Sequential Oxidation on Wood and Its Application in Pb²⁺ Removal from Contaminated Water

Round 1

Reviewer 1 Report

A green technology to remove toxic metal ion from water. The manuscript is well written and supported by good data. However, few points need to be revised to further improve the manuscript.

1. It has been mentioned ''we assume that the increase in carboxylate content and reduction in crystallinity in TCC''. It has been justified by WAXD-analysis. I would also like to consider DSC analysis to further evaluate the crystallinity.
2. Figure 1. Structure of (i) 6CC, (ii) TCC., please also mark in figure (i) and (ii).
3. Figure 2. (i) FTIR of wood, 6CC and TCC; this figure has been missed. 

Author Response

Green technology to remove toxic metal ions from water. The manuscript is well written and supported by good data. However, few points need to be revised to further improve the manuscript.

Comment 1: It has been mentioned ''we assume that the increase in carboxylate content and reduction in crystallinity in TCC''. It has been justified by WAXD-analysis. I would also like to consider DSC analysis to further evaluate the crystallinity.

Answer 1: Authors are thankful for this comment. Currently, the DSC facility at our department is down. Due to time constraints, we are so sorry that we cannot able to run the DSC measurements for the sample but in the future, we would include this measurement.

Comment 2. Figure 1. Structure of (i) 6CC, (ii) TCC., please also mark in figure (i) and (ii).

Answer 2. The figure numbering has been included.

Comment 3. (i) FTIR of wood, 6CC, and TCC; this figure has been missed. 

Answer 3.  The authors are sorry about this mistake. The FTIR figure has been added to the text.

Reviewer 2 Report

The manuscript submitted by Priyanka R. Sharma and co-workers is focused on the use of wood from the removal of Pb from contaminated Water. The work is too preliminary and many sentences too speculative. In fact, the title could confuse the reader because authors are not working with contaminated water (it could be one of the potential applications, but this is not explored in this research). Details about potential applications of this apporach must be added and compared with other similar approaches already described.

English must be revised. Not only the format but also the content of several sections is below the standards expected for a scientific manuscript.

Comments have been embedded through the MS to help the authors to improve this work. I hope you find them useful.

Comments for author File: Comments.pdf

Author Response

Comment 1. The manuscript submitted by Priyanka R. Sharma and co-workers is focused on the use of wood from the removal of Pb from contaminated Water. The work is too preliminary and many sentences too speculative. In fact, the title could confuse the reader because authors are not working with contaminated water (it could be one of the potential applications, but this is not explored in this research). Details about potential applications of this approach must be added and compared with other similar approaches already described.

Answer 1. We appreciate the reviewer’s thoughts. We have revised the manuscript based on reviewers’ comments.

We have changed the title to “ Sequential Oxidation on Wood and its Application in Pb²⁺ Removal from Water ”

Comment 2. English must be revised. Not only the format but also the content of several sections is below the standards expected for a scientific manuscript.

Comments have been embedded through the MS to help the authors to improve this work. I hope you find them useful.

Answer 2. The manuscript has been revised thoroughly. The answers to the comments made on MS are as follows:

(1) The reference format has been updated.

(2) The abstract has been revised and added conclusion of the work.

(3) Page 1, line 25: The tense was changed to fit the recommendation of the reviewer.

(4) Page 2, line 60: The sentence has been changed to “there have been few reports”

(5)  Page 2, line 71: We have added Material and Methods Sections.

(6)  Page 4, line 161: We agree with the reviewer’s comments that this structure is well reported in the literature. However, the authors would like to keep this structure in the text in order to provide easy reading to the viewers who are not closely related to this field.

(7) Page 5, line 204: We have performed (~20 runs) for each sample. We have included this information in the text.

(8) Page 8, line 252-253: We fully agree with the statement by reviewers. However, due to time constraints, it is difficult for us to record more AFM images. We hope that the reviewer will understand our situation.

(9) Page 8, line 252: Based on the reviewer’s comments, we have removed the speculated sentence “It means one of the phenomena during the remediation of Pb²⁺ ions using 6CC and TCC involves crosslinking (gelation).”

(9) Page 9, line 282, Table 1: The concentration of fibers used in the experiments were used from the single stock as well the standard variation for this is very very low (~0.0001). Therefore, the authors have not added this information to the table.

(10) Page 10, line 292, Figure 7(i): The error bar has been added. Figure7(i) is now Figure7(ii).

Reviewer 3 Report

The manuscript “Sequential Oxidation on Wood and its Application in Pb2+ Removal from Contaminated Water” describes the synthesis of 2,3,6-tricarboxycellulose nanofibers and their examination for model wastewater treatment from Pb(II) ions. The quality of proposed method of wood oxidation for cellulose modification is interesting and has some novelty, bur the adsorption section must be fully revised.

Main comments:

• 7(ii) is wrong and cannot be use for Langmuir isotherm building (doi:10.1016/j.cej.2009.09.013). As well as R² 0.7663 is too low for calculation of Langmuir parameters (doi.org/10.1016/j.chemphys.2018.06.022).
• Isotherms of Pb(II) ions adsorption has to provide for evaluation the maximum adsorption capacity.
• Adsorption capacity in Table 1 must be recalculated, the qe 5000 mg/g is not correct. Also, this value is not corresponding with EDS data for content of Pb in spent adsorbent.
• The pH of model solution and pHzpc have essential role in the adsorbent performance (doi:10.1016/j.cis.2012.01.005). This information has to provide in manuscript.
• The possibility of adsorbents regeneration for their multiply use is important characteristic for real adsorbent application.
• 5 is insufficient and non-informative for describing of adsorption results.
• The high effective composite adsorbents (https://doi.org/10.1080/10643389.2019.1607442, https://doi.org/10.1016/j.carbpol.2019.01.045, https://doi.org/10.1016/j.seppur.2016.11.040) should be compared with obtained nanofibers.

Author Response

The manuscript “Sequential Oxidation on Wood and its Application in Pb2+ Removal from Contaminated Water” describes the synthesis of 2,3,6-tricarboxycellulose nanofibers and their examination for model wastewater treatment from Pb(II) ions. The quality of proposed method of wood oxidation for cellulose modification is interesting and has some novelty, bur the adsorption section must be fully revised.

Additional comments:

1. 7(ii) is wrong and cannot be used for the Langmuir isotherm building (doi:10.1016/j.cej.2009.09.013). As well as R² 0.7663 is too low for calculation of Langmuir parameters (doi.org/10.1016/j.chemphys.2018.06.022).

Answer. Thank you so much for this comment. The figure and corresponding text in the manuscript have been revised.

2. Isotherms of Pb(II) ions adsorption has to provide for evaluation the maximum adsorption capacity.

Answer. In this study, we have provided the Langmuir Isotherm curve (revised) to evaluate the maximum adsorption capacity. 

3. Adsorption capacity in Table 1 must be recalculated, the qe 5000 mg/g is not correct. Also, this value is not corresponding with EDS data for content of Pb in spent adsorbent.

Answer. We have revised the calculation and made the necessary changes in the manuscript. The adsorption capacity obtained for TCC is 1569 mg/g. The quantitative estimation of this value is very difficult because EDS generally performs on a very small diameter of the sample.

4. The pH of model solution and pHzpc have essential role in the adsorbent performance (doi:10.1016/j.cis.2012.01.005). This information has to provide in manuscript.

Answer: Authors focused was to synthesize successfully the TCC substrate using the new Nitro-oxidation approach. Hence, the authors have not included this study in the presented project. However, in future, we will consider doing the pH study.

5. The possibility of adsorbents regeneration for their multiply use is important characteristic for real adsorbent application.

Answer: Authors focused was to synthesize successfully the TCC substrate using the new Nitro-oxidation approach hence, the authors have not included this study in the presented project. However, in future, we will consider doing the pH study.

 6. 5 is insufficient and non-informative for describing of adsorption results.

Answer: Figure 5 was added to demonstrate the physical changes that happened during the adsorption experiments.

 7. The high effective composite adsorbents (https://doi.org/10.1080/10643389.2019.1607442, https://doi.org/10.1016/j.carbpol.2019.01.045, https://doi.org/10.1016/j.seppur.2016.11.040) should be compared with obtained nanofibers.

Answer: We have added the description for the adsorbents mentioned in the references in the text.

Reviewer 4 Report

Dear Authors,

This manuscript requires a major revision.

I yellow highlighted some suggestions/ corrections in the manuscript (see attachment).

Briefly, I suggested in the manuscript, the following:

• Extensive English language revision. Many sentences must be reformulated. I yellow highlighted many misspelled words.
• Line 8: Insert abbreviation TCC.
• All the abbreviations must be detailed in text.
• It would be very suggestive to insert preparation schemes in the sections: 2.1; 2.2; 2.3.
• Latin words and names such as "via" must be written in italics: via.
• Authors must insert “i” and “ii” on the Figures 1.
• Figure 2(i) is missing!
• Authors confused Figure 1 (i) with Figure 2(i) which is missing.
• Figure 7 is not commented in the text.
• The section References must be revised!!! Check all the references! The Journal names and volumes are missing, etc.

• Authors must respect the format of the Journal!

Comments for author File: Comments.pdf

Author Response

Extensive English language revision. Many sentences must be reformulated. I yellow highlighted many misspelled words.

Answer: The manuscript has been thoroughly revised.

Additional comments from the attached PDF:

1. Page 1, line 8: Abbreviation for TCC added in per remark.
2. Page 2, line 77: We have a scheme for the preparation of TCC in Supplementary Information in Figure S4.
3. Page 2, line 80: We have now corrected ‘via’ in italics.
4. Page 2, line 90: same as the response to comment 2
5. Page 3, line 97: same as the response to comment 3
6. Page 3, line 102: same as the response to comment 2
7. Page 3, line 105: same as the response to comment 3
8. Page 3, line 109: same as the response to comment 3
9. Page 4, line 146: (i) and (ii): We have added Figure 1(iii) FTIR of wood, 6CC, and TCC.
10. Page 4, line 150: The word has been changed as per reviewer comment.
11. Page 4, line 154: The word shaper has been corrected to sharper.
12. Page 4, line 156: The grammatical error has been fixed.
13. Page 4, line 157: The superscript has been fixed.
14. Page 4, line 157: Wording of the sentence was adjusted to be more grammatically correct.
15. Page 4, line 177: (i) and (ii) have been added to Figure 1.
16. Page 4, line 179: The grammatical error has been fixed.
17. Page 5, line 183: The FTIR spectra of raw wood, 6CC, and TCC is now added as Figure 2(i).
18. Page 5, line 204: The FTIR spectra of raw wood, 6CC, and TCC is now added as Figure 2(i).
19. Page 5, line 207: The tense of the word was fixed to be grammatically correct.
20. Page 5, line 211: The grammatical error was fixed.
21. Page 5, lines 212-214: The sentence in question has been rewritten to be more grammatically correct.
22. Page 6, line 224: The grammatical error was fixed.
23. Page 6, line 225: A comma was inserted before ‘respectfully’ in order to be grammatically correct.
24. Page 7, line 229: We have inserted ‘and’ into the figure title.
25. Page 8, lines 252-254: We have removed the sentence” It means one of the phenomena during the remediation of Pb2+ 253 ions using 6CC and TCC involves crosslinking (gelation)” to avoid the speculated explanation.
26. Page 8, line 264: We have corrected the sentence.
27. Page 8, line 272: Wording changed to be consistent with the wording of the table.
28. Page 8, line 276: This sentence as well as the following sentence has been restructured to be more grammatically correct.
29. Page 10, line 292: The explanation for Figure 7(i) has been added on Page 9, line 282.
30. Page 10, line 296: Abbreviation for NOCNF has been defined.
31. Page 10, line 298: Extra parenthesis is taken out.
32. Page 10, line 300: Extra parenthesis is taken out.
33. Page 11, line 318: The sentence has been reworded to be more grammatically correct.
34. Page 11, line 320-322: The spacing of the paragraph has been readjusted.
35. Page 11, Line 333: References have been updated to be in accordance with MDPI standards.

Round 2

Reviewer 2 Report

Thank you very much for your time and effort addressing the comments made by this reviewer.

Author Response

Thank you so much for your valuable comments. We have now revised the minor English corrections (e.g., spacing, words, sentence)  in the text.

Reviewer 3 Report

The manuscript could be recommended for the publication.

Author Response

Thank you so much for your valuable comments.

Reviewer 4 Report

 Dear Authors,

There are some problems with this article:

1) The authors did not make all the suggested corrections (see the yellow highlighted words/numbers etc. in the attached manuscript):

• Latin words and names such as "via" must be written in italics: via.
• The section References must be revised!!! Check all the references! The Journal names and volumes are missing, etc.
• Figure 2 i) is missing!!!

2) The authors replaced several numerical values in the text (see Lines 18; 329; 330; 381; 391). The authors are undecided. What are the correct values?

3) Authors added other Figures in Fig.7. There are 2 Figures 7i) and 2 Figures 7 ii). The authors must choose only one figure i) and one figure ii)!

4) Figure 2 i) is missing!

Comments for author File: Comments.pdf

Author Response

We are thankful to the reviewer for the careful evaluation of the manuscript. We have revised the manuscript accordingly. The point by point answers to the comments as follows:

1) The authors did not make all the suggested corrections (see the yellow highlighted words/numbers etc. in the attached manuscript):

• Latin words and names such as "via" must be written in italics: via.
• The section References must be revised!!! Check all the references! The Journal names and volumes are missing, etc.
• Figure 2 i) is missing!!!

Answers:

• We have now corrected the Latin words into italics.
• The references have been revised (ref no. 48, 3, 13, 19, 50, 51,42, 38,25,26)
• Figure 2(i) has been added.

2) The authors replaced several numerical values in the text (see Lines 18; 329; 330; 381; 391). The authors are undecided. What are the correct values?

Answer: To address another reviewer’s comment in the first round of revision. We have revised Figure 7(i) which represents Langmuir Fitting Curve. After doing that the associated values changed. We have used the corrected values now in the manuscript. The following sentence in the manuscript describes the corrected values. “Based on the Langmuir isotherm model, the coefficient of the LSRL of Ce against Ce/Qe is 6.37316E-4 as the reciprocal of the adsorption capacity. Thus, the adsorption capacity (Qm) obtained for TCC was 1569 mg/g with R² 0.69531”.

3) Authors added other Figures in Fig.7. There are 2 Figures 7i) and 2 Figures 7 ii). The authors must choose only one figure i) and one figure ii)!

Answer: Figure 7(i) shows Langmuir Fitting Curve, Figure 7(ii) presents adsorption efficiency. We have revised the numbering in the main text (line no. 286). The manuscript has now one Figure 7(i) and one Figure 7(ii).

4) Figure 2 i) is missing!

Answer: Figure 2(i) has been added into the text.

Round 3

Reviewer 4 Report

The manuscript was improved.

My recommendation: Accept in the present form.

Author Response

Thank you so much for your acceptance.