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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

A comparison of the leaching resistance of diammine-copper complexes and copper carbonate precipitated in wood
1997 - IRG/WP 97-30158
Previous studies have shown that during treatment of wood with ammoniacal copper solutions, both simple copper precipitates and diammine-copper complexes are formed. The objective of the present study is to determine the relative importance of both forms of copper, on such aspects as preservative leachability and biological performance. In the current experiment, the leachability of copper carbonate precipitated in wood is compared with that of diammine-copper complexes. The results confirmed that both forms of copper resisted leaching by distilled water. However, when exposed to the more aggressive leaching conditions using the sodium citrate buffered solution, the diammine-copper complexes were significantly more ressistant to removal from the wood. Further studies are planned to examine the diammine-copper complexes present in the wood as well as the efficacy of these complexes against wood decay fungi.
Xiao Jiang, J N R Ruddick

Soil treatment tests with the three products of boric acid for the prevention of the hyphal growth of Serpula lacrymans
1992 - IRG/WP 92-3693
Laboratory soil treatment tests were conducted for the evaluation of fungicidal or fungistatic effect of boric acid products against Serpula lacrymans. Boric acid products tested were the following three: a thickened boric acid solution in triethanolamine, boric acid-silica gel complex granules, and a nonwoven fabric laminated with a polypropylene film and coated with boric acid granules on one side surface. Effects of these products were evaluated using ezomatsu (Picea jezoensis) wood blocks and Kanuma soil or unsterilized sandy loam as a soil substrate. The thickened boric acid solution exhibited the sufficient efficacy to suppress the hyphal growth and decay of wood with boric acid retention of 2.0 kg/m³ in Kanuma soil medium. The perfect effect of the boric acid-silica gel complex granules was shown with boric acid retention of 3.0 kg/m³. The hyphal growth of the fungus was almost inhibited by placing the nonwoven fabric with boric acid granules over the media incubated with the fungus.
S Doi, A Yamada, Y Mineki, M Mori

Dimensional stabilization and decay resistance of wood treated with brown-rotted lignin and copper sulfate
1990 - IRG/WP 3608
The objective of this study was to evaluate the potential usefulness of brown-rotted lignin (BRL) as a dimensional stabilization and copper complexing agent for wood treatment. For dimensional stabilization, aqueous solutions of the lignin extract were combined with either copper sulfate, glyoxal or other additives. Anti-shrink efficiency (ASE) values as high as 42% were obtained with wood treated with a BRL/Cu combination. By treating wood with a 6% solution of the lignin extract prior to treatment with copper sulfate, a two-fold increase in fixation of copper was attained. Soil block tests were also performed on wood treated with BRL and copper sulfate individually as well as in combination; it was found that the BRL increased the activity of Cu against Poria placenta.
L Jin, D D Nicholas, T Schultz

Biological test, AAS and EPR study of copper monoethanolamine complex with quaternary ammonium compounds as a wood preservative
2003 - IRG/WP 03-30321
Experiments were carried out on the wood preservative with a strong fungicidal activity based on Cu(II) carbonate, 2-aminoethanol (monoethanolamine) and quaternary ammonium compound (QAC). The object of the performed investigations was sapwood of Scots pine (Pinus sylvestris L.) treated with Cu-EA-QAC formulation. Mycological investigations were carried out according to EN 113 and EN 84 standards. The retention of the copper ions in the wood grows nonlinearly with concentration (in %) of the impregnating solution from 0,25 kg/m3 at 0.03% to 1,55 kg/m3 at 0.21% (i.e. nearly 6 times) whereas the copper leachability decreases 2,5 times from 15% to 6% in the same range. These results indicate good fixation of the copper to the wood and high leaching resistance. EPR results and computer simulations of the observed EPR spectra shows that in Cu-EA aqueous solution the Cu(EA)2(H2O)2 complexes exist and the main coordination plane is not destroyed in impregnating solution and in the wood. In Cu-EA-QAC-BA solution the Cu(EA)2(QAC)2 complexes appear whereas EPR spectra of the treated wood indicate coexistence of a few types of Cu-complexes. We have identified strongly fixed Cu(EA)2O2 and Cu(EA)2O complexes with oxygens atoms from wood functional groups.
B Mazela, I Polus, S K Hoffmann, J Goslar

Evaluation of tropolone as a wood preservative : activity and mode of action
2002 - IRG/WP 02-30282
The fungicidal activity of 2-hydroxy cyclohepta-2,4,6-trienone (tropolone) analogue of b-thujaplicin a natural product responsible for the durability of heart wood of several cupressaceous trees was investigated in vitro on growth of white and brown rot fungi. Results obtained show that tropolone, easily prepared from commercially available products, possesses strong fungicidal activity similar to that of fungicides currently used for wood preservation. In addition, laboratory malt-agar block tests indicate that tropolone, like b-thujaplicin, is able to protect wood blocks against brown rot fungi like Poria placenta but not against white rot fungi like Coriolus versicolor. These differences were investigated on the basis of the mechanism of action of tropolone. Fungal growth inhibition on malt-agar could be prevented by adding iron salts in the medium, which indicates that chelating properties of tropolone are important on its mode of action. Determination of the stoechiometry of the reaction between tropolone and ferric ion shows the formation of a strongly insoluble precipitate involving 3 equivalents of tropolone for 1 equivalent of Fe3+ with a solubility product (Ks) of approximately 10-28 which creates metal limitation conditions inhibiting fungal growth. Moreover, tropolone possesses weak antioxidative properties and is able to inhibit ferric iron reduction by catecholates lowering the redox potential of the iron couple. All these data are consistent with the hypothesis that tropolone inhibits wood degradation by Poria placenta by chelating iron present in wood thus avoiding initiation of Fenton reaction, while Coriolus versicolor which produces several lignolitic enzymes like laccases and peroxidases able to degrade rapidely tropolone is unaffected by tropolone.
P Gérardin, M Baya, N Delbarre, P N Diouf, D Perrin, P Soulounganga, E Gelhaye, J P Jacquot, C Rapin

Formation and Structure of Metal Azole Complexes
2008 - IRG/WP 08-30469
Divalent copper and zinc complexes with metal:azole ratio 1:2 were readily formed at room temperature with the fungicides tebuconazole and propiconazole. The structure of copper and zinc tebuconazole acetate and zinc cis-propiconazole chloride were examined by X-ray crystallography. In copper tebuconazole acetate, the copper atom lies on a crystallographic inversion centre and is coordinated to two triazole and two acetate ligands in a trans arrangement. The two binding tebuconazole N atoms and two close binding acetate O atoms form a square plane. The two remaining acetate O atoms have more distant interactions, thus forming an elongated octahedron around the copper atom. The coordination geometry of zinc tebuconazole acetate is tetrahedral and the metal is bound to two triazole and two acetate ligands. The geometry is distorted from regular owing to the size of the tebuconazole ligands. The butyl chains are less folded than for the copper tebuconazole complex, resulting in a more extended molecule. The coordination geometry of zinc cis-propiconazole chloride is also tetrahedral with the metal atom bonded to two triazole and two chloride ligands.
P D Evans, K J Schmalzl, C M Forsyth, G D Fallon, S Schmid, B Bendixen, S Heimdal

Mold-resistance Effect of Bamboo Wood Treated with CCC-organic Complexes
2009 - IRG/WP 09-30514
Mold resistant effect of CCA, ACQ, CuAz, CCC and the compound of CCC and propiconazole were researched on bamboo wood of Phyllostachys pubescens were reported in this paper. Results showed that all of the test fungicides could protect bamboo wood better from Penicillam citrinum than from Trichoderma viride and Aspergillus niger. The complex of CCC and propiconazole had the best resisting effect on all of the test mold fungi. ACQ had better resisting effect on Penicillam citrinum, but not so effective on Trichoderma viride and Aspergillus niger, especially on Aspergillus niger. CuAz had better effect only on Penicillam citrinum. CCA and CCC had better resisting effect on Penicillam citrinum only at higher retentions, but had poor effect on the other two test fungi.
Sun Fangli, Yang Le, Chen Anliang, Bao Binfu, Li Qiao

Termite resistance of copper-based preservative supplemented aspen strandboards
2012 - IRG/WP 12-30594
Termite resistance of aspen strandboards treated with various copper-based preservative systems was evaluated in field exposure tests. Five copper-based chemicals or zinc borate were blended into aspen furnish at three retention levels prior to pressing. Tebuconazole or 4,5-dichloro-2-N-octyl-4-isothiazolin-3-one (DCOI) were added as co-biocides to selected copper-based treatments. Sections from the panels were exposed to a colony of Formosan termite (Coptotermes formosanus) in an American Wood Protection Association Standard E21 test. Incorporating some combinations of copper-based preservative systems with organic co-biocides markedly improved the termite resistance of aspen oriented strandboard.
J J Morrell, C Vidrine, A Preston, L Jin

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

Impact of wetting agents on polyelectrolyte complex impregnation for wood fire-retardancy
2022 - IRG/WP 22-30768
Wood fire performance is a great concern in interior finishing due to the high risk of flame spread. To increase the use of wood in high building while ensuring the safety of building occupants, fire retardant (FR) treatments are required. Traditionally, two fireproofing strategies are employed: impregnation and coatings. They have been widely studied but they, respectively, are time and chemicals consuming and have poor aging resistance. Polyelectrolyte complexes (PEC) impregnation has shown a great potential in surface impregnation. PECs treatments are versatile, eco-friendly and economical. In this study, yellow birch (Betula alleghaniensis) was treated with polyethyleneimine (PEI) and sodium phytate (SPA) PECs. Fire-retardancy performance was evaluated using cone calorimeter and results have shown that it is strongly related to PECs weight gain. A minimal weight gain of 2 wt.-% was found to be necessary to achieve a significative fire-retardancy. To increase the weight gain and ensure a reproductible fire-retardancy, two commercial wetting agents (SCHWEGO wett 6292 and SCHWEGO wett 6237) were added at 0.1 wt.-% and 0.5 wt.-% to the PECs solutions. Surface tensions were measured using the Wilhelmy plate method. Effect on the wood wettability was also studied by dynamic contact angle. An increase of the weight gain was obtained by adding SCHWEGO wett 6237, whereas SCHWEGO wett 6292 has no significant effect. Finally, PECs with SCHWEGO wett 6237 were surface impregnated on yellow birch to study the impact on wood fire-retardancy.
M Soula, J B Grenier, S Duquesne, F Samyn, V Landry