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Amines – Promising Wood Preservatives
2002 - IRG/WP 02-30287
Environmental concerns require a new approach in the field of wood protection. Band of many traditional wood preservatives has lead to intense researches for new environmental-friendly wood preservatives. Amines seem to be promising substitutes for classical biocides. Fungicidal and leaching resistance as well as some other chemical analysis of beach and Norway spruce samples treated with ethanolamine, triethanolamine or ammonia was examined. Initially, percentage of fixed nitrogen in samples was established. Afterwards fungicidal resistance against Trametes versicolor and Gloeophyllum trabeum were determined according to the standard laboratory test EN 113. Finally, leaching resistance was performed according to the modified standard EN 1250 procedure. We found out that the mayor part of amines remained in wood and did not evaporate from it. The results indicated that amine treated wood increased resistance against wood decay fungi. On the other hand amine treated wood was not found suitable for use in hazard class 4, since amines were leached out of the wood.
M Humar, F Pohleven, Š Kesnar, P Kalan

Ammoniacal wood preservative for use in non-pressure treatment of spruce and aspen poplar. Part 1
1984 - IRG/WP 3273
End-matched lumber of Picea glauca (Moench)Voss (white spruce) and Populus tremuloides Michx. (aspen poplar) timbers was treated by a thermal diffusion process in open tank treating vessels using an ammoniacal copper-arsenate wood preservative. The process proved technically feasible with respect to controlling the vapourization of ammonia from open tanks during treatment at high temperatures. Treatments of 48 hours or more on unseasoned and partially dried lumber produced net oxide retentions above that required by the Canadian Standard Association CSA-080 wood preservation standard for timber in above ground contact situations. Although preservative penetrations did not meet the penetration requirements (10 mm), of the CSA 080.2 standard for ground contact, five of the seven non-pressure charges on spruce lumber had heartwood penetrations greater than 7 mm in depth. A 24-hour treatment on air-dried spruce had penetrations equivalent to a five-hour vacuum-pressure treatment. Retention was adequate for above-ground exposure
C D Ralph, J K Shields

Natural exposure weathering tests: Their role in the assessment of wood preservative efficacy
1993 - IRG/WP 93-20006
Previous work has demonstrated the potential and usefulness of natural ageing procedures in e evaluation of wood preservative efficacy. This results from the combination of physico-chemical influences and microbiological interactions with both substrate and wood preservative. In this paper, results are presented for a range of biocide types. Discussions are centred on the value of natural exposure weathering tests for preservative efficacy assessment and the importance of biological persistence in the design of effective wood preservatives.
G R Williams, J Brown

Some factors affecting the treatability of spruce roundwood with ammoniacal preservative solutions
1976 - IRG/WP 371
Permeable wood species for use in preservative-treated commodities are becoming depleted in Canada. Spruce can be a convenient replacement for them from local resources provided it can be treated to levels adequate for protection of commodities in ground contact. Basically, two approaches were taken to improve treatability of difficult-to-penetrate softwood species; first, to improve the permeability of wood and second, to improve the penetrating properties of liquids. The first approach involves various means of wood pre-treatment: biological (enzymes, moulds and bacteria including ponding), chemical (removal of extractives), mechanical (precompression) and technological (presteaming of green wood, replacement of water in wood by solvents). There are a great many publications devoted to individual topics mentioned here indicating the significance of the subject. The second approach is the selection of a solvent capable of penetrating into the wood better than conventional solvents for, preservative compounds.
J Rak

Decay resistance of densified ammonia-plasticized stems of oil palm (Elaeis guineensis)
1991 - IRG/WP 3673
When wafers of oil palm stems (Elaeis guineensis) were plasticized with 28% aqueous ammonia and immediately compressed mechanically, the treated material, gained 73% in basic density (average basic density, 0.695 g/cm³), and was highly resistant to decay by wood rot basidiomycetes. Compared with the control specimens (density, 0.403 g/cm³), resistance to decay of the densified specimens by Coriolus versicolor increased by 55%, and Gloeophyllum trabeum, 74%. Fungal decay was significantly correlated with basic density (densification effect) (r-value, between -0.77 and -0.92), mediated in part by a similar pattern of correlation (-0.86) between densification and decaying tissue moisture content. Mass losses of specimens which were plasticized but not subsequently densified, did not differ significantly (P<0.05) from the controls while basic density of such treated specimens decreased slightly (density, 0.358 g/cm³). Total nitrogen contents for the controls, specimens plasticized without densification, and densified plasticized specimens were respectively; 0.24, 0.65 and 0.63% (g/g), the control differing significantly from the rest. Substrate pH were similar among the three samples. It appeared that artificial densification (rather than total nitrogen levels) assumed an overriding influence on decay resistance of compressed ammonia-plasticized oil palm stems
A H H Wong, M P Koh

Preservative treatment of green timber by diffusion
1984 - IRG/WP 3291
The preservative treatment of green timber by diffusion is reviewed together with criteria which influence the economics of the process. New process options are described which should overcome some of the technical and economic disadvantages of double diffusion. These include the use of coagulating agents which increase the viscosity of the preservative solution and facilitate treatment by momentary immersion. It is anticipated that the main application for the diffusion treatment process will be for the treatment of refractory timbers for both ground contact and above ground exposure. The system is most suitable for low density and higher heartwood moisture content wood species - for example Sitka spruce, and is ideally suited for use in the tropics for treating both plantation grown softwoods and mixed tropical hardwoods.
P Vinden

Preservative treatment of wood by diffusion processes - Simulation of commercial treatment processes
1988 - IRG/WP 3498
Spruce (Picea abies), Scots pine (Pinus sylvestris) and birch (Betula pendula) were preservative treated by diffusion with mixtures of copper sulphate and arsenic pentoxide. The preservative was fixed after a suitable diffusion storage period by soaking in ammonia solution. A high standard of treatment could be achieved in spruce sapwood. This was attributed to its low wood density, and high wood moisture content. The variable treatability of spruce heartwood and poor treatability of Scots pine heartwood was related directly to their moisture-content. Complete preservative penetration could be achieved in spruce heartwood when moisture contents were 60% or above whereas Scots pine heartwood with a fresh moisture content of 30% was untreatable by diffusion. Preservative penetration was directly related to preservative retention and immobilisation by fixation. This was demonstrated clearly for birch which because of its high basic wood density tended to immobilise a greater quantity of preservative salt per unit volume. The effects of preservative retention and diffusion storage time on the subsequent distribution of preservative was determined for Pinus ponderosa. The relationships established can be used for defining suitable diffusion treatment schedules.
P Vinden

Decay and termite resistance of wood treated with boron-containing quaternary ammonia compound, didecyl dimethyl ammonium tetrafluoroborate (DBF) incorporated with acryl-silicon type resin
2004 - IRG/WP 04-30334
This study evaluates the decay and termite resistance of surface-treated wood with didecyl dimethyl ammonium tetrafluoroborate (DBF) incorporated with acryl-silicon type resin emulsion. DBF is a quaternary ammonia compound and contains boric tetrafluoride (BF4-) as a counter ion in its chemical structure. In the study, DBF was incorporated with an acryl-silicon type resin to increase water-resistant of the preservative solution, and, in turn, to increase decay and termite resistance of surface-treated wood after severe weathering processes. 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 tests using subterranean termites, Coptotermes formosanus. Wood specimens surface-treated with preservative solution including 2% DBF and the resin showed decay resistance against both F. palustris and T.versicolor even after severe weathering. Results suggested that treatment with DBF at 2% or greater concentrations containing acryl-silicon type resin emulsion would protect wood used outdoors against both fungal decay and termite attack.
S N Kartal, W J Hwang, K Shinoda, Y Imamura

Chemically modified tannin and tannin-copper complexes as preservatives for wood
2001 - IRG/WP 01-30271
The efficacy of Mimosa tannin, chemically modified tannin, and tannin-copper complexes as wood preservatives was studied. When the tannin-ammonia-CuCl2 solutions were impregnated into wood specimens in a one-step procedure, a large quantity of the tannin-copper complex was fixed in the specimens. Little of the complex was leached from specimens by a weathering treatment, and these specimens showed satisfactory decay resistance in a basidiomycete laboratory test according to the Japanese Industrial Standard (JIS) K 1571-1998. Only the tannin-treated wood had a retention of agent after treatment, in increasing order from untreated tannin (MT), resorcinolated tannin (RMT) and catecholated tannin (CMT). When RMT or CMT was mixed with ammonia¡copper, the wood retained twice as much of these solutions as the MT-ammonia-copper solution. The solutions penetrated 2~13mm from the tangential sections of the logs. Presumably, chemical modification increased the degree of retention by altering the structure of the tannin and increasing its hydrophilic properties. The degree of retention of RMT-NH3-Cu and CMT-NH3-Cu in logs with cross-sections ranged from 268 kg/m3 to 326 kg/m3. Wood decay by F. palustris was markedly suppressed by processing wood with agents made by mixing chemically modified tannins with ammonia and cupric chloride. When wood powder was treated with these agents, mycelial growth and generated protein increased to some extent. The preservative effects of the chemically modified tannins (RMT and CMT) or compound agents composed of the tannins and ammonia¡copper were considered to be due to inhibition of the activities of mannase and Cx-cellulase. In the culture medium which treated wood powder was put in with these agents, drop of pH by oxalic acid, which Fomitopsis palustris produces, is not generated. The potency of the effect was thought to be due to chelation of copper, an essential trace element for wood decay by F. palustris, by the tannin, and/or neutralization or suppression of oxalic acid production by ammonia-copper. Also, these active ingredients hindered eating-damage of wood by the termites. However, the mortality of the termites during the eating-damage test (over 21d) did not reach 100% for all active ingredients. The fact that living termites were still present suggests that tannin-ammonia-copper is not perfect for destroying termites.
H Yamaguchi

Preliminary evaluation of new quaternary ammonia compound, didecyl dimethyl ammonium tetrafluoroborate for preventing fungal decay and termite attack
2005 - IRG/WP 05-30375
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. DBF contains boric tetrafluoride as a counter ion in its chemical structure. 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 tests using subterranean termites, Coptotermes formosanus. Decay resistance tests showed that wood specimens treated with 0.5 and 1.0% DBF solutions were well protected from both fungi even after a 10-day severe weathering 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 weight losses in both weathered and unweathered wood specimens. These results suggested that DBF could be used effectively to protect wood used outdoors against both fungal decay and termite attack and discolorations by fungi.
S N Kartal, W J Hwang, Y Imamura

The fixation of copper in Pinus sylvestris using the sodium salts of two polyhydroxycarboxylic acids
1992 - IRG/WP 92-3706
As part of the research concerned with the development of fixed, copper based preservatives, the salts of polyhydroxycarboxyIic acids, have been used in copper sequestration studies and fixation trials in Pinus sylvestris splinters. Selected compounds have been shown to be effective sequestrants at low concentrations allowing alkaline solutions to be formulated. Leaching trials following a 48 hour wet fixation period at 40°C showed that aximum copper fixation can be achieved from formulations within the pH 7 to pH 9.0 range, providing sequestrant concentrations are optimised.
M Bacon, J A Cornfield

A Green and Novel Technology for Recovering Copper and Wood from Treated Waste - Part I
2015 - IRG/WP 15-50309
Preservative treatment of wood extends its service life. The US consumes about 70 million pounds of copper and produces about 7 billion board feet of treated wood annually. Burning and reusing CCA and copper treated wood wastes are disallowed by US EPA due to health and environmental concerns. Millions of pounds of copper and wood are disposed by landfill annually. The objective of this study was to develop a green technology that can remove copper from the treated wood wastes so that copper and wood can be reused. In this study, seven different aqueous solutions were evaluated for copper removal from treated wood sawdust and chips. Citric acid demonstrated the highest efficiency by recovering 100% copper followed by ammonium citrate and ammonium carbonate/bicarbonate solutions. Formation of copper complexes with the ligands such as citrate and ammonium ions attributed to the key chemical mechanisms for efficient copper removal. The changes of extraction solution color progressively from yellowish orange to dark blue corresponded to the changes in the ratio of citrate ions to ammonia in the solutions. Citric acid has been used extensively as a food and cosmetic additive. The safety, high efficiency and low cost of citric acid compared to the chemicals previously reported for treated wood remediation can overcome the obstacles for commercial consideration. The performance demonstrated in the extraction study by the ammonium salts provides a novel extraction system with further cost reduction options. The finding of excellent copper removal using treated wood chips is very significant since it saves a great amount of energy required to produce sawdust. After removal of copper, the chips offer more opportunities than sawdust for reuse in landscaping, pulping, energy production and many other applications. With the development of such a green and novel technology, we can reuse millions of tons of wood and copper to protect the environment, save natural resources and benefit generations to come.
S Chen