Mode of action of brown rot decay resistance in phenol-formaldehyde-modified wood: resistance to Fenton’s reagent

Holzforschung ◽  
2016 ◽  
Vol 70 (3) ◽  
pp. 253-259 ◽  
Author(s):  
Reza Hosseinpourpia ◽  
Carsten Mai
Keyword(s):  
Cell Wall ◽  
Mode Of Action ◽  
Fenton Reaction ◽  
Phenol Formaldehyde ◽  
Brown Rot ◽  
Weight Percent ◽  
Fenton’S Reagent ◽  
Fenton's Reagent ◽  
Brown Rot Decay ◽  
Modified Wood

Abstract The mode of action of phenol-formaldehyde (PF)-modified wood has been investigated with respect to its resistance to brown rot decay. The Fenton reaction is assumed to play a key role in the initial brown rot decay. Pine microveneers were modified to various weight percent gains (WPG) with low molecular weight PF and exposed to a solution containing Fenton’s reagent. The mass loss (ML) and tensile strength loss (TSL) as well as the decomposition of hydrogen peroxide within the incubation time decreased with the increasing WPG of the veneers. Incubation of untreated and PF-modified veneers in acetate buffer containing ferric ions without H2O2 revealed that the modification strongly reduces the uptake of iron by the wood cell wall. Further studies indicated that lignin promotes the decay of wood by Fenton’s reagent. The reason for the enhanced resistance of modified wood to the Fenton reaction is attributable to the impeded diffusion of iron ions into the cell wall rather than to the blocking of free phenolic sites of lignin, which accelerate redox cycling of iron.

scholarly journals Mode of action of brown rot decay resistance in modified wood: a review

Holzforschung ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 239-246 ◽  
Author(s):  
Rebecka Ringman ◽  
Annica Pilgård ◽  
Christian Brischke ◽  
Klaus Richter
Keyword(s):  
Cell Wall ◽  
Mode Of Action ◽  
Wood Decay ◽  
Brown Rot ◽  
Decay Resistance ◽  
Hydroxyl Groups ◽  
Decay Fungi ◽  
Brown Rot Decay ◽  
Thermally Modified Wood ◽  
Modified Wood

Abstract Chemically or physically modified wood materials have enhanced resistance to wood decay fungi. In contrast to treatments with traditional wood preservatives, where the resistance is caused mainly by the toxicity of the chemicals added, little is known about the mode of action of nontoxic wood modification methods. This study reviews established theories related to resistance in acetylated, furfurylated, dimethylol dihydroxyethyleneurea-treated, and thermally modified wood. The main conclusion is that only one theory provides a consistent explanation for the initial inhibition of brown rot degradation in modified wood, that is, moisture exclusion via the reduction of cell wall voids. Other proposed mechanisms, such as enzyme nonrecognition, micropore blocking, and reducing the number of free hydroxyl groups, may reduce the degradation rate when cell wall water uptake is no longer impeded.

Mode of action of brown rot decay resistance of thermally modified wood: resistance to Fenton’s reagent

Holzforschung ◽  
2016 ◽  
Vol 70 (7) ◽  
pp. 691-697 ◽  
Author(s):  
Reza Hosseinpourpia ◽  
Carsten Mai
Keyword(s):  
Cell Wall ◽  
Brown Rot ◽  
Strength Loss ◽  
Decay Resistance ◽  
Fenton’S Reagent ◽  
Fenton's Reagent ◽  
Brown Rot Fungi ◽  
Brown Rot Decay ◽  
Wood Resistance ◽  
Fe Ions

Abstract The resistance of heat treated (HT) wood to brown rot fungi has been investigated, while the role of the Fenton reaction (FR) in the initial phase of degradation was in focus. Micro-veneers made of Scots pine, were HT with various intensities and their mass losses (MLHT) were determined before soaking with a solution of Fenton’s reagent containing Fe ions and hydrogen peroxide. The mass loss of the veneers treated that way (MLFT), their tensile strength loss (TSLFT) and the H2O2 decomposition were observed. The MLFT, TSLFT, and H2O2 loss decreased with increasing MLHT of the veneers. Soaking of the veneers in acetate buffer containing only Fe without H2O2 revealed that the heat treatment (HT) strongly reduces the Fe uptake by the cell walls. FTIR spectroscopy indicated oxidation of the unmodified control veneers but did not reveal predominant decay of cell wall components; the HT veneers were not changed at all due to FR. It was concluded that the reason for the enhanced resistance of HT wood to FR is attributable to hindered diffusion of Fe ions into the wood cell wall.

Degradation of chemically modified Scots pine (Pinus sylvestris L.) with Fenton reagent

Holzforschung ◽  
2015 ◽  
Vol 69 (2) ◽  
pp. 153-161 ◽  
Author(s):  
Yanjun Xie ◽  
Zefang Xiao ◽  
Carsten Mai
Keyword(s):  
Fenton Reaction ◽  
Oxidative Degradation ◽  
Brown Rot ◽  
Fenton Reagent ◽  
Wood Degradation ◽  
Weight Percentage ◽  
Brown Rot Fungi ◽  
Minor Losses ◽  
Brown Rot Decay ◽  
Modified Wood

AbstractThe Fenton reaction is supposed to play a key role in the initial wood degradation by brown rot fungi. Wood was modified with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and glutaraldehyde (GA) to various weight percentage gains in order to study if these types of modifications are able to reduce wood degradation by Fenton reagent. Veneers modified with higher concentrations (1.2 and 2.0 mol l-1) of both chemicals exhibited minor losses in mass and tensile strength during treatment with Fenton reagent, which shows restrained oxidative degradation by hydroxyl radicals. The decomposition rate of H2O2was lower in the Fenton solutions containing modified veneers than in those containing unmodified controls. More CO2evolved in systems containing unmodified veneers than in systems with modified veneers, indicating that modification protected wood from mineralisation. The reason for the enhanced resistance of modified wood to the Fenton reaction is attributed to impeded diffusion of the reagent into the cell wall rather than to inhibition of the Fenton reaction itself. The results show that wood modification with DMDHEU and GA is able to restrain the degradation of wood by the Fenton reaction and can explain why modified wood is more resistant to brown rot decay.

scholarly journals The Importance of Moisture for Brown Rot Degradation of Modified Wood: A Critical Discussion

Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 522 ◽  
Author(s):  
Rebecka Ringman ◽  
Greeley Beck ◽  
Annica Pilgård
Keyword(s):  
Cell Wall ◽  
Capillary Condensation ◽  
Critical Factor ◽  
Weight Percent Gain ◽  
Brown Rot ◽  
Weight Percent ◽  
Critical Discussion ◽  
Wood Modification ◽  
Thermally Modified Wood ◽  
Modified Wood

The effect of wood modification on wood-water interactions in modified wood is poorly understood, even though water is a critical factor in fungal wood degradation. A previous review suggested that decay resistance in modified wood is caused by a reduced wood moisture content (MC) that inhibits the diffusion of oxidative fungal metabolites. It has been reported that a MC below 23%–25% will protect wood from decay, which correlates with the weight percent gain (WPG) level seen to inhibit decay in modified wood for several different kinds of wood modifications. In this review, the focus is on the role of water in brown rot decay of chemically and thermally modified wood. The study synthesizes recent advances in the inhibition of decay and the effects of wood modification on the MC and moisture relationships in modified wood. We discuss three potential mechanisms for diffusion inhibition in modified wood: (i) nanopore blocking; (ii) capillary condensation in nanopores; and (iii) plasticization of hemicelluloses. The nanopore blocking theory works well with cell wall bulking and crosslinking modifications, but it seems less applicable to thermal modification, which may increase nanoporosity. Preventing the formation of capillary water in nanopores also explains cell wall bulking modification well. However, the possibility of increased nanoporosity in thermally modified wood and increased wood-water surface tension for 1.3-dimethylol-4.5-dihydroxyethyleneurea (DMDHEU) modification complicate the interpretation of this theory for these modifications. Inhibition of hemicellulose plasticization fits well with diffusion prevention in acetylated, DMDHEU and thermally modified wood, but plasticity in furfurylated wood may be increased. We also point out that the different mechanisms are not mutually exclusive, and it may be the case that they all play some role to varying degrees for each modification. Furthermore, we highlight recent work which shows that brown rot fungi will eventually degrade modified wood materials, even at high treatment levels. The herein reviewed literature suggests that the modification itself may initially be degraded, followed by an increase in wood cell wall MC to a level where chemical transport is possible.

Myofibrillar cell wall extensions in the hyphal sheath of Postia placenta

1992 ◽  
Vol 38 (9) ◽  
pp. 905-911 ◽  
Author(s):  
Michael J. Larsen ◽  
Frederick Green III
Keyword(s):  
Cell Wall ◽  
Brown Rot ◽  
Decay Process ◽  
Structural Components ◽  
Hyphal Cell ◽  
Postia Placenta ◽  
Glass Cover ◽  
Hyphal Sheath ◽  
Brown Rot Decay ◽  
Extracellular Structures

Evidence is provided for the existence of linear extracellular fibrillar elements in the brown-rot fungus Postia placenta. These elements appear as structural components of the hyphal sheath and more closely resemble mycofibrils than fungal fimbriae. Mycofibrils are associated with and appear to originate from the hyphal surface when hyphae are grown on wood or inert substrates, such as glass cover slips and polycarbonate filters. These extracellular structures have a nominal diameter of 10–50 nm and are up to 25 μm in length. We conclude that mycofibrils are linear structural extensions of the hyphal cell wall. The precise function of mycofibrils in the brown-rot decay process of wood remains to be elucidated. Key words: Postia placenta, mycofibrils, fungal fimbriae, hyphal sheath, electron microscopy.

scholarly journals Effects of Wood Moisture Content and the Level of Acetylation on Brown Rot Decay

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 299 ◽  
Author(s):  
Samuel L. Zelinka ◽  
Grant T. Kirker ◽  
Amy B. Bishell ◽  
Samuel V. Glass
Keyword(s):  
Moisture Content ◽  
Mass Loss ◽  
Linear Trend ◽  
Fungal Growth ◽  
Weight Percent Gain ◽  
Brown Rot ◽  
Weight Percent ◽  
Wood Moisture Content ◽  
Wood Moisture ◽  
Brown Rot Decay

Acetylation is one of the most common types of wood modification and is commercially available throughout the world. Many studies have shown that acetylated wood is decay resistant at high levels of acetylation. Despite its widespread use, the mechanism by which acetylation prevents decay is still not fully understood. It is well known that at a given water activity, acetylation reduces the equilibrium moisture content of the wood cell wall. Furthermore, linear relationships have been found between the acetylation weight percent gain (WPG), wood moisture content, and the amount of mass loss in decay tests. This paper examines the relationships between wood moisture content and fungal growth in wood, with various levels of acetylation, by modifying the soil moisture content of standard soil block tests. The goal of the research is to determine if the reduction in fungal decay of acetylated wood is solely due to the reduction in moisture content or if there are additional antifungal effects of this chemical treatment. While a linear trend was observed between moisture content and mass loss caused by decay, it was not possible to separate out the effect of acetylation from fungal moisture generation. The data show significant deviations from previously proposed models for fungal moisture generation and suggest that these models cannot account for active moisture transport by the fungus. The study helps to advance our understanding of the role of moisture in the brown rot decay of modified wood.

Protection mechanisms of DMDHEU treated wood against white and brown rot fungi

Holzforschung ◽  
2009 ◽  
Vol 63 (3) ◽  
Author(s):  
Pradeep Verma ◽  
Ulrich Junga ◽  
Holger Militz ◽  
Carsten Mai
Keyword(s):  
Cell Wall ◽  
Treated Wood ◽  
Weight Percent Gain ◽  
Brown Rot ◽  
Weight Percent ◽  
Decay Resistance ◽  
Brown Rot Fungi ◽  
Protection Mechanisms ◽  
Mesh Bags ◽  
Fine Wood

AbstractThe resistance of beech and pine wood blocks treated with 1,3-dimethylol-4,5-dihydroxyethylene urea (DMDHEU) againstTrametes versicolorandConiophora puteanaincreased with increasing weight percent gain (WPG) of DMDHEU. Full protection [mass loss (ML) below 3%] was reached at WPGs of approximately 15% (beech) and 10% (pine). Untreated and DMDHEU treated blocks were infiltrated with nutrients and thiamine prior to fungal incubation and it was observed whether the destruction or removal of nutrients and vitamins during the modification process has an influence on the ML caused by the fungi. This study revealed that no considerable differences were found. Then, the cell wall integrity was partly destroyed by milling and the decay of the fine wood powder filled into steel mesh bags was compared to that of wood mini-blocks. The purpose of this study was to examine whether the effects of surface area, cell wall bulking, and reduction in micro-void diameters play a role in decay resistance. The ML caused by the fungi, however, also decreased with increasing WPG and showed comparable patterns similar to the case of mini-blocks. ML of powder bearing the highest WPG appeared to be caused by losses in DMDHEU during fungal incubation. For brown rotted wood, the infrared absorption ratios at 1030 cm-1and 1505 cm-1revealed decreasing decay of polysaccharides with increasing WPG of treated wood.

scholarly journals Cellulose Fibers Dissolution in Alkaline Solution

2019 ◽  
Vol 14 (2) ◽  
pp. 107-115
Author(s):  
Yasmeen Salih Mahdi ◽  
Asem Hassan Mohammed ◽  
Alaa Kareem Mohammed
Keyword(s):  
Treatment Time ◽  
Cellulose Fibers ◽  
Bath Temperature ◽  
Weight Percent ◽  
Fenton’S Reagent ◽  
Cellulose Dissolution ◽  
Fenton's Reagent ◽  
Cooling Bath ◽  
Reagent Treatment ◽  
Naoh Solution

In this study, NaOH dissolution method was applied to dissolve cellulose fibers which extracted from date palm fronds (type Al-Zahdi) taken from Iraqi gardens. In this process, (NaOH)-solution is brought into contact with the cellulose fibers at low temperature. Experiments were conducted with different concentrations of NaOH (4%, 6%, 8% and12%) weight percent at two cooling bath temperatures (-15 oC) and (-20oC). Maximum cellulose dissolution was 23 wt% which obtained at 8 wt% concentration of NaOH and at cooling bath temperature of -20oC. In order to enhance the cellulose fibers dissolution, the sample was pretreated with Fenton's reagent which consists of hydrogen peroxide (H2O2), oxalic acid (C2H2O4) and ferrous sulfate (FeSO4). This reagent reacts with cellulose fibers and produces free radicals which increase cellulose dissolution. In this work three variables were studied: cooling bath temperature (-15oCand-20oC), NaOH concentration (4%, 6%, 8% and12%) and time of Fenton's reagent treatment (1-48) hrs. The results showed that the best percent of cellulose dissolution was (42 wt %) which occurred at treatment time (24 hours), temperature (-20oC) and NaOH concentration 8%. In another set of experiments urea was added to NaOH solution as a catalyst with proportion (6%NaOH+4% urea) at two temperatures -15 and -20 oC. The results show that the solubility of cellulose increase to 62% for the sample which treated with Fenton's reagent and to 35% for the untreated sample, both values were obtained at -15oC.  

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