Application of Deep Eutectic Solvents (DES) for the Synthesis of Iron Heterogeneous Catalyst: Application to Sulfamethoxazole Degradation by Advanced Oxidation Processes
Round 1
Reviewer 1 Report
The submitted work explored the heterogeneous catalyst for the degradation of antibiotic sulfamethoxazole, which was prepared by DES method. This work is attractive and provides satisfactory analysis. The results mentioned in the manuscript are clearly explained. The work that has been presented will be beneficial for widespread use in SMX degradation. The present work may be accepted after solving followed minor issues.
Reviewer comments
Ø The author expects to mention the synthesis process for the preparation of Fe-DES catalysts. A description of the reaction mechanism followed this.
Ø How did the author test the stability of the DES-based heterogeneous catalyst? It should be tested for SMX degradation on at least three separate runs. Describe the stability of catalysts using structural analysis.
Ø The structural analysis of prepared catalysts, such as XRD, TEM, and XPS, is not clearly explained. The author should deconvolve the Fe 2p and O1s XPS spectra. This most recent study will be helpful in that investigation.; doi.org/10.1021/acssuschemeng.1c05335, doi.org/10.1016/j.jallcom.2022.167168.
Ø Insert the JCPDS card in XRD patterns for each phase and index the diffraction plane.
Author Response
Reviewer 1 _____________________________________________________________
Reviewer’s comment 1:
How did the author test the stability of the DES-based heterogeneous catalyst? It should be tested for SMX degradation on at least three separate runs. Describe the stability of catalysts using structural analysis.
Authors’ answer to the comment:
Due to time limitations to answer the comments of the reviewers it was not possible to perform analysis at the university service in so short period of time.
Reviewer’s comment 2:
The structural analysis of prepared catalysts, such as XRD, TEM, and XPS, is not clearly explained. The author should deconvolve the Fe 2p and O1s XPS spectra. This most recent study will be helpful in that investigation.; doi.org/10.1021/acssuschemeng.1c05335, doi.org/10.1016/j.jallcom.2022.167168.
Authors’ answer to the comment:
Thank you for your accurate comment According to the reviewer comment the explanation was improved considering the references provided
Reviewer’s comment 3:
Insert the JCPDS card in XRD patterns for each phase and index the diffraction plane.
Authors’ answer to the comment:
Following the reviewer’s comment, the JCPDS was added to the manuscript. Moreover, a change has been made in the XRD figure, putting the data more visual, although it is still in the text.
Reviewer 2 Report
My impression is that the manuscript is not suitable for publication in Catalysts because there is a lot of important information that is unclear and the author fails to convey it clearly especially in experimental and result & discussion section.
1. Abstract: summary of the characterization and photodegradation results should be included.
2. Recheck eqn 5
3. There is only 1 catalyst was used in this manuscript. Authors should do comparison with commercial iron for characterization and degradation studies to ensure the synthesis catalyst show a good potential for this study.
4. Authors failed to discuss characterization results properly. Authors only reporting the results without proper discussion. This probably due to there is no comparison of catalysts.
5. The peaks/bands in Fig. 1 a-d should be label properly. The quality of figure need to be improved.
6. Figure 3: Why authors not just state the concentration quantitively rather than use term low, medium and high? It is confusing. Please revise.
7. Method: add the instrument use for determination of removal percentage in adsorption, degradation and electrodegradation study.
8. English of this manuscript needs to be improved; many spelling error, typing and grammatical mistakes exists in the whole paper including caption of figure.
9. Novelty of the study did not emphasize clearly in any part of manuscript.
10. Conclusion section should be rewrite by including summary of the results.
Author Response
Reviewer 2 _____________________________________________________________
Reviewer’s comment 1:
Abstract: summary of the characterization and photodegradation results should be included.
Authors’ answer to the comment:
Thank you for your comment. The abstract has been expanded with more information. However, no photodegradation is reported due to it has not been evaluated in this work.
Reviewer’s comment 2:
Recheck eqn 5
Authors’ answer to the comment:
Thank you for your comment. The authors have checked the equation as requested by the reviewer and the nomenclature for the hydroxyl radical has been changed according to the literature. E.g. http://dx.doi.org/10.1016/j.cej.2016.10.064 Eq. 50, https://doi.org/10.1016/j.seppur.2018.05.028 Eq. 4).
Reviewer’s comment 3:
There is only 1 catalyst was used in this manuscript. Authors should do comparison with commercial iron for characterization and degradation studies to ensure the synthesis catalyst show a good potential for this study.
Authors’ answer to the comment:
We agree with the reviewer and for this purpose the authors have carried out a comparison between the Fe-DES and a homogeneous test under the same conditions (0.81 mM, A-E-PMS); reaching 100% elimination in half the time. These results makes Fe-DES continue to be interesting from the point of view of all the advantages offered by the heterogeneous catalyst.
Reviewer’s comment 4:
Authors failed to discuss characterization results properly. Authors only reporting the results without proper discussion. This probably due to there is no comparison of catalysts.
Authors’ answer to the comment:
Thank you for your comment. The characterisation part has been improved and more discussion has been added in the characterization part and also suggested by reviewer 2 including new references.
Reviewer’s comment 5:
The peaks/bands in Fig. 1 a-d should be label properly. The quality of figure need to be improved.
Authors’ answer to the comment:
Following reviewer comment, a change has been made in figure 1, putting the correspondences to the peaks (FTIR, RAMAN) and codes (XRD) to be more visual, although it is still in the text. In addition, the quality of the figures has been improved.
Reviewer’s comment 6:
Figure 3: Why authors not just state the concentration quantitively rather than use term low, medium and high? It is confusing. Please revise.
Authors’ answer to the comment:
The authors considered that in order to facilitate the understanding of the conditions selected those terminology was easier to follow. However, according to the reviewer comment the authors have replaced the terms “low, medium and high” by their respective concentrations.
Reviewer’s comment 7:
Method: add the instrument use for determination of removal percentage in adsorption, degradation and electrodegradation study.
Authors’ answer to the comment:
As it is state in the section 3.5.1 the concentration of pollutant was determined by HPLC operating at the described conditions.
Reviewer’s comment 8:
English of this manuscript needs to be improved; many spelling error, typing and grammatical mistakes exists in the whole paper including caption of figure.
Authors’ answer to the comment:
Thank you for your comment. The English of the manuscript has been checked and the manuscript modified accordingly, including the figure captions.
Reviewer’s comment 9:
Novelty of the study did not emphasize clearly in any part of manuscript.
Authors’ answer to the comment:
Thank you for your helpful comment. The novelty of the work has been remarked in the manuscript and it is now highlighted both in the abstract, in the final part of the introduction (objectives) and in the conclusions. This includes the novel parts of the work, which are the generation of the heterogeneous catalyst in absence of water (Fe-DES) and its use for the generation of a combination of hydroxyl radical and sulphate in a unique application, as well as the use of inexpensive PLA electrodes.
Reviewer’s comment 10:
Conclusion section should be rewrite by including summary of the results.
Authors’ answer to the comment:
Thank you for your comment. The conclusion section has been modified as suggested by the reviewer.
Reviewer 3 Report
1- Following references should be added to the introduction.
· https://doi.org/10.1016/j.xcrp.2022.100809
· https://doi.org/10.1016/j.cogsc.2022.100612
· https://doi.org/10.1007/s11164-022-04793-8
2- Summaries of different research, about applicability of DES to prepare nanomaterials and applicability of nanocatalyst in oxidation, should be added to the introduction.
· https://doi.org/10.1016/j.ica.2022.121268
· https://doi.org/10.3390/ma16020627
3- Important bonds should be added to the FTIR and Raman spectra.
4- Unfortunately, the XRD characterization is so weak. What are the JPDES codes, what is the crystallinity size? Which peaks related to which components or sheets?
5- Are you sure that Fig 1 (e) is EDS analysis !!! isn’t it mapping elemental analysis? If you insist on EDS analysis you should add more information about the amounts of elements and their ratios. Also as it is related to SEM picture, they are better to be merged with EDS and TEM pictures.
6- Please add a scale to the SEM pictures.
7- The amount of COD should be added for the optimized condition.
Author Response
Reviewer 3 _____________________________________________________________
Reviewer’s comment 1:
Following references should be added to the introduction.
- https://doi.org/10.1016/j.xcrp.2022.100809
- https://doi.org/10.1016/j.cogsc.2022.100612
- https://doi.org/10.1007/s11164-022-04793-8
Authors’ answer to the comment:
Following the reviewer suggestion, the indicated references have been added to the manuscript.
Reviewer’s comment 2:
Summaries of different research, about applicability of DES to prepare nanomaterials and applicability of nanocatalyst in oxidation, should be added to the introduction.
- https://doi.org/10.1016/j.ica.2022.121268
- https://doi.org/10.3390/ma16020627
Authors’ answer to the comment:
The indicated references have been added and briefly explained in the introduction.
Reviewer’s comment 3:
Important bonds should be added to the FTIR and Raman spectra.
Authors’ answer to the comment:
Thank you for your helpful comment. The figures have been modified as suggested by the reviewer.
Reviewer’s comment 4:
Unfortunately, the XRD characterization is so weak. What are the JPDES codes, what is the crystallinity size? Which peaks related to which components or sheets?
Authors’ answer to the comment:
Thank you for your comment. Following the reviewer’s comment, the XRD derived data have been improved including the JPDES code, the XRD figure, putting the identification in a more visual way were added to the manuscript.
Reviewer’s comment 5:
Are you sure that Fig 1 (e) is EDS analysis !!! isn’t it mapping elemental analysis? If you insist on EDS analysis you should add more information about the amounts of elements and their ratios. Also as it is related to SEM picture, they are better to be merged with EDS and TEM pictures.
Authors’ answer to the comment:
The reviewer is right. The figure has been modified and the mapping has been complemented with the results of the EDS analysis for the main components. The figure caption has been also modified accordingly.
Reviewer’s comment 6:
Please add a scale to the SEM pictures.
Authors’ answer to the comment:
Thank you for your helpful comment. The figure has been modified and the requested scale added to the SEM pictures.
Reviewer’s comment 7:
The amount of COD should be added for the optimized condition.
Authors’ answer to the comment:
In order to determine the progression of the degradation, the process was not followed by TOC or COD but the generation of short chain carboxylic acids which are the previous step to the complete mineralisation. These compounds let us know the degree of mineralization that has been reached along the process.
