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Adsorption of ionic liquids by Scots pine wood (Pinus sylvestris L.) and beech (Fagus sylvatica L.): equilibrium and kinetic modeling
2010 - IRG/WP 10-20447
In this paper methods for the adsorption study of quaternary ammonium-based ionic liquids on Scots pine (Pinus sylvestris L.) and beech (Fagus sylvatica L) are presented. Kinetic and equilibrium adsorption of compounds were evaluated. The equilibrium data fitted very well to the Langmuir adsorption models. The highest correlation coefficients determined from the pseudo-second order kinetic model confirm the key role of chemisorptions in the process of thickening of ionic liquids on the wood surface. The bonding identification of the ammonium nitrates into the Scots pine and beech wood was carried out using IR spectroscopy.
J Zabielska-Matejuk, A Stangierska, M Kot


Kinetic modelling of adsorption of quaternary ammonium compounds by Scots pine wood sawdust (Pinus sylvestris L.)
2005 - IRG/WP 05-30369
The adsorption of new quaternary ammonium compounds from aqueous solutions onto Scots pine wood (Pinus sylvestris L.) sawdust was studied. The pseudo first- and second- order kinetic models were used for the mathematical description of the sorption dynamic process of QACs onto wood. The highest correlation coefficients were obtained for the pseudo-second order kinetic model, those suggest that chemisorption is involved in the adsorption process.
J Zabielska-Matejuk


Selective adsorption of antisapstain actives from two aqueous suspensions, and movement of actives into wood
1996 - IRG/WP 96-30103
Green-off-saw rough sawn Pinus elliottii (slash pine) boards were dipped in aqueous suspensions of two antisapstain formulations, NeXgenâ and Busanâ Sap Stain Preventative (Busan 1009), at three product concentration levels. Concentrations of active ingredients (NeXgen: CTL (chloro-thalonil) and MTC (methylene bisthiocyanate); Busan 1009: TCMTB (2(thiocyanomethylthio)-benzothiazole) and MTC) were monitored with respect to the amount of material dipped. Selective adsorption (removal of actives from the suspension at greater than simple volumetric transfer rates) varied with formulation and active ingredient, and increased with decreasing product concentration. Movement of active ingredients into dipped boards was monitored for 30 days after dipping. Mobility order was MTC >> TCMTB > CTL. Surface depletion characteristics were obtained for each active ingredient.
M J Kennedy, T L Woods


Wood preservatives ecotoxicology on Gammarus pulex (L.) - toward an environmental monitoring method and a getting rid of pollution process
2005 - IRG/WP 05-50224-9
Wood preservatives can have a strong impact on freshwater invertebrates when used close to aquatic ecosystems. It has been reported in Jura that different arthropod taxa, specially crustaceans, have disappeared along several kilometers downstream from factories using insecticides and fungicides as wood preservatives. The crustacean Gammarus pulex (L.) is a relevant bioindicator to characterize the impact of wood preservatives on freshwater community. It presents a high sensitivity to wood preservatives but a relative tolerance to organic and nutrimental pollution. This abundant and ubiquitous crustacean has a key role in numerous aquatic ecosystems particularly in the decomposition of cellulose and as a prey for several fish species susceptible to be eaten by humans. In this study, we aim on the one hand to determine the adsorption capacity of different substrates of propiconazole, a fungicide widely used in the wood treatment, and on the other, to evaluate the toxicity of wood preservatives for G. pulex in controlled conditions. We hypothesize that the fungicide toxicity may be influenced by different types of substrate used in the test containers, i.e., coarse organic matter and gravel. These results should allow us to go, firstly toward the elaboration of sensors in order to detect product emissions in the aquatic environment, and secondly toward a depuration process in order to decrease the impact on the aquatic communities. These experiments should also allow us to develop a new biological monitoring method for the assessment of the impact of wood preservation on the aquatic ecosystems.
O Adam, F Degiorgi, G Crini, P-M Badot


Heat treated timber in Finland
2000 - IRG/WP 00-40158
Heat treatment permanently changes the physical and chemical properties of wood by means of high temperatures (150 - 240°C). Heat treatment darkens the colour of the wood. Heat treatment improves the equilibrium moisture content of the wood and the shrinkage and swelling of the wood is reduced. Very high temperatures improve the resistance to rot and also reduce the susceptibility to fungal decay. At the same time the strength properties of the timber are reduced: the bending strength can fall by 30%, depending on the treatment conditions and the cleavage strength (tensile strength perpendicular to fibres) may be reduced to a half, which makes heat treated timber split easily. The improved characteristics of heat treated timber offer the timber product industry many potential and attractive new opportunities. Also wood species having no commercial value as such can be heat treated and in this way new uses can be found for these species.
T Syrjänen, E Kangas


Maintaining the adoption of the equilibrium moisture content in timber by bifluorides under outdoor circumstance
1989 - IRG/WP 3541
A description is given of the practical application of bifluorides, f. ex. Diffusec in maintaining the adaption of the equilibrium moisture content in timber, as a result of a many years observation of treated timber under outdoor circumstances.
H F M Nijman


CCA Chemistry
1983 - IRG/WP 3268
A Pizzi


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


A contribution to the adsorption/desorption behaviour of zinc-hexa-fluoro-silicate in different soils
1995 - IRG/WP 95-50056
The estimation of a possible endangering of the groundwater through wood preservatives and thereof deriving measures for the avoidance of secondary damages require among others exact knowledge concerning the behaviour of wood preservative compounds in the soil matrix. Adsorption and desorption behaviour were determined at four soils of different characteristics, which were brought in contact with aqueous solutions of zinc-hexa-fluoro-silicate. For the respective experiments four concentrations were prepared containing 10, 50, 100 and 250 ppm zinc ions. Water of p.a. quality served as reference. As to be expected the soils in question behaved different: the adsorption of inserted ions increased with increasing clay content of the soil. On the other hand significant differences exist also with respect to the adsorption behaviour of the zinc cation in relation to the hexa-fluoro-silicate anion. Within the concentration interval investigated, the same soil adsorbed approximately the same proportional zinc quantity. However, when increasing the hexa-fluoro-silicate-ion concentration a proportional decrease concerning the degree of adsorption was observed. The results show that it is not possible to conclude from partial results achieved with individual preservative compounds to the overall system "wood preservative"-soil and that further investigations are necessary for an inclusive description of the problem.
E Melcher, R-D Peek


Kinetic of the wood degradation produced by wood decay fung
1993 - IRG/WP 93-20016
The degradation degree of a wooden structure has a direct influence on its loss of mechanical strength. It's necessary to deepen in non destructive techniques which permit to extrapolate the results obtained in laboratory to structural timber used in the building's construction. This work studies the relationship existing between the pulse velocity of ultrasonic waves and the weight loss suffered by samples of two different wood species (Pinus sylvestris and Fagus sylvatica) exposed to attack of two fungi representatives of white rot and brown rot (Coriolus versicolor and Gloeophyllum trabeum) during the time (1 to 5 months). The results demonstrate that decay produces a progressive decreasing of ultrasonic velocities that runs in direct relation to weight loss.
M T De Troya, A M Navarrete, A Sanchez, V Bucur


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 risk assessment of treated timber in service: The Environment Focus Group approach
2000 - IRG/WP 00-50162
In the context of the Biocidal Products Directive (98/8/EC), and of the OECD work on wood preservatives, the Environment Focus Group (EFG), comprising 8 institutes and the European Wood Preservative Manufacturers Group, has been working on the environmental risk assessment of treated timber in service. A literature review of emissions from treated timber has revealed that very little existing data is usable for environmental risk assessment; the most relevant data are kinetic curves of emissions over time, which show clearly the non-linear emissions behaviour of treated wood over time. The EFG has suggested real exposure conditions for treated timber in the environment, and listed typical exposure scenarios. Five representative scenarios are characterised in detail, for use in the calculation of Predicted Environmental Concentrations (PECs). The existing methods to determine emissions from treated wood have been reviewed. Most existing experimental models cannot be used to predict environmental emissions. Monitoring of commodities in service has its specific constraints. Chemical analysis and ecotoxicity testing have also been reviewed and their relationship has been discussed. Principles for the design of experimental models, for the determination of emission fluxes from treated wood to the environment, have been established.
G Deroubaix, G Labat, I Le Bayon, S Legay, P Marchal, C Yrieix, E Melcher, R-D Peek, S De Geyter, J Van Acker, W J Homan, D J Dickinson, R J Murphy, E D Suttie, A J Nurmi, A-C Ritschkoff, D Rudolph, I Stephan, D Aston, E F Baines, J B Simonin


Properties of hot oil treated wood and the possible chemical reactions between wood and soybean oil during heat treatment
2005 - IRG/WP 05-40304
Thermal treatment with hot oil as the heating media based on the original idea from oil-heat treatment in Germany was investigated. The treatment was mainly carried out at 200ºC and 220ºC for 2 hours and 4 hours, and the wood species were mainly spruce and fir. This paper focuses on the difference between soybean oil and palm oil and the possible chemical reactions between wood and soybean oil. Generally palm oil was slightly better than soybean oil in improving the moisture resistance properties of heat-treated wood. But soybean oil treated wood appeared to have better decay and mould resistance. The mass loss of wood treated in soybean oil at 220ºC for 4 hours was below 20 % after exposure to Gloeophyllum trabeum in a soil block test, so the treated wood can be classified as “Resistant” according to ASTM D 2017 standards. Natural weathering exposure also shows that soybean oil treated wood is more mould resistant than palm oil treated wood. In order to investigate the effects of absorbed oil on the properties of treated wood and the possible reactions between wood and oils, extraction of different vegetable oil treated wood with chloroform and other solvents was carried out. The results suggest that part of the soybean oil could undergo chemical reactions with wood that renders it of low extractability.
Jieying Wang, P A Cooper


Preliminary modelling of methylisothiocyanate movement through Douglas fir transmission poles
1988 - IRG/WP 3466
Methylisothiocyanate is a volatile solid that is the active ingredient of several registered and experimental wood fumigants. Information on the sorption and diffusion of this chemical in Douglas-fir heartwood and sapwood was used to develop a two-dimensional model of fumigant movement within a single horizontal cross-section of a transmission pole. The model indicated that dry wood (14% MC) strongly sorbed MIT, which resulted in lower rates of MIT movement. Conversely, it was predicted that wetter wood (22 or 40% MC) held MIT less strongly and had a more rapid rate of chemical movement. In addition, predictions suggest that the presence of an oil-treated peripheral shell had a strong influence on loss of fumigant from the surface of the pole, but had little effect on concentration which developed in the heartwood zone. The results indicate that MIT movement can be effectively modeled. Further studies are underway to account for longitudinal movement of MIT in the model and to simulate extended time periods.
A R Zahora, P E Humphrey, J J Morrell


Equilibrium distribution of toxic elements in the burning of impregnated wood
2001 - IRG/WP 01-50172
The current work focuses on predicting the behavior of arsenic, chromium, and copper in the burning of impregnated wood. A theoretical method is used to study the chemistry of the system, with special interest directed towards the vaporization tendency of the potentially toxic elements. The core of the study is the global equilibrium analysis that simultaneously takes into consideration all chemical reactions. The results of the present study indicate that chromium and copper are unlikely to volatilize at combustion temperatures. Arsenic appears to be more volatile. Nevertheless, the prediction showed that it may be captured by calcium of the wood ash, and small amounts are likely to dissolve in the slag-phase of the ash. It may also form non-volatile compounds with magnesium, copper, and chromium and other elements of the impregnated wood, which efficiently hinders its emissions as gaseous species.
K Sandelin, R Backman


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


The Effect on Biological and Moisture Resistance of Epichlorohydrin Chemically Modified Wood
2002 - IRG/WP 02-40224
Southern pine solid wood and fiber were chemically modified with epichlorohydrin to help in understanding the role of moisture in the mechanism of biological effectiveness of chemically modified wood. The solid wood had weight gains from 11% to 34%, while the fiber had weight gains from 9% to 75%. After modification, part of the specimens were water leached for 2 weeks or extracted for 2 hours with a toluene:ethanol (2:1) solution. The equilibrium moisture content (EMC) at 30%, 65%, and 90% relative humidity (RH) and 27 °C was determined on all specimens. Laboratory soil block decay testing using the brown-rot fungus Gloeophyllum trabeum was performed and weight loss calculated. Results show that epichlorohydrin modified specimens did not lower the EMC significantly, yet there was biological effectiveness at 31% weight gain for the solid wood and 60% weight gain for the fiber. This indicates that the mechanism of efficacy may be due to substrate modification rather than moisture exclusion. Energy dispersive x-ray analysis (EDXA) was performed locating the chlorine throughout the wood cell wall.
R E Ibach, B-G Lee


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


Biosorption of metals for wood waste effluent clean up
1997 - IRG/WP 97-50090
The common filamentous fungi can sorb metal ions from aqueous solutions. The biosorption of metal ions like copper Cu2+, chromium Cr6+ and arsenic As5+ by dead fungal mycelia was investigated. Two industrial fermentation byproducts are tested: Mucor miehei and Aspergillus oryzae. The adsorption of metal ions depends on parameters such as chemical treatment of fungi before biosorption (acid or basic treatment), pH, adsorption time, metal ions and biomass concentrations. 88% of Cu2+ is recovered in one hour by Aspergillus oryzae and Mucor miehei (untreated and basic biomass). Cr6+ is adsorbed in 24 hours by these untreated biomass with a yield comprising between 40% and 65%. Similar results are observed for As5+ adsorption with Mucor miehei in regulated pH conditions. The most efficient systems Aspergillus oryzae (basic treatment) and Mucor miehei (untreated) were investigated in adsorption experiments on CCA-preservative solution (3% m/m). The adsorption yields for copper and chromium are respectively 90% and 80% in 24 hours. Removal of metals from CCA wastewater could be realized by these developped systems on site instead of conventional expensive processes.
S Legay, G Labat


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


Methods for the assessment of wood preservative movement in soil
1995 - IRG/WP 95-50040-08
This paper presents preliminary results from a series of experiments constructed to provide laboratory data for the evaluation of the leaching of wood preservatives into and through soil. The experiments included: i) measurement of the adsorption of preservatives by soil; ii) determination of the concentration gradient of preservatives in soil following percolation of preservative solution through soil; iii) determination of the changes in concentration gradient by subsequent leaching of contaminated soil with water. From an assessment of these laboratory procedures, based upon their practicalness and the results obtained, it was concluded that this range of tests could provide the necessary data to allow a rational appraisal of the potential of a wood preservative to contaminate soil. However, the experimental methodology needs to be examined further using a greater range of soil types, wood preservatives and water sources in order to establish the general acceptability of the approach and to allow standard procedures to be developed.
G E Holland, R J Orsler


The effect of heat treatment on the properties of spruce
1994 - IRG/WP 94-40032
The effect of high temperature treatment (above 150°C) on the wood quality is studied at the VTT. Improved dimensional stability, lower equilibrium moisture content and increased durability against biodeterioration is achieved, depending on the environmental factors. The biodeterioration resistance of spruce is improved due to changes in chemical composition and lower equilibrium moisture content. As a result of the treatment, darkening of colour and reduction of the strenght of the wood due to changes in microstructure is also observed.
H Viitanen, S Jämsä, L Paajanen, A J Nurmi, P Viitaniemi


Kiln drying of LSOP treated timber: rate of solvent evaporation, overpaintability and recovery of the solvent
1992 - IRG/WP 92-3711
The rate of solvent evaporation from LOSP treated timber dried in a kiln at 35°C has been investigated. Around 50% solvent removal has been found to be consistent with good overpaintability using a water based acrylic primer. It has been demonstrated that an activated carbon solvent recovery system is capable of removing all the solvent vapour from the outlet of a commercial joinery drying kiIn, that the solvent is subsequently recoverable using steam and that the recovered solvent is suitable for re-use.
P Warburton, L B Sheard


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