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Micronized Copper Preservative Systems: Observations on the Release of Cupric ion (Cu2+) from Treated Wood and Performance against Wood Decay Fungi
2009 - IRG/WP 09-30519
In an attempt to address the mechanism of action of micronized copper preservatives, a 20-week continuous water leaching study was conducted. The leaching results indicated that, once impregnated in wood, micronized copper preservatives continuously release cupric ion, and the levels of cupric ion released from micronized copper treated wood are higher than those released from CCA treated wood, and similar to those from ACQ-D treated wood with the exception of the first few leaching cycles. A 30-month soil bed fungal cellar test was also conducted, and the results revealed that micronized copper quat performed at least as well as ACQ-D against soft rot, confirming the presence of mobile cupric ion in the S2 layer of wood cell wall. In addition, two field stake studies of micronized copper preservatives were also conducted, and the results indicate that micronized preservative systems provide excellent long-term protection against wood destroying fungi and insects, and perform at least as well as ACQ-D.
J Zhang, R Ziobro


Detection of trace organics by ion mobility spectrometry
1990 - IRG/WP 3635
Ion Mobility Spectrometry (IMS) is a time of flight analytical technique that is suited to detect chemicals in the low parts per billion range. Some of the advantages of IMS are: operation at atmospheric pressure, fast response time (0.1-10 sec), and the ability to characterize individual chemical species in complex matrices without any prior sample preparation. In this paper, the utility of IMS in providing a rapid, qualitative analytical technique for trace organics is reported for a number of application areas: narcotic traces on the hands of overdose victims, drug residues in body fluids, identification of wood species, detection of early decay in wood. The advantages and limitations of the use of IMS as a chemical sensor are discussed, and the application of mathematical models and algorithms to extract useful information from IMS signals are also be described.
A H Lawrence


Detection of brown rot decay in wood by ion mobility spectrometry
1991 - IRG/WP 2377
A test method for the detection of brown rot decay in wood is described and involves a two-step procedure: thermal release of vapours from wood samples followed by analysis using Ion Mobility Spectrometry (IMS), with results being obtained in 5-10 seconds. The advantages, limitations as well as the detection limit of the technique are presented.
A H Lawrence, T Nilsson


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.
S-E Dahlgren


Determination of total fluoride in preservative-treated wood by ion selective electrode, without steam distillation
1996 - IRG/WP 96-20086
An analytical method was developed to determine total fluoride in wood treated with aqueous fluoride or borate-fluoride formulations. Ground wood was mixed with 60% sodium hydroxide solution and oven-dried overnight before furnacing at 600°C. The cool fused product was dissolved in warm water before adding a powerful complexant/buffer solution containing sulphosalicylic acid and EDTA. Fluoride was measured by ion-selective electrode (ISE) against appropriately matrix-matched calibration standards containing 1, 10, or 100 ppm F. The method compared favourably with two alternatives; one employed the time-consuming distillation step included in the AWPA A2 1994 method, with a titration finish, and the second employed a double fusion and ISE finish, using TISAB buffer. The chosen buffer system exhibited better capacity than TISAB to complex excesses of model interferant Al. B and Si were also accommodated. Recovery from spiked Eucalyptus maculata (at 0.05-0.5% m/m F) was 94-96%. Precision when analysing Alstonia scholaris containing 0.35% m/m F was about 2%. The method enables better throughput than the AWPA A2 94 method
M J Kennedy


Oxalate production and calcium oxalate accumulation by Gloeophyllum trabeum in buffered cultures
1994 - IRG/WP 94-10075
Most basidiomycetous fungi produce oxalic acid as a result of their metabolic activities and nutrient procurement. There is currently a renewed interest in the role that oxalic acid may play in the decomposition of wood by basidiomycete fungi. It has been observed that although most wood degrading fungi have the capacity to produce oxalic acid, not all of these organisms express this capacity equally in the wood environment. In addition, not all of the fungi which produce oxalic acid will accumulate this metabolite. Very often the production of oxalic acid is coincident with the precipitation of oxalate salts such as calcium oxalate. At this time it is unclear as to what controls the differential production and accumulation of oxalate by wood degrading fungi. An investigative series of experiments was established using the brown rot fungus Gloeophyllum trabeum to examine the conditions which favor oxalate production and accumulation as manifested through the production of metastable calcium oxalate dihydrate crystals. Batch cultures which were buffered by base cation exchange sites of mineral amendments stimulated the production of calcium oxalate crystals. The results of these buffering experiments indicate that at pH values below approximately 6.0 there is a diminution of oxalate accumulation, and that a pH environment of approximately 3.0 is consistently attained in weakly buffered cultures inoculated with this fungus. These pH values correspond to the pH optima for oxaloacetase (EC 3.7.1.1) and oxalate decarboxylase (EC 4.1.1.2) respectively, and thereby suggest a mechanism for both pH control and oxalate production and accumulation.
J H Connolly, J Jellison


An evaluation of the potential of ion mobility spectrometry for detection of organic wood preservative components in solutions and treated wood
1994 - IRG/WP 94-20038
For the disposal of wood waste under ecological sound conditions information about its hazardous potential is required. Until now, no highly sensitive rapid analytical methods are available for the detection of wood preservatives under industrial process conditions. Preliminary experiments showed that Ion Mobility Spectrometry (IMS) could be a promising method for rapid detection of organic preservatives in waste wood. A number of organic wood preservatives (i.e. Al-HDO, Quat, Armoblen, Azaconzole, HCH, Creosote, DCFN, Furmecylox, MBT, Methyl-parathion, PCP, Permethrin, K-o-PP, TBTO, TCMTB and Tebuconazole) was studied. Both solutions and treated wood samples were analyzed with IMS. IMS-spectra are generated by analyzing the ionized volatile compounds of the samples. The time each ion needs to proceed to a detector is specific and can be characterized by a comparable Ko value, the so-called reduced mobility constant. A 'fingerprint' of the wood and the chemicals is obtained. IMS was able to distinguish between most of the preservatives. However, in wood, some of the chemicals could not be determined. So far the results are provisional and further investigation is needed.
A Voss, J N R Ruddick, W J Homan, H Militz, H Willeitner


Determination of total fluoride and boron in preservative-treated wood fluoride by ion selective electrode without steam distillation, and boron colorimetrically using azornethine-h
1998 - IRG/WP 98-20135
An analytical method was developed to determine total fluoride and boron in wood treated with aqueous or solid diffusing fluoride or borate-fluoride formulations. Ground wood was mixed with 30% sodium hydroxide solution and oven-dried for 2 hours before furnacing at 600° C for 1 hour. The cool fused product was dissolved in hot water, transferred to a plastic beaker and neutralised. Fluoride was measured by ion-selective electrode (ISE), after adding Ionic Strength Adjustment Buffers (ISAB), against appropriately pH and matrix-matched calibration standards containing 1, 3, 5, 10 and 50 ppm F. Boron was determined colorimetrically on the same neutralised solution using azomethine-H chemistry. Citric acid, sulphuric acid and nitric acid were evaluated as neutralising agents. While the choice of neutralising acid had no significant influence on the determination of boron by azomethine-H, speed and stability of the ISE for fluoride was best with nitric acid at 3.75M. The ISABs Sulphosalicylic acid and EDTA (SSA-EDTA); tri-sodium citrate and potassium nitrate; tiron and sodium nitrate; and TISAB were all evaluated for fluoride determination. Only SSA-EDTA was found to complex aluminium adequately, also accommodating borate, silicate and iron. Although SSA-EDTA has been traditionally used at pH 9.5 for the determination of fluoride in large amounts of aluminium, we found that use at this pH led to significant problems from hydroxide ion interference, slow electrode response, and pH changes due to loss of ammonia, all resulting in poor detection limits and reproducibility. To improve method performance, the pH of standards and samples was adjusted to 8.7, and all samples were spiked with an additional 1 mg/L fluoride. Interference from aluminium increased marginally, but the SSA-EDTA buffer was still capable of masking aluminium at a ratio of 20:1 AI:F, when measuring solutions containing 5 mg(F)/L. The method compared favourably with two alternatives; one employed the time-consuming distillation step included in the AWPA A2-1994 method, with a titration finish, and the second employed a double fusion and ISE finish, using TISAB buffer. Mean recovery from spiked Tasmanian oak (Eucalyptus regnans) at 0.05% - 0.20% m/m B/F was 95-105%. Precision at 0.2% m/m B/F in wood was about 3% for F and 1% for B. Detection limits of 30 mg/Kg for F and 20 mg/Kg for B were adequate for monitoring movement of toxicants within remedially-treated hardwood poles.
P A Collins, M J Kennedy


Selective chromate elimination from the storage-drainage-water of a wood impregnation plant
1980 - IRG/WP 3153
With the Enviro-Chrom-Ex process it is possible to eliminate ecologically and economically hexavalent chromium (chromate) from water selectively. The process which is based on the principle of selective ion exchange works with different chromate concentrations and under the presence of other ions, irrespective of the water hardness. The values of water-offtake reach 0.1 mg CrVI at maximum, causing neither pH alteration nor concentration of the salt-content of the water. The plant which has been installed in the Holzimprägnierwerk AG, Waldkirch, Switzerland, for treating chromium-containing drainage-water permits the chromium-containing regenerates to be recycled into the impregnation process. Using this chromate-recycling-process the harmful substance can be eliminated optimally.
O Wälchli, R Ott, R Hugener, E Graf, B Lieberherr


The probable mechanism of action of boric acid and borates as wood preservatives
1990 - IRG/WP 1450
The tetrahydroxyborate ion [B(OH)4-] acts by complexation with poly-ols and probably attacks decay fungi through extracellular substrate sequestration; intracellular substrate sequestration; enzyme inhibition; and change in membrane function. Work was carried out to investigate this further and to try to explain certain phenomena observed in the area of boron preservation. The effect of Na borate in the presence of different concentrations or various carbohydrates upon the radial growth rate of certain fungi was investigated; along with parallel experiments on the activity of 6-phosphogluconate dehydrogenase as an example of a borate inhibited enzyme system. It was found that upon the addition of certain poly-ols, the inhibitory effect of borate on both fungal growth and enzyme activity could be reduced. These results have been used in the development of our understanding of the mechanism of action of borates as wood preservatives. The commonly held belief that certain mould species are resistant to borates may also need re-evaluation.
J D Lloyd, D J Dickinson, R J Murphy


The mechanism of leaching of copper-chrome-arsenic preservatives from treated timber in saline waters
1976 - IRG/WP 374
A mechanism for the leaching of copper-chrome-arsenic preservatives is proposed on the basis of theoretical calculations and experimental studies using timber subjected to a range of water types of different ionic compositions. Complex formation by copper (II) and chromium (III) with chloride and hydroxide ions is shown to affect the leaching rate. Of even greater importance is the salt effect on the activity coefficients. The various complexes formed at different pH values are discussed. Two minima are observed in the plot of copper leaching versus water salinity; these are attributed to the presence of the copper fixation compounds Cu2(OH)AsO4 and Cu3(AsO4)2. At low salinities NaCl is shown to have a coagulating effect on the copper fixation compounds, reducing their solubility, whereas at higher salinities complex formation dominates. With chromium the coagulation effect is not observed and leaching increases with increasing salinity. Loss of arsenic is shown to lag behind that of copper and chromium and is related to the chromium excess in the preservative formula: the greater the excess, the longer the delay in arsenic loss. The suggested mechanism adequately explains the experimental results.
J Irvine, S-E Dahlgren


Site characteristics impacting historic waterlogged wood: A review
2000 - IRG/WP 00-10344
Survival of waterlogged wood from hundreds and in rare cases millions of years presents scientists with a unique opportunity to examine wood specimens which, due to select properties of the wood itself and/or the depostional environment, have not been completely degraded. Although degradation patterns of various types of microbial wood decay have been studied in detail, the site parameters of the zone from which the wood was removed has not been systematically characterized and correlated to the specific types and cause of degradation. Studies have been conducted attempting to relate factors such as hydrogen-ion concentration (pH), redox potential (Eh), oxygen (O2) concentration, and chemical end-member concentration to specific environments, but there has been no unification of testing methodology. This paper proposes to review the literature concerning site characteristics that impact the biodegradation of historic submerged wood, and discuss the implication of such research to future needs for further advancement of the science.
B A Jordan, E L Schmidt


Some practical implications from recent research on the fixation of CCA preservatives
1975 - IRG/WP 358
The mechanism of fixation of CCA preservatives is briefly described. If the temperature is increased during the primary fixation period, the formation of intermediate fixation compounds is less extensive. The length of the primary fixation period is of practical interest. It is determined by preservative composition and concentration, temperature and wood species. Diagrams are given for Pinus sylvestris. Light exposure and drying during the primary fixation period cause variability in colour intensity of CCA treated wood. Disproportionation of preservative elements with penetration depth is explained by the fixation mechanism. Conversion of intermediate fixation compounds into stable ones occurs even below the fibre saturation point, as long as the moisture ratio is sufficiently high to allow ion transport. Conversion reactions are very slow. A correlation was found between the final pH of treated timber and leachability in fresh water of copper and arsenic. The final pH depends on preservative composition and concentration, wood species and to some degree of drying and storage conditions. An electrolyte such as sodium sulfate does not affect the leachability. In saline waters leachability is increased by complex formation of Cu(II) and Cr(III) with chloride and hydroxide and the salt effect on activity coefficients. The leaching of arsenic is delayed.
S-E Dahlgren


Optimisation of an analytical method for the determination of total fluoride in preservative-contaminated soils using water steam distillation and an ion-selective electrode
1999 - IRG/WP 99-20153
This paper describes a simple modified procedure for the quantitative fluoride determination of different origin in a soil matrix using a water steam distillation and an ion-selective electrode. Distillation methods generally require a preliminary preparation step like fusing. The modified method presented here is based on the direct distillation of fluoride so that no further sample preparation is necessary. The separation is carried out in a perchloric acid medium and the analysis takes place by means of a reduced Total Ionic Adjustment Buffer (TISAB) solution. This technique allows also the application of a battery equipment, i. e. simultaneous distillation will be possible. Using a 2-flask system approximately 10 soil samples with two parallels can be analysed per day. The adaptation of the test method, possible checked parameters of influence, the obtained results and observed problems are discussed. The results showed that in general satisfying (>90%) recovery rates can be received.
E Melcher


Time-of-Flight Secondary Ion Mass Spectrometry Analysis of Polyethylene Glycol Penetration into Wood Cell Walls
2006 - IRG/WP 06-20328
Penetration of high molecular weight polyethylene glycol (PEG) into wood cell walls was investigated in red pine. PEG of different molecular weights (1000, 8000 and 20000) was labelled by bromination and treated samples were analyzed on Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) in dynamic mode. Both negative and positive spectra of the samples were collected in high spatial (bunched), high spectral (burst), and an intermediate (burst alignment) resolution mode. Spectral and image data were statistically analysed by principal component analysis (PCA). Negative spectra distinguished untreated from treated samples, showing Br allocation in cell walls of all treated samples. Positive spectra did not provide differentiation between PEG and wood components. Penetration of PEG of all molecular weights into cell walls was confirmed even in case of treatments with PEG 20000.
D Jeremic, P Cooper, P Brodersen


Copper nanoparticles in southern pine wood treated with a micronised preservative: Can nanoparticles penetrate the cell walls of tracheids and ray parenchyma?
2010 - IRG/WP 10-30547
This study tests the hypothesis that copper nanoparticles can penetrate the cell walls of southern pine wood treated with a micronised preservative. We examined the nanodistribution of particles in tracheid and ray parenchyma cell walls using state-of-the-art HR (High Resolution)-TEM and HR-STEM (Scanning Transmission Electron Microscope)-EDX. These devices are capable of atomic-scale resolution. FIB (Focused Ion Beam) processing was used to make ultra-thin sections for electron microscopy. Our results show that FIB sectioning in combination with HR-TEM and HR-STEM is a powerful tool for observing the penetration of wood cell walls by nanoparticles or clusters of metal atoms. HR-STEM with a Cs corrector revealed that copper carbonate nanoparticles could not penetrate the cell walls of tracheids. Copper, however, is present in cell walls of tracheids as atoms or ions. In contrast, small copper nanoparticles (2.5 nm in diameter) were able to penetrate ray parenchyma cell walls. These particles were identified as copper carbonate by HR-TEM lattice image analysis. We conclude that the cell walls of unlignified ray parenchyma tissue in southern pine are accessible to copper nanoparticles whereas nanoparticles are excluded from lignified tracheid walls.
H Matsunaga, Y Kataoka, M Kiguchi, P Evans


Copper Nanoparticles in Southern Pine Wood Treated with a Micronised Preservative: Nanodistribution of Copper in the Pit Membrane and Border of an Earlywood Bordered Pit
2011 - IRG/WP 11-30566
Copper nanoparticles can penetrate the cell walls of unlignified parenchyma cells in southern pine wood treated with a micronised wood preservative, but they are excluded from lignified tracheid walls. This paper extends these observations to include the cell wall layers of the bordered pit. Focused ion beam and ion milling were used to make an ultra-thin section of the cell wall layers of an earlywood bordered pit excised from southern pine wood that had been treated with a micronised wood preservative. High resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy in combination with energy dispersive analysis of X-rays were used to detect and examine the penetration of the torus and pit border by copper. Copper was more abundant in the torus than in the pit border, but the depth of penetration of copper in both cell wall layers was approximately the same, ~100nm. High resolution transmission electron microscopy was unable to detect crystalline material in either the torus or pit border. Therefore we conclude that copper nanoparticles are unable to penetrate the torus and border of the bordered pit in accord with our previous observation that nanoparticles are excluded from the cell walls of lignified tracheids.
H Matsunaga, Y Kataoka, M Kiguchi, P Evans


Accessibility of Wood Cell Walls to Well-defined Platinum Nanoparticles
2012 - IRG/WP 12-20494
Copper nanoparticles are found in the walls of parenchyma cells in southern pine sapwood treated with a micronised wood preservative, but they are absent from tracheid walls. Hence, we hypothesized that small nanoparticles can penetrate the walls of unlignified parenchyma cells, but are excluded from lignified tracheid walls. This paper tests this hypothesis by treating pine sapwood with an aqueous emulsion of coated, inert, platinum nanoparticles (2-4 nm). A focused ion beam was used to make ultra-thin sections of the cell wall layers of earlywood tracheid and ray parenchyma cells excised from treated southern pine sapwood. High resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy in combination with energy dispersive analysis of x-rays were used to examine the penetration of cell walls by platinum nanoparticles. Platinum nanoparticles were only deposited on the wall adjacent to the cell lumen of tracheids and were not detected in the cell wall. In contrast, platinum nanoparticles penetrated ray parenchyma cell walls. These particles were identified as crystalline (metallic) platinum by lattice image analysis in high resolution transmission electron microscopy. Therefore we conclude that small nanoparticles (2-4 nm) are able to penetrate ray parenchyma cell walls, but are excluded from lignified tracheid walls.
H Matsunaga, Y Kataoka, M Kiguchi, P D Evans


Curing kinetics of nano cupric oxide (CuO) modified PF resin as wood adhesive: Effect of surfactant
2013 - IRG/WP 13-40620
The effect of nano cupric oxide (CuO) in combination with surfactants on the curing kinetics of phenol formaldehyde (PF) resin, as well as the bonding strength of plywood prepared using the modified resin were investigated in this study using dynamic and isothermal differential scanning calorimetry (DSC). The result showed that the incorporation of nano CuO along with alkane surfactant made in the laboratory clearly reduced the apparent activation energy of the PF resin and improved the addition and condensation reactions of the PF resin. Inclusion of the surfactant had the further effect of compensating the influence of diffusion control caused by nano CuO alone. The shear strength of plywood suggested that the addition of nano CuO (1%) alone or in combination with alkane surfactant (0.55%) or sodium lignosolfonate (0.55%) in the PF resin mixture was sufficient to meet the requirement of wood-based composites manufacturing.
Wei Gao, Guanben Du


Dynamic mechanical analysis (DMA) of nano cupric oxide (CuO) modified aqueous phenol formaldehyde (PF) resin
2014 - IRG/WP 14-40654
Phenol formaldehyde (PF) resins, modified by nano CuO incorporating alkane surfactant and polyvinyl alcohol (PVA) 17-99, were analyzed by dynamic mechanical analysis (DMA). The mechanical properties of its bonded plywood including tensile strength, modulus of rupture (MOR), modulus of elasticity (MOE) and shear strength under five test conditions were evaluated. Results indicated that the incorporation of nano CuO and PVA 17-99 separated the gel point and vitrification point delaying of moisture loss in modified PF resin during the curing process. The modification caused adverse effect on tensile strength but only minimal influence on MOR and MOE. Additionally, PVA 17-99 reduced the water resistance of cure PF resins. However, under the special test conditions, PVA consolidated the re-curing effect and compensated for the strength loss by hydrolysis.
Wei Gao, Guanben Du