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EPR investigations of interactions between ammoniacal Cu(II) octanoate and wood
1996 - IRG/WP 96-30110
Ammoniacal solutions of copper(II) octanoate [ C u . h l f . 2 . r h l f.(O2CC7H15)4], interactions of these solutions with wood and wood components, and leaching of copper(II) octanoate from impregnated wood samples, have been studied by electron paramagnetic resonance (EPR) method. It is still not clear if in the Cu(II) octanoate - water - ammonia system, Cu(II) remains in a (copper(II) octanoate - ammonia) complex. The majority of leached Cu(II) with distilled water and a solution simulating acid precipitations was washed out in the first five hours of leaching procedure (up to 35% of initial Cu(II)). Time dependence studies of interactions of ammoniacal Cu(II) octanoate with wood, cellulose and brown rotted lignin showed, that the fastest and most significant was the reaction with lignin. Cu(II) is immobilised also on cellulose. A significant contribution of ammonia evaporation to the fixation mechanism of the preservative was observed as well.
F Dagarin, M Petric, F Pohleven, M Sentjurc

Fungicidal activity of some new water borne copper octanoate based formulations
1999 - IRG/WP 99-30198
Four new water borne formulations for preservation of wood were prepared: the composition of Cu(II) octanoate, 2-aminoethanol (ethanolamine) and water; the composition of complex of Cu(II) octanoate with nicotinamide, 2-aminoethanol and water; the one of Cu(II) octanoate, organic boron complex, 2-aminoethanol, dimethyl sulfoxide and water and finally, the mixture of Cu(II) octanoate, diazene, 2-aminoethanol and water. Fungicidal activity of these new formulations against Trametes versicolor, Antrodia vaillantii and Coniophora puteana was determined by filter paper and mini-block test methods. Compared to the commercially used wood preservative containing Cu(II) naphthenate / Cu(II) 2-ethylhexanoate, the new compositions have stronger fungicidal activity. The strongest biocidal activity was exhibited by the formulation with a Cu(II) octanoate/nicotinamide complex.
M Petric, M Pavlic, F Pohleven, P Segedin, B Kozlevcar, S Polanc, B Stefane, R Lenarsic

Influence of fungal exposure on the redistribution of copper in treated spruce wood
2002 - IRG/WP 02-10450
The redistribution of copper in treated wood after exposure to basidiomycete decay fungi is described. The micro-distribution of copper in copper(II) sulphate or copper(II) octanoate/ethanolamine treated Norway spruce wood before and after exposure to 3 different wood decay fungi was studied using transmission electron microscopy with X-ray microanalysis. The copper content of the mycelium and the nutrient medium was also determined by atomic absorption spectroscopy. Finally, light microscopic analyses of decayed samples was performed. Both copper-tolerant (Antrodia vaillantii) and copper-sensitive fungi (Trametes versicolor and Gloeophyllum trabeum) changed the distribution of copper in the treated wood after 16 weeks of exposure. The redistribution of copper in copper sulphate treated samples exposed to tolerant A. vaillantii was characterised by the excretion of oxalic acid and formation of copper oxalate in the cell lumens, on the surface of treated wood blocks and on the fungal hyphae. In the presence of ethanolamine, the formation of copper oxalate by A. vaillantii did not occur but instead diffusion of copper into regions of lower copper concentration (centre of the blocks and nutrient medium) took place. This type of redistribution/diffusion of copper was also observed when treated wood specimens were exposed to the copper-sensitive fungi.
M Humar, F Pohleven, R J Murphy, D J Dickinson, I Moris, M Zupancic, P Kalan, M Petric

Metal carboxylates for wood pest control
1996 - IRG/WP 96-30109
Metal carboxylates have been used as wood preservatives for more than fifty years. Predominantly salts of naphtenic acids have been commercially applied so far. They have water repellent as well as fungicidal and insecticidal properties. In the last years, metal carboxylates of saturated fatty acids were introduced. Fatty acids with 7-10 carbon atoms already have fungicidal activity by themselves. However, their efficacy is markedly increased in a complex with metal ion such as copper and zinc. This carboxylates are environment friendly and low toxic for humans. We studied fungicidal, insecticidal and termiticidal effectiveness of copper and zinc carboxylates by European standard methods. The strongest fungicidal and insecticidal activity showed copper and zinc naphtenates and copper octanoate. The metal octanoates are soluble in white spirit and, moreover in aqueous ammonia solutions. One day after treatment, the leaching of some carboxylates from wood was very low. These carboxylates did not increase the flammability of treated wood.
F Pohleven, M Petric

The influence of copper (II) chemicals on the weathering of treated wood. Part 1: ACQ treatment of wood on its weathering
1994 - IRG/WP 94-30040
Wood weathering can be accelerated by alkylammonium compound (AAC) treatment, and slowed by ammoniacal copper quat (ACQ) treatment. This study aims at investigating the influence of ACQ treatment of wood, especially the present of copper (II), on its weathering. ACQ, CCA and DDAC treated microtomed sections of southern yellow pine earlywood were prepared and naturally weathered for five periods, totally 35 days. The compositional changes in the weathered samples with preservatives, retention and exposure time were examined using FTIR spectroscopy. The FTIR spectra showed that ACQ treatment slowed wood photodegradation mainly via inhibiting the formation of carbonyls and delignification during weathering. 2% ACQ treatment provided effective protection against wood photo-oxidation.
Ruiying Liu, J N R Ruddick, L Jin

Studies of the mechanism of chromated-copper preservative. Fixation using electron spin resonance
1992 - IRG/WP 92-3701
Two softwoods and one hardwood species were treated with chromium trioxide, copper sulphate, chromated-copper wood preservative (CCA). The treated wood samples were analyzed during fixation by electron spin resonance (ESR). ESR spectra indicated that more than one Cr(V) species was generated from Cr(VI) soon after CCA treatment. The Cr(V) signal became strong within increased several hours followed by the gradual decay of Cr(V) accompanying with generation of single broad Cr(III) species. Cr(V) signal still remained at least up to six months after the treatment. ESR spectral parameters from Cu(II) signal consisted of a quadruplet at lower field with a unresolved absorption of higher field, suggesting a evidence of a dX²-Y² ground state of Cu2+ ions bound in inner-sphare complexes with "O4" ("O6") ligands arranged in square planar cordination (distorted octahedral) cordination. Cu(II) signal did not change significantly during fixation.
K Yamamoto, J N R Ruddick

Quantification of mobile copper (II) levels in micronized copper treated wood
2011 - IRG/WP 11-40550
The purpose of this study is to quantify the mobile copper(II) levels in micronized copper treated wood using electron paramagnetic resonance (EPR) spectroscopy. A correlation between EPR and EDX intensities on mobile copper levels in a series of copper sulphate treated wood was created as a calibration standard. Laboratory treatments using micronized copper formulations were then carried out and monitored by EPR over 7 days. The mobile copper levels produced were visualized and quantified by comparing the EPR spectral intensities against the calibration standard. The influence of time on the variations in the mobile copper levels was also investigated. The amount of mobile copper was found to increase initially before reaching an optimum and then decreased slightly at the end of a 7-day monitoring period. Up to 2000 ppm of mobile copper was measured in the treated samples.
Wei Xue, P Kennepohl J N R Ruddick

Mobilized copper(II) concentrations in earlywood and latewood of micronized copper treated red pine
2012 - IRG/WP 12-30596
Electron paramagnetic resonance (EPR) was used in conjunction with energy dispersive x-ray spectroscopy (EDX) to quantify total copper and mobilized copper retentions in MCQ and MCA treated red pine. The MCQ treated red pine was found to have higher copper retention than that of the MCA treated one. Earlywood in general had higher total copper content than latewood. The mobilized and complexed copper retentions were similar in earlywood and latewood reflecting a similar capacity of each to solubilise and complex the mobile copper.
Wei Xue, P Kennepohl, J N R Ruddick

Effect of soil contact on reacted copper(II) levels in micronized copper treated wood
2013 - IRG/WP 13-30616
Small 3 to 4 mm thick and approximately 80 to 100 mm long, samples were removed from wood treated with micronized copper quat (MCQ) or micronized copper azole (MCA) and buried full length in a soil bed. Samples were removed after 2, 4 and 8 weeks. The total copper was determined by x-ray fluorescence (XRF) spectroscopy and the amount of reacted micronized copper measured by electron paramagnetic resonance (EPR) spectroscopy. The results showed that the amount of total copper retention decreased slightly with time, whereas the reacted copper levels increased with increasing soil exposure time, eventually reaching a maximum of 0.24% Cu for MCQ and 0.28% Cu for MCA. This observation confirms that mobilization of micronized copper can continue in treated wood in ground contact provided that there is unreacted micronized copper carbonate present.
Wei Xue, P Kennepohl, Xingguo Jin, J N R Ruddick

A Green and Novel Technology for Recovering Copper and Wood from Treated Wood Waste – Part II: Optimization, copper metal recovery, and process design
2017 - IRG/WP 17-50326
The US consumes 70 million pounds of copper and produces 580 million cubic feet treated wood annually. The EPA disallows burning and reusing treated wood waste due to health/environmental concerns. Vast quantities of copper and wood are landfilled. Two safe and low cost extraction systems, citric acid and ammonium citrate, were identified in Part I of this study. In Part II of the study, effects of extraction conditions such as time, temperature, and equilibrium copper concentration were determined. More than 95% of copper was removed either at ambient temperature for 8 hours or at 40oC for 4 hours. The resulting solution was used in consecutive extractions with new batches of wood until copper reached its rate limiting concentration. The study demonstrated that copper in the extraction solutions could be electroplated onto various metal surfaces, thus efficiently recovered. This process regenerated aqueous solutions to be reused for future extraction. A chemical/engineering process was developed with this study for extracting copper from treated wood wastes, recovering copper from extraction solutions by electroplating, and cyclic use of regenerated aqueous solution. This green and novel technology can keep copper and wood from the landfill and bring tremendous environmental, economic, and social benefits.
S Chen, R Patel

Copper-octanoate - a potential reference preservative replacement for CCA in field test standards?
2022 - IRG/WP 22-20688
Finding a CCA reference replacement for use in standardised test methods is of high priority since this chemical is being phased out and may in the near future be banned also for experimental and approval purposes. In this paper we assess the possibility to replace CCA reference preservative with an historical copper octanoate product. There is a huge amount of lab and field test data available for a copper octanoate preservative, “Cuprinol Tryck”, which was in use in the Nordic countries during the 70s and 80s showing that it might work as a substitute for CCA in test standards. We managed to reproduce the production process for this preservative in laboratory scale. In this study, we have examined the copper octanoate product from an impregnation point of view as well as from a wood protection point of view. Impregnation related results show that copper octanoate has a liquid uptake in wood that is significantly better than water (as measured with Wilhelmy plate), that the impregnation liquid readily penetrates the sapwood in samples mimicking poles of 15 x 15 cm cross-section. ENV 807 tests showed that a retention of 1,9 kg Cu/m³ (21 kg product/m³) fully protected the wood against biological attack in both soft-rot dominated garden compost soil and brown rot dominated sandy soil, to a level equal to CCA 9 kg/m³ and CC 10 kg/m³, while a retention of 0,6 kg Cu/m³ reduced mass loss to approximately the same extent as CCA at low retention level (2 kg/m³). These results are in accordance with old results from field test with Cuprinol Tryck in several Nordic test fields. In order to evaluate the correlation in degradation between CCA and Cuprinol Tryck in field testing according to EN 252, series of retentions reflecting the sample copper levels have been prepared for a Round Robin test. These will be installed in a number of test sites during spring 2022. Results from these experiments will be reported in future papers. Based on our current results, we conclude that the copper-octanoate preservative product would be a potential substitute for CCA in standardized durability testing.
R Ringman, M Westin, M Klamer, A Christof, F Friese

Comparative study of the properties of silicate coatings with different mineral pigments (titanium dioxide, iron (III) oxide, copper (II) oxide) on the surface of wood
2022 - IRG/WP 22-40936
Silicate coatings are attractive alternatives to conventional organic-based coatings for wood protection. In this work, silicate coatings were prepared with a potassium silicate binder modified with a methyl siliconate solution, and three types of mineral pigments titanium dioxide, iron (III) oxide and copper (II) oxide. The coatings were applied on beech wood and cured under ambient conditions. The colour, surface roughness, adhesion strength, and resistance to cold liquids of the cured coatings were determined and reactions to fire of the coatings were compared using single flame source tests. The surface of wood was well masked by the coatings and the colour of the coatings was a function of the pigments. The coating layers were rough with arithmetic average roughness values Sa between 3 μm and 5 μm and maximum peak-to-valley height between 45 μm and 48 μm. The adhesion of the coatings was comparable, and sufficiently high (> 3 MPa) for application of the coatings to the surface of wood without a primer. The coatings were not considerably affected by the cold liquids. The single flame source tests showed that coatings containing titanium dioxide and copper (II) oxide reduced the charred area of the wood underneath, while coating with iron (III) oxide increased the charred area compared to the uncoated reference. A pigment such as iron (III) oxide which promotes the formation of char could produce an early layer of char at the surface of wood decreasing the spread of the fire within the wood. Further studies are planned to completely describe the fire behaviour of the coatings and extend the work to other pigments.
A M Cheumani Yona, M Petrič

Minutes of the meetings of WG II
1983 - IRG/WP 2207
IRG Secretariat

Agenda WG II
1989 - IRG/WP 2337
IRG Secretariat

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

Minutes of the WG II meetings 1974
1974 - IRG/WP 241
IRG Secretariat

Agenda WG II
1974 - IRG/WP 237
IRG Secretariat

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

IRG Working Group II. Co-operative leaching test (letter to collaborators)
1974 - IRG/WP 240
J W W Morgan

Agenda WG II
1981 - IRG/WP 2158
IRG Secretariat

Minutes of the WG II meetings 1975
1975 - IRG/WP 256
IRG Secretariat

Agenda WG II
1990 - IRG/WP 2352
IRG Secretariat

Minutes of the WG II meetings 1976
1976 - IRG/WP 274
IRG Secretariat

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

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