Your search resulted in 6 documents.
Treatment of messmate (Eucalyptus obliqua L'Hérit) by double-diffusion: Preliminary report
1983 - IRG/WP 3234
Modified double-diffusion is suggested as a method of impregnation for mixed tropical hardwoods for certain types of ground contact use in less developed countries. Compared with vacuum/pressure impregnation, capital costs are low and little skill is needed for the operations involved. Treatment of messmate (Eucalyptus obliqua L'Herit) rounds involving pre-heating in water prior to their immersion in the first stage solutions is described. Preliminary indications are that (i) there is a deeper penetration of arsenic when a compound of this element is used in the first stage solution (ii) a more even and deeper penetration of chromium is obtained when sodium chromate, rather than sodium dichromate, is used in the second stage solution. It is concluded that quality control in double-diffusion may be a limiting factor in the adoption of the process for the treatment of wood unless a simple but effective method is found to control solution concentrations and elemental ratios.
F F K Ampong, C-W Chin
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
Ecotoxicological effects of exposed CCA preservative treated wood in environments
2001 - IRG/WP 01-50173
For the evaluation of environmental effect of CCA treated wood exposd in the field, the simulated soil pot system of the laboratory was used. The effective components of preservatives were leached and determined after artificially conditioning a soil pot of CCA treated wood with more than 500mm water, the average monthly precipitation. As the water passed through the soil, As, Cr and Cu in the soil as well as the filtrtes were analyzed, and they were measured after scrubbing the CCA treated wood in the water. In order to discover the influence of the CCA treated wood on the aquaticecosystem, Daphnia magna, Selenastrum capricornutum and Chironomus riparius were raised in leachates of CCA treated wood. The concentrations of As, Cr and Cu after 22 days of leaching were 0.12, 1.71 and 1.76mg/L, and those in scrubbed in water for 10 minutes were 0.012, 1.99 and 2,81mg/L, respectively. The concentrations of heavy metals, As, Cr and Cu, leached by water of which the volume was 10 times of CCA treated wood during 24 hours, were 0.0076, 1.46 and 5.11mg/L, respectively. These concentrations did not affect the life action of O. latipes and Chironomus riparius. The life action of 37% among D. magna slowly occurred after 48-hours of exposure to leachates. The LC50 on S. capricornutum was reduced to 86% of heavy metal concentrations in which were washed by 10 times the volume of water of the CCA treated wood.
Dong-heub Lee, Dong-won Son
Non-pressure preservation technique of five less durable timber species – Kadam (Anthocephalus cadamba), Shimul (Bombax ceiba), Pithalu (Trewia nudiflora), Am (Mangifera indica) and Boroi (Ziziphus jujube) of Bangladesh
2006 - IRG/WP 06-40322
Wood is a versatile renewable resource, which has been extensively used as a reliable construction material as well in furniture ever since the beginning of civilization. The Major disadvantage of wood is its susceptibility to biodeterioration by fungi, insects and bacteria. In tropical countries like Bangladesh, fungi is the most significant of these biodeterioration agents. Kadam (Anthocephalus cadamba), Shimul (Bombax ceiba), Pithalu (Trewia nudiflora), Am (Magnifera indica), and Boroi (Ziziphus jujube) are five, local and available, useful but less durable timber species of Bangladesh. The heartwood of these timber species is more or less resistant to decay and insects, but sapwood faces quick deterioration while exposed to moisture and wood enemies. On the other hand, wood can be protected from attacks from these enemies with the appropriate preservative treatment, by reducing or changing the form of its food toxic to wood enemies. So, appropriate preservative treatment is required to increase the durability of these timber species. The study of chemical preservative treatment of these five timber species has been undertaken using a mixture of Chromate-copper-boron (CCB) at 2:2:1 ratio with four different concentrations of 4, 6, 8 and 10% and different treatment durations of 8, 16 and 24 hours by non-pressure dipping method. It has been observed that Pithalu showed comparatively higher preservative retention than other four species, which indicates that Pithalu is a permeable and diffuse specie for dipping method. A preservative penetration test provided the information that air dried wood samples using 10% preservative concentration with 8 hour and 24 hours duration of dipping gave the best result for copper, while 10% preservative concentration with 24 hours duration used on green wood has shown the best result for boron penetration. The major physical properties of wood viz., moisture content, density and shrinkage have also been studied. Anthocephalus cadamba showed a lower density, while Ziziphus jujube had a higher density. Bombax ceiba and Trewia nudiflora are very close to Anthocephalus cadamba and Magnifera indica is very close to Ziziphus jujube with respect to the moisture content. Bombax ceiba, Trewia nudiflora and Magnifera indica showed all moderate positions with respect to density.
G N M Ilias, A H Kabir, F Begum, M F Alam
Microwave-Assisted Organic Acids Extraction of Chromate Copper Arsenate (CCA)-Treated Southern Pine
2010 - IRG/WP 10-50267
The extraction effects of acid concentration, reaction time and temperature in a microwave reactor on recovery of CCA-treated wood were evaluated. Extraction of copper, chromium, and arsenic metals from chromated copper arsenate (CCA)-treated southern pine wood samples with two different organic acids (i.e., acetic acid and oxalic acid) was investigated using a microwave reactor. Oxalic acid was effective in removing 100% of the chromium and arsenic at 160ºC and 30 min. reaction time. Acetic acid could remove 98% of the copper and arsenic at the same condition. Oxalic acid significantly improved the extraction efficiency of arsenic and chromium when time was prolonged from 10min. to 30min. The HSAB (Pearson acid base concept) concept was applied to explain why oxalic acid removed more chromium and less copper compared with acetic acid. Acetic acid also showed an improved ability to remove arsenic and copper when the reaction temperature was increased from 90ºC to 160ºC.
Bin Yu, Chung Y Hse, T F Shupe
40 year results from the largest preservative in-ground stake trial conducted in Australia
2013 - IRG/WP 13-30624
The final results from Australia’s largest preservative in-ground stake trial are listed. There were eight test sites, six in Australia and two in Papua New Guinea. The preservatives tested include low and high temperature creosotes, PCP and various water-borne preservatives including CCA and copper chromate. The main timbers examined were sawn Pinus radiata sapwood, sawn Eucalyptus regnans heartwood, and E. regnans natural rounds (mainly sapwood). The number of treatments (preservative/retention/timber combinations) tested was 208, although not at every site. The 15 to 16 year inspection results are provided in an appendix for Taree (NSW), O’Shannassy (Vic), Keravat (PNG), Brown River (PNG), Millaroo (Qld), Innisfail (Qld), Sydney (Pennant Hills, NSW) and Walpeup (Vic). Mean ratings, and median specimen lives, are also provided for the latter three test sites after 39.3-41.8 years’ exposure.
L J Cookson