Pyrolysis of Chromated Copper Arsenate-Treated Wood: Investigation of Temperature, Granulometry, Biochar Yield, and Metal Pathways
Open accessAbstract
Chromated copper arsenate-treated (cca) wood disposal faces environmental restrictions due to its toxicity, heavy metal leaching in storage sites, and greenhouse gas emissions during incineration. Thus, finding new management methods for this contaminated wood at the end of life is crucial. This study evaluated the effect of pyrolysis temperature (300, 400, and 500 °C), particle size, biochar yield, and the behavior of arsenic (As), chromium (Cr), and copper (Cu) during treated-wood pyrolysis. The highest biochar yield was obtained at 300 °C for fine particles. The biochar retention of heavy metals decreased with increasing pyrolysis temperature. At 300 °C, the highest biochar As, Cr, and Cu retentions were 76, 91, and 83%. At 500 °C, biochar only retained 43% of the As. Additionally, heavy metal leaching from the biochar exceeded the Environmental Protection Agency’s (EPA) maximum concentration limit of 5 mg/L. High-density polyethylene encapsulation of contaminated biochar reduced the leaching of As, Cr, and Cu by 96, 95, and 91%, respectively. Thus, combining pyrolysis and plastic encapsulation to produce a composite material could be a solution for reducing waste (conversion of CCA-wood into biochar) and for the safe disposal of contaminated wood.
AI snapshot
Written from the paper’s full text.
TL;DR
Slow pyrolysis of chromated copper arsenate-treated wood concentrated As, Cr, and Cu in biochar, with lower pyrolysis temperature favoring higher biochar yield and metal retention. Encapsulating the contaminated biochar in high-density polyethylene reduced metal leaching, suggesting a combined pyrolysis–encapsulation route for safe disposal.
Key findings
- The highest biochar yield was obtained at 300 °C for fine particles; high biochar yields up to 50% at 300 °C indicated incomplete thermochemical conversion.
- At 300 °C, the highest biochar retentions were 76% As, 91% Cr, and 83% Cu; at 500 °C, biochar retained only 43% of the As.
- Heavy metal leaching from biochar exceeded the EPA maximum concentration limit of 5 mg/L.
- HDPE encapsulation reduced leaching of As, Cr, and Cu by 96, 95, and 91%, respectively, according to the abstract; Table 5 reports reductions of 88.4%, 95.0%, and 94.8%.
Methods
- CCA-treated red pine pole waste (type C; 45.2% CrO₃, 26.4% CuO, 28.4% As₂O₅) was pyrolyzed in an in-house pilot-scale furnace at 300, 400, and 500 °C, with particle sizes 0.85–1.4 mm (G1), 1.4–2 mm (G2), and 2–3.35 mm (G3), under nitrogen at 2 L/min and ~1 h residence time.
- Biochar yield, metal retention, and leaching were measured; metals were quantified by ICP-MS, microstructure by SEM-EDS, and leaching by TCLP.
- Biochar was encapsulated in 80% HDPE/20% biochar composites via twin-screw extrusion at 160 °C; data were analyzed by two-factor ANOVA in SAS v9.4 at α = 0.05.
Limitations
- The paper states that only one encapsulation formulation (80% HDPE and 20% biochar) was tested, and further studies are needed to optimize plastic composition and HDPE/biochar proportions; recycled plastic waste is suggested as a possible low-cost alternative.
- The paper states that investigations on the composites’ in-service and environmental performance are still needed.
- The text makes evident additional limitations: sample heterogeneity produced high standard deviations, the As retention model had a low R² = 0.34 (66% unexplained), and the authors note that interactions were difficult to interpret.
Model-written summary. Check it against the paper before relying on it.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
2 of 47 cited sources checked · 1 supported · 0 flagged · accuracy not yet measured
- Premisecitation
The main advantage of the biochar-HDPE composite is its dimensional stability due to biochar hydrophobicity.
“The main advantage of such material is its dimensional stability due to biochar hydrophobicity [56].”
Quote in the paperNot a substantial claim1 of 1 sources checked- cites [56] Ayadi, R., Koubaa, A., Braghiroli, F., Migneault, S., Wang, H., and Bradai, C. (2020). Effect of the Pyro-Gasification Temperature of Wood on the Physical and Mechanical Properties of Biochar-Polymer Biocomposites. Materials, 13. source
- Findingown data
HDPE encapsulation of contaminated biochar reduced the leaching of As, Cr, and Cu by 96, 95, and 91%, respectively.
“High-density polyethylene encapsulation of contaminated biochar reduced the leaching of As, Cr, and Cu by 96, 95, and 91%, respectively.”
Quote in the paperSubstantial claim - Findingown data
Heavy metal leaching from the biochar exceeded the EPA maximum concentration limit of 5 mg/L.
“Additionally, heavy metal leaching from the biochar exceeded the Environmental Protection Agency's (EPA) maximum concentration limit of 5 mg/L.”
Quote in the paperSubstantial claim - Findingown data
At 500 °C, biochar only retained 43% of the As.
“At 500 • C, biochar only retained 43% of the As.”
Quote in the paperSubstantial claim - Findingown data
The biochar retention of heavy metals decreased with increasing pyrolysis temperature.
“The biochar retention of heavy metals decreased with increasing pyrolysis temperature.”
Quote in the paperSubstantial claim
- Findingnone given
The highest biochar yield was obtained at 300 °C for fine particles.
“The highest biochar yield was obtained at 300 • C for fine particles.”
Quote in the paperNot a substantial claim - Findingown data
The retention capacity of As has a lower regression coefficient (R2 = 0.34) compared to Cr and Cu (0.76 and 0.61, respectively).
“The retention capacity of As has a lower regression coefficient (R 2 = 0.34) compared to Cr and Cu (0.76 and 0.61, respectively).”
Quote in the paperSubstantial claim - Findingown data
For medium-sized particles (G2), Cr retention in biochar at 300°C was 91%.
“Cr and Cu retention percentages at 300 • C were 91% and 83%, respectively.”
Quote in the paperSubstantial claim - Findingown data
The effect of pyrolysis temperature was significant on As leaching.
“The effect of pyrolysis temperature was significant on As leaching but did not significantly affect Cr and Cu leaching (Table 4).”
Quote in the paperSubstantial claim - Findingown data
For medium-sized particles (G2), As retention in biochar reached 76% at 300°C, compared to 43% at 500°C.
“For the medium-sized particles (G2), As retention in biochar reached 76% at 300 • C, compared to 43% at 500 • C.”
Quote in the paperSubstantial claim - Findingreasoning
66% of the observed values are explained by factors other than those studied (particle size, temperature, and their interaction).
“Thus, 66% of the observed values are explained by factors other than those studied (particle size, temperature, and their interaction).”
Quote in the paperNot a substantial claim - Findingown data
The effects of particle size on As, Cr, and Cu leaching are highly significant.
“The effects of particle size on AS, Cr, and Cu leaching are highly significant (Table 4).”
Quote in the paperSubstantial claim - Findingown data
Very high As, Cr, and Cu concentrations were found in the CCA-treated wood.
“Very high As, Cr, and Cu concentrations were found in the CCA-treated wood.”
Quote in the paperSubstantial claim - Findingown data
Particle size, pyrolysis temperature, and their interaction significantly affected As, Cr, and Cu concentrations.
“Table 4 shows that particle size, pyrolysis temperature, and their interaction significantly affected As, Cr, and Cu concentrations.”
Quote in the paperSubstantial claim - Findingnone given
The effect of particle size does not seem to be significant during pyrolysis for any of the metals.
“However, the effect of particle size does not seem to be significant during pyrolysis for any of the metals.”
Quote in the paperNot a substantial claim - Findingcitation
At 500°C, the decrease in metal retention capacity is more pronounced.
“At 500 • C, the decrease is more pronounced and suggests that the high volatilization of metal compounds occurs at higher pyrolysis temperatures [38].”
Quote in the paperSubstantial claim - Findingown data
The studied factors explain 91% of the variation for the Cr and Cu concentrations.
“The studied factors explain 91% of the variation for the Cr and Cu concentrations.”
Quote in the paperNot a substantial claim - Findingown data
The effect of pyrolysis temperature did not significantly affect Cr and Cu leaching.
“The effect of pyrolysis temperature was significant on As leaching but did not significantly affect Cr and Cu leaching (Table 4).”
Quote in the paperSubstantial claim - Findingnone given
The concentrations of As, Cr, and Cu (1539, 2856 and 1585 mg/kg, respectively) are much lower in fine particles (0.85 < G1 < 1.4 mm) than the concentrations (2850, 3580, and 2107 mg/kg, respectively) in medium particles (1.4 < G2 < 2 mm).
“For example, the concentrations of As, Cr, and Cu (1539, 2856 and 1585 mg/kg, respectively) are much lower in fine particles (0.85 < G1 < 1.4 mm) than the concentrations (2850, 3580, and 2107 mg/kg, respectively) in medium particles (1.4 < G2 < 2 mm).”
Quote in the paperSubstantial claim - Findingown data
The ANOVA results confirm that pyrolysis temperature had a very significant effect, especially for Cr and Cu.
“The ANOVA results confirm that pyrolysis temperature had a very significant effect, especially for Cr and Cu (Table 4).”
Quote in the paperSubstantial claim - Findingown data
87% of the variation in As concentration is explained by the studied factors.
“For example, 87% of the variation in As concentration is explained by the studied factors.”
Quote in the paperSubstantial claim - Findingreasoning
A significant decrease in biochar yield was observed by increasing the pyrolysis temperature from 300 to 500 °C.
“In addition, a significant decrease in biochar yield was observed by increasing the pyrolysis temperature from 300 to 500 • C.”
Quote in the paperSubstantial claim - Findingcitation
With a temperature increase, the retention of the three metals decreased due to the increase in the metals' volatilization.
“With a temperature increase, the retention of the three metals decreased due to the increase in the metals' volatilization [38].”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [38] Cuypers, 2011, Pyrolysis of Chromated Copper Arsenate (CCA) Treated Wood Waste at Elevated Pressure: Influence of Particle Size, Heating Rate, Residence Time, Temperature and Pressure, J. Anal. Appl. Pyrolysis source
- Findingown data
The smallest volume of biochar with the lowest metal concentrations was produced at 500°C.
“Additionally, the greatest amount of biochar with the highest metal concentrations was produced at 300 • C, while the smallest volume of biochar with the lowest metal concentrations was produced at 500 • C.”
Quote in the paperSubstantial claim - Findingreasoning
Initial concentrations of As, Cr, and Cu measured in CCA-treated wood in this study differ from those reported in the literature.
“Initial concentrations of As, Cr, and Cu measured in CCA-treated wood in this study differ from those reported in the literature [13,[51][52][53].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [13,[51][52][53]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Findingown data
Particle size and pyrolysis temperature have a highly significant effect on the biochar yield.
“Particle size and pyrolysis temperature have a highly significant effect on the biochar yield (Table 4).”
Quote in the paperSubstantial claim - Findingreasoning
The retention capacity for the three metals in biochar did not reach 100% at 300°C.
“The retention capacity for the three metals in biochar did not reach 100% at 300 • C.”
Quote in the paperSubstantial claim - Findingown data
The high coefficients of determination (R2) of the statistical models suggest that variations in metal concentration are mainly explained by the studied factors (size, pyrolysis temperature, and their interaction).
“The high coefficients of determination (R 2 ) of the statistical models suggest that variations in metal concentration are mainly explained by the studied factors (size, pyrolysis temperature, and their interaction).”
Quote in the paperSubstantial claim - Findingreasoning
The ash content was higher for the contaminated wood than the untreated one due to inorganic elements (As, Cr, and Cu).
“The ash content was higher for the contaminated wood than the untreated one due to inorganic elements (As, Cr, and Cu).”
Quote in the paperNot a substantial claim - Findingown data
The most leached compound is at particle sizes G2 and G3 and higher pyrolysis temperatures.
“The most leached compound is at particle sizes G2 and G3 and higher pyrolysis temperatures (Figure 5a).”
Quote in the paperNot a substantial claim - Findingown data
Particle size, pyrolysis temperature, and their interaction explained 84% of the total variation in metal concentration.
“The high coefficient of determination for As indicates that particle size, pyrolysis temperature, and their interaction explained 84% of the total variation in metal concentration.”
Quote in the paperSubstantial claim - Findingown data
For medium-sized particles (G2), Cu retention in biochar at 300°C was 83%.
“Cr and Cu retention percentages at 300 • C were 91% and 83%, respectively.”
Quote in the paperNot a substantial claim - Findingnone given
Metal retention capacity decreases slightly at 400°C.
“It is also important to mention that the metal retention capacity decreases slightly at 400 • C.”
Quote in the paperSubstantial claim - Findingown data
For Cr and Cu, the unexplained variation (24% and 39%, respectively) is higher than that for As.
“For Cr and Cu, the unexplained variation (24% and 39%, respectively) is higher than that for As.”
Quote in the paperNot a substantial claim - Findingown data
TCLP leaching tests showed that biochar is a hazardous waste because of the high As and Cr content in leaching solutions.
“As previously described, leaching tests (TCLP) showed that biochar is a hazardous waste because of the high As and Cr content in leaching solutions.”
Quote in the paperSubstantial claim - Findingown data
Biochar obtained after pyrolysis contains large amounts of heavy metals.
“Biochar obtained after pyrolysis contains large amounts of heavy metals.”
Quote in the paperSubstantial claim - Findingown data
The TCLP tests show a significant reduction in As, Cr, and Cu concentrations in leaching solutions before and after encapsulation compared with their concentrations in samples before pyrolysis.
“The TCLP tests show a significant reduction in As, Cr, and Cu concentrations in leaching solutions before and after encapsulation compared with their concentrations in samples before pyrolysis.”
Quote in the paperSubstantial claim - Findingnone given
Metal leaching increases under the effect of pyrolysis temperature.
“In addition, metal leaching increases under the effect of pyrolysis temperature.”
Quote in the paperNot a substantial claim - Findingown data
Pyrolysis at 300°C with particle size 1.4-2 mm retained 75% of the arsenate in biochar.
“It retained 75% of the arsenate, 91% of the chromium, and 83% of the copper in the biochar, while encapsulation reduced metal leaching.”
Quote in the paperSubstantial claim - Findingown data
The residual metal contents in the leaching solutions were below tolerated limits (<5 mg/L) according to environmental regulations in Québec.
“Indeed, the residual metal contents in the leaching solutions were below tolerated limits (<5 mg/L) according to environmental regulations in Québec.”
Quote in the paperSubstantial claim - Findingown data
Pyrolysis temperature and CCA-treated wood particle size affected As, Cr, and Cu leaching from biochar.
“Thus, pyrolysis temperature and CCA-treated wood particle size affected As (Figure 5a), Cr (Figure 5b) and Cu (Figure 5c) leaching from biochar.”
Quote in the paperSubstantial claim - Findingnone given
Pyrolysis of CCA-treated wood at 300°C with a particle size varying between 1.4 to 2 mm reduced the contaminated biomass by 25%.
“The pyrolysis of CCA-treated wood at 300 • C with a particle size varying between 1.4 to 2 mm reduced the contaminated biomass by 25%.”
Quote in the paperSubstantial claim - Premisecitation
Helsen et al. found that the highest char yield of CCA-treated wood was 27% at 390 °C compared to 7% at 700 °C.
“Helsen et al. [28] found that the highest char yield of CCA-treated wood was 27% at 390 • C compared to 7% at 700 • C.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [28] Helsen, 1999, Low-Temperature Pyrolysis of CCA-Treated Wood: Thermogravimetric Analysis, J. Anal. Appl. Pyrolysis source
- Premisecitation
In the case of CCA-treated wood, particle size strongly influenced the retention of As and Cr present in the biochar.
“In the case of CCA-treated wood, particle size strongly influenced the retention of As and Cr present in the biochar.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [38] Cuypers, 2011, Pyrolysis of Chromated Copper Arsenate (CCA) Treated Wood Waste at Elevated Pressure: Influence of Particle Size, Heating Rate, Residence Time, Temperature and Pressure, J. Anal. Appl. Pyrolysis source
- Premisecitation
As release during wood pyrolysis is governed by a reduction reaction of arsenate (As2O5) to arsenite (As2O3).
“The As release during wood pyrolysis is governed by a reduction reaction of arsenate (As 2 O 5 ) to arsenite (As 2 O 3 ).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [29] Helsen, 2003, Metal Retention in the Solid Residue after Low-Temperature Pyrolysis of Chromated Copper Arsenate (CCA)-Treated Wood, Environ. Eng. Sci. source
- Interpretationreasoning
Pyrolysis at 300°C remains safer since the retention of the three metals is more important than at other temperatures.
“Finally, pyrolysis at 300 • C remains safer since the retention of the three metals is more important than at other temperatures.”
Quote in the paperSubstantial claim - Interpretationreasoning
High biochar yields (up to 50%) at a low temperature (300 °C) indicate that wood thermochemical conversion was incomplete.
“High biochar yields (up to 50%) at a low temperature (300 • C) indicate that wood thermochemical conversion was incomplete.”
Quote in the paperNot a substantial claim - Interpretationreasoning
The difference between the initial concentrations of As or Cu for the three selected samples explains the high standard deviation.
“The difference between the initial concentrations of As or Cu for the three selected samples explains the high standard deviation.”
Quote in the paperSubstantial claim - Premisecitation
This reduction reaction occurs at about 327°C.
“This reaction occurs at about 327 • C.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [29] Helsen, 2003, Metal Retention in the Solid Residue after Low-Temperature Pyrolysis of Chromated Copper Arsenate (CCA)-Treated Wood, Environ. Eng. Sci. source
- Interpretationreasoning
The difference in retention capacity from 100% can be explained by the extended residence time in the furnace.
“This difference can be explained by the extended residence time in the furnace.”
Quote in the paperNot a substantial claim - Interpretationreasoning
The decrease in biochar yield as a function of particle size is explained by the high concentrations of As, Cr, and Cu in CCA-treated wood.
“The decrease in biochar yield as a function of particle size is explained by the high concentrations of As, Cr, and Cu in CCA-treated wood.”
Quote in the paperSubstantial claim - Premisecitation
The thermal decomposition of the inorganic components of CCA-treated wood can be influenced by their interaction with the decomposition products of wood.
“The thermal decomposition of the inorganic components of CAA-treated wood can be influenced by their interaction with the decomposition products of wood.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [29] Helsen, 2003, Metal Retention in the Solid Residue after Low-Temperature Pyrolysis of Chromated Copper Arsenate (CCA)-Treated Wood, Environ. Eng. Sci. source
- Interpretationcitation
High volatilization of metal compounds occurs at higher pyrolysis temperatures.
“At 500 • C, the decrease is more pronounced and suggests that the high volatilization of metal compounds occurs at higher pyrolysis temperatures [38].”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [38] Cuypers, 2011, Pyrolysis of Chromated Copper Arsenate (CCA) Treated Wood Waste at Elevated Pressure: Influence of Particle Size, Heating Rate, Residence Time, Temperature and Pressure, J. Anal. Appl. Pyrolysis source
- Interpretationown data
Based on the results of metal retention capacities, a temperature of 300°C and a particle size of 1.4 to 2 mm are optimal parameters for stabilizing metals in the biochar.
“Based on the results of metal retention capacities, it has been demonstrated that a temperature of 300 °C and a particle size of 1.4 to 2 mm are optimal parameters for stabilizing metals in the biochar.”
Quote in the paperSubstantial claim - Interpretationown data
The biochar-HDPE pressurized and agglomerated mixture is a reliable option to stabilize metals in biochar.
“Therefore, the biochar-HDPE pressurized and agglomerated mixture is a reliable option to stabilize metals in biochar.”
Quote in the paperSubstantial claim - Interpretationown data
Biochar is a hazardous waste even after thermochemical stabilization.
“These results confirm that biochar is a hazardous waste even after thermochemical stabilization.”
- Also stated in: § 3.5. Metal Leaching of CCA-Contaminated Biochar · plain
“As previously described, leaching tests (TCLP) showed that biochar is a hazardous waste because of the high As and Cr content in leaching solutions.”
Quote in the paperSubstantial claim - Also stated in: § 3.5. Metal Leaching of CCA-Contaminated Biochar · plain
- Interpretationcitation
The results obtained in this study agree with those reported in the literature on the encapsulation of waste containing arsenic using other types of binders (Portland cement, asphalt concrete, an amorphous matrix of glass at a high temperature).
“The results obtained in this study agree with those reported in the literature on the encapsulation of waste containing arsenic using other types of binders (Portland cement, asphalt concrete, an amorphous matrix of glass at a high temperature)] [57,58].”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites [57] Conner, 1993, Treatment of Land and Arsenic Wastes at TSDFs, Pollut. Technol. Rev.
Not checked in the free run.
- cites [58] Rechichi, D. (2002). Encapsulation of Hazardous Waste Materials. (6,399,848 B1), U.S. Patent, Available online: https://patentimages.storage.googleapis.com/10/44/c4/05a54a30064fda/US6399848.pdf.
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Interpretationown data
Metal retention in biochar confirmed the potential of pyrolysis for heavy metal stabilization.
“The metal retention in biochar confirmed the potential of pyrolysis for heavy metal stabilization.”
Quote in the paperSubstantial claim
- Classified as probably not a substantial claim. 30
- May combine two claims. 25
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationAfter S/S treatment, the heavy metal leaching of highly contaminated samples ranged from 0.002 to 0.225 mg/L.
“After S/S treatment, the heavy metal (lead, zinc, arsenic, chromium, copper, and nickel) leaching of highly contaminated samples ranged from 0.002 to 0.225 mg/L.”
Quote in the paperNot a substantial claim1 of 1 sources checked- cites [44] Wang, 2015, The Performance of Blended Conventional and Novel Binders in the In-Situ Stabilisation/Solidification of a Contaminated Site Soil, J. Hazard. Mater. source
Section 3.1 (page unavailable) reports metal leaching from S/S-treated samples, including Pb, Zn, Cu and Ni. It does not give the claimed 0.002–0.225 mg/L range or report leaching results for arsenic and chromium; its stated highest Ni concentration is 0.09 mg/L. (LLM, conf=0.86)
Experimental — accuracy not yet measured
May combine two claims.
Findingown dataAt 300 °C, the highest biochar As, Cr, and Cu retentions were 76, 91, and 83%.
“At 300 • C, the highest biochar As, Cr, and Cu retentions were 76, 91, and 83%.”
Quote in the paperSubstantial claimMay combine two claims.
FindingreasoningSamples belonging to the G2 particle size had the highest concentration of metals, while the samples with G1 particle sizes had the lowest concentration in As, Cr, and Cu.
“Samples belonging to the G2 particle size had the highest concentration of metals, while the samples with G1 particle sizes had the lowest concentration in As, Cr, and Cu.”
Quote in the paperSubstantial claimMay combine two claims.
Findingnone givenThe CCA-treated wood used in this study was type C and composed of 45.2% CrO3, 26.4% CuO, and 28.4% As2O5.
“The CCA-treated wood was type C and composed of 45.2% CrO 3 , 26.4% CuO, and 28.4% As 2 O 5 .”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
FindingcitationMeasured proportions of C, H, and O in CCA-treated wood were 45.6%, 6.6%, and 47.8%, respectively.
“Measured proportions of C, H, and O in CCA-treated wood were comparable to those found in this project: 45.6%, 6.6%, and 47.8%, respectively (Table 2).”
Quote in the paperNot a substantial claimMay combine two claims.
FindingcitationC, H, N, and S percentages for the untreated and CCA-treated wood samples are comparable, showing that treating wood using a metal agent (e.g., CCA) does not affect its elemental composition.
“C, H, N, and S percentages for the untreated and CCA-treated wood samples are comparable, showing that treating wood using a metal agent (e.g., CCA) does not affect its elemental composition [50].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [50] Bridgwater, 2003, Renewable Fuels and Chemicals by Thermal Processing of Biomass, Chem. Eng. J. source
May combine two claims.
Findingown dataThe moisture content of untreated wood and CCA-treated wood was similar, with an average value of 6.9%, and the biochar had an average humidity of 1.86%.
“The moisture content of untreated wood and CCA-treated wood was similar, with an average value of 6.9%, and the biochar had an average humidity of 1.86% (Table 2).”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown dataThe ANOVA models were highly significant, with 84%, 76%, and 61% coefficients of determination for As, Cr, and Cu leaching, respectively.
“The ANOVA models were highly significant, with 84%, 76%, and 61% coefficients of determination for AS, Cr, and Cu leaching, respectively (Table 4).”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataThe greatest amount of biochar with the highest metal concentrations was produced at 300°C.
“Additionally, the greatest amount of biochar with the highest metal concentrations was produced at 300 • C, while the smallest volume of biochar with the lowest metal concentrations was produced at 500 • C.”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataThe established model explains 84% and 66% of the observed variation in As and Cr leaching, respectively.
“According to the regression coefficients, the established model explains 84% and 66% of the observed variation in As and Cr leaching.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationDue to its toxicity, the use of CCA-treated wood for residential use was prohibited in 2004 and is highly regulated nowadays.
“Due to its toxicity, the use of CCA-treated wood for residential use was prohibited in 2004 and is highly regulated nowadays [5].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [5] Health Canada, and Pest Management Regulatory Agency (2010). Heavy Duty Wood Preservatives: Creosote, Pentachlorophenol, Chromated Copper Arsenate (CCA) and Ammoniacal Copper Zinc Arsenate (ACZA), Health Canada Pest Management Regulatory Agency.
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
May combine two claims.
PremisecitationLarge biomass particles have a high resistance to mass transfer to release As and Cr; therefore, biochar presents higher retention of both metals.
“Large biomass particles (9.5 cm long) had a high resistance to mass transfer to release As and Cr; therefore, biochar presents higher retention of both metals [38].”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [38] Cuypers, 2011, Pyrolysis of Chromated Copper Arsenate (CCA) Treated Wood Waste at Elevated Pressure: Influence of Particle Size, Heating Rate, Residence Time, Temperature and Pressure, J. Anal. Appl. Pyrolysis source
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationThree CCA formulations have been developed: types A, B, and C.
“According to the American Wood Protection Association (AWPA), three CCA formulations have been developed: types A, B, and C [7] (Table 1).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [7] AWPA American Wood Protection Association (1997). Book of Standards. American Wood Protection Association.
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationType C has been the most commercially popular CCA formulation from 1980 to 2000.
“Type C has been the most commercially popular in the past few years (from 1980 to 2000 [11]).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [11] Freeman, 2003, Past, Present, and Future of the Wood Preservation Industry: Wood Is a Renewable Natural Resource That Typically Is Preservative Treated to Ensure Structural Integrity in Many Exterior Applications, For. Prod. J.
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
May combine two claims.
Interpretationown dataCombining pyrolysis and plastic encapsulation to produce a composite material could be a solution for reducing waste and for the safe disposal of contaminated wood.
“Thus, combining pyrolysis and plastic encapsulation to produce a composite material could be a solution for reducing waste (conversion of CCA-wood into biochar) and for the safe disposal of contaminated wood.”
Quote in the paperSubstantial claim- Rests on an assumption: No studies have tested the encapsulation of biochar obtained by pyrolysis of CCA-treated wood.
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationThe three CCA formulations contain about 19% copper oxide (CuO).
“The three formulations contain about 19% copper oxide (CuO) [8,9].”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites [8] Helsen, 2000, Metal Behavior during the Low-Temperature Pyrolysis of Chromated Copper Arsenate-Treated Wood Waste, Environ. Sci. Technol. source
- cites [9] Janin, A. (2009). Développement d’un Procédé Chimique de Décontamination de Bois Usagé Traité à l’arseniate de Cuivre Chromaté. [Ph.D. Thesis, Université du Québec, Institut National de la Recherche Scientifique].
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Classified as probably not a substantial claim.
PremisecitationCCA used as a wood preservative in power distribution poles, railway ties, etc., is often associated with the risk of metal leaching from storage sites or landfills where they are discarded.
“For example, CCA used as a wood preservative in power distribution poles, railway ties, etc., is often associated with the risk of metal leaching from storage sites or landfills where they are discarded [4].”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [4] Shalat, 2006, A Pilot Study of Children’s Exposure to CCA-Treated Wood from Playground Equipment, Sci. Total Environ. source
May combine two claims.
PremisecitationCr and Cu releases were negligible, while As release was less than 10% at a pyrolysis temperature of 400 °C and residence time of 10 min.
“Cr and Cu releases were negligible, while As release was less than 10% at a pyrolysis temperature of 400 • C and residence time of 10 min.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [28] Helsen, 1999, Low-Temperature Pyrolysis of CCA-Treated Wood: Thermogravimetric Analysis, J. Anal. Appl. Pyrolysis source
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationOperating conditions such as residence time, temperature, heating rate, biomass precursor, and particle size can affect pyrolytic products' chemical composition and distribution.
“Operating conditions such as residence time, temperature, heating rate, biomass precursor, and particle size can affect pyrolytic products' chemical composition and distribution [27].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [27] Fahmi, 2007, The Effect of Alkali Metals on Combustion and Pyrolysis of Lolium and Festuca Grasses, Switchgrass and Willow, Fuel source
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationDuring pyrolysis, heat transfer phenomena depend on the size of wood particles.
“Additionally, during pyrolysis, heat transfer phenomena depend on the size of wood particles [31].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [31] Larfeldt, 2000, Modelling and Measurements of the Pyrolysis of Large Wood Particles, Fuel source
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationPyrolysis of CCA-treated wood is complex due to the wood's interaction between metals and biopolymers.
“The pyrolysis of CCA-treated wood is complex due to the wood's interaction between metals and biopolymers [17].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [17] Poletto, 2017, Preparation and Characterization of a Metal-Rich Activated Carbon from CCA-Treated Wood for CO2 Capture, Chem. Eng. J. source
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationFor pyrolysis of oil mallee woody biomass at 500 °C, Shen et al. found that biochar yield increased from 33 to 90% when particle size increased from 0.3 to more than 3 mm.
“For pyrolysis of oil mallee woody biomass at 500 • C, Shen et al. [36] found that biochar yield increased from 33 to 90% when particle size increased from 0.3 to more than 3 mm.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [36] Shen, 2009, Effects of Particle Size on the Fast Pyrolysis of Oil Mallee Woody Biomass, Fuel source
May combine two claims.
PremisecitationAs(V) is reduced to arsenic trioxide (As2O3), decomposes, and becomes volatile during pyrolysis, even at 200 °C.
“These findings are in good agreement with other studies that reported that As (V) is reduced to arsenic trioxide (As 2 O 3 ), decomposes, and becomes volatile during pyrolysis, even at 200 • C [29,30].”
Quote in the paperNot a substantial claim0 of 2 sources checkedProbably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationAll hazardous residual materials or contaminated soils with metals are treated by S/S before being disposed of in landfills in Quebec, Canada.
“For example, all hazardous residual materials or contaminated soils with metals are treated by S/S before being disposed of in landfills in Quebec, Canada [43].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [43] (2022, July 08). Ministère de l’environnement et de la Lutte Contre les Changements Climatiques Lignes Directrices Sur La Gestion Des Matières Résiduelles et Des Sols Contaminés Traités Par Stabilisation et Solidification; Ministère de l’Environnement et de la Lutte Contre les Changements Climatiques: Québec, QC, Canada, 2021. Available online: https://www.environnement.gouv.qc.ca/matieres/mat_res/ld-gestion-matres-sols-stabilisation-solid.pdf.
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
May combine two claims.
PremisecitationType A contains 65.5% chromium, while types B and C contain 45.1% and 34.0% arsenic and 35.3% and 47.5% chromium, respectively.
“Type A contains a significant amount of chromium (65.5%), while types B and C contain comparable amounts of arsenic (45.1% and 34.0%, respectively) and chromium (35.3% and 47.5%, respectively) [10,11].”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites [10] Nicholas, D.D., and Loos, W.E. (1982). Wood Deterioration and Its Prevention by Preservative Treatments. 1: Degradation and Protection of Wood, Syracuse University Press. 2. print.
Not checked in the free run.
- cites [11] Freeman, 2003, Past, Present, and Future of the Wood Preservation Industry: Wood Is a Renewable Natural Resource That Typically Is Preservative Treated to Ensure Structural Integrity in Many Exterior Applications, For. Prod. J.
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
May combine two claims.
PremisecitationThe increase in CCA-treated wood volume, leaching, toxic nature of the waste, and tightening of regulations concerning its incineration are the main factors motivating development of new management methods for its disposal or recovery.
“The increase in CCA-treated wood volume, the leaching, the toxic nature of the waste, and the tightening of regulations concerning its incineration are the main factors that have motivated the development of new management methods for its disposal or recovery [6].”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [6] Coudert, L. (2013). Décontamination de Déchets de Bois Traité à Base de Composés Cuivrés En Vue de Leur Revalorisation. [Ph.D. Thesis, Université du Québec, Institut National de la Recherche Scientifique].
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationInorganic salts act as catalysts in pyrolysis reactions, which leads to increased biochar yield.
“Indeed, inorganic salts act as catalysts in pyrolysis reactions, which leads to increased biochar yield [16,17,28,39,40].”
Quote in the paperNot a substantial claim0 of 5 sources checked- cites [16] Kakitani, 2006, Designing a Purification Process for Chromium-, Copper- and Arsenic-Contaminated Wood, Waste Manag. source
- cites [17] Poletto, 2017, Preparation and Characterization of a Metal-Rich Activated Carbon from CCA-Treated Wood for CO2 Capture, Chem. Eng. J. source
- cites [28] Helsen, 1999, Low-Temperature Pyrolysis of CCA-Treated Wood: Thermogravimetric Analysis, J. Anal. Appl. Pyrolysis source
- cites [39] Fu, 2008, Understanding the Pyrolysis of CCA-Treated Wood, J. Anal. Appl. Pyrolysis source
- cites [40] Kinata, 2012, Influence of Impregnation Method on Metal Retention of CCB-Treated Wood in Slow Pyrolysis Process, J. Hazard. Mater. source
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationSadhukhan et al. found that the larger the particle size, the higher the temperature gradients, which maximizes biochar production.
“Sadhukhan et al. [34] found that the larger the particle size, the higher the temperature gradients, which maximizes biochar production.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [34] Peters, 2003, Drying and Pyrolysis of Wood Particles: Experiments and Simulation, J. Anal. Appl. Pyrolysis source
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationHeating chromium and arsenic oxides volatilizes free arsenic oxide, some of which reacts with Cr2O3 to form chromium arsenate (CrAsO4).
“Similarly, heating chromium and arsenic oxides volatilize free arsenic oxide, some of which reacts with Cr 2 O 3 to form chromium arsenate (CrAsO 4 ).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [29] Helsen, 2003, Metal Retention in the Solid Residue after Low-Temperature Pyrolysis of Chromated Copper Arsenate (CCA)-Treated Wood, Environ. Eng. Sci. source
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
InterpretationcitationThe interaction of arsenate with glucose might result in acceleration of the decomposition reaction, oxidation-reduction reactions, and formation and decomposition of arsenate esters.
“It might result in the acceleration of the decomposition reaction, oxidation-reduction reactions, and the formation and decomposition of arsenate esters [29].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [29] Helsen, 2003, Metal Retention in the Solid Residue after Low-Temperature Pyrolysis of Chromated Copper Arsenate (CCA)-Treated Wood, Environ. Eng. Sci. source
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
InterpretationreasoningThe remaining 16% of the total variation is unexplained and can be attributed to other factors and experimental errors.
“The remaining 16% of the total variation is unexplained and can be attributed to other factors and experimental errors.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
InterpretationreasoningThe initial concentration of the inorganic metals in CCA-treated wood may explain the model.
“The other factor that may explain the model is the initial concentration of the inorganic metals in CCA-treated wood.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationBiomass moisture content should not exceed 10% to not affect the quality of pyrolysis products.
“According to previous reports [50,51], biomass moisture content should not exceed 10% to not affect the quality of pyrolysis products.”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites [50] Bridgwater, 2003, Renewable Fuels and Chemicals by Thermal Processing of Biomass, Chem. Eng. J. source
- cites [51] Kim, 2012, Characterization of Pyrolytic Products Obtained from Fast Pyrolysis of Chromated Copper Arsenate (CCA)- and Alkaline Copper Quaternary Compounds (ACQ)-Treated Wood Biomasses, J. Hazard. Mater. source
Probably not a substantial claim: may not pass S3 (load-bearing).
InterpretationcitationThese low concentrations confirm the efficiency of the S/S process.
“These low concentrations confirm the efficiency of the process.”
Quote in the paperNot a substantial claimClassified as probably not a substantial claim. May combine two claims.
PremisecitationHeating copper and arsenic oxides volatilizes part of the arsenic oxide, and the remaining part reacts with copper oxide to form mixed copper arsenates (2CuO.As2O5 and Cu3(AsO4)2).
“Heating copper and arsenic oxides volatilize part of the arsenic oxide, and the remaining part reacts with copper oxide to form mixed copper arsenates (2 CuO.As 2 O 5 and Cu 3 (AsO 4 ) 2 ).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites [29] Helsen, 2003, Metal Retention in the Solid Residue after Low-Temperature Pyrolysis of Chromated Copper Arsenate (CCA)-Treated Wood, Environ. Eng. Sci. source
Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing). May combine two claims.
PremisecitationAccording to environmental regulators, solidification technology transforms hazardous waste into a homogeneous, leaching-resistant compound and, therefore, environmentally acceptable.
“According to environmental regulators, this solidification technology transforms the hazardous waste into a homogeneous, leaching-resistant compound and, therefore, environmentally acceptable [42].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [42] Spence, R.D., and Shi, C. (2019). Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes, CRC Press.
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationThe decomposition of arsenate is highly influenced by the presence of glucose.
“For instance, the decomposition of arsenate is highly influenced by the presence of glucose.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [29] Helsen, 2003, Metal Retention in the Solid Residue after Low-Temperature Pyrolysis of Chromated Copper Arsenate (CCA)-Treated Wood, Environ. Eng. Sci. source
May combine two claims.
InterpretationreasoningAt 300°C, As is reduced to arsenic trioxide, which is retained in the biochar.
“At 300 • C, As is reduced to arsenic trioxide, which is retained in the biochar.”
Quote in the paperSubstantial claimMay combine two claims.
InterpretationreasoningAt temperatures above 400°C, the arsenic compound formed is no longer stable, and total As is significantly volatilized.
“However, at temperatures above 400 • C, the compound formed is no longer stable, and total As is significantly volatilized.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing), S4 (based).
InterpretationreasoningThis high dispersion may be due to the heterogeneous nature of the shredding of the treated poles.
“This high dispersion may be due to the heterogeneous nature of the shredding of the treated poles.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationRechichi [58] found that the leaching rate of As was less than 5 mg/L when the waste was encapsulated in a mixture of aluminum sulfate, iron chloride, and calcium carbonate.
“Rechichi [58] found that the leaching rate of As was less than 5 mg/L when the waste was encapsulated in a mixture of aluminum sulfate, iron chloride, and calcium carbonate.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [58] Rechichi, D. (2002). Encapsulation of Hazardous Waste Materials. (6,399,848 B1), U.S. Patent, Available online: https://patentimages.storage.googleapis.com/10/44/c4/05a54a30064fda/US6399848.pdf.
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationBefore landfill disposal, hazardous waste must be stabilized and solidified according to the guidelines of the Government of Québec, Canada.
“Before landfill disposal, hazardous waste must be stabilized and solidified according to the guidelines of the Government of Québec, Canada [43].”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [43] (2022, July 08). Ministère de l’environnement et de la Lutte Contre les Changements Climatiques Lignes Directrices Sur La Gestion Des Matières Résiduelles et Des Sols Contaminés Traités Par Stabilisation et Solidification; Ministère de l’Environnement et de la Lutte Contre les Changements Climatiques: Québec, QC, Canada, 2021. Available online: https://www.environnement.gouv.qc.ca/matieres/mat_res/ld-gestion-matres-sols-stabilisation-solid.pdf.
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Classified as probably not a substantial claim.
Study design and conductnone givenIn this study, only one formulation was tested (80% HDPE and 20% biochar) to evaluate the potential of encapsulation in the immobilization of the three metals.
“In this study, only one formulation was tested (80% HDPE and 20% biochar) to evaluate the potential of encapsulation in the immobilization of the three metals, but further studies are needed to optimize the plastic composition and the proportions of HDPE and biochar.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).
Study design and conductreasoningThe initial concentration of metals in the wood may depend on several other factors.
“However, as mentioned previously, the initial concentration of metals in the wood may depend on several other factors.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductnone givenThe high standard deviation is related to the heterogeneity of the samples despite the use of grinding and sampling techniques.
“The high standard deviation is related to the heterogeneity of the samples despite the use of grinding and sampling techniques.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationConner and Lear [57] showed that As leaching from stabilized/solidified waste was 0.016 mg/L while leaching from untreated waste was much higher (4.20 mg/L) from contaminated soils.
“For example, Conner and Lear [57] showed that As leaching from stabilized/solidified waste was 0.016 mg/L while leaching from untreated waste was much higher (4.20 mg/L) from contaminated soils.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites [57] Conner, 1993, Treatment of Land and Arsenic Wastes at TSDFs, Pollut. Technol. Rev.
Not checked in the free run.
The paper relies on this without support.
No studies have tested the encapsulation of biochar obtained by pyrolysis of CCA-treated wood.
“However, no studies have tested the encapsulation of biochar obtained by pyrolysis of CCA-treated wood.”
The paper relies on this without support.
Most studies conducted on the pyrolysis of CCA-treated wood have been limited to the prospect of pyrolysis reactions and the volatilization profile of metals.
“In addition, most studies conducted on the pyrolysis of CCA-treated wood have been limited to the prospect of pyrolysis reactions and the volatilization profile of metals.”
The paper relies on this without support.
No studies have compared the mobility of contaminants by leaching before and after wood thermochemical conversion to determine a pathway for its recovery.
“Furthermore, no studies have compared the mobility of contaminants by leaching before and after wood thermochemical conversion to determine a pathway for its recovery.”
The paper relies on this without support.
Cr+3 is the most dominant and thermodynamically stable element under ambient redox conditions in CCA-treated wood.
“However, Cr +3 is the most dominant and thermodynamically stable element under ambient redox conditions in CCA-treated wood.”
The paper relies on this without support.
Chromium trioxide is the product of the decomposition of chromium arsenate, which volatilizes at lower temperatures than As following the formation of organochlorine compounds.
“On the other hand, chromium trioxide is the product of the decomposition of chromium arsenate, which volatilizes at lower temperatures than As following the formation of organochlorine compounds.”
The paper relies on this without support.
The stabilization process converts residual contaminants into a more chemically stable and leach-resistant form that contributes to their immobilization.
“The stabilization process converts residual contaminants into a more chemically stable and leach-resistant form that contributes to their immobilization.”
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Chromium concentration model F value disagrees with its component F values
MajorThe reported size, temperature, and interaction F values for Cr concentration, weighted by their respective 2, 2, and 4 degrees of freedom, give a model F of 5.22 rather than 22.2. This also calls the reported model fit for Cr concentration into question.
Reported 22.2 · recomputed 5.22
“| Model | 8 | 74.6 ** | 1.17 ns | 8.09 ** | 4.03 ** | 14.6 ** | 22.2 ** | 22.8 ** | 11.9 ** | 7.07 ** | 3.49 * |”
Claimed 25% biomass reduction conflicts with the maximum reported char yield
MajorA 25% reduction in biomass implies a 75% remaining biochar yield. The results instead describe yields of up to 50% at 300 °C, the temperature specified in the conclusion.
“The pyrolysis of CCA-treated wood at 300 • C with a particle size varying between 1.4 to 2 mm reduced the contaminated biomass by 25%.”
“High biochar yields (up to 50%) at a low temperature (300 • C) indicate that wood thermochemical conversion was incomplete.”
Discussion gives the wrong explained variation for chromium leaching
MinorThe discussion says the model explains 66% of variation in Cr leaching, whereas Table 4 reports an R2 of 0.76, or 76%.
“According to the regression coefficients, the established model explains 84% and 66% of the observed variation in As and Cr leaching.”
“| R 2 | | 0.97 | 0.34 | 0.78 | 0.64 | 0.87 | 0.91 | 0.91 | 0.84 | 0.76 | 0.61 |”
Retention-model R2 values disagree with Table 4
MinorThe discussion gives retention-model R2 values of 0.76 for Cr and 0.61 for Cu. Table 4 lists 0.78 and 0.64, respectively; 0.76 and 0.61 are instead its metal-leaching R2 values.
“The retention capacity of As has a lower regression coefficient (R 2 = 0.34) compared to Cr and Cu (0.76 and 0.61, respectively).”
“| R 2 | | 0.97 | 0.34 | 0.78 | 0.64 | 0.87 | 0.91 | 0.91 | 0.84 | 0.76 | 0.61 |”
Arsenic concentration model F value disagrees with its component F values
MinorFor the ANOVA in Table 4, the model F value must be the degrees-of-freedom-weighted mean of the size, temperature, and interaction F values, which share an error term. The reported component values for As concentration give 22.785, not the model's 14.6.
Reported 14.6 · recomputed 22.785
“| Model | 8 | 74.6 ** | 1.17 ns | 8.09 ** | 4.03 ** | 14.6 ** | 22.2 ** | 22.8 ** | 11.9 ** | 7.07 ** | 3.49 * |”
Arsenic leaching rises before encapsulation, contrary to the stated reduction
MinorThe text says leaching was reduced both before and after encapsulation relative to before pyrolysis. Table 5 instead shows mean arsenic leaching rising from 9.23 mg/L before pyrolysis to 25.95 mg/L before encapsulation.
“The TCLP tests show a significant reduction in As, Cr, and Cu concentrations in leaching solutions before and after encapsulation compared with their concentrations in samples before pyrolysis.”
“| Before pyrolysis | 9.23 ± 1.04 | 2.24 ± 0.27 | 13.0 ± 1.44 | | Before encapsulation | 25.95 ± 19.73 | 0.99 ± 0.84 | 9.96 ± 5.20 |”
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Understanding the pyrolysis of CCA-treated wood
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- Authors
- Gmar, M., Bouafif, H., Bouslimi, B., Braghiroli, F. L., & Koubaa, A.
- Affiliations
- Université du Québec en Abitibi-Témiscamingue (CA)
- Centre Technologique des Résidus Industriels (CA)
- Corresponding author
- Koubaa, Ahmed
- Venue
- Energies
- Publisher
- MDPI AG
- Published
- 2022-07-12
- Volume
- 15
- Issue
- 14
- Pages
- 5071
- ISSN
- 1996-1073 (ISSN-L)
- OpenAlex
- W4285030258
- Semantic Scholar
- a0971bb0b8cbc4cb82d50637640105b5e0c2aa00
- Cited by
- 8
- References
- 45
- Citations by year
- 2026: 1 · 2025: 4 · 2024: 2 · 2023: 1
- FWCI
- 0.47
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Energies (publishedVersion, cc-by)
- RePEc: Research Papers in Economics (submittedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Funders
- The Canada Research Chair Program (543210, 2016-039-C21, IT11796)
- CRIBIQ (543210, 2016-039-C21, IT11796)
- MITACS (543210, 2016-039-C21, IT11796)
- Topics
- Physical Sciences › Engineering › Biomedical Engineering › Thermochemical Biomass Conversion Processes
- Physical Sciences › Engineering › Building and Construction › Recycling and utilization of industrial and municipal waste in materials production
- Physical Sciences › Environmental Science › Water Science and Technology › Adsorption and biosorption for pollutant removal
- Keywords
- wood pyrolysis, biochar, heavy metal retention, arsenic, chromium, copper, pyrolysis temperature, particle size
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-18.
Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-18.
Cited sources are checked by gpt-6-sol.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
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