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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. [ABSTRACT FROM AUTHOR]

• Waterborne treated wood has high concentrations of arsenic, copper, and chromium. • Arsenic limits recycling of disposed wood with peak disposal of 18,400 metric tons. • Copper replaced arsenic in residential formulations. • Projected disposal of copper is estimated at 20,900 tons per year by 2030. • Extreme sorting will be necessary for C&D wood to meet industrial risk based levels. Construction and demolition (C&D) wood can be recycled as mulch for landscaping or cogeneration. Limitations to such recycling are dependent on metals concentrations in mulch (As, Cu, and Cr) from the inclusion of waterborne-preservative treated wood. The objective of this study was to evaluate the amount of waterborne-preservative treated wood (by wood volume and by mass of metal) that enters the C&D wood waste stream in the U.S. by utilizing a mass balance approach. A model was developed using wood treatment industry production statistics, estimated leaching rates of metal-based preservatives, and typical service lives of wood products. Outputs of the model indicate that the volumes of waterborne preservative treated wood disposed of may exceed 16 million m3 per year by 2030. The peak yearly metal mass disposed of corresponded to 18,400 metric tons for arsenic and 24,500 tons of chromium in 2013. Given the current trends in production, the mass of copper disposed of will increase to 20,900 tons by 2030. In order to meet regulatory guidelines regarding metals in recycled C&D wood, waterborne-preservative treated wood must be separated and removed. This separation mitigates environmental contamination from wood preservatives such as chromated copper arsenate (CCA). [ABSTRACT FROM AUTHOR]

Abstract: In the present study, wood vinegar was used to extract chromium, copper, and arsenic from chromated copper arsenate (CCA)-treated wood. The extraction efficiency for CCA elements was evaluated using various concentrations of wood vinegar, extraction temperatures, and extraction periods. The extraction efficiency for CCA elements increased with increasing the concentration of wood vinegar and the extraction conditions, resulting in maximal removal rate of copper (95.7%), followed by arsenic (92.7%) and chromium (86.3%). Since wood vinegar afforded high levels of copper extraction, its use was extended to copper-based preservative-treated wood, wherein significant extraction of copper up to 97.6% and 95.7% was obtained from alkaline copper quats (ACQ)- and copper azole (CuAz)-treated sawdust, respectively. To the best of our knowledge, this is the first study on the application of wood vinegar for the extraction of metal elements from CCA-treated wood. [Copyright &y& Elsevier]

Abstract: Chromated copper arsenate (CCA)-treated wood was widely used until 2004 for residential and industrial applications. Since 2004, CCA was replaced by alternative copper preservatives such as alkaline copper quaternary (ACQ), copper azole (CA) and micronized copper quaternary (MCQ), for residential applications due to health concerns. Treated wood waste disposal is becoming an issue. Previous studies identified a chemical process for decontaminating CCA-treated wood waste based on sulfuric acid leaching. The potential application of this process to wood treated with the copper-based preservatives (alkaline copper quaternary (ACQ), copper azole (CA) and micronized copper quaternary (MCQ)) is investigated here. Three consecutive leaching steps with 0.1M sulfuric acid at 75°C for 2h were successful for all the types of treated wood and achieved more than 98% copper solubilisation. The different acidic leachates produced were successively treated by coagulation using ferric chloride and precipitation (pH=7) using sodium hydroxide. Between 94 and 99% of copper in leachates could be recovered by electrodeposition after 90min using 2A electrical current. Thus, the process previously developed for CCA-treated wood waste decontamination could be efficiently applied for CA-, ACQ- or MCQ-treated wood. [Copyright &y& Elsevier]

Abstract: The aim of this study was to investigate the biodegradable chelating agents S,S-ethylenediaminedisuccinic acid (SS-EDDS) and nitrilotriacetic acid (NTA) as potential alternatives and compare them with ethylenediaminetetraacetic acid (EDTA) for effectiveness. Extraction of heavy metals from chromated copper arsenate (CCA)-treated wood with EDDS, NTA, or EDTA solvent was evaluated at various solvent pH levels and stoichiometric ratios. Based on the present data, the recommended extraction conditions are pH 4.0 and EDDS–CCA stoichiometric ratios of 10. [Copyright &y& Elsevier]

The purpose of this study was to evaluate the bioremediation of CCA-treated wood wastes by brown rot fungi, as well as to improve the metal removal from treated wood by altering an existing bioremediation process. In Process I, CCA-treated wood sawdust was added and bioremediated after accumulating oxalic acid in a fermentation broth. In Process II, simplification of the bioremediation process and improvement of metal removal efficiency were attempted. Thus, the treated sawdust and fungal inocula were simultaneously placed in a fermentation broth. In addition, the efficiency of the fermentation broth containing oxalic acid was compared with that of commercial oxalic acid. The results obtained using Process I showed that the greatest reduction in arsenic and chromium (98% and 91%, respectively) was achieved by an unknown Polyporales species. On the other hand, the most efficient removal of copper (82%) was achieved by Daedalea dickinsii, which had the lowest oxalic acid production. Using Process II, the highest copper, chromium and arsenic removal rates (96%, 92% and 98%, respectively) were obtained by Fomitopsis palustris. Process II could be a very valuable method for metal removal from CCA-treated wood when F. palustris is used. Our results also suggest that oxalic acid produced from fungus can be used as an alternative to commercial oxalic acid. [ABSTRACT FROM AUTHOR]

The disposal of wood waste treated with chromated copper arsenate (CCA) is a problem in many countries. We have proposed a novel chelating extraction technique for CCA-treated wood using bioxalate, a solution of oxalic acid containing sufficient sodium hydroxide to adjust the pH to 3.2, which is an effective way to obtain an extraction efficiency of 90% for chromium, copper, and arsenic. The purpose of the present study was to investigate the characteristics of bioxalate extraction of CCA-treated wood. Extractions of CCA-treated western hemlock chips with solutions of bioxalate, oxalic acid, and sodium hydroxide were carried out. The use of bioxalate was confirmed as the most effective extraction technique for chromium, copper and arsenic, with an efficiency of 90%. Extraction with simple oxalic acid was ineffective for copper (less than 40% extraction efficiency), but effective for chromium and arsenic, with 90% efficiency. Sodium hydroxide showed a similar tendency, being ineffective for chromium and copper (less than 20% extraction efficiency), but relatively effective for arsenic (around 70–80% efficiency). We also discovered an interesting phenomenon whereby the addition of sodium hydroxide to a simple oxalic acid solution during the oxalic acid extraction progress resulted in dramatically increased extraction efficiency for copper, chromium and arsenic, up to 90%. Although oxalic acid was ineffective for copper extraction, the addition of sodium hydroxide during the oxalic acid extraction process rendered it effective. [Copyright &y& Elsevier]

Abstract: The pyrolysis process of chromated copper arsenate-treated wood impregnated with phosphoric acid (2–6wt.%) has been investigated using a Kugelrohr short-path distillation apparatus. The presence of phosphoric acid is shown to change the overall pyrolysis kinetics and yields of products resulting in a decrease in the amount of volatile products and an increase in the char formation. The yield of levoglucosan was found to decrease in the presence of relatively higher concentrations of phosphoric acid, while the yield of levoglucosenone increased. The pyrolysis of chromated copper arsenate-treated wood in the presence of phosphoric acid gave rise to 22% (on water-free tar basis) levoglucosenone. Such data demonstrates the potential for a new pathway toward the rational utilization of chromated copper arsenate-treated wood waste. [Copyright &y& Elsevier]

Abstract: When chromated copper arsenate (CCA)-treated wood is removed from service and turns into waste, the contents of Cu, Cr and As remain high due to the strong fixation of CCA in the wood. This high content of toxic compounds presents a disposal challenge. Incineration of CCA-treated waste wood is not allowed in Denmark; instead, the wood is to be land-filled until new methods for handling the wood are available. Since the amounts of CCA-treated wood being removed from service is expected to increase in the years to come, the need for finding alternative handling methods is very relevant. In this study, the usefulness of Electrodialytic Remediation was demonstrated for handling of CCA-treated waste wood in pilot scale. The electrodialytic remediation method, which uses a low-level direct current (DC) as the cleaning agent, combines electrokinetic movement of ions in the wood matrix with the principles of electrodialysis. It has previously been shown that it is possible to remove Cu, Cr and As from CCA-treated wood using electrodialytic remediation in laboratory scale, but until now, the method had not been studied in large scale. The pilot-scale plant used in this study was designed to contain up to 2 m3 wood chips. Six remediation experiments were carried out. In these experiments, the process was up-scaled stepwise by increasing the distance between the electrodes from initially 60 cm to finally 150 cm. The remediation time was varied between 11 and 21 days, and phosphoric acid and/or oxalic acid was used to facilitate the desorption of CCA from the wood. In the most successful of the experiments carried out, the concentration of CCA in the wood was reduced by up to 82% for Cr, 88% for Cu and at least 96% for As. [Copyright &y& Elsevier]

The production of landscape mulch is a major market for the recycling of yard trash and waste wood. When wood recovered from construction and demolition (C&D) debris is used as mulch, it sometimes contains chromated copper arsenate (CCA)-treated wood. The presence of CCA-treated wood may cause some potential environmental problems as a result of the chromium, copper, and arsenic present. Research was performed to examine the leachability of the three metals from a variety of processed wood mixtures in Florida. The mixtures tested included mixed wood from C&D debris recycling facilities and mulch purchased from retail outlets. The synthetic precipitation leaching procedure (SPLP) was performed to examine the leaching of chromium, copper and arsenic. Results were compared to Florida''s groundwater cleanup target levels (GWCTLs). Eighteen of the 22 samples collected from C&D debris processing facilities leached arsenic at concentrations greater than Florida''s GWCTL of 50 μg/l. The mean leachable arsenic concentration for the C&D debris samples was 153 μg/l with a maximum of 558 μg/l. One of the colored mulch samples purchased from a retail outlet leached arsenic above 50 μg/l, while purchased mulch samples derived from virgin materials did not leach detectable arsenic (<5 μg/l). A mass balance approach was used to compute the potential metal concentrations (mg/kg) that would result from CCA-treated wood being present in wood mulch. Less than 0.1% CCA-treated wood would cause a mulch to exceed Florida''s residential clean soil guideline for arsenic (0.8 mg/kg). [Copyright &y& Elsevier]