested, however, it was effective for only short-term protection (1 or 2 weeks) at lower concentrations. These results suggest that DBF is promising to protect wood to be used outdoors against both fungal decay and termite attack however field tests are needed to observe the performance of DBF-treated wood in ground contact. Zusammenfassung Diese Studie bewertet die Fäulnis- und Termitenresistenz von Holz, das mit der neu entwickelten quaternären, borhaltigen Ammoniakverbindung, Didecyl-Dimethyl-Ammoniumtetrafluoroborat, behandelt wurde. Dazu wurden Laborversuche mit Braunfäulepilzen Fomitopsis palustris sowie Weissfäulepilzen Trametes versicolor durchgeführt. Die behandelten Holzproben wurden ebenfalls einem dreiwöchigen Termitenbefall ausgesetzt. Dabei wurden die Bodentermiten Coptotermes formosanus verwendet. Es zeigte sich, dass die mit einer 0,5 und 1,0 % DBF-Lösung behandelten Holzproben nach einem zehntägigen Auswaschversuch gut gegen die beiden Pilzarten geschützt waren. Dies ist ein Hinweis auf eine ausreichende Fixierung von DBF im Holz. Geht man von den Masseverlusten in sowohl ausgewaschenen als auch nicht ausgewaschenen Holzproben aus, erwies sich eine Behandlung mit einer 0.1% DBF –Lösung auch gegen die Bodentermiten Coptotermes formosanus Shiraki als wirksam. Die Eignung von DBF zur Verhinderung von Verfärbungen durch ausgewählte Schimmel- und Verfärbungspilze wurde ebenfalls in Laborversuchen untersucht. Dabei wurde festgestellt, dass hochkonzentriertes DBF (1%) einen gewissen Schutz gegen die getesteten Schimmel- und Verfärbungspilze lieferte, jedoch bei niedrigeren Konzentrationen nur kurzfristig (1 oder 2 Wochen) wirksam war.Diese Ergebnisse zeigen, dass DBF zum Schutz gegen Pilz- und Termitenbefall von im Aussenbereich verwendetem Holz Erfolg versprechend ist. Allerdings muss die Wirksamkeit bei Holz in Erdkontakt noch in Feldversuchen näher untersucht werden.

Fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds and common fire retardants

In this study, the fire performance and decay resistance of solid wood and plywood treated with quaternary ammonia compounds (didecyl dimethyl ammonium chloride (DDAC) and didecyl dimethyl ammonium tetrafluoroborate (DBF)) were compared with the performance of untreated control specimens and specimens treated with common fire retardants ((monoammonium phosphate (MAP), diammonium phosphate (DAP) and ammonium sulphate (AS)). Test specimens were treated with 1% and 4% (% m/v) aqueous solutions of the chemicals. The fire performance tests were the fire tube test (ASTM E 69) which measures mass losses in the specimens and the cone calorimeter test (ASTM E 1354) which measures mass loss, heat release rate, time for sustained ignition, effective heat of combustion, and specific extinction area. The results from the cone calorimeter tests were used to estimate the flame spread index (FSI) in the Steiner tunnel test (ASTM E 84). Heat release rates of the specimens treated with MAP, DAP, and AS were lower than those of both DDAC and DBF-treated specimens and the untreated control specimens. Compared with the untreated specimens, higher heat release rates were observed for the specimens treated with the quaternary ammonia compounds, DDAC and DBF. The estimates for the FSI for DDAC and DBF were for values equal to or higher than for the untreated control specimens. At higher concentration levels, MAP, DAP and AS were effective in decreasing initial contribution of heat release to potential fire. Decay resistance tests were done according to AWPA E 10 standard method using one brown-rot fungus and one white rot-fungus. Decay resistance tests revealed that solid wood specimens treated with DDAC and DBF showed resistance against the fungi tested, however, MAP, DAP and AS did not provide complete protection. While DBF and DDAC increased resistance of plywood specimens, high mass losses in plywood specimens treated with MAP, DAP and AS were obtained.ZusammenfassungIn dieser Studie wurden das Brandverhalten und die Fäuleresistenz von mit quaternären Ammoniumverbindungen (Didecyl-Dimethyl-Ammoniumchlorid (DDAC) und Didecyl-Imethyl-Ammonium-Tetrafluoroborat (DBF)) imprägniertem Massivholz und Sperrholz verglichen mit dem Verhalten von unbehandelten Kontrollproben sowie Proben, die mit üblichen Feuerschutzmitteln (Monoammoniumphosphat (MAP), Diammoniumphosphat (DAP) und Ammoniumsulphat (AS)) imprägniert wurden. Die Prüfkörper wurden mit 1% und 4% wässrigen Lösungen der Chemikalien imprägniert. Durchgeführt wurden die Prüfung mit dem Brennrohr nach ASTM E 69, bei der die Masseverluste in den Prüfkörpern bestimmt werden, und die Cone-Calorimeter-Prüfung nach ASTM E 1354, bei der die Masseverluste, die Wärmefreisetzungsrate, der Entzündungszeitpunkt, die Gesamtwärmefreisetzung und die spezifische Rauchentwicklung bestimmt werden. Die Ergebnisse der Cone-Calorimeter-Prüfungen dienten zur Bestimmung des Flammenausbreitungsindex (FSI) im Steiner-Tunnel-Test nach ASTM E 84. Die Wärmefreisetzungsrate der mit MAP, DAP und AS imprägnierten Proben war niedriger als die der mit DDAC bzw. mit DBF imprägnierten Proben als auch der unbehandelten Kontrollproben. Die Wärmefreisetzungsraten der mit den quaternären Ammoniumverbindungen DDAC und DBF imprägnierten Proben waren höher als die der unbehandelten Proben. Der Flammenausbreitungsindex (FSI) der mit DDAC und DBF behandelten Proben war gleich oder höher dem der unbehandelten Kontrollproben. Durch Behandlung mit höheren Konzentrationen an MAP, DAP und AS konnte die Wärmefreisetzung verzögert werden. Fäuleresistenzversuche wurden gemäß der AWPA E 10 Methode unter Verwendung eines Braunfäule- und eines Weißfäulepilzes durchgeführt. Fäuleresistenzversuche zeigten, dass mit DDAC und DBF behandelte Massivholzproben gegen die beiden Pilze resistent waren, während MAP, DAP und AS keinen Komplettschutz boten. Während DBF und DDAC die Resistenz der Sperrholzproben erhöhten, zeigten sich bei den mit MAP, DAP und AS behandelten Sperrholzproben hohe Masseverluste.

Strength, decay and termite resistance of oriented kenaf fiberboards

The development of oriented fiberboards made from kenaf (Hibiscus cannabinus L.) and their suitability as a construction material has been investigated. Three different types of boards consisting of five layers with individual orientations were prepared using a combination of low molecular weight and high molecular weight phenol-formaldehyde (PF) resin for impregnation and adhesion purposes. Additional boards with the same structure were prepared using high molecular weight PF resin only. The mechanical properties of the boards have been examined as well as their resistance against fungal decay and termite attack. All kenaf fiberboards showed elevated mechanical properties compared with medium-density fiberboard made from wood fibers, and showed increased decay and termite resistance. Differences in the decay and termite resistance between the board types were caused by the presence of the low molecular weight PF resin for the impregnation of the fibers. No significant difference was found for the mechanical properties. The effect of the PF resin for impregnation was much clearer in fungal decay resistance than for termite resistance; however, fiber orientation had no effect on both decay and termite resistance of the specimens.

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

The resistance of heat-modified sugi (Cryptomeria 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) virens, but not against Aspergillus niger. 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. versicolor.

Comparative effectiveness of two alkylammonium compounds as wood preservatives

This study describes a laboratory evaluation of the efficacy of two alkylammonium compounds [didecyldimethylammonium tetrafluoroborate (DBF) and didecyldimethylammonium chloride (DDAC)] when applied via vacuum impregnation or superficial treatment. Treated wood specimens were tested for their termite and microbial resistance under controlled laboratory conditions. The higher chemical retentions were needed to suppress the feeding by Coptotermes formosanus ≦3% mass loss in the multichoice test than in the no-choice test. The DBF and DDAC retention levels necessary to meet the performance requirement ≦3% mass loss after 12-week fungal exposure varied with wood species. The retention level of 3 kg/m3 for DBF and DDAC was generally high to keep the nondurable wood species free of decay. Although there was no difference between DBF and DDAC in the efficacy against decay and termite attack, the former slightly outperformed the latter as an antimold and antisapstain agent.