Your search resulted in 7 documents.
Soft-rot control in hardwoods treated with chromated copper arsenate preservatives. Part 3: Influence of wood substrate and copper loadings
1977 - IRG/WP 2100
The hypothesis is proposed that hardwoods need more chromated copper arsenate (CCA) than softwoods to protect them from soft-rot attack mainly because hardwoods are more readily consumed by soft-rot fungi. Simple model systems, using copper-supplemented agar or groundwood pulp treated with CCA showed that fungi tolerated more toxicant (copper) as more available substrate (malt) was provided. Soft-rot tests with CCA-treated hardwood blocks provided typical dosage-response curves when results were expressed as a ratio of substrate to toxicant (wood to copper). Furthermore, hardwoods needed 10 to 20 times more copper as CCA than softwoods to prevent soft-rot attack. When CCA was substituted by ammoniacal copper arsenate in 5 hardwoods, similar threshold values for soft-rot attack were obtained in terms of a wood-to-copper ratio. Hence, CCA may be behaving poorly against soft-rot fungi in our hardwood specimens mainly because the substrate contained too little copper. The practical implications of these results are discussed.
M A Hulme, J A Butcher
Effects of the anaerobic wood decay bacterium Clostridium xylanolyticum on unbleached Pinus and Eucalyptus pulp
1991 - IRG/WP 1506
Clostridium xylanolyticum has been shown to produce extracellular enzymes capable of degrading wood. The present work was conducted to quantify growth on various lignocellulosic substrates and degradation of pulped wood fibre. In the latter tests Clostridium xylanolyticum was incubated at 35°C under anaerobic conditions in a medium containing 0.2% (w/v) peptone and 4% (w/v) unbleached Pinus and Eucalyptus pulp. Xylan (0.1% w/v) was included to stimulate growth and induce xylanase production. After 1 weeks incubation material from both the uninoculated controls and inoculated tests was removed, washed, dried and hydrolysed using (72% w/v) sulphuric acid at 30°C for 45 minutes followed by 3% (w/v) sulphuric acid at 121°C for two hours. The hydrolysates were analysed for xylose content using HPLC which showed enzymatic degradation of the xylan fraction of the pulp. Other pulp tests showed that paper made from degraded Eucalyptus pulp had improved brightness, suggesting a possible role for this bacterium in future biological pulp bleaching research.
G D Shelver, U Matai, W Van Wyk, A A W Baecker
A preliminary comparison of GC, HPLC and ELISA analysis of resin acids in pulp mill effluents
1997 - IRG/WP 97-20120
Resin acids are naturally occurring diterpenoid carboxylic acids present in most Canadian softwoods. There are eight common resin acids that are classified into two groups; the abietanes and the pimaranes. During processing of wood products they can be released into the environment where they are of concern because of their acute toxicity toward fish and other aquatic life. Traditionally resin acids are analyzed by gas chromatography (GC) which requires extraction of analytes from a sample matrix, derivatization to increase analyte volatility and separation by solid phase extraction. This process is difficult, tedious and expensive but provides quantification of the individual resin acids with low detection limits. Recently a fast and simple high performance liquid chromatography (HPLC) method was developed to analyze dehydroabietic acid (DHA) directly from pulp mill effluents. Our laboratory has developed an enzyme-linked immunosorbent assay (ELISA) based on polyclonal antibodies that was successfully used to directly quantify the abietanes in CTMP effluent.. We compared the three techniques by analysing effluent samples from the Quesnel River Pulp Mill at various stages of the pulping process. Preliminary results showed good agreement for DHA analysis between the HPLC and GC methods. Since it analyzed for all the abietanes, ELISA measured a greater proportion of the resin acids in the samples than the HPLC. The merits and disadvantages of each method will be further discussed.
A N Serreqi, K Stark, Xiumei Feng, J N Saddler, C Breuil
Attempts to isolate tunnelling bacteria through physical separation from other bacteria by the use of cellophane
1992 - IRG/WP 92-1535
During attempts to isolate tunnelling bacteria in pure culture, physical separation from other bacteria was successfully achieved by the use of cellophane. Cellophane was used in liquid cultures as a substrate for tunnelling bacteria that were present in a mixture with other bacteria. By tunnelling into cellophane, TB were physically removed from contaminating bacteria which could then be removed by simple washing of the cellophane surface. The physically separated bacteria within the cellophane failed, however, to grow on various agar or liquid media. The reasons for this are discussed.
T Nilsson, G F Daniel
Influence of the decay of spruce chips by the selected fungi on their chemical structure and the pulp properties
2004 - IRG/WP 04-10510
The paper focuses on changes in the weight and in the molecular structure of spruce chips submitted to long-term storing as well as to medium- and long-term model rotting degradation caused by some chosen fungi identified at storing processes on the pile. For the model decay of chips under laboratory conditions during 3 or 6 weeks the white-rot fungi: Phanerochaete chrysosporium, Heterobasidion annosum, Onnia circinata or Climacocystis borealis, and the brown-rot fungus Fomitopsis pinicola, have been used. Mass losses and changes in chemical composition of chips depended on the fungus used and time of decay. The highest weight losses were caused by the fungi H.annosum and F.pinicola, the most of cellulose was removed due to F.pinicola, the most of lignin due to H.annosum, at which the amounts of removed lipophilic extractives depended selectively on the fungus and time of degradation. The further aim of this work was to evaluate biodegradation processes in wood for the pulp production. Pulps prepared from the model rotted chips and also from the long-term stored chips had changed properties, obviously reduced Kappa number, content of rejects, tear length and tear index.
R Solár, L Reinprecht, A Geffert, F Kacík
Comparison of moisture loss and its increment during the rehearsal process based on natural drying and water soaking application with or without sealing the trial discs of Common black poplar (Populus nigra L.)
2013 - IRG/WP 13-40639
This study was subjected to be set up to prove the pattern of moisture loss and moisture increment within the same wood samples prepared as the discs (30x23±3 cm diameter) with or without the bark intact during drying and in the duration of the water soaking application. In this concept, wood was exemplified by Common black poplar (Populus nigra L.) of the five 12 year old trees that are grown indigenously in the same wooded area. The moisture loss was checked by the natural drying process of 25 days, and the moisture increment was tested by the water soaking application of 25 days. Both natural drying process and water soaking application were carried out in the manner that one after the other based on the interdependent relationship between experimental condition and wood moisture content. The two tests were designed: test 1 was took place at the standard room temperature and relative humidity, and arranged with the experimental wood samples of the control (debarked), the unsealed (debarked before water soaking), the sealed (around the disc was coated with waterproof material before drying), test 1 was conducted at the warmer and cooler places indoor at the air temperature of 23 °C and 18 °C respectively, and the water temperature of water was at 20 degrees Celsius for soaking application. The experimental observations showed that the condition of the experimental area and the situation of the wood samples were more effective for either loosing or gaining moisture. The bark illustrated the ability to regulate evaporation of free water in the wood during natural drying and the stable condition of the experimental places that decreased the sapwater loss per unit of processive time after 15 days. According to the experimental findings, the dried-wood has limited potential for receiving the similar moisture content at once it was dried to below the fibre saturation point. In this case, the ability to recover of naturally dried-wood in the frame of moisture increment at the end of the water soaking application was found to be just over half of the initial moisture level before the natural drying process was started.
Bio-preservative properties of technical lignins from South African pulp mills: An investigation towards a conceptualized development of natural compound-based wood preservatives
2018 - IRG/WP 18-30724
The depletion of naturally durable timber and the risk posed by some of the conventional wood preservatives to human health and the environment continue to drive research efforts towards developing new formulations that are benign. Furthermore, the global concept of environmental sustainability aims at optimal use of resources and to comprehensively include conversion of waste to value added products. In view of these, it becomes a point of interest to utilize compounds from waste streams such as technical lignin obtainable from pulp black liquor by-products in the development of formulations to be used either as a sole material or component of wood preservatives. The incorporation of lignin into wood preservative formulations have only been previously achieved by means of a two-stage process involving fixation with metal salts, lignosulphonate copolymerisation and use of metal ammonia complexes as impregnants. However, the overall limitation of these processes is the inadaptability to industrial practice, owing to time factors, high cost of copolymerized lignins, and inability to use certain lignins. In view of the increasing global interest in green economy and environmental sustainability, the prospect of developing a natural compound-based wood preservative formulation using technical lignin alongside other natural compounds from biomaterial waste becomes invaluable. It is anticipated that the proposed preservative formulation would be suitable for a single-stage process adaptable to industrial practice. The suitability of lignin as a component in the development of the natural compound-based wood preservative depends on its properties. These properties vary with origin and isolation method. To this end, this study will investigate the bio preservative properties of technical lignin recovered from pulp black liquors (PBLs) obtained from different biomass origins and pulping processes commercially employed in the South African pulp industry.
A Alade, L Tyhoda, M Meincken