Prediction of long-term leaching potential of preservative-treated wood by diffusion modeling

Abstract An approach to modeling leaching and leaching impacts of preservative components from treated wood is presented based on three simple laboratory determinations: the amount of preservative component available for leaching (Le), equilibrium dissociation of preservative into free water in wood (Di) and diffusion coefficients for component leaching in different wood directions (D). In this study, the following inorganic wood preservative systems were investigated: chromated copper arsenate (CCA), the copper component of copper azole (CA) and alkaline copper quaternary (ACQ), and boron in disodium octaborate tetrahydrate (DOT). Aggressive leaching of finely ground wood showed that amounts of preservative compounds available for leaching were highest for borates, followed by copper in copper amine systems and arsenic in CCA, copper in CCA and chromium in CCA. The equilibrium dissociation or solubility of components in free water in the wood was much higher for borates and copper amine, followed by copper and arsenic in CCA and chromium in CCA. Use of the applicable diffusion coefficient (D) and Di or Le values in a diffusion model allows the prediction of total amount leached and emission or flux rate at different times of exposure for products with different dimensions and geometries. The approach was tested and generally validated through application of the model to results of laboratory water spray leaching of full-size lumber samples. The approach explains the rapid leaching of boron compounds (large diffusion coefficient and high initial dissociated concentration) compared to other preservative components and predicts that ACQ will have higher initial leaching rates compared to CCA and CA, but the latter preservatives will continue to leach copper at a measurable rate for a much longer time. The practical implications and limitations of the approach are discussed.

Download Full-text

Effect of ammonia addition to alkaline copper quaternary wood preservative solution on the distribution of copper complexes and leaching

Holzforschung ◽

10.1515/hf.2011.155 ◽

2012 ◽

Vol 66 (3) ◽

Cited By ~ 2

Author(s):

Sedric Pankras ◽

Paul A. Cooper

Keyword(s):

Copper Complexes ◽

Treated Wood ◽

Wood Preservative ◽

Exchange Capacity ◽

Lower Amount ◽

Divalent Copper ◽

Copper Leaching ◽

Ammonia Addition ◽

Alkaline Copper Quaternary ◽

High Ligand

Abstract The effects of ammonia (NH3) addition to monoethanolamine (Mea)-based alkaline copper quaternary (ACQ) on the predicted distribution of cupric (Cu2+) species in solution and copper leaching from treated wood were investigated. Addition of ammonia in higher proportions reduced the amount of neutral copper-Mea complex at high pH and increased the amounts of divalent copper-NH3 complexes. At lower pH, the amounts of high-ligand copper-Mea complexes were reduced. These effects should promote better fixation and diminish copper leaching. However, ammonia addition also reduced the monovalent copper-Mea complex and the amount of copper fixed by precipitation at lower pH. This effect could, potentially, reduce fixation and leach resistance. Ammonia addition to the ACQ formulation from a Cu:Mea:NH3 ratio of 1:4:0 (normal Mea formulation, pH=9) to 1:4:2 (pH 10–10.2) and 1:4:4 (pH 10.4–10.5) did not significantly affect the amount of copper leached. However, a further increase in ammonia to 1:4:6 (pH 10.6–10.7) resulted in a significant reduction in copper leaching. At pH 9, an increase in the proportional amount of ammonia increased the amount of copper leached by reducing the amount of monovalent copper-Mea complex and increasing the divalent copper-NH3 complexes. Ammonia addition with a lower amount of Mea, 1:2.5:4 formulation (pH 10.5–10.7), significantly reduced copper leaching as a result of higher amounts of divalent copper-NH3 complexes adsorbed at higher pH (higher cation exchange capacity) without compromising the amount of copper precipitated at lower pH.

Download Full-text

Copper extraction and recovery from alkaline copper quaternary and copper azole treated wood using sulfuric acid leaching and ion exchange or electrodeposition

Journal of Cleaner Production ◽

10.1016/j.jclepro.2020.123687 ◽

2021 ◽

Vol 279 ◽

pp. 123687

Author(s):

Amélie Janin ◽

Lucie Coudert ◽

Guy Mercier ◽

Jean-François Blais

Keyword(s):

Sulfuric Acid ◽

Ion Exchange ◽

Acid Leaching ◽

Treated Wood ◽

Copper Extraction ◽

Sulfuric Acid Leaching ◽

Alkaline Copper Quaternary ◽

Copper Azole

Download Full-text

The effects of pH on copper leaching from wood treated with copper amine-based preservatives

Holzforschung ◽

10.1515/hf-2019-0218 ◽

2020 ◽

Vol 74 (9) ◽

pp. 891-897

Author(s):

Jeong-Joo Oh ◽

Gyu-Hyeok Kim

Keyword(s):

Photoelectron Spectroscopy ◽

Treated Wood ◽

Brown Rot ◽

Wood Preservative ◽

Radiata Pine ◽

Practical Applications ◽

Copper Loss ◽

Effects Of Ph ◽

Alkaline Copper Quat ◽

Copper Amine

AbstractAs pH of leaching medium is an important factor in the leaching of wood preservative components, its effects on leaching should be quantified to ensure environmentally safe use of treated wood. In this study, the effects of pH on leaching of copper from wood treated with copper amine-based preservatives [alkaline copper quat (ACQ)-2, bis-(N-cyclohexyldiazeniumdioxy)-copper (CuHDO)-3, and copper azole (CUAZ)-3] were evaluated in comparison with wood treated with chromated copper arsenate (CCA)-3. Radiata pine sapwood blocks treated with these preservatives were leached at five pH levels (3.0, 3.5, 4.0, 4.5, and 6.5). The leached blocks were subjected to laboratory-scale decay tests using two brown-rot fungi. The blocks treated with copper amine-based preservatives leached significant amounts of copper at pH levels below 4.0. At all pH levels, the CuHDO-3-treated samples generally leached the most copper, followed by the samples treated with ACQ-2, CUAZ-3, and CCA-3. When the treated blocks were leached at pH 3.0, the degradation of hemicelluloses, which can chemically adsorb copper, was confirmed through Fourier transform infrared attenuated total reflectance (FTIR-ATR) analysis. Moreover, X-ray photoelectron spectroscopy (XPS) analysis indicated that the ratio of precipitates of the remaining copper in the treated wood severely decreased after leaching at pH levels below 4.0. Subsequent reduction in the biological effectiveness of wood treated with copper amine-based preservatives was not hardly observed after leaching at pH levels 4.0 or above. These results indicate that copper loss at pH levels 4.0 or above is not great enough to cause public concern about environmental problems and reduction of biological efficacy in practical applications.

Download Full-text

Enhancement of Wood Biological Resistance and Fire Retardant Properties after Laccase Assisted Enzymatic Grafting

Forests ◽

10.3390/f12081102 ◽

2021 ◽

Vol 12 (8) ◽

pp. 1102

Author(s):

Cristian Bolaño ◽

Sabrina Palanti ◽

Luigi Benni ◽

Diego Moldes

Keyword(s):

Silver Nanoparticles ◽

Flame Retardant ◽

Toxic Substance ◽

Treated Wood ◽

Fire Retardant ◽

Wood Preservative ◽

Decay Resistance ◽

Kraft Lignin ◽

Fire Retardant Properties ◽

Wood Surfaces

Several treatments of wood, based on laccase assisted grafting, were evaluated in this paper. Firstly, the efficacy of lignosulfonate and kraft lignin from Eucalyptus spp. as a wood preservative was assessed. Both ligno products were anchored to wood surfaces via laccase treatment in order to avoid leaching. Moreover, some of these wood preservative treatments were completed with the addition of silver nanoparticles. For comparison, a commercial product was also analyzed in terms of its fungal decay resistance during surface application, in accordance to use class 3, CEN EN 335. Secondly, the anchoring of a flame retardant based on tetrabromobisphenol-A (TBBPA) was attempted, to limit the dispersion of this toxic substance from treated wood. In both cases, kraft lignin and lignosulfonate showed an improvement in wood durability, even after leaching. However, the addition of silver nanoparticles did not improve the efficacy. On the other hand, the efficacy of TBBPA as a flame retardant was not improved by grafting it with laccase treatment or by adding O2, a co-factor of laccase.

Download Full-text

Effect of Concrete on the pH and Susceptibility of Treated Pine to Decay by Brown-Rot Fungi

Forests ◽

10.3390/f11010041 ◽

2019 ◽

Vol 11 (1) ◽

pp. 41 ◽

Cited By ~ 2

Author(s):

Darrel Nicholas ◽

Amy Rowlen ◽

David Milsted

Keyword(s):

Treated Wood ◽

Untreated Wood ◽

Brown Rot ◽

Consistent Difference ◽

Ground Contact ◽

Decay Fungi ◽

Brown Rot Fungi ◽

Organic Systems ◽

Decay Tests ◽

Copper Azole

Treated wood timbers employed in ground contact are often installed with a cement collar to firmly fix the structural wood post in place. Few prior studies have determined the effect of concrete on decay efficacy on treated wood, however. Treated wood nominal 4 × 4 posts were installed at four locations, with the upper ground-contact portion of each post encased in concrete, and the samples removed at various times for pH measurements. The wood alkalinity quickly increased at all four sites for the portion of the treated wood in concrete contact compared to the wood in ground contact without concrete. In laboratory decay tests employing three decay fungi, untreated wood which was first exposed or unexposed to concrete had no consistent difference in decay susceptibility. For wood treated with three different commercial copper/organic systems, cement exposure had no effect on wood treated with an amine copper azole system, while treatment with amine copper quat showed a statistically significant fungal efficacy enhancement for cement-exposed samples with both copper-tolerant fungi. Conversely, with a micronized copper azole preservative, cement exposure resulted in reduced fungal efficacy compared to treated samples which were not cement-exposed for all three decay fungi.

Download Full-text

Electron Paramagnetic Resonance Spectroscopic (EPR) Study of Copper Amine Treated Southern Pine in Wood Preservation

Holzforschung ◽

10.1515/hf.2000.060 ◽

2000 ◽

Vol 54 (4) ◽

pp. 343-348 ◽

Cited By ~ 6

Author(s):

J. Zhang ◽

D. P. Kamdem

Keyword(s):

Electron Paramagnetic Resonance ◽

Copper Complexes ◽

Electron Paramagnetic Resonance Spectroscopy ◽

Treated Wood ◽

Wood Preservation ◽

Resonance Spectroscopy ◽

Paramagnetic Resonance ◽

Electronic Parameters ◽

Electron Paramagnetic ◽

Copper Amine

Summary The structure of copper complexes in copper amine treated wood samples were elucidated by the application of electron paramagnetic resonance spectroscopy (EPR). EPR axial spectra were observed for all Cu-amine treated samples irrespective of the formulations. The values of A∥ and g∥ of the axial spectra indicate that the stereo-structure of copper complexes in copper amine treated wood was either tetragonal-based octahedral or square-based pyramidal. Comparison of electronic parameters of A∥ and g∥ in Cu-amine treated wood with those of the Cu-amine treating solution and the values in literature suggests that the interaction of wood with copper amine is through complexation in which wood functional groups are complexed with copper amine perpendicularly. The copper complexes in both treating solution and treated wood are in the form of CuN2O2, where copper is ligated with 2 nitrogen and 2 oxygen.

Download Full-text

Diffusion of Water in the Wheat Grain: Nuclear Magnetic Resonance and Radioisotopic Methods Provide Complementary Information

Functional Plant Biology ◽

10.1071/pp9900107 ◽

1990 ◽

Vol 17 (2) ◽

pp. 107 ◽

Cited By ~ 6

Author(s):

CF Jenner ◽

GP Jones

Keyword(s):

Diffusion Coefficient ◽

Tritiated Water ◽

Free Water ◽

Wheat Grain ◽

Freezing And Thawing ◽

Complementary Information ◽

Average Diffusion Coefficient ◽

Average Diffusion ◽

Polymeric Component ◽

Developing Grains

Diffusion of water within developing grains of wheat has been evaluated by two independent methods: by kinetic analysis of the movement of tritiated water (THO) through the grain, and by n.m.r. procedures. Both methods provided different but complementary information. Movement of THO basipetally through grains attached to the ear was faster than diffusion could explain, and a reversal of the gradient of THO at the base of the grain also could not be accounted for by diffusion. These observations are adduced as evidence for recirculation of water within the grain. The average diffusion coefficient measured by both methods indicated that the diffusive motion of water was substantially hindered. Freezing and thawing resulted in an increase in diffusion but did not increase diffusion to values expected of free water. Starch, the major polymeric component of the grain, was not responsible for the residual reduction in diffusion coefficient in frozen and thawed tissue.

Download Full-text

Diffusional Properties of Methanogenic Granular Sludge: 1H NMR Characterization

Applied and Environmental Microbiology ◽

10.1128/aem.69.11.6644-6649.2003 ◽

2003 ◽

Vol 69 (11) ◽

pp. 6644-6649 ◽

Cited By ~ 19

Author(s):

Piet N. L. Lens ◽

Rakel Gastesi ◽

Frank Vergeldt ◽

Adriaan C. van Aelst ◽

Antonio G. Pisabarro ◽

...

Keyword(s):

Diffusion Coefficient ◽

Relaxation Time ◽

Nmr Spectroscopy ◽

Diffusion Coefficients ◽

Metal Sulfide ◽

Free Water ◽

Granular Sludge ◽

Self Diffusion ◽

Nmr Characterization ◽

Self Diffusion Coefficient

ABSTRACT The diffusive properties of anaerobic methanogenic and sulfidogenic aggregates present in wastewater treatment bioreactors were studied using diffusion analysis by relaxation time-separated pulsed-field gradient nuclear magnetic resonance (NMR) spectroscopy and NMR imaging. NMR spectroscopy measurements were performed at 22°C with 10 ml of granular sludge at a magnetic field strength of 0.5 T (20 MHz resonance frequency for protons). Self-diffusion coefficients of H2O in the investigated series of mesophilic aggregates were found to be 51 to 78% lower than the self-diffusion coefficient of free water. Interestingly, self-diffusion coefficients of H2O were independent of the aggregate size for the size fractions investigated. Diffusional transport occurred faster in aggregates growing under nutrient-rich conditions (e.g., the bottom of a reactor) or at high (55°C) temperatures than in aggregates cultivated in nutrient-poor conditions or at low (10°C) temperatures. Exposure of aggregates to 2.5% glutaraldehyde or heat (70 or 90°C for 30 min) modified the diffusional transport up to 20%. In contrast, deactivation of aggregates by HgCl2 did not affect the H2O self-diffusion coefficient in aggregates. Analysis of NMR images of a single aggregate shows that methanogenic aggregates possess a spin-spin relaxation time and self-diffusion coefficient distribution, which are due to both physical (porosity) and chemical (metal sulfide precipitates) factors.

Download Full-text