Exploring Activated Carbons for Sustainable Biogas Upgrading: A Comprehensive Review
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe present contribution is a comprehensive review on the recent advances on the design and tuning of carbonaceous materials, particularly activated carbons and biocarbons, to evaluate some important techno-economic aspects of the adsorption behavior for the biogas (CO2/CH4 mixtures) separation. This work also explores future research on the design, selection and optimization of new materials and process in order to attain more efficient, cost-effective and climate-relevant biogas upgrading systems.
Author Response
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Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis quality of this review is too poor. I am not optimistic that this review can be accepted on the current state. Reject is suggested.
Main issues:
1. It lacks of Figures, Tables and Schemes in the text.
2. The source of Activated Carbon need be described.
3. The relationship about structure-function of Activated Carbons are not well clarified and discussed.
4. The role of adsorbent textural and chemical properties on gas adsorption behavior need be illustrated in Schemes or Figures.
5. The advantage and disadvantage of Activated Carbons need be well illustrated by comparing with other materials.
6. The prospects of this topic need be well discussed.
7. This review is not well organized. The authors should read some related reviews to improve the quality of this review.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThis review paper submitted by Peredo-Mancilla et al. focuses on the critical role of activated carbons in the purification of biogas to biomethane. It emphasizes the urgency of transitioning to renewable energy sources like biofuels to mitigate climate change, addresses the efficiency of activated carbons on carbon dioxide adsorptive separation for biogas upgrading, and highlighting biomethane as a clean energy alternative that also aids in waste valorization and greenhouse gas emission reduction.
Additionally, authors addressed the important factors in terms of the gas sorption properties including textural properties, surface areas, pore volumes, pore size distributions, as well as total pore volume, providing additional guidance for the characterization of the materials, highlighting the significance of the structural-property relationships from the materials design perspective.
A few details could be added to make the current manuscript better:
- The long-term stability and regeneration efficiency of modified ACs under realistic biogas conditions.
- While different characterization methods have been provided, the lack of details as well as standardized testing protocols for evaluating AC performance for biogas upgrading should be elaborated.
- In Section 3, a Table summarizing all the state-of-the-art ACs mentioned in the manuscript can be provided for better comparison of such materials.
Author Response
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Reviewer 4 Report
Comments and Suggestions for AuthorsSome references are not in the list (e.g. Saadi, Prauncher....).
There isn't any structure on section 3. It looks like they review activation processes. While they state that "The present review offers a comprehensive analysis on the factors that influence the efficiency of activated carbons on carbon dioxide adsorption and separation for biogas upgrading. The influence of activation methods, activation conditions and precursors on the biogas adsorption performance of activated carbons is revised" the performance of the materials is missing in most cases.
Author Response
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Author Response File: Author Response.pdf
Reviewer 5 Report
Comments and Suggestions for Authors1) In the abstract, the statement "research gaps in industrial transferability of the are also identified" is ambiguous. Please correct it. Also, there is no section in the body of the manuscript on this statement. Please add some relevant studies and explain them.
2) Avoid this format for references: [5], [6], [7], [8], [9], [10]. Add the quantitative parameters here to explore how the factors are affecting composition. Similarly, [7], [8], [9], [10], [11], [12], [13]. Please check the complete manuscript to avoid this type of reference.
3) Add the text in the background and body of the manuscript to compare the role of activated carbon with MOFs and polymers for CO₂ capture. Read these papers and add the comparison.
https://doi.org/10.1016/j.mtsust.2024.100879
https://doi.org/10.1016/j.solidstatesciences.2025.107855
4) For adsorbent performance, the properties including textural properties (specific surface area, pore size distribution), surface chemistry, stability, and regeneration have a direct link, so provide some latest studies on them with figures and tables.
5) Add a summary of section 2 at the end.
6) Similarly, for section 3, add figures and tables of the latest studies and compare them.
7) Divide section 3 into subsections for clear flow.
8) Add the summary at the end of section 3.
9) Add suggestions and future prospects before the conclusion.
10) Merge the conclusion into one paragraph and add the main quantitative findings rather than the general statements.
Comments on the Quality of English Language
The English language must be improved before acceptance.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors have good attitue to revise this manuscript. Its quality has significant improvement. I think this revised version can be accepted as it is.
Reviewer 4 Report
Comments and Suggestions for AuthorsI think this manuscript is now ready to be accepted
