Your search resulted in 49 documents. Displaying 25 entries per page.
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
An investigation into the influence of soil cation exchange capacity on preservative component depletion
1994 - IRG/WP 94-20050
The mobility of preservative components from treated wood into the soil environment is regarded as an important determinant of preservative performance. Standard procedures for the investigation of this phenomenon have not been developed to any great extent. Soil bed studies conducted in this laboratory using natural soil and modified soil media have provided interesting comparative data on the influence of cation exchange capacity on preservative depletion. Some of these data are discussed with reference to the development of a standard soil contact depletion procedure.
K J Archer, L Jin
Soil chemistry and wood decay
1978 - IRG/WP 2109
Soil is a most complex biological, chemical and physical material; its study is effectively a separate branch of science but almost entirely in relation to ist ability to grow plants - this paper is intendet just to note some known facets that might have relevance to the decay of wood and the performance of wood preservatives.
E A Hilditch
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
Rates of emission from CCA-treated wood in the marine environment: measurement, modelling and requirements for further research
2001 - IRG/WP 01-50166-12
Accurate estimates of rates of emission of leachate from preservative treated wood are crucial for realistic predictions of the environmental impact of its use in maritime construction. Estimates are available for some commonly used preservatives, but these vary widely. Though variable, these measurements suggest that emission generally decreases exponentially with time. Part of the variation is due to differences in methodology employed. Physical and chemical characteristics of the seawater used (e.g. temperature, salinity, pH and oxygen content) affect emission rate. So too do the specifics of the treatment process especially the preservative formulation used, and pre- and post-treatment handling of the wood. The nature of the treated wood samples is also important, with misleadingly high estimates being obtained from samples with unrepresentatively high proportions of cross-cut surfaces. A suggested strategy for developing an informative and standardised methodology is discussed. To form useful models of impacts of leaching, emission rates need to be considered in conjunction with site-specific information regarding a) water exchange rates between the area where leaching occurs and the sea, and b) the extent of partitioning of leachate between the water column, biota and sediment. The risk of environmental impact may be reduced by modification to treatment procedures and by careful planning of installation.
S M Cragg, C J Brown, R A Albuquerque, R A Eaton
Collaborative soft rot tests: Programme and test method
1973 - IRG/WP 229
J G Savory, J K Carey
Iron promotes decay capacity of Serpula lacrymans
1993 - IRG/WP 93-10008
The influence of iron and iron compounds on the decay capacity of Serpula lacrymans was studied. Mass losses of pine wood caused by dry rot fungus were increased when FeSO4 was added into the culture medium or when there were iron nails or stone wool on the culture medium. This supports the hypothesis that iron in stone-based building materials is one reason for the increased decay capacity of Serpula lacrymans.
Production of treated wood in Brazil in 1982 and 1983
1985 - IRG/WP 3327
The data of Brazilian production of treated sleepers, poles, crossarms, fence posts and other commodities are given for the years of 1982 and 1983. This report updates information given to the Group in Document No: IRG/WP/3321 Wood Preservation in Brazil, STU information no 445
M S Cavalcante
Some observations on miniaturised soil/block tests
1988 - IRG/WP 2317
Results are presented for miniaturised soil/block tests carried out in 120 ml capacity glass jars. The four test fungi (Coniophora puteana, Coriolus versicolor, Gloeophyllum trabeum and Poria placenta) reacted differently to different moisture regimes established by varying the soil moisture content. Acceptable levels of decay were achieved by the three brown rot fungi with soil at 110% whc; however, soil at 150% whc failed to provide a high enough moisture content in the test blocks for decay by the white rot Coriolus versicolor. Overlaying test blocks exposed to Coriolus versicolor with moist sterile vermiculite increased both moisture contents and decay.
J K Carey
A new laboratory technique devised with the intention of determining whether, related to practical conditions, there should be a relationship between growth rate and decay capacity (of different strains) of Serpula lacrymans
1989 - IRG/WP 1384
Most laboratory techniques for the determination of growth rate not only use a medium (agar) unrelated to practice, but also yield values that are often far less than those found in practice. Also, most laboratory techniques for the determination of decay capacity ensure that the whole of a small test block becomes fully surface-colonised within the first few days; whereas in Australian practice Serpula lacrymans most often grows in one direction, from the walls across floorboards, with resulting collapse first evident near the ends of boards adjacent to that wall. This paper reports on a new, medium-scale, laboratory technique enabling growth rate measurements and (subsequently) a decay capacity measurement, all using the same piece of timber. Eight strains of Serpula lacrymans have been used in the three evaluation experiments carried out to date. Mean values for growth rate on wood have been suitably high, probably as high as for the most favourable practical situations. Resulting mass losses have, as was intended, been reduced in comparison with values previously obtained in small-scale techniques. This direct technique has confirmed the conclusions that others have made based on their comparisons; that it seems unlikely that the pattern of differences between growth rates of different strains has any consistent similarity with their corresponding decay capacities.
J D Thornton
Report on the status of collaborative experiments within the Sub-group on Basidiomycete tests
1983 - IRG/WP 2194
This report summarises the results of co-operative work carried out within the Sub-Group on Basidiomycete tests up to December 1982. The principle findings are recorded in the Conclusions Section. Work intended between IRG-13 in Turkey and IRG-14 in Australia is cited under Future Programme. An Annex provides a response sheet for existing and new participants to notify their contributions.
A F Bravery
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.
Iron in stone wool - one reason for the increased growth and decay capacity of Serpula lacrymans
1992 - IRG/WP 92-1537
The chemical compositions of stone wool and glass wool were analysed. There was more iron in the stone wool than in the glass wool. It was found that iron present in stone wool was easily dissolved by oxalic acid that Serpula lacrymans is able to produce. The stone wool promoted the decay of pine wood by Serpula lacrymans. The glass wool had no effect on the decay capacity of Serpula Iacrymans. The iron derived from the stone wool may be one reason for the increased growth and decay capacity of Serpula lacrymans. Transition metals (Fe2+, Mn2+, etc.) combined with hydrogen peroxide (H2O2) are believed to be necessary for the oxidative breakdown of polysaccharides.
L Paajanen, A-C Ritschkoff
Leaching tests - A paper for discussion
1973 - IRG/WP 221
J W W Morgan
Testing wood in ground contact: An artificial soil
1977 - IRG/WP 280
This document is an interim report on the development of the artificial soil medium. It includes some information on the relationship between soil, wood and water which is of relevance in testing.
E F Baines, D J Dickinson, J F Levy
Copper binding capacity of modified wood flour
1992 - IRG/WP 92-3709
Wood flour was modified by reaction with oxidising agents and CCA preservative. The copper chromium and arsenic were removed from the CCA treated wood flour by an acid leaching procedure. The modified wood flours were allowed to react with copper acetate solution and the level of copper fixation achieved was determined. The modified wood flours had greater affinity for copper ions present in solution than unmodified wood flour.
N C Milowych, W B Banks, J A Cornfield
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 18.104.22.168) and oxalate decarboxylase (EC 22.214.171.124) respectively, and thereby suggest a mechanism for both pH control and oxalate production and accumulation.
J H Connolly, J Jellison
Soil-bed studies. Part 2: The efficacy of wood preservative
1983 - IRG/WP 2205
Various methods of decay assessment were investigated. Three stages or phases of decay were identified which could be used to describe the efficacy of a preservative system or virulence of a soil-bed testing medium. These included the lag, decay, and senescent phase. Premature senescence could arise if wood samples became waterlogged. It was concluded that time to failure was unsuitable as a method of decay assessment. Decay assessment by deflection testing was therefore limited to assessing linear losses in elasticity against time.
P Vinden, J F Levy, D J Dickinson
The foreign exchange situation and fate of wood preservation in Nigeria
1989 - IRG/WP 3558
Up to about 15 years ago, wood utilization industry in Nigeria gave no serious thoughts to wood preservation. After this period however, as a result of escalated local demand for sawn timber, logs with wider sapwood and mainly of secondary tree species requiring protection of the sawn timber became dominant in the local timber scene. Preservatives both for protection in and out of ground contacts were available in the past in the market and at affordable prices. However, the value of local currency which has depreciated by about 86% within 48 months has made importation of preservatives a very expensive business. The paper suggests both short-term and long-term solutions for tackling the assult on the forest conservation programme which lack of wood preservation strategy has occasioned in Nigeria.
M A Odeyinde, S C Ifebueme
A comparison of inductively coupled plasma spectroscopy and neutron activity analysis for the determination of concentrations in wood
1993 - IRG/WP 93-10048
As wood decays the ionic composition changes, with increases often being seen in the concentrations of Ca, Mg, Fe, Mn and sometimes K. The concentration of eight cations in red spruce sapwood and heartwood samples was determined independently by inductively coupled plasma spectroscopy (ICP) and by neutron activation analysis (NAA) as part of an effort to standardize our analytical procedures and create a uniform wood standard for use by multiple researchers. Preliminary studies indicate a difference in the values of Ca and K as estimated by ICP and NAA, possibly due to a loss of these elements due to volatilization during ashing.
J Jellison, J Connolly, K C Smith, W T Shortle
Preliminary studies to assess the effects of aeration and lowered humidity on the decay capacity, growth and survival of the dry rot fungus Serpula lacrymans (Wulf ex. Fr.)
1997 - IRG/WP 97-10208
Novel microcosms were used to test separately the effects of aeration and humidity on the decay capacity, linear spread and survival of Serpula lacrymans. The application of a pumped air supply resulted in an effective cessation of fungal activity when all but the lowest of the air flow rates was used. Furthermore, the lowest air flow rate caused marked growth tropisms away from the stress. In separate chambers used to create a range of relative humidities, growth and decay were permitted only in the higher humidity regimes. In both the air flow and the humidity experiments, the loss of growth and decay abilities was not always accompanied by a loss of fungal survival. A test to compare the decay capacities of domestic building isolates and "wild" Himalayan isolates of S. lacrymans was also performed, as were comparisons of radial growth rates on malt agar. Significant differences between the two groups occurred in both tests.
G A Low, J W Palfreyman, N A White, H J Staines, A Bruce
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
A study of the colonization of wood blocks in a laboratory unsterile soil test
1988 - IRG/WP 2318
CCA treated and untreated beech blocks were exposed to a defined horticultural loam using the method proposed for the collaborative soft rot test in the soft rot sub-group of Working Group Two. At intervals during the incubation wood samples were removed and fungal isolations were made using selective media. Fungi were identified and tested for their cellulolytic ability and their decay capacity in beech in pure culture. Replicate wood samples were examined by microscopy for colonisation and decay.
M T De Troya, S M Gray, D J Dickinson
Evaluating the potential of amine chemicals for use as wood protecting agents. Part 1: Investigation of cation components of quaternary ammonium compounds
1994 - IRG/WP 94-30049
Quaternary ammonium compounds (quats) have shown a great potential as more environmentally acceptable wood preservatives. In order to identify chemicals possessing the wood protecting potential, an evaluation was carried out of a range of commercially available 'quats', using a modified soil block test. Ponderosa pine sapwood blocks were treated with selected 'quat', leached with water and sterilized with gamma radiation. The blocks then were exposed to Postia placenta, Gloeophyllum trabeum and Trametes versicolor in soil jars. After incubation at 25°C for twelve weeks, weight losses of the blocks after the test were calculated and the fungal toxic threshold determined. The four 'quats' examined were very effective in preventing attack of ponderosa pine sapwood blocks by the three fungi.
Hang Tang, J N R Ruddick
Studies on the permeability of Norway spruce (Picea abies)
1987 - IRG/WP 2295
It is well known that the bordered pits play a dominating role for liquid transport in softwoods. The mechanism behind pit aspiration during drying or heartwood formation seems to be well understood. The reason why the fixation of the membrane (torus) to the pit opening remains almost irreversible is, however, still unclear. A technique has been developed combining so-called "solvent exchange drying" with scanning electron microscopy. In this way the pit system can be "frozen" and the number of pits in aspiration can be determined. The technique has been used to widen the understanding of pit aspiration. It has also been used to follow pit aspiration during air drying and in connection with efforts to pit aspirated pits by different physical and chemical methods.
I Johansson, K Nordman-Edberg