CCA-treated Wood Research Articles

Deactivation of chromated copper arsenate as a catalyst in smouldering of wood

Chromated copper arsenate (CCA) is a preservative treatment that enhances the biodegradation resistance of wood, essential for prolonging the service life of exterior infrastructure. However, the susceptibility of CCA-treated wood to smouldering combustion presents a significant challenge, as the metals present in the CCA catalyze the smouldering. In this work, we examined the oxidative behaviour of char produced from CCA-treated wood through dynamic thermogravimetric analysis. There was a gradual decrease in the catalytic activity of the CCA as temperature increased, particularly above 400 °C. At this stage, lignin undergoes secondary pyrolysis, and thermal decomposition of CCA complexes occurs. The thermal decomposition of CCA-treated wood at temperatures above 650 °C was similar to that of untreated wood, indicating the possible deactivation of the CCA. The agglomeration of species containing Cu or Cr above 650 °C might be responsible for the deactivation. This process is influenced by simultaneous lignin pyrolysis and decomposition of CCA complexes, which are also likely contributors to the loss of CCA's catalytic activity. This research introduced a novel experimental approach to assess the catalytic effects of CCA on char oxidation at elevated temperatures, offering valuable insights into CCA deactivation and its implications for fire safety. It also contributes to the development of potential modifications to CCA formulations aimed to reduce smouldering in wildfire-prone regions.

Sustainable Supercapacitor Electrode Based on Activated Biochar Derived from Preserved Wood Waste

Due to the inherent metals (Cu, As and Cr) in preserved wood waste (CCA-treated wood waste) that pose a risk to both the environment and human health, it is crucial to dispose of CCA-treated wood properly. Carbon materials have received widespread attention for their high porosity, renewability and simplicity of fabrication. This work presents a simple and effective process for producing carbon materials from leftover CCA-treated wood (chromated copper arsenate). Utilizing CCA-treated wood derived carbon (CCA-BC) and activating it with KOH (CCA-AC), electrode materials for supercapacitor applications were created and its electrochemical characteristics were investigated. The resulting material combines the conductivity of the metal in preserved wood with the good porosity provided by carbon materials. Compared with common wood biomass, carbon (W-BC) and common wood activated carbon (W-AC), CCA-BC and CCA-AC have better electrochemical properties. After being pyrolyzed at 600 °C for two hours, CCA-AC performed optimally electrochemically in 1 M Na2SO4 electrolyte, demonstrating a 72% capacity retention rate after 2000 charge and discharge cycles and a specific capacity of 76.7 F/g. This study provides a novel approach for the manufacture of supercapacitor electrodes, which also allows preserved wood waste an environmentally nondestructive form of elimination.

Wood from Field Tests as a Model for Assessing the Suitability of Post-Consumer Wood

The circular economy forces societies to take actions aimed at giving post-consumer products a “second life”. As we know, wood is perfect for this. Moreover, reusing wood helps keep carbon in circulation, thus limiting its emissions into the atmosphere. It turns out that extensive research on determining the durability of wood is very useful and valuable for one more reason. Well, they can be used to create a model to determine the usefulness of wood, which has only apparently lost its utility value during many years of exposure to external factors. The research subject was samples of wood impregnated with protection agents and modified, originating from many years of field tests. The aim of the research was to correlate the results of wood durability determined after a period of exposure in open space with the results of determining the potential usefulness of such wood. On this basis, a model for determining the value of post-consumer wood was created. As a main result of post-consumer wood analysis, the high durabilities against C. puteana with mass loss below 3% were noticed for acetylated, furfurylated, and CCA-treated wood. Moreover, high color stabilities (ΔE < 10) were observed for thermowood and furfurylated wood.

Experimental study on the factors affecting smouldering behaviour of CCA-treated wood

Waterborne chromated copper arsenate (CCA) is a highly effective, widely used wood preservative. While it does not appear to markedly alter the flaming behaviour of treated wood, there are significant concerns regarding post-fire smouldering. Our understanding of the mechanisms and factors affecting smouldering behaviour is currently insufficiently developed. This study used a multiscale approach to better understand smouldering in slash pine treated to different CCA retentions and investigated reaction kinetics through thermogravimetric analysis (TGA) in addition to Cone Calorimeter smouldering tests. Derivative thermogravimetry (DTG) showed that the temperatures at the onset of pyrolysis and oxidation, and where the maximum rate of decomposition occurred were both lowered by CCA treatment, and effects became more pronounced as CCA retention increased. Bench-scale smouldering tests showed that the smouldering mass loss rate increased with higher CCA retention, lower wood density, and prolonged heat exposure. Smouldering mode changed from a steady to an unsteady pattern as CCA retentions decreased to a threshold from combined pyrolysis and oxidation to isolated char-to-ash oxidation. Once initiated, the reaction can be self-sustaining until all the mass has been consumed regardless of the initial smouldering rate.

A Comparative Study on Heavy Metal Removal from CCA-Treated Wood Waste by Yarrowia lipolytica: Effects of Metal Stress.

Bioremediation is an effective way to remove heavy metals from pollutants. This study investigated the effects of Yarrowia lipolytica (Y. lipolytica) on the bioremediation of chromated copper arsenate (CCA)-treated wood wastes. Copper ions stressed the yeast strains to improve their bioremediation efficiency. A comparison of changes in morphology, chemical composition, and metal content of CCA wood before and after bioremediation was conducted. The amount of arsenic (As), chromium (Cr), and copper (Cu) was quantified by microwave plasma atomic emission spectrometer. The results showed that yeast strains remained on the surface of CCA-treated wood after bioremediation. The morphologies of the strains changed from net to spherical because of the Cu2+ stress. Fourier-transform infrared spectroscopy showed that carboxylic acid groups of wood were released after removing heavy metals. A large amount of oxalic acid was observed when the optical density (OD600nm) was 0.05 on the 21st day. Meanwhile, the highest removal rate of Cu, As, and Cr was 82.8%, 68.3%, and 43.1%, respectively. Furthermore, the Cu removal from CCA-treated wood increased by about 20% after Cu2+ stress. This study showed that it is feasible to remove heavy metals from CCA-treated wood by Y. lipolytica without destroying the wood structure, especially by copper-induced Y. lipolytica.

Assessment of the Potential of Waste Copper Chromium and Arsenic (CCA)-Treated Timber Fibre Reinforced Polypropylene Composites for Construction

This paper investigates the potential of recycling waste copper chromium and arsenic (CCA)-treated timber for use as a reinforcement material in wood–plastic composites (WPCs) produced for use in construction, including an assessment of mechanical properties and the leaching of heavy metals. Wood flour was obtained through mechanical grinding, and fibres were obtained through alkaline digestion followed by bleaching. Composites produced with 40 wt.% bleached fibres showed increased tensile strength from 18.5 MPa for the polypropylene used as the matrix to 27.6 MPa. Likewise, the Young’s modulus was increased from 0.84 to 2.33 GPa. The treatment of fibres was found to reduce arsenic concentration by up to 99.9%. Furthermore, the arsenic in the leachate from composites was found to decrease from 41.29 to 0.07 ppb when comparing CCA-treated wood flour composites to bleached fibre composites. The composites’ material properties indicate that the use of end-of-life CCA-treated timber could be used to produce a composite material that could be used in New Zealand’s building sector to meet the requirements of semi-structural applications.

Copper-Doped Carbon Nanodots with Superior Photocatalysis, Directly Obtained from Chromium-Copper-Arsenic-Treated Wood Waste

An ecofriendly approach was developed for preparing copper-doped carbon dots (CDs) with superior photocatalysis using chromium-copper-arsenic (CCA)-treated wood waste as a precursor. Original wood (W-CDs), CCA-treated wood (C-CDs), and bioremediation CCA wood (Y-CDs) were used as the precursors. The chemical composition and structural, morphological, and optical properties, as well as the photocatalytic ability of the synthesized CDs varied with wood type. The C-CDs and W-CDs had similar characteristics: quasispherical in shape and with a diameter of 2 to 4.5 nm. However, the Y-CDs particles were irregular and stacked together, with a size of 1.5-3 nm. The presence of nitrogen prevented the formation of an aromatic structure for those CDs fabricated from bioremediation CCA wood. The three synthesized CDs showed a broad absorption peak at 260 nm and a weak absorption peak at 320 nm. Proof of the model study for the fabrication of luminescent CDs from CCA wood waste for bioimaging was provided. The degradation rate of CD photocatalytic MB was 97.8% for 30 min. Copper doping gives the CDs electron acceptor properties, improving their photocatalytic efficiency. This study provides novel ways to prepare nanomaterials from decommissioned wood as a nontoxic and low-cost alternative to fluorescent dots.

Identification and quantification of Cr, Cu, and As incidental nanomaterials derived from CCA-treated wood in wildland-urban interface fire ashes

In addition to the combustion of vegetation, fires at the wildland-urban interface (WUI) burn structural materials, including chromated copper arsenate (CCA)-treated wood. This study identifies, quantifies, and characterizes Cr-, Cu-, and As-bearing incidental nanomaterials (INMs) in WUI fire ashes collected from three residential structures suspected to have originated from the combustion of CCA-treated wood. The total elemental concentrations were determined by inductively coupled plasma-time of flight-mass spectrometry (ICP-TOF-MS) following acid digestion. The crystalline phases were determined using transmission electron microscopy (TEM), specifically using electron diffraction and high-resolution imaging. The multi-element single particle composition and size distribution were determined by single particle (SP)-ICP-TOF-MS coupled with agglomerative hierarchical clustering analysis. Chromium, Cu, and As are the dominant elements in the ashes and together account for 93%, 83%, and 24% of the total mass of measured elements in the ash samples. Chromium, Cu, and As phases, analyzed by TEM, most closely match CrO3, CrO2, eskolaite (Cr2O3), CuCrO2, CuCr2O4, CrAs2O6, As2O5, AsO2, claudetite (As2O3, monoclinic), or arsenolite (As2O3, cubic), although a bona fide phase identification for each particle was not always possible. These phases occur predominantly as heteroaggregates. Multi-element single particle analyses demonstrate that Cr occurs as a pure phase (i.e., Cr oxides) as well as in association with other elements (e.g., Cu and As); Cu occurs predominantly in association with Cr and As; and As occurs as As oxides and in association with Cu and Cr. Several Cr, Cu, and As clusters were identified and the molar ratios of Cr/Cu and Cr/As within these clusters are consistent with the crystalline phases identified by TEM as well as their heteroaggregates. These results indicate that WUI fires can lead to significant release of CCA constituents and their combustion-transformed by-products into the surrounding environment. This study also provides a method to identify and track CCA constituents in environmental systems based on multi-element analysis using SP-ICP-TOF-MS.

Bioleaching of heavy metals from preservative-treated wood using Aspergillus tubingensis

Abstract Although fungal bioleaching with Aspergillus niger has been investigated to remove metal from treated wood wastes, toxicological concerns limit the practical use of the species, necessitating the search for non-toxic species with comparable or greater metal removal efficiency. The removal of metals from wood treated with chromated copper arsenate (CCA) and copper amine-based preservatives was investigated using the non-ochratoxigenic mold Aspergillus tubingensis in comparison to A. niger via bioleaching. Metals were bioleached for 10 days by immersing treated wood sawdust in fungal culture filtrates. Culture filtrates were prepared by growing fungi in malt extract (ME) and sucrose media and then filtering the fungal biomass. Oxalic acid and citric acid were the predominant organic acids in A. tubingensis culture filtrate in ME and sucrose media, respectively. Citric acid present in sucrose media was found to be a more effective leaching agent for metals from preservative-treated wood. Citric acid produced by A. tubingensis and A. niger in sucrose media removed nearly 95% of copper, 80%–85% of chromium, and arsenic from CCA-treated wood, and 80%–90% of copper from wood treated with copper amine-based preservatives. As a result of its non-toxigenic characteristics and high metal removal efficiency, A. tubingensis may be a useful fungus for bioleaching metal components from inorganic preservative-treated wood.

Toxicity of fly ash effluent from the combustion of (chromated copper arsenate)-treated wood

Wood is extensively used in Brazil and other countries to produce paper, building materials, and furniture, and a large amount of wood waste is produced. Chromated copper arsenate (CCA) is a preservative used in wood treatment because it can inhibit the action on biodeteriorating agents, therefore increasing the durability of the wood. As a result, environmental problems will arise due to the large amount of wood waste treated with CCA. The wasted CCA-treated wood is used as a fuel, resulting in the emission of toxic chemical compounds. Therefore, the aim of this work was to determine the toxicological effects of fly ash from the combustion of wood treated with CCA compared to the fly ash from untreated wood. Commercial samples of treated and untreated wood were subjected to controlled combustion. The particulate material, fly ash, was precipitated in water and in an acidic medium. The effluent from the HNO3 medium was submitted to analysis of metals (As, Cr, Cu) and polycyclic aromatic hydrocarbons (PAHs), and that collected in water was used for analysis of toxicity. The analysis of metals showed the presence of As and Cr in the effluent, main components of the chromated copper arsenate (CCA) salt. The toxicity analysis showed, in most cases, a significant increase in toxicity of the effluent from the combustion of the treated wood. However, there was some toxic effect on the effluent from the fly ashes of the untreated wood due to the presence of PAHs in them.

Ecotoxic, genotoxic, and cytotoxic potential of leachate obtained from chromated copper arsenate-treated wood ashes.

Preservative treatments increase the durability of wood, and one of the alternative treatments involves the use of chromated copper arsenate (CCA). Due to the toxicity of CCA, the disposal of CCA-treated wood residues is problematic, and burning is considered to provide a solution. The ecotoxicological potential of ash can be high when these components are toxic and mutagenic. The aim of this study was to evaluate the toxicity and genotoxicity of bottom ash leachates originating from CCA-treated wood burning. Physical-chemical analysis of the leachates revealed that in treated wood ashes leachate (CCA-TWBAL), the contents of arsenic and chromium were 59.45 mg.L-1 and 54.28 mg.L-1, respectively. In untreated wood ashes leachate (UWBAL), these contents were 0.70 mg.L-1 and 0.30 mg.L-1, respectively. CCA-TWBAL caused significant toxicity in Lactuca sativa, Allium cepa, and microcrustacean Artemia spp. (LC50 = 12.12 mg.mL-1). Comet assay analyses using NIH3T3 cells revealed that concentrations ranging from 1.0 and 2.5 mg.mL-1 increase the damage frequency (DF) and damage index (DI). According to MTT assay results, CCA-TWBAL at concentrations as low as 1 mg.mL-1 caused a significant decrease in cellular viability. Hemolysis assay analyses suggest that the arsenic and chromium leachate contents are important for the ecotoxic, cytotoxic, and genotoxic effects of CCA-TWBAL.

2-21 CCA処理木材の熱処理における有害元素の放出挙動

2-21 CCA処理木材の熱処理における有害元素の放出挙動

Release behavior of arsenic, chromium, and copper during heat treatments of CCA-treated wood

Release behavior of arsenic, chromium, and copper during heat treatments of CCA-treated wood

Evaluating sustainable product alternatives by combining life cycle assessment with full-cost accounting: A highway guardrail case study

Full-cost accounting techniques incorporate the environmental and societal burdens a product generates through its manufacture, use, and disposal into that product’s price. This research generates full-cost prices for functionally equivalent chromated copper arsenate (CCA) treated wood and galvanized steel guardrail posts by combining previously conducted life cycle inventory analyses results with secondary emission valuation data. Based on the analysis, both CCA-treated posts and galvanized steel posts have environmental damage costs associated with emissions generated through the product’s manufacturing, use, and disposal stages. After developing full-cost prices for product alternatives, CCA-treated wood guardrail posts were found to be a more economical and environmentally responsible alternative to galvanized steel. In addition to generating full-cost prices, this research uses Monte Carlo simulation to provide estimates of variability around CCA-treated wood and galvanized steel damage costs.

Comparative Cr, As and CCA induced Cytostaticity in mice kidney: A contribution to assess CCA toxicity

CCA (Chromium Copper Arsenate) treated wood, widely used in outdoor residential structures and playgrounds, poses considerable dangers of leaching of its components to the environment.In this study, mouse kidney samples were used to evaluate the effects of CCA, chromium trioxide (CrO3) and arsenic pentoxide (As2O5) on cell pathophysiology by flow cytometry. Samples were collected after 14, 24, 48 and 96 h of animal exposure. While Cr had no statistically significant cytostatic effects, As2O5 induced a S-phase delay in animals exposed for 24 h, and over time a G0/G1 phase blockage. The effects of CCA in S-phase were similar, but more severe than those of As2O5. Since environmental and public health hazards due to the long durability of CCA-treated wood products, these data confirm that CCA has profoundly toxic effects on cell cycle, distinct from the compounds themselves. These cytostatic effects support cell cycle dynamics as a valuable endpoint to assess the toxicity of remaining CCA-treated infrastructures, and the expected increased waste stream over the coming decades.

Fractionation and Potential Applications of Components from Microwave Liquefaction of Chromate Copper Arsenate-Treated Wood

Decommissioned chromate copper arsenate (CCA)-treated wood poles were subjected to a microwave liquefaction process. The liquefied products were separated into cellulosic component, lignin fractions, and spent liquor. Analysis of the distribution of the CCA elements showed that the resulting cellulosic component and lignins were detoxified. Compared with the CCA-treated wood, the fractionated detoxified cellulosic component had become micro-sized and had a higher glucan content, crystallinity, and glucose conversion yield, as well as a larger surface area. Thus, the detoxified cellulosic component has potential as a raw material for biorefinery usage or for cellulosic material reinforced composite production. The constituents, such as glucose, xylose, glycerol, and their derivatives, as well as the metal elements in the spent liquor, are appropriate ingredients for the preparation of antifungal and insect resistant polyurethane foams. The fractionated detoxified cellulosic component and lignin products, in addition to the potential application for the spent liquor in the polyurethane industry, confirmed that the microwave liquefaction process coupled with a fractionation procedure is an environmentally conscious approach for the integrated utilization of decommissioned chromate copper arsenate treated wood.

Metals content of recycled construction and demolition wood before and after implementation of best management practices

A limitation to recycling wood from construction and demolition (C&D) waste is contamination of metals from the inadvertent inclusion of preservative treated wood, in particular wood treated with chromated copper arsenate (CCA) and newer copper-based formulations. To minimize contamination many regions have developed best management practices (BMPs) for separating treated from untreated wood. The objective of this study was to evaluate the fraction of preservative treated wood in recycled C&D wood after the implementation of BMPs, using Florida as a case study. Methods involved collecting recycled C&D wood samples from throughout the state, measuring metals concentrations (As, Cu, and Cr) in the samples to compute the fraction of recycled wood treated with waterborne wood preservatives, and comparing measurements with those taken prior to the formalization of BMPs. Metals concentrations were measured using two methods, one based on traditional laboratory digestion methods and another using a more rapid hand-held X-ray Fluorescence (XRF) device in the field. The proportion of waterborne preservative-treated wood in recycled wood products has reduced significantly in the intervening 20 years (from 6% to 2.9%), and the fraction of CCA-treated wood has been reduced even further, to 1.4%. The remaining fraction of waterborne preservative-treated wood is comprised of new formulations of copper-based preservatives. This suggests that restrictions from the wood preservation industry and best management practices implemented at recycling facilities have been effective in reducing heavy metal contamination from pressure treated lumber in recycled wood products.

Use of Recycled Pulped Chromated Copper Arsenate-Treated Wood Fibre in Polymer Composites

The goal of this study was to investigate if it is possible to recycle chromated copper arsenate (CCA)-treated wood for use in wood polymer composites. This was done by soda pulping wood chips of CCA-treated lumber in a laboratory-scale digester. Composites of 10–30 weight percentage of filler in polypropylene were produced with and without the addition of maleic anhydride grafted polypropylene (MAPP) as a coupling agent. These composites were produced using extrusion compounding and injection moulding. The mechanical properties were determined using tensile testing; the properties examined in this study are the ultimate tensile strength, Young’s modulus and strain at break. The effect of the CCA-treated filler on the dimensional stability was investigated by comparing the moisture absorption with virgin wood-filled composites. It was found that ultimate tensile strength improves with increasing filler percentage for the compositions with MAPP. The Young’s modulus increases with increasing filler percentage for all compositions, and failure strain decreases with increasing filler percentage for all compositions. Moisture absorption studies show that the moisture absorption decreases when MAPP is added to the composite, and a slight decrease in moisture uptake is observed for the CCA-treated wood composites with respect to the virgin wood composites.

Removal of toxic elements from wastewater generated in the decontamination of CCA-treated Eucalyptus sp. and Pinus canadense wood

The objective of this study was to apply extraction with hot sulfuric acid to remove Cu, Cr, and As from different species of wood treated with CCA and subsequently evaluate treatment processes for the effluents generated in acid decontamination. This study was conducted in two stages: the first involved applying acid extraction to decontaminate different species of Eucalyptus sp. and Pinus resinosa treated with CCA and the second stage consisted of optimizing the treatment of acidic effluents generated in this process based on precipitation and coagulation. When compared to the initial levels, As, Cu, and Cr removal in the three extraction cycles was over 79%. Classification tests were performed to determine decontamination of the solid wastes generated in the extraction process and the results were lower than the limit established for hazardous waste, according to local legislation. The decontaminated wood obtained in this process can be considered for disposal in landfills or potential reuse. Precipitation was performed using FeCl3 as coagulant and NaOH or Ca(OH)2 as alkalizing agents. The results indicated that the use of FeCl3 and Ca(OH)2 ensures compliance with environmental legislation for both effluents tested, allowing As, Cu, and Cr removal above 98.5%. These findings demonstrate that precipitation can be used to successfully remove toxic elements from wastewater generated by decontamination of CCA-treated wood, opening the possibility of applying this process on an industrial scale.

Preparation and characterization of a metal-rich activated carbon from CCA-treated wood for CO2 capture

The disposal of eucalyptus poles used in the electricity network distribution is considered a potential contamination to the environment due to the chromated copper arsenate (CCA) used as a wood preservative. The thermochemical process can be an alternative to this toxic waste disposal. In this work, the slow pyrolysis of CCA-treated wood followed by the production and application of activated carbon was proposed. Metal retention (ICP-OES), concentration of non-condensable gases produced in the pyrolysis process (via GC), as well as the capacity of activated carbon on CO2 adsorption (via TGA) were investigated. The highest formation rate of non-condensable gases was observed at 500°C, while the maximum H2 concentration was at 700°C. The char obtained in the pyrolysis was chemically treated with H3PO4 and activated in CO2 flow. The pore size distribution of activated carbons showed pore sizes lower than 1nm. The activated carbons showed a CO2 adsorption capacity of 70–83mg/g. The presence of chromium and copper may have influenced the CO2 adsorption. The fast adsorption and desorption showed by the activated carbon produced from CCA-treated wood is interesting to systems that operate in short-time cycles, as pressure swing adsorption (PSA). The reuse of CCA-treated wood for activated carbon production and its application in the CO2 adsorption could be a solution to minimize the environmental damage caused by this waste.