Adsorption and Photocatalytic Degradation of Methylene Blue in Carbon Nanotubes: A Review with Bibliometric Analysis

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Betancourt et al. provided a review article on the bibliometric analysis on carbon-nanotubes as photocatalysts for methylene blue dye degradation. I suggested the manuscript a revision to solve the following issues.

First, the abstract is poorly written with too many mistakes and errors in English and unsuitable usage of terms and words as I have highlighted in yellow.

Secondly, the authors should add discussion on the mechanism of carbon-nanotube as photocatalysts, why this carbon-based nanomaterials can generate photocatalytic activity, the authors should put more stress on it.

Thirdly, the current manuscript is too lengthy, some less important part should be shortened or cut and more emphasis should be put on the photocatalysis part.

Four, the authors should provide an overview of the current published review article in this theme and explain the reason for a new review manuscript.

Five, the authors should add more discussion on the relationship between adsorption and photocatalysis of carbon-nanotube at the beginning of this manuscript.

Six, some important articles should be cited,  Science China：Chemistry，2022, DOI10.1007/s11426-022-1350-1, ; Materials, 2021, 14, 5600; Materials, 2020, 13, 1734 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The abstract is poorly written with too many mistakes and errors in English and unsuitable usage of terms and words. I have highlighted the English mistakes and errors in yellow in the attached files above.

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The present manuscript reviewed the existing research studies regarding adsorption and photodegradation of methylene blue with bibliometric analysis. The title of this manuscript is “Photocatalytic degradation of methylene blue in carbon nanotubes: a critical review with bibliometric analysis,” and the content should (or I expect) be focused more on photocatalytic degradation, methylene blue, and carbon nanotubes. However, the authors focused much more on the topic of adsorption instead of photocatalytic degradation in the main text, for example, the content in the introduction (Line 379-531), results (Line 722-862), and discussion (Line 917-931) are all about adsorption. As a result, I feel that the title is misleading, and the content of this review manuscript does not fit the journal well. In addition, I think the information provided and discussed in this manuscript is too general. The current manuscript skims over the very available content (e.g., what are nanostructured materials at Line 67-105 and how to remove dye at Line 277-377) in the textbook but lacks the depth of critical analysis of the topic regarding photocatalytic degradation, methylene blue, and carbon nanotubes. I suggest the authors add more content about the photocatalytic degradation of methylene blue by carbon nanotubes and consider adding “adsorption” to the manuscript’s title. Overall, I cannot support the publication of the current version of this manuscript. I kindly suggest that the authors revise the manuscript before seeking publication. Some extra specific comments are listed as follows:

1.     Figure 11 (Line 566): I also tried to search "Photocatalysis" and "Photocatalysis and visible light" on PubMed but the number of publications does not match the data shown in this figure. Please double check.

2.     Line 575: Should be “PubMed” (not Pub Med). There are some extra typos (e.g., “(MMWCNT)” at Line 834 and “de” at Line 895) in the manuscript, the authors should double check their manuscript.

3.     Line 804: Should be “MB” (not mb). In addition, if the authors want to use MB as an abbreviation for methylene blue, please make consistency in the main text.

4.     Table 10 (Line 810): Please add a note about what is “qo” in Table 10.

5.     Section 6.5.3 (Line 863-875): The transition from adsorption to degradation is missing, which makes the reader hard to follow.

6.     Figure 22 (Line 900): The Ref. [90] does not match the Figure. Should be Ref. [91]?

 

7.     Reference [24]-[27] (Line 1060-1069): Some extra numbers in front of the authors’ name (e.g., 11, 12, 13), please delete.

Author Response

"Please see the attachment."

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I appreciate the author's effort to revise the manuscript based on my previous comments. The manuscript has improved somewhere but still has problems that must be addressed. This manuscript is overly verbose. The author should focus on the topic of this manuscript, which should be adsorption and photocatalytic degradation, methylene blue, and carbon nanotubes. The other unrelated or less related topics in the manuscript should be excluded, such as the other dyes, carbon materials, and toxicity /safety of carbon nanotubes. There is no way to include every topic in one manuscript. Second, there are still too many typos in this revised manuscript, for example, “V”an der Waals (should be “v”an), “UV(ultraviolet)” (should be ultraviolet (UV)), “pore-Volume” (should be pore-volume or Pore-Volume), “MMWCNT” (should be MWCNT) and so on. This kind of mistake indeed raises my worries about the quality of the manuscript. In addition, again in my previous comments, please consistently use abbreviations in the manuscript, especially for CNT, SWCNT, and MWCNT. Some extra specific comments are listed as follows:

Line 270-290: The author never discusses why we should be concerned about methylene blue over the other dyes.

Line 293-310: the content of section 3.2 should be moved before section 3.1.

Line 327 (Figure 3): I don’t see any value for Figure 3 (just a general idea). The authors should delete it.

Line 344 (Table 3): The authors should revise the content in Table 3 and provide the reference. Or delete it since it is just a general understanding of physical and chemical adsorption.

Line 368 (Table 4): The authors should revise the content in Table 4. The information is not correct.

Line 413: “(the search in PubMed included Books and Documents, Review, and Systematic Review)” should be moved to the method section.

Line 636 (Table 5): Table 5 should be revised. Only left the topic about methylene blue and carbon nanotubes. The first column (Keywords belonging to the articles) and the other unrelated/less-related topics should be deleted.

Line 640: The content of section 6.5 should be moved after section 6.7. In addition, the Table 6 should be revised. Again, unrelated/less-related topics should be deleted. Just left the topic about methylene blue and carbon nanotubes.

Line 676: The content of section 6.6 needs to be improved. Sections 6.6.1 and 6.6.2 review one article with one figure for each. I don’t think it is a very valuable way to review articles. Either adding more information to support your idea in kinetics or conciseing the current content.

Line 728: The Figure caption is not correct. It is not for TiO2.

Line 729: The content in section 7 Discussion

Line 798-838, the repeated information should be deleted, and just focus on your topic, which is methylene blue and carbon nanotubes.

 

Line 928-982. The content in section 7.6. (Safety and Environmental Impact), needs to be shortened. The discussion here is not directly related to this manuscript's main topic.

Author Response

Response to Reviewer 2 - Round 2

Dear Reviewer 2,

 

We would like to extend our sincere gratitude for your continued engagement with our manuscript, "Adsorption and photocatalytic degradation of methylene blue in carbon nanotubes: a review with bibliometric analysis." Your valuable feedback in the initial review greatly contributed to the enhancement of our work. We appreciate the opportunity to address your comments in this second round of review.

In this re-submission, we have incorporated your suggestions to improve the manuscript. Your insightful remarks have played an important role in improving the overall quality of our manuscript.

Below, we provide a detailed response to each of your concerns, addressing how we have addressed them in the revised version of the manuscript.

We appreciate your time and effort in reviewing our work, and we are confident that the changes made will ensure the publication of a more robust and valuable contribution to the field. Please find the detailed responses to your comments within the revised manuscript.

 

Thank you for your continued support and guidance.

 

On behalf of all authors,

 

Dr. María Luisa García-Betancourt

Centro de Investigaciones Químicas

Universidad Autónoma del Estado de Morelos

 

 

 

 

 

 

 

 

 

RESPONSES TO REVIEWER 2

 

I appreciate the author's effort to revise the manuscript based on my previous comments. The manuscript has improved somewhere but still has problems that must be addressed. This manuscript is overly verbose. The author should focus on the topic of this manuscript, which should be adsorption and photocatalytic degradation, methylene blue, and carbon nanotubes. The other unrelated or less related topics in the manuscript should be excluded, such as the other dyes, carbon materials, and toxicity /safety of carbon nanotubes. There is no way to include every topic in one manuscript.

On behalf of the co-authors, I appreciate the comments and recognition of the work carried out. In this second round we marked the modification in the manuscript in magenta color lettering.

As recommended in this part, the next sections were removed:

6. Topic related to photocatalysis of other dyes removed as suggested; 12 cites were changed for new examples of photocatalysis using methylene blue in Table 6.
7. Keywords were updated.
8. Generalization such as carbonaceous materials were adapted to the context of the manuscript.
9. Remained a section for methylene blue instead dyes.
10. Deleted the sections “Safety concerns associated with CNT use in photocatalysis”, “Adsorption of organic dyes on carbon nanotubes”, “Types of carbon nanotubes”, and “Dyes and dye removal”.
11. Discussion was resumed.
12. Figures 1 and 2 were deleted considered unnecessary.

Second, there are still too many typos in this revised manuscript, for example, “V”an der Waals (should be “v”an), “UV(ultraviolet)” (should be ultraviolet (UV)), “pore-Volume” (should be pore-volume or Pore-Volume), “MMWCNT” (should be MWCNT) and so on. This kind of mistake indeed raises my worries about the quality of the manuscript. In addition, again in my previous comments, please consistently use abbreviations in the manuscript, especially for CNT, SWCNT, and MWCNT.

Thanks for the careful revision and for the observations. The corrections were carried out. Some comments about the use of the abbreviations CNT, SWCNT, and MWCNT should be considered with respect to the monotony for the reading: i) defining by first time as CNT, SWCNT, and MWCNT without using “s”; ii) after that we may use abbreviations in the rest of the text, however the writing does not allow it, mainly when refer to them in plural, additionally, if use abbreviations after defining, the text becomes monotonous. For example, combine CNT, carbon nanotube, and carbon nanotubes may help to resolve monotony and problems of singular of plural.

Some extra specific comments are listed as follows:

We acknowledge each observation and comment. Each issue was attended.

Line 270-290: The author never discusses why we should be concerned about methylene blue over the other dyes.

We welcome the reviewer's comment on the need to explain the choice of methylene blue in this review manuscript. The omission of this context was unintentional and represents an important aspect that requires attention. Focusing on the study of methylene blue does not dismiss other dye pollutants but represents recalcitrant ones and can be chosen as model dye for the study of adsorption and photocatalytic activity of carbon nanotubes. For cover this issue, we considered some aspects of methylene blue in the introduction at the lines 42-45, 49-53, and 74-76; methylene blue section 3 at lines 287-305; and conclusion at lines 908-912.

Line 293-310: the content of section 3.2 should be moved before section 3.1.

Thanks for the observation. As suggested above, we removed all the generalization of dyes and kept a resume for methylene blue, considering justification and motivation to study methylene blue in this work, indicated in the previous issue.

Line 327 (Figure 3): I don’t see any value for Figure 3 (just a general idea). The authors should delete it.

Thanks for reading and for the observation, we deleted such figure.

Line 344 (Table 3): The authors should revise the content in Table 3 and provide the reference. Or delete it since it is just a general understanding of physical and chemical adsorption.

Thanks for the observation, such table was deleted.

Line 368 (Table 4): The authors should revise the content in Table 4. The information is not correct.

Thanks for the observation, such table was deleted because it didn’t contain the information of all the isotherms; in the text it was indicated the basic models and others which could be consulted in the reference at the end of the paragraph that describes the general approaches of isotherms.

Line 413: “(the search in PubMed included Books and Documents, Review, and Systematic Review)” should be moved to the method section.

Thanks for the observation, the sentence was moved. Additionally created the section 6.4.1. Search “Photocatalysis” and “Photocatalysis and visible light” for the consistence of the bibliometric information.

Line 636 (Table 5): Table 5 should be revised. Only left the topic about methylene blue and carbon nanotubes. The first column (Keywords belonging to the articles) and the other unrelated/less-related topics should be deleted.

We acknowledge this improvement for the presentation of the data which was updated. We kept information only for carbon nanotubes and methylene blue.

Thanks again for the comment, the section moved after 6.7, and table 6 was also updated.

 

Line 676: The content of section 6.6 needs to be improved. Sections 6.6.1 and 6.6.2 review one article with one figure for each. I don’t think it is a very valuable way to review articles. Either adding more information to support your idea in kinetics or conciseing the current content.

We acknowledge the observation. For this section, a simple rewriting, resalting the physicochemical interaction of methylene blue with carbon nanotubes, was done. And removed at the section “4.2. Kinetics of adsorption” after the resume of isotherms model.

Line 728: The Figure caption is not correct. It is not for TiO2.

Thanks for the observation, the caption was corrected.

Line 729: The content in section 7 Discussion

Line 798-838, the repeated information should be deleted, and just focus on your topic, which is methylene blue and carbon nanotubes.

Thanks for your valuable feedback. We resumed the section, and deleted the information which is not relevant to methylene blue and carbon nanotubes.

Line 928-982. The content in section 7.6. (Safety and Environmental Impact), needs to be shortened. The discussion here is not directly related to this manuscript's main topic.

Thanks for the recommendation. The section was shortened and placed together with future directions.