Catalytic Ozonation of Atrazine Enhanced by Mesoporous CeO₂: Morphology, Performance and Intermediates

Round 1

Reviewer 1 Report

The paper focus on Lab-scale experimental studies of catalytic ozonation of atrazine with using mesoporous CeO2 as catalyst. Several catalytic characterizations (SEM, TEM, BET) were done

 In general, the results mostly support the authors' conclusions. However, some aspects of the manuscript must be carefully reviewed, discussed and improved.

1°) The originality, mechanism, and scientific reliability of the work are unclear. In my opinion, there are some major points that the authors should address before it is accepted for publication.

2°) Why do authors study the removal of these compound: atrazine? Authors must indicate why the removal of this compound could be interesting and also the effect of intermediates by-products on the process performance. 

4°) What is the distance between catalyst and inner tube? Please reconsider the explanation and give a detailed dimensions of reactor ?

5°) There are many research on direct and indirect of wastewater (plasma or ozonation) combined with catalysis such this reference (Journal of Water Process Engineering 38, 101664 (2020)). This data must be added to manuscript introduction in order to be more correct

6°) Eq. 6- 8 (page 6/10) Please give more description about the contribution of reactive species  (OH°; O2°-; O°) (pH effect)

7°) Give the exact equation to determinate the equation to determinate the ozone concentration in water

 8°) at any moment the authors discussed the results of TOC removal (mineralization).

Author Response

Thank you for your comments concerning our manuscript. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to your comments are in the word.

Author Response File: Author Response.pdf

Reviewer 2 Report

In this manuscript, Zhang et al. discussed the synthesis of mesoporous CeO2 using a template method and investigated its catalytic performance toward the ozonation of atrazine. A significant catalytic enhancement was found relative to a commercial control sample, and the enhancement was found to be attributed to the high surface area, well ordered mesoporous structure, and redox Ce3+/Ce4+ couple. Overall, this work was well organized and presented and appeals to the readership of Water. This reviewer recommends its publication after the below minor points are properly addressed.

1. In Table S1, the authors compared the BET surface area of synthetic CeO2 with other materials reported in previous literature. How is the catalytic performance of the synthetic CeO2 when compared with other reported catalysts?

2. The authors analysed the XPS data of O1s, but did not make discussion about oxygen vacancy (yet, oxygen vacancy was somehow claimed to be relevant to catalysis).

3. The authors started the Introduction section with a direct background introduction of atrazine. To appeal to a broader readership of the journal Water, it is suggested to include some more background info about water treatment and/or heterogeneous catalysis. Recent works related to this are suggested to be referenced in the Introduction (e.g., ACS Sustainable Chem. Eng. 2022, 10, 1899-1909; Trends in Chemistry, 2019, 1, 410-424).

4. Third paragraph of Introduction, when mentioning other researchers’ work, only their surnames need to be provided rather than the full names.

5. Line 115, “Twice samples were repeated at each experiment.” Please clarify what is “twice samples”.

6. Line 145, the unit of wavelength should be provided.

7. Table S1, column name “BET” should be revised into “BET surface area”.

8. Please give definition of dXRD in Equation 1.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

This paper describes the synthesis of CeO2 and its application in the ozonation of Atrazine. There are the following concerns. The authors also described the morphologies, plausible mechanisms, and intermediates in this study.

1.        The results and authors` claims are not supported well with the evidences.

2.        The main reason for rejection is that the presence of Ce3+ among Ce4+ is not convincing. Ce3+could be produced during ozonation reaction but a simply prepared CeO2cannot show described the amount of Ce3+. The author’s claim is subject to doubt.

3.        Another reason for rejection is that if the presence of Ce3+/Ce4+ is the reason for the higher degradation efficiency of prepared CeO2 then why commercially available CeO2 with a comparable higher Ce3+/Ce4+ ratio showed a much lower efficiency of 46.4%. The results are not convincing based on the provided evidences.

4.        There are many typo errors and grammar mistakes. The manuscript should be revised for these mistakes.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Authors have addressed all my points. The Ms has improved a lot, very interesting paper actually. I can recommend the Ms for publication now.

Author Response

Thank you again for your guidance and suggestions!

Reviewer 3 Report

The authors revised the manuscript well.

The authors should add more details on the role of various factors including Ce3+/Ce4+ ratio, surface area, etc. in detail for the readers to get a clear understanding.

Author Response

Please see the attachment

Author Response File: Author Response.pdf