Chromated Copper Arsenate Wood Research Articles

Visible Light-Induced Photocatalytic Degradation of Methylene Blue Using Copper-Doped Carbon Dots One-Step Derived from CCA-Wood

Developing novel eco-friendly broad-spectrum visible light photocatalysts for dye removal is one of the urgent problems for water treatment. Here, copper-doped carbon dots (CDs) were reported to be directly fabricated from chromated copper arsenate (CCA) wood waste for the photocatalytic degradation of the methylene blue dye. The properties of the resulting CDs were thoroughly characterized and analyzed, preceding an investigation into the adsorption kinetics of dye degradation. The kinetic study showed that reactant concentration was the rate-limiting factor. The obtained CDs showed a 151 mg/g photocatalytic degradation capacity. Comparing pure CDs to CDs/TiO2 composites, the former demonstrated higher photodegradation efficiency. This superiority can be attributed to the synergistic action of adsorption and photocatalytic degradation working in tandem. This study prepared Cu doped CDs and elucidated the photocatalysis mechanism of methylene blue degradation by CDs. The photodegradation of organic dyes through CDs derived from waste CCA wood emerges as an eco-friendly, facile, and highly efficient method.

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.

PARTICLEBOARD PRODUCED WITH CHROMATED COPPER ARSENATE- AND BORATE-TREATED CAIXETA WOOD: A TECHNICAL FEASIBILITY STUDY

Brazilian flora has more than 12 thousand tropical wood species, which can be the raw material for the construction industry. Chromated copper borate (CCB) and chromated copper arsenate (CCA) are wood preservative chemicals, which can generate toxic waste. Particleboards are usually produced from Pinus sp. and Eucalyptus sp. wood particles and a polymeric matrix (often formaldehyde-based), and they are used as raw material mainly for the furniture industry. This study aimed to investigate the technical feasibility of particleboard production using caixeta wood (Simarouba amara Aubl.) particles and bicomponent castor oil-based polyurethane resin for tropical wood waste management, as well as study the impact of CCA/CCB treatments on the performance of these panels according to NBR 14810 standards. Analysis of variance (ANOVA) tests was performed to compare ten physical and mechanical properties of the panels produced with CCA, CCB, and non-treated caixeta wood particles. The performance of caixeta wood panels was similar to the usually produced boards (using Pinus sp. and Eucalyptus sp. wood). Furthermore, preservative treatments did not change significantly the mechanical performance of panels. However, water absorption increased and thickness swelling decreased in CCA/CCB treated samples.

An uptake and elimination kinetics approach to assess the bioavailability of chromium, copper, and arsenic to earthworms (Eisenia andrei) in contaminated field soils

The aim of this study was to determine the bioavailability of metals in field soils contaminated with chromated copper arsenate (CCA) mixtures. The uptake and elimination kinetics of chromium, copper, and arsenic were assessed in the earthworm Eisenia andrei exposed to soils from a gradient of CCA wood preservative contamination near Hartola, Finland. In soils contaminated with 1480–1590 mg Cr/kg dry soil, 642–791 mg Cu/kg dry soil, and 850–2810 mg Ag/kg dry soil, uptake and elimination kinetics patterns were similar for Cr and Cu. Both metals were rapidly taken up and rapidly excreted by Eisenia andrei with equilibrium reached within 1 day. The metalloid As, however, showed very slow uptake and elimination in the earthworms and body concentrations did not reach equilibrium within 21 days. Bioaccumulation factors (BAF) were low for Cu and Cr (< 0.1), but high for As at 0.54–1.8. The potential risk of CCA exposure for the terrestrial ecosystem therefore is mainly due to As.

Persistent Hazardous Waste and the Quest Toward a Circular Economy: The Example of Arsenic in Chromated Copper Arsenate–Treated Wood

SummaryThe importance of a circular economy is today widely accepted and advocated, but among the challenges in achieving this, we find difficulties in the implementation of legislation and policies designed to control various waste streams from society. The example used in this article is wood that has been treated with chromated copper arsenate (CCA), which, in Sweden, has been covered by the rules for hazardous waste since 2002. One year later, in 2003, a survey showed that only 42% to 50% of the expected amount of CCA waste could be traced to the public waste management system. An updated material flow analysis for 2010 revealed that the figure had increased to 73%, whereas the fraction of correctly treated CCA wood waste had increased from 11% to 35%. However, almost one third of the expected volume was still not tracable, and half of the amount that was correctly submitted was incinerated together with nontoxic waste fractions. This results in, for example, arsenic contamination of slag and fly ashes that prevents the further use of these residue products. So, despite legislative instruments, there is still an urgent need for an improved collection of hazardous wood waste, as well as better routines for identifying hazardous flows and separating them from nonhazardous ones. For a circular economy to be achievable, a key priority should be to reduce the gap between intended directions and legislation, on one hand, and activities in practice on the other.

Novel biomaterials from citric acid fermentation as biosorbents for removal of metals from waste chromated copper arsenate wood leachates

The paper discusses the potential of different waste biomaterials for biosorption. Waste biomaterials after citric acid fermentation and chitosan extraction using Aspergillus niger were evaluated for biosorption of toxic metals (Cu, Cr and As) from leachates of chromated copper arsenate woods. The different waste BMs, such as fungal biomass (living and dead), alkali insoluble material and acid and alkali insoluble material were used in this study. The effect of different parameters, such as biosorbent concentration, metal concentration and contact time were investigated. The fitness of biosorption data for Freundlich and Langmuir adsorption models was investigated through batch adsorption technique. Among the adsorption isotherm tested, Langmuir isotherm gave the best fit with correlation coefficients (R2) value ranging from 0.89 to 0.97; 0.96–0.99 and 0.76–0.95 for As, Cr and Cu, respectively using solid state fermented biomass. Similarly, the significant removal of metals (>60% in leachate 2) from waste CCA wood leachate was achieved with the different BMs. Therefore, this study demonstrates the potential of CA fermentation derived waste BMs for biosorption of toxic metals from waste waters.

Elimination of arsenic-containing emissions from gasification of chromated copper arsenate wood

The behavior of arsenic in chromated copper arsenate containing wood during gasification was modeled using thermodynamic equilibrium calculations. The results of the model were validated using bench-scale gasification tests. It is shown that over 99.6% of arsenic can be removed from the product gas by a hot filter when the gas is cooled below the predicted condensation temperature.

Residential Exposures to Arsenic and Hexavalent Chromium from CCA Wood

Residential Exposures to Arsenic and Hexavalent Chromium from CCA WoodAbstract Number:1551 Ky Gress* and Lena Ma Ky Gress* University of Florida, United States, E-mail Address: [email protected] Search for more papers by this author and Lena Ma University of Florida, United States, E-mail Address: [email protected] Search for more papers by this author AbstractArsenic exposure from wood treated with chromated copper arsenate (CCA) remains a concern due to its presence around homes. These studies explored exposure to arsenic (As) and hexavalent chromium (CrVI) from CCA wood in several settings, including children’s exposure outside apartment buildings, homeowner’s exposure from power-washing CCA decking and animal exposure from living in zoo enclosures made from CCA wood. Children’s exposure to As from 2-story staircases was estimated through determination of bioaccessible soil As and wipe sampling of dislodgeable arsenic (DA) on hand railings, steps and surfaces of objects stored under staircases. Total As concentrations in soil samples ranged from 1.2–66.6 mg/kg. Lifetime average daily doses from ingestion of DA and soil ranged from 8.1 × 10-6 to 3.0 × 10-5 mg/kg/day. In Florida, homeowners typically powerwash CCA wood using bleach solutions, which can oxidize CrIII to CrVI, a known carcinogen. This study evaluated potential exposures to As and Cr(VI) on the wood surface, in rinsate and in nearby soil, finding concentrations of As in rinsate up to 1.6 mg/L. CCA wood is commonly found on farms and in zoos. Captive animals living in enclosures made from CCA wood can be in constant contact with arsenic-contaminated soil. Soil sampling inside animal enclosures at a zoo in Florida found widespread arsenic contamination, with concentrations up to 9 times higher than allowed at industrial sites. This study is ongoing and includes biomonitoring of animals, including endangered species in a captive breeding program.

Evaluating the potential for environmental pollution from chromated copper arsenate (CCA)-treated wood waste: A new mass balance approach

The potential for pollution from arsenic, chromium and copper in chromated copper arsenate (CCA) treated wood waste was assessed using two lysimeter studies. The first utilised lysimeters containing soil and CCA wood waste mulch exposed to natural conditions over a five month period. The second study used the same lysimeter setup in a regulated greenhouse setting with a manual watering regime. Woodchip, soil and leachate samples were evaluated for arsenic, chromium and copper concentrations. Resultant concentration data were used to produce mass balances, an approach thus far unused in such studies. This novel analysis revealed new patterns of mobility and distribution of the elements in the system. The results suggest that CCA wood waste tends to leach on initial exposure to a leachant and during weathering of the wood. When in contact with soil, metal(loid) transport is reduced due to complexation reactions. With higher water application or where the adsorption capacity of the soil is exceeded, the metal(loid)s are transported through the soil column as leachate. Overall, there was an unexplained loss of metal(loid)s from the system that might be attributed to volatilisation of arsenic and plant uptake. This suggests a hitherto unidentified risk to both the environment and human health.

Assessment of children's exposure to arsenic from CCA-wood staircases at apartment complexes in Florida

Arsenic exposure from wood treated with chromated copper arsenate (CCA) remains a concern due to its presence around homes. This study evaluated children's exposure to As from CCA-treated staircases through determination of bioaccessible soil As and measurements of dislodgeable As on hand railings, steps and surfaces of household objects impacted by CCA–wood leachate. Total As concentrations in 84 soil samples from 4 apartment complexes were elevated at 1.2–66.6mg/kg with bioaccessible As at 17–84%. Deterministic risk equations were used to estimate daily doses of As in children with estimates ranging from 0.41–54.9μg/day from ingestion of dislodgeable As. Lifetime average daily doses from ingestion of dislodgeable As and soil ranged from 8.1×10−6 to 3.0×10−5mg/kg/day, with estimated cancer risks being 1.2–4.5×10−5. Collectively, these results highlight potential health risks in children who have near-daily exposure to As from CCA-wood and are consistent with estimates generated by USEPA's SHEDS-Wood probabilistic exposure model.

Pyrolysis of chromated copper arsenate (CCA) treated wood waste at elevated pressure: Influence of particle size, heating rate, residence time, temperature and pressure

Lab-scale pyrolysis experiments with weathered CCA treated wood chips have been performed and the influence of particle size, residence time (10–40 min), heating rate (5–20 °C/min), temperature (330–430 °C) and pressure (0 bar, 5 bar) has been investigated. Few data, covering the pyrolysis of weathered wood was found in the literature and the literature data on pyrolysis experiments with a controlled CCA wood input, showed that results were often highly affected by experimental uncertainty. In order to reduce the uncertainty on the results, a thorough characterization of the wood input has been performed and a ratio method has been proposed which allows to study the effect of particle size on arsenic and chromium volatilization. Larger wood particles show a higher arsenic and chromium retention during pyrolysis which is attributed to the higher mass transfer resistance in these particles. Residence time has a limited effect on arsenic retentions. Increasing heating rate results in a limited increase in arsenic retentions and a more profound increase in chromium retentions. The latter is attributed to a lower average particle temperature during heating caused by the thermal lag in larger particles. Elevated pressure results in a significant increase of arsenic retentions, which is probably due to higher mass transfer resistance. Increasing temperature results in a slight decrease in arsenic retentions till 390 °C, with a sharp decrease at higher temperatures. Chromium retentions are less affected by increasing temperature, especially at higher temperatures. To conclude, a mechanism is proposed for the volatilization of chromium and arsenic during low temperature pyrolysis of CCA wood. Mass transfer resistance and the formation of As 4O 6 are crucial for the control of arsenic volatilization, while heat transfer resistance and thermal lag are more important for the control of chromium volatilization.

Thermal behaviour of arsenic trioxide adsorbed on activated carbon

The thermal stability and desorption of arsenic trioxide (As 2O 3) adsorbed on activated carbon (AC) was investigated as this phenomenon is expected to influence the arsenic release during low temperature pyrolysis of chromated copper arsenate (CCA) wood waste. Firstly, a thermogravimetric (TG) experiment with arsenolite, an allotropic form of As 2O 3, was performed. The sample starts to sublime at temperatures lower than 200 °C with a sublimation peak temperature of 271 °C. Subsequently, TG experiments with samples of As 2O 3 adsorbed on AC revealed that only very little (max. 6 ± 3 wt%) As 2O 3 was volatilised at temperatures below 280 °C, while still 41.6 (±5) wt% of the original arsenic concentration was retained at 440 °C and 28.5 (±3) wt% at 600 °C. The major arsenic volatilisation occurred between 300 °C and 500 °C. The kinetic parameters of desorption, activation energy of desorption ( E d) and pre-exponential factor ( A), were determined by fitting an Arrhenius model to the experimental data, resulting in E d = 69 kJ/mol, A = 1.21 × 10 4 s −1. It can be concluded that the adsorption of As 2O 3 on AC can contribute to the thermal stabilisation of As 2O 3. Consequently, during low temperature pyrolysis of CCA wood arsenic release may be prevented by adsorption of As 2O 3 on the coal-type product formed during the thermal decomposition of the wood.

Evaluation of effect of leaching medium on the release of copper, chromium, and arsenic from treated wood

There is increasing public concern about environmental contamination from preservative treated wood due to release of toxic preservative components to the environment. Leaching of wood preservatives from treated wood in service can be affected by a number of factors such as wood and preservative treatment characteristics and properties of water and soil substrate in which treated wood is placed i.e. salinity, pH, and temperature. Laboratory leaching tests usually require distilled or deionized water for leaching procedure however treated wood is generally exposed to different types of water and soil conditions. This study evaluates the release of copper, chromium and arsenic elements from chromated copper arsenate (CCA)-treated wood exposed to either distilled water, tap water, sea water or humic acid. Leaching tests were conducted in laboratory conditions using wood blocks treated with CCA wood preservative at either low or high retention levels. Results showed that tap water resulted in less preservative release when compared to the other leaching media used in the study. Humic acid was the most effective medium causing more element leaching. The percentage of components leached was always higher in wood blocks treated at the high retention in comparison with the low retention level. Our results from the leaching tests can be important in developing more realistic standard leaching methods to evaluate preservative components to be released from treated wood.

Chromium on the Hands of Children After Playing in Playgrounds Built from Chromated Copper Arsenate (CCA)–Treated Wood

Children’s exposure to arsenic and chromium from playground equipment constructed with chromated copper arsenate (CCA)–treated wood is a potential concern because of children’s hand-to-mouth activity. However, there exists no direct measure of Cr levels on the hands of children after playing in such playgrounds. In this study we measured both soluble and total Cr on the hands of 139 children playing in playgrounds, eight of which were constructed with CCA-treated wood and eight of which were not. Children’s age and duration of play were recorded. The hands of each child were washed after play with 150 mL deionized water, which was collected in a bag and subsequently underwent analysis of Cr and 20 other elements, using inductively coupled plasma mass spectrometry. Total average Cr on the hands of 63 children who played in CCA playgrounds was 1,112 ± 1,089 ng (median, 688; range 78–5,875). Total average Cr on the hands of 64 children who played in non-CCA playgrounds was 652 ± 586 ng (median, 492; range 61–3,377). The difference between the two groups is statistically significant (p < 0.01). Cr levels were highly correlated to both Cu (r = 0.672) and As (r = 0.736) levels in CCA playgrounds (p ≤ 0.01), but not non-CCA playgrounds (r = 0.252 and 0.486 for Cu and As, respectively). Principal-component analysis indicates that Cr, Cu, and As are more closely grouped together in CCA than in non-CCA playgrounds. These results suggest that the elevated levels of Cr and As on children’s hands are due to direct contact with CCA wood.

Method to recover and reuse chromated copper arsenate wood preservative from spent treated wood

The volume of chromated copper arsenate (CCA) treated wood products coming out of service is expected to increase dramatically during the next decade. There is a need for an alternative waste management approach to landfilling. This paper investigates the variables affecting extraction of CCA components from wood particles and the potential to oxidize and reuse the recovered chemicals. Most of the CCA components could be extracted by 10% H 2O 2 at 50 °C in 6 h with an average extraction efficiency of 95% for Cr, 94% for Cu and 98% for As. The extract containing Cr III, Cu II and As V could be oxidized in several stages by aqueous 2.5% w/w H 2O 2 in less than 2 h to a condition where it was compatible with CCA treating solutions and could be reused for treating new wood. When the recovered extract was mixed with fresh CCA solution in different ratios, the mixed CCA-C solutions had similar solution stability as freshly prepared CCA-C solution and treated wood had similar leaching properties as wood treated with fresh solution.

Control of Chromated Copper Arsenate Wood Incineration Air Emissions and Ash Leaching Using Sorbent Technology

Chromated copper arsenate (CCA) has been the predominant wood preservative used in North America in recent years. The emission of volatile metals and leaching from the combustion ash of CCA-treated wood pose serious concerns. In this work, mineral sorbents were evaluated for their capabilities to control both problems. Results of thermodynamic analyses suggested that alkali and alkaline earth metal-based sorbents can potentially react with the metals during combustion. Experiments were conducted by mixing and burning mineral sorbents including lime and soda ash with CCA-treated wood in a fixed bed. Calcium-based sorbents showed great increase in the retention of arsenic (from 60 to 85%) and chromium (from 55 to 80%) and reduction in the leaching of arsenic (from 200 down to 0.1 mg/L) and copper (from 100 down to 1 mg/L). Sodium-based sorbents successfully retained metals in the ash below 750°C, but the products were highly leachable (over 1000 mg/L). The speciation of the products plays a critical role in...

Suicide by ingestion of a CCA wood preservative

Chromated–copper–arsenate (CCA) is a compound used worldwide for wood preservation. Occupational hazards from chronic exposure to CCA are well known, but acute ingestion of CCA wood preservative is very rare. We describe a case of suicide by ingestion of a CCA wood preservative. A 33-year-old man attempted suicide by ingesting an unknown liquid, later identified as a CCA wood preservative, 75 min before his arrival in the emergency department. He was in severe respiratory distress, drooling, tachycardic, and hypotensive. There was an orange color on the palms of both hands. Severe, green colored burns of the buccal mucosa were observed. He was intubated shortly after arrival. The larynx was edematous, but a 7-mm endotracheal tube was successfully introduced. Blood tests revealed partially compensated metabolic acidosis. The patient deteriorated rapidly; the systolic blood pressure dropped to 70 mmHg, and he passed bloody diarrhea. He developed multiple premature atrial contractions and supraventricular tachycardia, and later in the intensive care unit, refractory ventricular tachycardia and ventricular fibrillation. The patient was declared dead 2 1 2 h after his arrival. Unfortunately, postmortem blood levels of heavy metals and autopsy were not performed because of refusal by the family for religious reasons.

Chromated Copper Arsenate-Treated Wood in Recovered Wood

Wood represents approximately 25% of the C&D waste stream, and a possible limitation to wood recycling is the presence of CCA-treated wood. Research was performed to measure the percentage of chromated copper arsenate (CCA)-treated wood present in recovered wood stockpiles at construction and demolition (C&D) waste recycling facilities in Florida. Because of the elevated levels of chromium, copper, and arsenic in CCA-treated wood the presence of this material in C&D-recovered wood waste limits possible management options. Quantifying the fraction of C&D wood waste comprised of CCA-treated wood is a necessary first step in addressing this issue. Shredded wood samples were collected from the 12 C&D recycling facilities in Florida in an effort to quantify the fraction of recovered wood that was treated with the waterborne preservative CCA. The samples were further size reduced and mixed, and ultimately ashed at 550°C in a laboratory furnace. Copper and chromium concentrations in the ash were measured using a flame atomic absorption spectrophotometer. These concentrations were used to calculate the amount of CCA-treated wood present in the original wood samples. The average percentage of 0.25-pcf standard retention, Type C, CCA-treated wood was estimated to be 6.5% based on copper and 5.9% based on chromium. In addition to providing needed measurements of CCA wood presence in C&D-recovered wood, this paper presents a methodology for estimating CCA wood amounts at other locations. Key words: Construction and demolition waste; CCA; chromium; copper; waste wood; recycling; treated wood; wood; solid waste

Reduction in toxicity of chromated copper arsenate (CCA)-treated wood as assessed by community study

Panels of chromated copper arsenate (CCA)-treated wood and control (untreated) wood were placed into an estuary and examined after one month for differences in settlement of organisms. The community on the CCA wood exhibited greatly reduced species richness, biomass, and diversity. When the community on each panel (treated and untreated) was removed and the boards replaced into the estuary, the epibiota settling during the following month showed a smaller difference between the CCA panels and the control wood. After removal of the community and immersion of the wood for a third month, there were no statistically significant differences in the community that formed on the two materials. However, qualitative differences were still visible, particularly in the growth of the alga Enteromorpha and the bryozoan Conopeum. Differences in algal and bryozoan cover persisted after a year of submersion. The decreased toxicity of the CCA wood with repeated trials is probably related to decreased rate of leaching, as observed earlier in laboratory experiments, and suggests that the treated wood would have reduced environmental impact if it were soaked out at the treatment facility before being marketed for use in the aquatic environment. Bioaccumulation of the metals in the epibiota on the CCA wood generally declined over time, but remained far above control levels.

Anion mobilization from aqueous media by ion associate extraction into supercritical carbon dioxide with on-line detection by flame atomic absorption spectrometry

The nebulizer assembly of a flame atomic absorption spectrometer was modified to operate with conventional flows corresponding to ⩽2.2 l min–1 of decompressed supercritical carbon dioxide (SC-CO2) extractor eluate. Supplemental heating of the inlet air to 200 °C resulted in a flow injection system–on-line detector which provided approximately a 10-fold improvement over conventional flow injection operation. The detector was used to evaluate the feasibility of mobilizing/purging anions (chromate, selenate or selenite) from aqueous media by adding an alkylammonium halide directly to the SC-CO2 mobile phase. At 30.6 MPa and 80 °C, SC-CO2 solublized sufficient tetrahexylammonium bromide (THAB) to effect the efficient purging (93%) of selenate (60 µg) from aqueous solution during a 40 min extraction. At 24.1 MPa and 50 °C, there was little difference in the recoveries (66 versus 62%) using THAB or tetrabutylammonium dibutyldithiocarbamate (TBADBDTC) as pairing reagent. Selenite or chromate was also efficiently mobilized with either reagent. Mathematical models of the declination in AAS response with time suggested that whereas selenite (half-life, t1/2= 3.6 min) was mobilized at a rate that was not appreciably different from cation–dithiocarbamate complexes, chromate was mobilized appreciably more slowly (t1/2= 19.5 min) under identical extractor operating conditions. The Cr and Cu in an aqueous suspension containing chromated copper arsenate wood preservative were simultaneously mobilized using a mixture of THAB and TBADBDTC. Despite appreciable interactions with other components of the sample, 89 and 98%, respectively, of the Cr and Cu burdens were purged from the sample during a 45 min extraction using a decompressed flow rate of 2.2 l min–1.