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Cited by 111Adsorption and biosorption for pollutant removalThermochemical Biomass Conversion ProcessesAdsorption, diffusion, and thermodynamic properties of materials

The DOI matches its Crossref record; 35 of the 35 references it cites were found in a registry or an index; none of the 16 sources its claims cite is checked for support yet.

Activated Carbon Produced by Pyrolysis of Waste Wood and Straw for Potential Wastewater Adsorption

Open access
Januszewicz, Katarzyna, Kazimierski, Paweł, Klein, Maciej, Kardaś, Dariusz, Łuczak, Justyna·2020·Materials
DOI 10.3390/ma13092047PMC PMC7254296
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Abstract

Pyrolysis of straw pellets and wood strips was performed in a fixed bed reactor. The chars, solid products of thermal degradation, were used as potential materials for activated carbon production. Chemical and physical activation processes were used to compare properties of the products. The chemical activation agent KOH was chosen and the physical activation was conducted with steam and carbon dioxide as oxidising gases. The effect of the activation process on the surface area, pore volume, structure and composition of the biochar was examined. The samples with the highest surface area (1349.6 and 1194.4 m2/g for straw and wood activated carbons, respectively) were obtained when the chemical activation with KOH solution was applied. The sample with the highest surface area was used as an adsorbent for model wastewater contamination removal.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

Pyrolysis of waste straw pellets and beech wood strips at 800 °C produced biochars that were activated chemically with KOH or physically with steam/CO₂. KOH activation gave the highest surface areas, and the best straw-derived activated carbon removed Rhodamine B from model aqueous solutions.

Key findings

  • Chemical activation with KOH produced the highest surface areas: 1349.6 m²/g for straw-derived activated carbon and 1194.4 m²/g for wood-derived activated carbon.
  • Physical activation with CO₂ at a 1:1 gas-to-carbon molar ratio gave lower surface areas: 682.1 m²/g and 0.35 cm³/g pore volume for straw, and 385 m²/g and 0.2 cm³/g for wood; lower gas ratios (1:0.5) gave less extended surface area.
  • Unactivated biochars had low surface areas: 3.1 m²/g for straw char and 27.3 m²/g for wood char.
  • In Rhodamine B adsorption tests using the 1349.6 m²/g straw-based activated carbon, 4.1 mg of AC decreased RhB concentration by 30%, and total removal of the model solution colour occurred when 15.3 mg AC was added.

Methods

  • Fast pyrolysis of about 100 g biomass was performed in a fixed-bed steel reactor at 800 °C for 30 min with a heating rate of 100 °C/min under limited air; char yields used were 23.8 g for straw pellets and 22.5 g for wood chips.
  • Activation methods: chemical activation with solid KOH at a 1:2 char:KOH mass ratio, heated at 850 °C for 1 h under N₂ at 50 mL/min; physical activation with steam or CO₂ at 850 °C, gas flow 10 dm³/h for 0.5 or 1 h, using biochar-to-gas molar ratios of 1:0.5 and 1:1.
  • Materials were characterised by CHNS-O analysis, thermogravimetry, moisture and calorific value analysis, BET N₂ adsorption–desorption at 77 K, and SEM; RhB adsorption was tested at 25 °C with 20 mL of 30 mg/dm³ dye solution, AC doses from 2.7 to 20.6 mg, 30 min shaking at 120 rpm, and UV-VIS at 553 nm.

Limitations

  • The paper states that in the adsorption study the authors used only one, but the most important parameter, to confirm sorption properties of the straw-derived AC; pH, temperature, ionic strength, and other solution parameters were kept constant rather than varied.
  • Evident from the text: adsorption was tested only with Rhodamine B as a model contaminant, at a single initial concentration of 30 mg/dm³, and only with the highest-surface-area straw-based KOH-activated carbon.
  • Evident from the text: no regeneration, reusability, continuous-flow, or real wastewater tests are reported, and the adsorption analysis does not include kinetic or equilibrium isotherm modelling.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3390/ma13092047

Cites

35 of 35 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 16 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Chemical activation was more effective than physical activation.

    “The results of the surface analysis revealed that the mechanism of chemical activation was more effective in comparison to the use of other activation agents.”
    • Also stated in: § 4. Conclusions · plain
      “Nevertheless, the chemical activation was more effective than the physical method.”
    Quote in the paperSubstantial claim
  • Findingown data

    The higher the amount of the activation agent, the greater is the adsorption surface.

    “Moreover, it was shown that the higher the amount of the activation agent, the greater is the adsorption surface.”
    Quote in the paperSubstantial claim
  • Findingown data

    A higher surface area was obtained when CO2 was used as an agent in comparison to steam.

    “A higher surface area was obtained when CO2 was used as an agent in comparison to steam.”
    Quote in the paperSubstantial claim
  • Findingown data

    The effectiveness of adsorption increased with increasing amounts of the activated carbon used in the experiment until the complete discoloration of the solution.

    “As expected, the effectiveness of adsorption increased with increasing amounts of the activated carbon used in the experiment until the complete discoloration of the solution.”
    Quote in the paperNot a substantial claim
  • Findingown data

    In both physical activation experiments, a lower gas (CO2 and steam) to carbon molar ratio (1:0.5) provided a less extended surface area of the final material.

    “In both experiments, a lower gas (CO2 and steam) to carbon molar ratio (1:0.5) provided a less extended surface area of the final material.”
    Quote in the paperNot a substantial claim
  • It may state two separate claims as one. 16
  • Probably not a substantial claim. 16

  • It may state two separate claims as one.

    Findingreasoning

    In biochars, relative content of hydrogen decreased and nitrogen increased up to 3.4-3.5 wt.%.

    “As a consequence of the substrate thermal decomposition, the relative content of hydrogen decreased (released in the gas phase), whereas nitrogen increased (up to 3.4–3.5 wt.%).”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    With increasing surface area, the number of single particles decreased and the surface became less frayed.

    “It was observed that with increasing surface area, the number of single particles decreased and the surface became less frayed.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data

    The highest surface area and pore volume of physically treated samples was obtained for a CO2 to carbon molar ratio of 1:1, with 682.1 m2/g and 0.35 cm3/g for straw and 385 m2/g and 0.2 cm3/g for wood.

    “The highest surface area and pore volume of the physically treated samples was obtained for a CO2 to carbon molar ratio of 1:1, with results of 682.1 m2/g: 0.35 cm3/g as determined for straw and 385 m2/g: 0.2 cm3/g for wood.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    Waste straw contained 85.6 wt.% volatiles, 6.7 wt.% moisture and 5.9 wt.% ash.

    “For comparison, waste straw contained more volatiles (85.6 wt.%) and more ash 5.9 (wt.%), but less moisture (6.7 wt.%).”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    RhB was completely adsorbed on porous material and could not be detected using UV-VIS analysis.

    “RhB was completely adsorbed on porous material and could not be detected using UV-VIS analysis.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data

    Surface area of reference biochar samples was 3.1 m2/g for straw and 27.3 m2/g for wood.

    “The surface area of these samples (reference samples shown in Table 2) was relatively low: 3.1 m2/g and 27.3 m2/g for straw and wood char, respectively.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    Straw contained 49.0 wt.% carbon, 6.9 wt.% hydrogen, 1.7 wt.% nitrogen and 36.6 wt.% oxygen.

    “According to the elemental analysis the content of carbon, hydrogen, nitrogen and oxygen in the straw was 49.0 wt.%, 6.9 wt.%, 1.7 wt.% and 36.6 wt.%, respectively.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data

    The DTG curve for wood contains a main degradation peak and a smaller one on the left side, while straw pellet degradation revealed only one main characteristic peak.

    “The main difference in both characteristics is that the derivative of mass loss (DTG) curve (Figure 3B), representing pyrolysis of the wood, contains a main degradation peak as well as a smaller one appearing on the left side (wood degrades gradually). The straw pellet degradation, in turn, revealed only one main characteristic peak.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    Elemental analysis confirmed an increase in carbon content up to 76.2 wt.% (from 49 wt.% before pyrolysis) in straw chars and 74.0 wt.% (from 45 wt.% before pyrolysis) in wood chars.

    “As expected, the elemental analysis confirmed an increase in the carbon content up to 76.2 wt.% (from 49 wt.% before pyrolysis) and 74.0 wt.% (from 45 wt.% before pyrolysis) in the straw and wood chars, respectively.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    Wood samples contained 67.9 wt.% volatiles, 8.4 wt.% moisture and 2.3 wt.% of ash.

    “The wood samples contained 67.9 wt.% volatiles, 8.4 wt.% moisture and 2.3 wt.% of ash.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data

    The maximum of the main degradation peak for wood was at 350 °C and was higher than that for straw (maximum at 300 °C).

    “However, the maximum of the main peak representing the degradation of wood was detected at 350 °C and this peak was higher than that obtained for straw (maximum at 300 °C).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    Steam or carbon dioxide used as physical activation agents penetrate solid structure, remove volatile residues and facilitate their desorption.

    “Steam or carbon dioxide used as physical activation agents, in turn, penetrate solid structure, remove volatile residues and facilitate their desorption [30].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [30] Cha, 2016, Production and utilization of biochar: A review, J. Ind. Eng. Chem. source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Study design and conductnone given

    In all RhB removal experiments, particle size, temperature, contact time (30 min), initial concentration, pH and concentration of other ions were kept constant.

    “In all experiments of the RhB removal, the particle size, temperature, contact time (30 min), initial concentration, pH and concentration of the other ions were kept constant.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim.

    Premisecitation

    The KOH dosage was chosen based on previous investigation [30] which revealed that an increase in the KOH:char mass ratio provides a higher surface area of the material.

    “The KOH dosage was chosen based on the previous investigation [30], which revealed that an increase in the KOH: char mass ratio provides a higher surface area of the material.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [30] Cha, 2016, Production and utilization of biochar: A review, J. Ind. Eng. Chem. source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    The quality and quantity of each pyrolysis product are highly influenced by the temperature of the process, residence time, heating rate, and size and shape of the biomass particles.

    “The quality and quantity of each product are highly influenced by the temperature of the process, residence time, heating rate, and size and shape of the biomass particles [6].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [6] Tripathi, 2016, Effect of process parameters on production of biochar from biomass waste through pyrolysis: A review, Renew. Sustain. Energy Rev. source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    The value of pH does not significantly affect the efficiency of dye adsorption.

    “However, the value of pH does not significantly affect the efficiency of dye adsorption.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34] Hema, 2009, Rhodamine B adsorption by activated carbon: Kinetic and equilibrium studies, Indian J. Chem. Technol.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    During pyrolysis, biomass is thermally decomposed in oxygen-depleted conditions with temperatures between 300 and 1200 °C.

    “During pyrolysis, biomass is thermally decomposed in the oxygen-depleted conditions with temperatures between 300 and 1200 °C.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [2] Sharma, 2015, Biomass pyrolysis—A review of modelling, process parameters and catalytic studies, Renew. Sustain. Energy Rev. source
    • cites [3] Pawel, 2017, Utjecaj temperature na sastav proizvoda pirolize drva, Drv. Ind.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    Activation processes increase porosity, enhance surface areas and modify chemical properties by introducing a variety of surface sites such as carboxylic, phenolic, hydroxylic and carbonyl groups.

    “Activation processes increase porosity, enhance surface areas and modify chemical properties by introducing a variety of surface sites such as carboxylic, phenolic, hydroxylic and carbonyl groups [22].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [22] Figueiredo, 1999, Modification of the surface chemistry of activated carbons, Carbon N.Y. source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    pH determines formation of various ionic species in solutions and influences surface charge of the carbon.

    “Nevertheless, pH determines formation of various ionic species in solutions and influences surface charge of the carbon [34,39].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [34] Hema, 2009, Rhodamine B adsorption by activated carbon: Kinetic and equilibrium studies, Indian J. Chem. Technol.
    • cites [39] Arivoli, 2009, Adsorption of rhodamine B by acid activated carbon-kinetic, thermodynamic and equilibrium studies, Orbital source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Thermal degradation processes, like pyrolysis or gasification, convert organic matter into gases, oils and chars.

    “Thermal degradation processes, like pyrolysis or gasification, were designed to convert the organic matter into a variety of products including gases, oils and chars [1].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [1] Zhang, 2010, Overview of recent advances in thermo-chemical conversion of biomass, Energy Convers. Manag. source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Study design and conductnone given

    In this study, authors used only one parameter to confirm sorption properties of AC obtained from straw biomass.

    “In this study authors used only one, but the most important parameter, to confirm sorption properties of AC obtained from straw biomass.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Chemical activation with KOH above 700 °C results in formation of metallic potassium which may influence the biochar structure contributing to larger specific surface area and higher volume of pores.

    “According to the literature the chemical activation with KOH above 700 °C results in formation of metallic potassium which may influence the biochar structure contributing in larger specific surface area and higher volume of pores after BET analysis.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    In similar conditions of activating the process, biomass samples prepared with NaOH had lower surface area and micropore volumes than those with KOH.

    “The comparison of two typical alkaline activation agents, KOH and NaOH, revealed that in the similar condition of activating the process the biomass samples prepared with NaOH had lower surface area and micropore volumes than those with KOH [27].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [27] Ahmadpour, 2013, Comparing the Performance of KOH with NaOH-Activated Anthracites in terms of Methane Storage, Adsorpt. Sci. Technol. source

  • Probably not a substantial claim. It may state two separate claims as one.

    Premisecitation

    Char with low commercial value formed from waste biomaterials can be activated to produce adsorbents for various industrial processes or used directly as a fuel.

    “Char with low commercial value formed from waste biomaterials can be activated to produce adsorbents for various industrial processes or used directly as a fuel [7].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [7] Ellem, 2012, Biomass char as a fuel for internal combustion engines, Asia-Pac. J. Chem. Eng. source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Chemical activation with alkaline reagents, especially KOH, is widely used, providing materials with very high surface area and defined micropore size distribution.

    “Chemical activation with alkaline reagents, especially KOH, is widely used, providing materials with very high surface area and defined micropore size distribution [25].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [25] Borhan, 2014, Characterization of activated carbon from wood sawdust prepared via chemical activation using potassium hydroxide, Adv. Mater. Res. source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    Increasing temperature and ionic strength of the solution may improve dye adsorption due to enlargement of pore size, activation of the adsorbent, and reduction of the repulsion between carbon and contaminant.

    “Additionally, increasing temperature and ionic strength of the solution may also improve the dye adsorption due to enlargement of pore size, activation of the adsorbent as well as reduction of the repulsion between carbon and contaminant [34,39].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [34] Hema, 2009, Rhodamine B adsorption by activated carbon: Kinetic and equilibrium studies, Indian J. Chem. Technol.
    • cites [39] Arivoli, 2009, Adsorption of rhodamine B by acid activated carbon-kinetic, thermodynamic and equilibrium studies, Orbital source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation

    In Poland, the overproduction of straw in relation to agricultural demand reaches about 10 million tons per year, which is equivalent to around 6 million tons of coal.

    “For example, in Poland, the overproduction of straw in relation to agricultural demand reaches about 10 million tons per year, which is equivalent to around 6 million tons of coal [33].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [33] Karcz, 2013, The feasibility of straw as a fuel source for power generating boilers, Inżynieria środowiska
27 of 27

  • The paper relies on this without support.

    Wood is composed of relatively more densely packed cells and is therefore a harder material (hardness above 500 KG/cm2).

    “Wood is composed of relatively more densely packed cells, and is therefore a harder material (hardness above 500 KG/cm2).”

  • The paper relies on this without support.

    Rhodamine B is a suitable model contaminant for wastewater adsorption.

    “In this experiment, Rhodamine B was used as a model water contaminant to observe the efficiency of the adsorption by the activated carbon.”

  • The paper relies on this without support.

    Straw pellets are a heterogeneous mixture of various waste straw, like wheat and rye, and are commonly used in Polish agriculture and commercially available.

    “Typically, the straw pellets are a heterogeneous mixture of various waste straw, like wheat and rye. This pellet is commonly used in Polish agriculture and is commercially available, therefore such biomass was chosen for the experiments.”

  • The paper relies on this without support.

    The final surface properties and functionalities of the char are determined by the nature of pyrolyzed precursors and the type of activation process.

    “The final surface properties and functionalities of the char are determined by the nature of pyrolyzed precursors and the type of activation process.”
4 of 4

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.

  • Physical-activation molar ratio is stated in opposite directions

    Major

    The methods give the 1:0.5 ratio as biochar to activating gas, while the results describe the same specified ratio as gas to carbon. Reversing a 1:0.5 ratio changes the relative amount of gas.

  • Macadamia nutshell study attributed to the wrong listed reference

    Minor

    The text attributes a macadamia nutshell activation study to reference [27], but the listed title of [27] concerns KOH- and NaOH-activated anthracites, not macadamia nutshells.

  • KOH activation described as both solution-based and solid-based

    Minor

    The abstract says the highest-surface-area samples were produced using KOH solution, but the activation procedure says the char was mixed with solid KOH before heating. Water was added only after activation.

3 of 3

Citations

Cites

Flagged first, then by citations

Research works printed but not linked: 4

  1. Pawel, 2017, Utjecaj temperature na sastav proizvoda pirolize drva, Drv. Ind., 68, 307
  2. McMillan, J.D., Adney, W.S., Mielenz, J.R., and Klasson, K.T. (2006). Applied Biochemistry and Biotechnology, Humana Press.
  3. Karcz, 2013, The feasibility of straw as a fuel source for power generating boilers, Inżynieria środowiska, XI–XII, 8
  4. Enaime, 2017, Preparation and characterization of activated carbons from olive wastes by physical and chemical activation: Application to Indigo carmine adsorption, J. Mater. Environ. Sci., 8, 4125

Cited by

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Related

Metadata

Authors
Januszewicz, K., Kazimierski, P., Klein, M., Kardaś, D., & Łuczak, J.
Affiliations
  • Gdańsk University of Technology (PL)
  • Institute of Fluid Flow-Machinery (PL)
  • Nanyang Technological University (SG)
Corresponding author
Januszewicz, Katarzyna
ORCID
Venue
Materials
Publisher
MDPI AG
Published
2020-04-27
Volume
13
Issue
9
Pages
2047
ISSN
1996-1944 (ISSN-L)
DOI
10.3390/ma13092047
PMC
PMC7254296
OpenAlex
W3017937534
Semantic Scholar
85a6d7a287800aa7b97019bfda605e2e85db8e47
Cited by
111
References
35
Citations by year
2026: 9 · 2025: 19 · 2024: 17 · 2023: 26 · 2022: 16 · 2021: 16 · 2020: 8
FWCI
5.13
Type
journal article
Language
en
Open access
Licence
Locations
  • Materials (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • DR-NTU (Nanyang Technological University) (submittedVersion, cc-by)
Topics
  • Physical Sciences › Environmental Science › Water Science and Technology › Adsorption and biosorption for pollutant removal
  • Physical Sciences › Energy › Fuel Technology › Thermochemical Biomass Conversion Processes
  • Physical Sciences › Chemistry › Physical and Theoretical Chemistry › Adsorption, diffusion, and thermodynamic properties of materials
Keywords
activated carbon, pyrolysis, wood waste, straw, biochar, chemical activation, KOH activation, physical activation, steam activation, CO2 activation, surface area, pore volume, fixed-bed reactor

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