Accelerating Electricity Generation and Cr (VI) Removal Using Anatase–Biochar-Modified Cathode Microbial Fuel Cells
Round 1
Reviewer 1 Report
The topic addressed is of great relevance, especially in the area of energy production.
Below are some suggestions:
1. In the introduction section, the references discussed need improvement. I suggest adding more references. In order to highlight the contributions of your work, it would be interesting to place a table highlighting the advantages and disadvantages of each revised work, including the proposal that the authors are bringing.
2. In the results and discussion section, the figures need to have more analysis on the interpretation of numerical results.
3. Finally, the reviewer considers that after (or in the same) section of the conclusions, the authors should highlight the limitations of the proposal, as well as future work in this line of research.
Author Response
1#
The topic addressed is of great relevance, especially in the area of energy production.
Below are some suggestions:
Thank you for your careful and timely review of our manuscript, your meticulous scrutiny of the details is admirable. Your comments make the details of our manuscript more perfect and make our article more logical. Here, we have seriously revised your comments point-by-point, and the modified parts are marked in red font so that you can check them easily and fast. Thanks again.
- In the introduction section, the references discussed need improvement. I suggest adding more references. In order to highlight the contributions of your work, it would be interesting to place a table highlighting the advantages and disadvantages of each revised work, including the proposal that the authors are bringing.
Response: We gratefully apricated for your suggestion. According to your suggestion, we have added more references in the introduction. Modification details are as follows:
Line 34: Environmental pollution and energy shortage are common challenges facing the whole world (Ombaka et al., 2022; AlSalka et al., 2023). Notably, the pollutants are mainly divided into organic pollutants and heavy metal (Gao et al., 2022).
Line 43: Microbial fuel cells (MFC) are specialized devices that utilize electroactive microorganisms to convert organic compounds into electricity. As a novel type of bioelectrochemical system, MFCs exhibit great potential for the degradation of heavy metal pollution (Mian et al., 2019).
Line 49: Therefore, researchers have been looking for suitable approaches to improve the performance of MFC (Badi et al., 2022). Among several improvement methods, using highly efficient electrode catalytic materials has always been one of the research hotspots [10,11, Rahman et al., 2023]. The researchers loaded CNT/NiCoAl-LDH on the substrate of stainless-steel mesh for the cathode of MFC. The voltage reached 450 mV, and the maximum power density was 433.5 ± 14.8 mW/m2 (Chen et al., 2021).
Line 59: In ethanol fuel cell, Pt/Ru-Sn oxide /C catalyst effectively enhances the current and power density of the cell (Chen et al., 2018). Furthermore, by thermal decomposition of Ru-Sn mixed oxide and adsorption of Pt nanoparticles, the anode catalyst with strong low potential activity was prepared. Its battery voltage is up to 0.3 V-0.5 V (Huang et al., 2020).
TiO2 itself has electrochemical properties that can enhance the catalytic activity of oxygen reduction reactions, and it can also transport electrons (Zlámalová et al., 2022).
- In the results and discussion section, the figures need to have more analysis on the interpretation of numerical results.
Response: Thank you very much for your valuable suggestion. Your comments have been very constructive for further refining our manuscript. According to your suggestion, we added the explanation of the numerical results in the results and discussion section. The details are as follows：
Line 231: This result is originally attributed to biochar supported anatase composites with rich functional groups on the surface, which have good electron transport ability (Qu et al., 2023; Li et ai., 2020)
Line 258: Notably, the oxygen reduction reaction process on the MFC cathode is slow, and efficient electrode catalysts help to accelerate the reaction process, thereby improving battery performance (Singh et al., 2019). Furthermore, the combination of biochar and TiO2 can effectively solve the problem of easy recombination of holes and electrons, so as to improve the electrical production performance of MFC (Feng et al., 2018).
Line 292: Notably, compared with previous studies, the degradation rate of Cr (VI) increased by 11.85% (Juliastuti et al., 2019). In addition, Cr (VI) acts as an electron acceptor in the cathode. And the higher the electron transfer efficiency of the MFC system, the faster the removal rate of Cr (VI) (Zhao et al., 2023).
Line 378: Moreover, the acidity of the solution affects the surface charge of the adsorbent, and the surface of the electrode catalyst in Cr (VI) solution tends to be positively charged under acidic conditions. This is conducive to improving the electron transfer efficiency of the system, which accelerates the degradation of Cr (VI) (Putra et al., 2022).
- Finally, the reviewer considers that after (or in the same) section of the conclusions, the authors should highlight the limitations of the proposal, as well as future work in this line of research.
Response: Thanks for your professional guidance, and this is a very meaningful suggestion to consider. According to your suggestion, we have added the limitations of our work and future research goals to the conclusion. Thank you again for your valuable comments. Modification details are as follows: At present, the low degradation efficiency of high concentration Cr (â…¥) is a bottleneck of Ana-B MFC. Considering that Ana-B is a photocatalyst, further use of Ana-B as a photocatalytic material for the cathode will be the target of our next research.
Thanks a lot.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The article is devoted to the development of microbial fuel cell technology. At the moment, this scientific direction is actual. I consider that the manuscript reflects new data in the area to improve this approach.
1) In the introduction section the relevance and work scope of other groups are briefly described. The description of the current research in this area should be significantly expanded 2) In section 2 should be added schematics of the experimental stand or methods Overall, the paper can be published after minor revision
Author Response
2#
The article is devoted to the development of microbial fuel cell technology. At the moment, this scientific direction is actual. I consider that the manuscript reflects new data in the area to improve this approach.
We gratefully thank the editor and all reviewers for their time spend making their constructive remarks and useful suggestions. We have carefully considered all comments from reviewer, which help us to improve the manuscript substantially. Here, we have seriously revised your comments point-by-point, and the modified parts are marked in red font so that you can check them easily and fast.
1) In the introduction section the relevance and work scope of other groups are briefly described. The description of the current research in this area should be significantly expanded 2) In section 2 should be added schematics of the experimental stand or methods Overall, the paper can be published after minor revision
Response: Thank you very much for your valuable advice. According to your comments, we added the description of the current research in this area. Meanwhile, we added method schematics in section 2. Thank you again for your valuable advice. Specific modification details are as follows:
Line 34: Environmental pollution and energy shortage are common challenges facing the whole world (Ombaka et al., 2022; AlSalka et al., 2023). Notably, the pollutants are mainly divided into organic pollutants and heavy metal (Gao et al., 2022).
Line 51: Among several improvement methods, using highly efficient electrode catalytic materials has always been one of the research hotspots [10,11]. The researchers loaded CNT/NiCoAl-LDH on the substrate of stainless-steel mesh for the cathode of MFC. The voltage reached 450 mV, and the maximum power density was 433.5 ± 14.8 mW/m2 (Chen et al., 2021).
Line 59: In ethanol fuel cell, Pt/Ru-Sn oxide /C catalyst effectively enhances the current and power density of the cell (Chen et al., 2018). Furthermore, by thermal decomposition of Ru-Sn mixed oxide and adsorption of Pt nanoparticles, the anode catalyst with strong low potential activity was prepared. Its battery voltage is up to 0.3 V-0.5 V (Huang et al., 2020).
It is worth noting that TiO2, as a typical semiconductor mineral, has great application potential as a cathode catalyst [18]. TiO2 itself has electrochemical properties that can enhance the catalytic activity of oxygen reduction reactions, and it can also transport electrons (Zlámalová et al., 2022). Based on the above features of TiO2, researchers have developed a one-dimensional TiO2/Fe2O3 photoanode that effectively improves MFC power generation performance.
Thanks again.
Reviewer 3 Report
Please see the attachment.
Comments for author File: Comments.pdf
Moderate editing of English language required
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
1. In the literature the authors have explained only the various process of experiments done by other researchers. The literature needs improvements explaining the important findings of the research carried out by other researchers.
2. Cite very recently published articles to give more informed and updated information on MFC and biochar application. Most preferably cite some of the articles published in Energies.
3. Last paragraph of the introduction should explain the research gap you identified in the literature review. Ans suggest your idea or methodologies you are going to adopt to fulfill the gap, which will be the novelty of your work.
4. The originality of the paper needs to be stated clearly. It is important to have sufficient results to justify the novelty of a high-quality journal paper. The Introduction should make a compelling case for why the study is useful along with a clear statement of its novelty or originality by providing relevant information and providing answers to basic questions such as: What is already known in the open literature? What is missing (i.e., research gaps)? What needs to be done, why and how? Clear statements of the novelty of the work should also appear briefly in the Abstract and Conclusions sections.
5. The Abstract should contain answers to the following questions: What problem was studied and why is it important? What methods were used? What are the important results? What conclusions can be drawn from the results? What is the novelty of the work and where does it go beyond previous efforts in the literature? Please include specific and quantitative results in your Abstract, while ensuring that it is suitable for a broad audience. References, figures, tables, equations, and abbreviations should be avoided. The background, significance, and novelty of this study should be presented in the abstract.
6. Why power density falls after 95 mA/m2 for the case of Ana-B and other trails too? A complete explanation of the trend needs to be included.
7. The manuscript lacks an explanation of why biochar is inferior in comparison to Ana-B and vice-versa.
8. Why transmissive losses were not considered in the analysis?
9. How authors confirm that the experiment is error-free? What tool or error measurement was adopted to find the accuracy?
10. The degradation rate of Ana-B, anatase, and biochar improved by 71.5%, 45.7%, and 19.4%, respectively, compared to the blank MFC. This is what everyone can understand from the figure. But, why it is so? Where is your explanation for that? Explaining the causes are called research.....understand. Add complete technical explanation to all the technical happenings.
11. Ana-B MFC has the highest reaction rate constant 0.3318±0.0116, which further 260 indicates that the system has the fastest Cr (VI) degradation rate. Why???? give an explanation with the support of literature.
12. Line 269-272 "In this study, in order to verify the different concentrations of Cr (VI) the impact on the MFC, set 10 mg/L respectively, 30 mg/L, 50 mg/L, 70 mg/L four different initial concentrations to explore the influence of different concentrations of pollutants of MFC degradation rate." Meaningless statements.
13. Line 273, "The experimental results and the corresponding degradation curve are shown in Figure 6a" - Ambiguous statement, "Which corresponding???"
14. Lines 273-290 need a clear and detailed explanation.
15. Rewrite Section 3.6 "Mechanism of Ana-B cathode catalysis". Explain why more focus was given to biochar in this analysis. However, Ana-B was earlier considered to be the best one.
A major revision is required.
English language editing is required. Moreover, many ambiguous sentences are there which need to rephrase for clarity.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 5 Report
The manuscript needs some essential revisions as below;
1. The similarity index is %37. It is very high. Especially 10% of this paper copied from another paper in mdpi. It is not ethical.
2. There is a graphical abstract and sum figures in material and method part to be improve the paper quality and readability.
3. The theory is very weak. There is need some explanation for theory.
4. The SEM and XPS results can be increased for more samples.
5. Figure 8 quality can be increased.
6. The references can be increased with more current references. And more paper can be read the increase paper quality. A few of them given below;
-Mian, M. M., Liu, G., & Fu, B. (2019). Conversion of sewage sludge into environmental catalyst and microbial fuel cell electrode material: A review. Science of The Total Environment, 666, 525-539.
Rahman, S., Al Balushi, N. J., Nayak, J. K., Al-Mamun, A., Al-Abri, M., Al Alawi, M., & Sana, A. (2023). A review on semiconductor photocathode in bio electrochemical systems: Mechanism, limitation, and environmental application. Materials Today Sustainability, 22, 100349.
Maden, T., & Åžahin, M. (2019). Modelling of The PEM Type Fuel Cells. Turk. J. Mater, 4, 1-10.
Badi, N., Theodore, A. M., Alghamdi, S. A., Al-Aoh, H. A., Lakhouit, A., Roy, A. S., ... & Ignatiev, A. (2022). Fabrication and Characterization of Flexible Solid Polymers Electrolytes for Supercapacitor Application. Polymers, 14(18), 3837.
Åžahin, M. E., Blaabjerg, F., & SangwongwanÄ°ch, A. (2021). Modelling of supercapacitor based on simplified equivalent circuit. CPSS Transactions on Power Electronics and Applications, 6(1), 31-39.
7. The typo and grammar errors must be checked.
8. If the system is compared with a model then can be more correct.
9. The paper is not seen as more related to the aim and scope of this journal.
10. The contribution of all authors must be given.
It is modarate but need to read by a professional proof reader.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Congratulations on the improvements in the manuscript. In the reviewer's opinion, the document in its current state is sufficient to be published.
In addition, the reviewer encourages the authors to continue developing their research in this area, we hope in the future to have news about more news and advances.
Author Response
Thanks a lot
Reviewer 3 Report
I would like to thank the authors for responding to the reviewer's comments and improving their manuscript
Author Response
Thanks a lot
Reviewer 4 Report
My earlier comments sl. 8, and sl. 9 are not addressed properly.
8. "Why transmissive losses were not considered in the analysis?" Add transmission loss in the manuscript results.
9. "How do authors confirm that the experiment is error-free? What tool or error measurement was adopted to find the accuracy?" Add error analysis methods and tools. Also, add the errors to the experimental results and show the error bar in the figures with upper and lower ranges.
Needs improvement
Author Response
Please check the attachment.
Author Response File: Author Response.pdf
Reviewer 5 Report
The revisions are not satisfied and the manuscript needs still some essential revisions as below;
1. The similarity index is %41 still. It is very high and not ethical.
2. The graphical abstract can be more comprehensive and must be include the chemical reactions. What is the 1000 ohm there?? Please check this papers for more details;
……..Microbial fuel cells—challenges and applications. Environmental science & technology, 40(17), 5172-5180.
……. A photovoltaic powered electrolysis converter system with maximum power point tracking control. International Journal of Hydrogen Energy, 45(16), 9293-9304.
3. The theory is very weak. There is need some explanation for theory. Chemical and mathematical part of system especially.
4. The SEM and XPS results can be increased for more samples. Not enough given results.
5. The references can be increased with more current references. And more paper can be read the increase paper quality. A few of them given previous round and seen that not all of them not read;
6. If the system compared with a model than can be more correct. Please check the MATLAB/Simulink models for fuel cells for example.
7. Abbreviations must be used more correctly. Some of them can be given a few time in title and first sentence of some parts.
8. The references must be increased and updated not given all related articles in references.
9. The organisation shame of the manuscript must be changed. There are a lot of unrequired subtitles for example.
10. There is required a table for numerical results and a compression table also need.
It can be improved.
Author Response
Please check the attachment.
Author Response File: Author Response.pdf
Round 3
Reviewer 4 Report
Accept
Moderate editing of English language required
Reviewer 5 Report
The revisions are not satisfied and the manuscript needs still some essential revisions as below;
1. The similarity index is %40 still. It is very high and not ethical.
2. The graphical abstract can be more comprehensive and must be include the chemical enthalpy reactions. Please check this papers for more details and refer them;
……..Microbial fuel cells—challenges and applications. Environmental science & technology, 40(17), 5172-5180.
……. A photovoltaic powered electrolysis converter system with maximum power point tracking control. International Journal of Hydrogen Energy, 45(16), 9293-9304.
3. The theory is very weak. There is need some explanation for theory. Chemical and mathematical part of system especially.
4. The SEM and XPS results can be increased for more samples. Not enough given results.
5. The references can be increased with more current references. And more paper can be read the increase paper quality.
6. If the system compared with a model than can be more correct. Please check the MATLAB/Simulink models for fuel cells for example.
7. The proposed table is not seen in manuscript version three.
It can be improved
