PONE-D-25-01514Impacts of the quinone-functionalized biochar on anaerobic digestion: Beyond the redox property of biocharPLOS ONE

Dear Dr. Jiang,

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PLOS ONE

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“Suqian Sci&Tech Program (Grant NO. K202333), Scientific Research Foundation of Suqian University (NO.106-CK00042/060)”

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“The preparation of algal biochar and anaerobic digestion test were performed at Jiangsu key laboratory of anaerobic biotechnology, Jiangnan University. This study was financially supported by Suqian Sci&Tech Program (Grant NO. K202333), Scientific Research Foundation of Suqian University (NO.106-CK00042/060). “

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The manuscript demonstrates a highly relevant issue related to attempts of intensification of biogas production using engineered biochar. It was hypothesized that quinone functional groups could intensify methane production due to increase of redox potential of biochar. Results showed opposite influence on the overall methane production meaning its inhibition, but acidogenesis rate was improved. Previous results were presented in the Introduction section including the description of knowledge gaps. Detailed protocols and methods for chemical analysis and measurements are presented as supporting information online. Details of the methodology are sufficient to allow the experiments to be reproduced. Units of measurement were clearly defined in all tables and figures. P-values were reported for parameters of electron capacity of different types of biochar (p < 0.01). Displaying data in plots is sufficient.

At the same time, I came up with some major and minor concerns.

1. Section Introduction is well-designed for reader without specific knowledge in this area, but statement of hypothesis is lack.

2. Authors claimed accepting of PLOS’s Data Availability policy, but I could find dataset of experiment’s results in SI, and original data are not deposited in appropriate repositories.

3. Section Materials and Methods was very well described, but a paragraph about Statistical analysis should be developed. It is not clear from the text which measures of variance (standard deviation, standard error of the mean, confidence intervals) and central tendency (mean, median) were being presented.

4. Presented results related to biochar properties and methane production are relevant and important, but no regression analyses or relationships between those parameters were found.

5. There is a lack of argumentation and discussion about the choice of substrate for biochar production and its ecological safety due to waste origin and probability of containing some pollutants (line76).

6. The number of samples for analysis was not found in the manuscript.

7. It was stated that glucose served as the sole carbon source for the anaerobic digestion test to avoid possible interference from substrates (line 110), but it’s not clear if the same results of methane production will be obtained in the case of real-stated biogas reactor with common substrate.

8. In the Model fitting analysis paragraph reference to SI was stated as well as series of other reports. Which reports have been meant?

9. Sections Results and Discussion are combined, but it will be easier to read manuscript if they are separated.

10. Obtained results are explained and discussed, but practical implications are lacking as well as further research due to the rejecting of initial assumptions about the influence of modified biochar on methane production.

11. The manuscript is well organized but written not enough clearly to be accessible to non-specialists.

However, the study itself shows sufficient potential that the authors are encouraged to resubmit a revised version according to mentioned comments.

Reviewer #2: In this manuscript, anthraquinone-2-sulfonate (AQS) was immobilized on algal biochar (ABC)

by surface doping method, and the impacts of the quinone-functionalization process on algal biochar for regulating methane production were investigated. Furthermore, the authors have explored the mechanisms associated with the methanogenic performances with the addition of quinone-functionalized biochar (ABC-AQS). Interestingly, the study's findings will help to clarify the purpose and importance of the quinone-functionalization process on algal biochar in controlling methane generation, which will be helpful in the development of designed biochar for real-world uses. Overall, this is a meticulous and informative work, which is a topic of interest to the researchers in the related areas. Although the work is well designed and experiments are well organized, however, some major concerns have arisen on reading the manuscript which should be addressed.

1. The abstract is not well-organized. Regarding the abstract, it should be noted that a good abstract should contain the following points:

• The state of the field and/or the gap your research is filling

• Describing what you did to develop your argument

• The summary of major findings

• The larger implications of your findings

In the abstract of the current manuscript, the authors have mainly described what they have done and the summary of their major findings. However, the other three points are missing in the current abstract. In this aspect, the abstract is not compelling. The authors are advised to organize the abstract by discussing the above-mentioned points one by one and highlight the significance/novelty of the work. Additionally, for further improvement of the Abstract reach, I suggest that you incorporate a note in your end statement, commenting on the novelty of the work.

2. In the introduction part, please include a schematic diagram in order to get an in-depth knowledge on the purpose of the current study. It will further strengthen the novelty of the current study.

3. Statistical analysis is missing in Figure 2(b) and (c). The authors are strongly recommended to include error bars in the mentioned Figures.

4. Materials and Methods: Some experimental details are missing in the current manuscript. Various techniques described as cyclic voltammetry (CV) method and X-ray diffraction measurements should be described in detail with different parameters used for the analysis. What is the concentration used for those analysis? What is the solvent used for these studies? Please mention all these things in the methods.

5. For completeness purposes, please include a comparison of the results reported in this work and others.

6. The authors are advised to briefly address the future perspectives, limitations, and drawbacks of the current study in the conclusion part. It is not necessary to go into great depth when describing the scope of future study; a rough sketch of the areas needing additional research and/or optimization should do.

7. Please provide a descriptive supporting information section in the manuscript with at least 2-3 sentences.

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Reviewer #1: No

Reviewer #2: No

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Attachments

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Submitted filename: PONE-D-25-01514_reviewer.docx

Attachment

Submitted filename: Comments.pdf

<p>Impacts of the quinone-functionalized biochar on anaerobic digestion: Beyond the redox property of biochar

PONE-D-25-01514R1

Dear Dr. Jiang,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Ivan P. Kozyatnyk, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Dear authors,

thank you for your detailed responses on each of my questions and comments.

I satisfy with answers.

Reviewer #2: The authors have addressed all the comments and revised the manuscript as suggested. Therefore, it is recommended for publication.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: Yes:  Dr. Pooja Ghosh

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