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The course of fixation of Cu-Cr-As wood preservatives
1972 - IRG/WP 307
Copper-chrome-arsenic (CCA) preservatives in contact with wood result in an instant extensive increase of pH, because of ion-exchange and adsorption reactions with the wood. During precipitation of the active elements the pH continuously increases but reaches a maximum, when all chrome is consumed. Some of the early reaction products are unstable and slowly convert via dissolution into stable compounds. The conversion proceeds by proton liberating as well as proton consuming reactions. The pH therefore alternatively decreases and increases until the reactions cease after several months. The final equilibrium fixation products are: ion-exchange fixation of Cu to the wood CrAsO4, Cu(OH)CuAsO4 and Cr(OH)3. The chrome fixation is 2nd order with respect to hexavalent chrome in the liquid phase, four regions with distinct chrome fixation rate constants were found. A hypothesis is given for the mechanism of fixation.
CCA modifications and their effect on soft rot in hardwoods. Part 2
1983 - IRG/WP 3244
The work outlined in this document is a continuation of that presented in Document No: IRG/WP/3201. The findings described in the previous paper are summarised below: a double treatment of CCB followed by arsenic (CCB+A) is more effective than a double treatment of boron followed by CCA (B+CCA) or a single treatment of CCA, CCB or CCAB in controlling soft-rot due to Chaetomium globosum in birch. CCB+A is as effective as the other formulations in controlling Coniophora puteana and Coriolus versicolor in birch and scots pine. CCB fails to copper tolerant basidiomycetes such as Coniophora puteana (F.P.R.L. 11E). A further investigation into the relative activities of CCA and CCB+A was carried out in a soil-bed using loss in strength and loss in weight as the criteria of decay. At the same time some aspects of the chemical nature of the formulations were examined in an attempt to explain the different performances of the treatments in birch. Amongst these tests, gross chemical analysis of the treated woodblocks and observation of the progressive fixation of the preservatives were the most significant.
S M Gray, D J Dickinson
Environmental fate of copper-based wood preservatives in different soil substrates - Part 2: Study of the metal sorption and migration potential under simulated rainfall
1998 - IRG/WP 98-50101-21 b
In order to examine the potential environmental impact of spillages of the saltborne wood preservative CCA in treatment plants, four large scale experiments are set-up so as to follow the water transport and ion mobility in various field soils. A plastic container is filled with a sand, silt, clay and potting soil, made up at their respective bulk density and wetted to a given moisture content. Using a rain simulator on top, a homogeneous spillage of a ready-to-use CCA solution is applied, followed by a rainfall simulation after 3 days and a 3 weeks redistribution period. Soil augers that are taken prior to each new perturbance reveal the distribution and migration pattern of the heavy metals. Copper and arsenic are strongly adsorbed in the upper soil layers, depending on the soil characteristics. Chromium, however, is percolated easily through the soil column and is readily extractable from the soil using pure water.
G M F Van Eetvelde, R Hartmann, J M Mwangi, H S Öztürk, M Stevens
Adsorption of ACQ and CuMEA Wood Preservatives in Red pine
2005 - IRG/WP 05-30374
The rates of stabilization or fixation of ACQ subcomponents (CuO, DDAC and MEA) in red pine (Pinus resinosa) were compared for different solution concentrations (0.75%, 1.5%, 2.25% and 3% ACQ-D) and post treatment conditioning temperatures. Preservative solutions were impregnated into red pine sapwood by a full-cell treatment. Copper and MEA adsorptions from copper monoethanolamine solutions without DDAC were also evaluated for comparison. After the treatments, samples were conditioned without drying either at 22° C for seven weeks or at 50° C for one week. At different times after treatment, expressate from the specimen blocks was analyzed for copper, DDAC and MEA. Copper and MEA adsorption by the wood cell walls followed similar trends. The equilibrium copper adsorption ranged from 44% at high ACQ retentions to about 95% for the lowest retention while the values in the CuMEA system were slightly higher for the higher retentions, ranging from about 54% to 93%. This suggests that DDAC may compete with CuMEA for reaction sites at high ACQ concentrations. Adsorption of DDAC into the wood cell wall matrix was rapid; at all solution concentrations, more than 80% of DDAC was adsorbed by red pine sapwood within minutes after treatment.
C Tascioglu, P A Cooper, Y T Ung
Environmental fate of copper-based wood preservatives in different soil substrates - Part 1: Screening of the metal adsorption potential
1998 - IRG/WP 98-50101-21 a
In treatment plants, spillage of wood preservatives onto soil may be of environmental concern. This potential soil contamination served as an objective for a screening study. Three different mineral soils, a mineral substrate and two horticultural substrates are examined for their sorptive potential of copper through mixing with wood preservative solutions. Depending on the soil/substrate characteristics and the chemical nature of the preservatives used, copper is adsorbed to a higher extent with increasing concentration of the test solution. Soils with low organic matter and clay content show an upper limit of adsorption, irrespective of the product tested. The other soil types clearly exhibit a levelling-out effect from 2 to 4 hours on, often correlating with the initial metal concentration of the product though dependent on the chemical nature and buffering capacity of the active ingredients.
G M F Van Eetvelde, J M Mwangi, F Tack, R Hartmann, M Stevens
Diffusion and interaction of components of water-borne preservatives in the wood cell wall
1988 - IRG/WP 3474
This study investigates the rates of diffusion and ultimate distributions of copper and arsenate components of wood preservatives in wood cell walls following vacuum treatment. Adsorption studies of copper on red pine (Pinus resinosa) and trembling aspen (Populus tremuloides) wood confirm the importance of cation exchange reactions on the ultimate distribution of copper in the wood substance and its strong dependence on pH of the treating solution. Formulations containing both copper and zinc preferentially adsorb or exchange copper relative to zinc. Under high pH conditions, the arsenate anion is significantly adsorbed into the cell wall. The combined adsorption and fixation of low pH CCA solutions is much slower than adsorption of high pH ACA and CZA formulations, but the reaction with wood is more complete. Diffusion coefficients were estimated for the movement of copper and arsenate components of ACA in cell wall material of both aspen and pine sapwood using a simple membrane model for non-steady state diffusion. The longer diffusion paths inherent in the diffuse porous hardwood (aspen) resulted in much slower equalization of the solute in the cell wall matrix than in red pine. However, in both species, equalization was achieved in a relative short time compared to accepted fixation times for conventional waterborne wood preservatives.
P A Cooper
Copper based water-borne preservatives: Copper adsorption in relation to performance against soft rot
1987 - IRG/WP 3452
As part of a fundamental study concerned with the performance of copper based water-borne preservatives the adsorption of copper from aqueous solutions by 4 hardwood and 1 softwood species has been studied. Experiments were conducted to determine the influence of solution pH, solution concentration and solution temperature. The results obtained were consistent with an acid form ion-exchange mechanism for copper adsorption. These properties of water-borne preservative solutions containing copper are discussed in relation to hardwood performance against soft rot decay.
P M S Rennie, S M Gray, D J Dickinson
Amine copper reaction with wood components: acidity versus copper adsorption
1997 - IRG/WP 97-30161
The bonding sites for copper in wood from CCA, as well as ammoniacal/amine based systems, has long been a topic of investigation. Both phenolic and carboxylic functional groups have been discussed as potential bonding sites for copper. However, no consensus on the adsorption mechanism has been realized. Thus, the selective adsorption of copper in southern yellow pine from ethanolamine-copper solutions and its correlation to wood acidity is currently being investigated. The wood acidity has been determined by acid/base titration, and is due to more than one type of acidic group. The acid(s) can be removed by thermal treatment or extraction techniques, and, interestingly, the selective adsorption of copper was observed to track the presence of particular acid functionalities. The preferential adsorption of copper and the mechanisms behind such will be discussed.
S M Thomason, E A Pasek
Adsorption of ACQ components in wood
2010 - IRG/WP 10-30522
To investigate the chemical adsorption capacity of copper-monoethanolamine (Cu-Mea) components on wood, the Na+ cation exchange capacity (CEC) of red pine (Pinus resinosa Ait.) was determined and compared to the adsorption capacity of free Mea and Cu-Mea complexes. The CEC increased with increasing pH. Free Mea adsorption as a function of pH followed the sodium adsorption curve except at pH over 9, when it exceeded the CEC. Cu-Mea adsorbed up to the CEC at pH 9.0-9.5 apparently as Cu(Mea)+, whereas the complex in solution is predominantly of the form Cu(Mea)2+. For the quaternary ammonium compound, alkyl dimethyl benzyl ammonium chloride (ADBAC) adsorption isotherm showed two different adsorption mechanisms into wood: ion exchange reaction at low concentration and hydrophobic interaction at high concentration. ADBAC adsorbed at solution concentrations below a critical concentration (hemi-micelle concentration) had high leaching resistance while ADBAC adsorbed into wood at above the critical micelle concentration (CMC) had low leaching resistance. The CMC decreased with addition of Mea and Cu-Mea. The anion, Cl- of ADBAC was only adsorbed at solution concentrations above the CMC and was easily leached out. The adsorption capacity of ADBAC into wood by cation exchange reaction did not achieve the cation exchange capacity (CEC) of wood. However, the total adsorption of ADBAC and Cu achieve the CEC of wood in the presence of copper amine, and ADBAC competes with copper to occupy the same sites in wood.
Myung Jae Lee, P Cooper
Preliminary study of the fungicidal and structural variability in copper naphthenates and naphthenic acids
1996 - IRG/WP 96-30114
Copper naphthenates, an oil-borne wood preservative listed by the American Wood-Preservers' Association (AWPA), is manufactured by complexing copper(II) with naphthenic acids. Prior to AWPA listing as a wood preservative, field experiments showed that copper naphthenates generally had good stability and were active against wood-destroying organisms. Recently, however, there have been reports of some copper naphthenate-treated poles rapidly failing. One possible explanation for the varying effectiveness could be that the structure, and resulting biological activity, of the naphthenic acids used to make copper naphthenate may vary. To test this hypothesis several naphthenic acids and copper naphenates were obtained and their fungicidal activity against three wood-destroying fungi measured. In addition, the chemical structure of the naphthenic acids were examined by proton- and carbon- NMR. Different activities were observed, especially against a copper-tolerant fungus. Some apparent correlations were seen between the fungicidal activity and chemical structures for the few samples studied.
T Schultz, D D Nicholas, L L Ingram Jr, T H Fisher
Sequestration of copper ions by the extracellular mucilaginous material (ECMM) of two wood rotting basidiomycetes
2004 - IRG/WP 04-10533
The radial growth rate of colonies originating from either whole or ECMM-free inocula of Coriolus versicolor was investigated. The presence of ECMM allowed colonies to maintain higher growth rates than those form ECMM-free inocula up to 2 mM CuSO4 in the medium. The ECMM of C. versicolor and G. trabeum was able to reduce the diffusion of copper ions in solution. The ‘raw’ ECMM of both fungi had a greater ability to reduce the diffusion of copper ions than ECMM which had been subject to dialysis to remove soluble, low molecular weight components. The ‘insoluble’ fraction of ECMM for both species was more effective than the ‘soluble’ fraction at reducing the diffusion of copper ions. It is concluded that ECMM confers some protection to hyphae against the toxic effects of copper ions on growth in vivo and that this due to the binding of copper ions to both the polysaccharide and to low molecular weight components of the ECMM
D Vesentini, D J Dickinson, R J Murphy
Influence of different fixation and ageing procedures on the leaching behaviour of copper from selected wood preservatives in laboratory trials
2003 - IRG/WP 03-20264
The paper focuses on the role of different parameters, such as fixation, sample size, wood species, and leaching in internationally standardized ageing procedures for wood preservatives from Europe, Japan and the United States. The leaching protocols used were EN 84, JIS K 1571 and AWPA E11 protocols. The wood species were Scots pine, Sugi and Southern Yellow Pine respectively. Three types of commercially important copper-based wood preservatives were used as model formulations, namely copper/copper-HDO, ammoniacal copper/quat and CCA. The most important factors determining the extent of copper leaching in the different lab trials were the sample size (volume/surface ratio) and the fixation conditions prior to leaching. On the other hand, the wood species and the leaching protocol itself were found to have only minor influence on the copper leaching rate in the test methods included in this study.
J Habicht, D Häntzschel, J Wittenzellner
International collaborative laboratory comparison of two wood preservatives against subterranean termites: Third update and first report
1996 - IRG/WP 96-10174
At the 24th annual meeting of IRG in Orlando, USA, in May 1993 an international subterranean termite laboratory bioassay to compare the various preferred termite protocols used by IRG termitologists was initiated. The author was nominated to co-ordinate this comparative laboratory evaluation of two wood preservatives, copper-chrome-arsenic (CCA) and copper naphthenate (Cu-Na) against the subterranean termites used as test termites in Australia, France, Japan, Thailand, United Kingdom and the Unites States of America. Solutions of these two wood preservatives were prepared and impregnated into Pinus radiata wood blocks to obtain loading of 0.0, 0.5, 1.0, 2.0 and 4.0 kg/m³ respectively. All preservative treatments were carried out at the Division of Forestry and Forest Products in Melbourne. The treated specimens were dispatched to the participating researchers who subjected these specimens to attack by their test termite species, and have now returned the specimens to Melbourne. This paper reports the amount of wood consumed and the mean mass loss (%) on both treated and untreated wood blocks by the termites in the various laboratory bioassays.
J R J French
Types of decay observed in CCA-treated pine posts in horticultural situations in New Zealand
1984 - IRG/WP 1226
The few reported failures of 11-12-year-old horticultural posts in New Zealand in 1982 were caused by brown-rot. A subsequent survey of CCA-treated posts in all the major horticultural areas has revealed decay of many posts. A microscopic examination of these posts has shown decay by brown-rot, white-rot, soft-rot and bacteria. Several types of bacterial decay have been observed.
J A Drysdale, M E Hedley
An investigation of the effects of pre-steaming on the treatment of sawn spruce timber with Celcure A, a copper-chrome-arsenic preservative
1981 - IRG/WP 3150
Difficulties in the treatment of spruce using standard vacuum/pressure techniques with both water-borne and organic solvent preservatives are well known. We have evaluated the influence of steaming on treatability with a waterborne CCA preservative.
C R Coggins
Electrodialytic remediation of creosote and CCA treated timber wastes
2002 - IRG/WP 02-50190
There is a growing concern about the environmental issue of impregnated timber waste management, since an increase in the amount of waste of treated wood is expected over the next decades. Presently, no well-documented treatment technique is yet available for this type of waste. Alternative options concerning the disposal of treated wood are becoming more attractive to study, especially the ones that may promote its re-use. Inside this approach, the electrodialytic process (ED) seems a promising technique for removal of preservative chemicals from treated wood waste. The method uses a direct electric current and its effects in the matrix as the “cleaning agent”, combining the electrokinetic movement (mainly due to electromigration, but also electro-osmosis and electrophoresis), with the principle of electrodialysis. This work reports results from the application of the electrodialytic process to an out-of-service Portuguese creosote and CCA-treated Pinus pinaster Ait. railway sleeper and pole. The behaviour of the process is described and the main results discussed. The average removal rate, estimated in accordance with prEN 12490, for creosote from treated timber waste was around 40 %.. For CCA treated timber waste, experimental conditions that could optimise the process efficiency (e.g. current density, time) were studied. The highest removal rates obtained until now, in our studies, were 93 % of Cu, 95 % of Cr and 99 % of As for sawdust using 2.5 % oxalic acid (w/w) as the assisting agent. For CCA treated wood waste in the form of chips, the best removal rates obtained until now were 84 % of Cu, 91 % of Cr and 97 % of As.
E P Mateus, A B Ribeiro, L Ottosen
Fungicidal activity of some organic solvents, copper carboxylates and their complexes with 2-aminoethanol
1997 - IRG/WP 97-30136
We evaluated the activity of eight organic solvents against wood - rotting fungus Trametes versicolor in order to choose the most appropriate one for rapid screening tests of some copper(II) carboxylates and their adducts with 2-aminoethanol. Their activity against the selected fungus was classified in the following order: chloroform > N,N-dimethylformamide > acetonitrile > methanol > dimethyl sulfoxide > ethanol > acetone. The non-polar white spirit did not dissolve in the growth medium and the results could not be directly compared with the results for other solvents. As an appropriate solvent for screening of the tested copper(II) carboxylates, dimethyl sulfoxide (DMSO) was chosen. Minimal inhibitory concentration against Trametes versicolor of the screened carboxylates was in the concentration range of 1x10-4 to 1x10-3 mol/l. Coordinated amine ligands slightly, and not significantly, decreased fungicidal properties of the tested carboxylates.
M Petric, F Pohleven
Termite resistance of pine wood treated with chromated copper arsenates
1997 - IRG/WP 97-30128
Two four-week, no-choice laboratory tests were performed with CCA-treated southern yellow pine and radiata pine against Formosan subterranean termites, Coptotermes formosanus. CCA retentions as low as 0.05 kg/m3 (0.03 pcf) provided protection from all but light termite attack (rating of 9 on a 10-point visual scale). Similar and consistent light attack on wafers containing retentions as high as 6.4 kg/m3 (0.4 pcf), coupled with complete termite mortality, demonstrates that the mode of action of CCA treatments relies upon toxicity rather than having any repellent effects against termites.
J K Grace
Problems of fixation of CCA-preservatives in palm-wood
1985 - IRG/WP 3338
Palm-wood may be used for posts and poles where it needs proper treatment for long time use. Based on observations by W. Killmann on low CCA-fixation in palm-wood, samples of Jubaea-palm grown in a Greenhouse at Hamburg, have been treated in two different series with a 4% solution of CCA-type B. After 1-16 weeks of storage the blocks were split into sticks of 1-2 mm² and leached. In all series 50% of the chromium and copper content of the individual blocks was leached independent of the time of storage, whereas simultaneously treated pinewood samples showed complete fixation after 4 weeks of storage.
H Willeitner, K Brandt
Field Testing of Copper Carboxylate Preservatives
2003 - IRG/WP 03-30322
This paper details our ongoing experience with field testing of copper naphthenate and other copper carboxylate preservative systems. Results from field stake tests at an AWPA Hazard Zone 4 test site are presented. In general, copper carboxylates made with ‘synthetics’ yielded results equivalent to or only slightly lower than systems with straight nap acids or nap acids amended with synthetic neo acid bottoms.
H M Barnes, M G Sanders, T L Amburgey
The leaching of copper, chrome and arsenate from CCA-impregnated poles stored for ten years in running water
1978 - IRG/WP 3122
There is no evidence to indicate that the chromium and copper components are leached from the outermost 5 mm of sapwood in poles impregnated with Boliden K33 and Tanalith C and stored in running water for ten years. The arsenic component, however, seems to be leached out during the first few months to an extent of about 20% of the initial amount. The leaching time is dependent on the preservative used.
F G Evans
Recent soft-rot research in softwoods and hardwoods
1980 - IRG/WP 1108
The purpose of this paper is to describe briefly the current status of our research on soft-rot fungi. The work to be discussed is still in progress and any results described must be regarded as provisional.
J A Butcher
A new concept of oxalic acid biosynthesis in physiology of copper-tolerant brown-rot fungi
2001 - IRG/WP 01-10394
Recently, a wide variety of roles of oxalic acid (oxalate) in wood decay systems have been receiving much attention. Copper tolerance of wood-rotting basidiomycetes has been believed to be due to the detoxification of copper wood preservatives by oxalate produced by these fungi. However, biochemical mechanism of oxalate biosynthesis in relation to physiology of wood-rotting fungi has not been elucidated although two oxalate-forming enzymes, oxaloacetase and glyoxylate dehydrogenase, have been studied in our laboratory. Recently, a new role of glyoxylate cycle in oxalate biosynthesis in wood- rotting fungi has been presented, and the cycle commonly occurred to varying extents among the fungi although they were grown on glucose. Enzymatic analyses showed that isocitrate was cleaved by isocitrate lyase in the glyoxylate cycle rather than oxidized by isocitrate dehydrogenase in tricarboxylic acid (TCA) cycle, and the fungi were found to lack a normal TCA cycle due to the absence of - ketoglutarate dehydrogenase. It is noteworthy that glucose was efficiently converted to oxalate in a theoretical yield of about 80%, accumulating in the culture media of F. palustris. The results further indicate that acetyl-CoA derived from glucose was not completely oxidized to CO2 in TCA cycle but was mainly converted to oxalate with help of the other coupling metabolic cycles, including glyoxylate cycle. Formation of oxalate from several intermediary metabolites using cell-free extracts of F. palustris confirmed that oxalate is also the final product of the metabolic pathway in the in vitro system. Thus, it is proposed as a new concept that most of copper-tolerant brown-rot fungi may acquire the energy by oxidizing glucose to oxalate, i.e. oxalate fermentation expressed in the following equation; Glucose + 5O2 --> 2 Oxalate + 2CO2 + 4H2O.
E Munir, T Hattori, M Shimada
Copper naphthenate performance: A new way to look at old data
2000 - IRG/WP 00-30215
Although copper naphthenate has over a 50-year test history, it is still considered as a "new" preservative in the United States when it is used for utility poles. It has also been extensively used in remedial treatments for poles and has considerable retail or over-the-counter sales. The test history includes a number of different tests and a rationale for evaluating this data and comparing the performance of copper naphthenate to other common pole preservatives is presented. Thus, the efficacy of copper naphthenate can be easily summarized.
C R McIntyre
The biostatic effect of copper on decay of fire retardant-treated mining timber
1991 - IRG/WP 1507
Blocks of Eucalyptus grandis were treated with 20kg/m³ ammonium sulphate as fire retardant and challenged with Coriolus versicolor. Replicates were soil buried. A second set of blocks was treated with retardant and copper at 6.6 kg/m³ (ie 1% w/w), and challenged similarly. After 8 weeks weight losses produced by Coriolus versicolor in untreated, retardant treated and copper supplemented blocks were 45, 25, and 0% respectively, and corresponding weight losses in soil were 27, 25 and 10%. These results, and electronmicroscopical observations, showed conclusively that Eucalyptus grandis treated with fire retardant was rapidly decayed, and that copper inhibited such decay.
G D Shelver, E A Shelver, A A W Baecker