Synthesis of Activated Porous Carbon from Red Dragon Fruit Peel Waste for Highly Active Catalytic Reduction in Toxic Organic Dyes
Round 1
Reviewer 1 Report
In the manuscript titled “Heteroatoms-doped porous carbons for reduction of toxic organic dyes” authors have claimed the synthesis of porous carbon (PC) from dragon fruit peels and its utilization as a carbon source for a metal-free catalyst for dye reduction. They used many characterizations method such as g XRD, FE-SEM, FE-TEM, XPS, EDS to show synthesized composites' physical, structural, and optical characteristics. The work is adequate and can be published in Catalyst after minor revisions.
Comments:
1- Please improve the English grammar and writing skills for this paper.
2- Your abstract didn’t begin with a brief but precise statement of the problem or issue only it has a description of the research. in addition, you should add the significant findings, and the conclusions reached to your abstract.
3- Provide some references to support the XRD, Raman and FTIR study results.
4- The prepared material exhibited good surface area and adsorption abilities, but during dye degradation study the adsorption study is missing?
5- The authors claimed”, the 0.6 mg of catalyst showed the highest reduction 586 rate of 0.2473 min−1 among the dosages at 25 °C, exhibiting the best catalytic activity”.? What about the catalyst dose > 0.6 mg?
6- From the degradation contours from Figure 8 (a-c), the degradation of dyes is not 100%, since the absorption peaks are existing not touching the zero on x-axis?
7- Write down the conditions and light source for dye reduction experiment.
8- The introduction and results and discussion method can be enriched by citing some recent works(10.3390/catal12111388 ,doi.org/10.1002/slct.202201913, doi.org/10.1016/j.optmat.2022.112211).
9- There are some typo mistakes, especially in subscripts and supersubscripts.
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewers Comments
Manuscript ID: catalysts-2200396
TITLE: Heteroatoms-doped porous carbons for reduction of toxic organic dyes
Authors: Pitchaimani Veerakumar, Shih-Tung Hung, Pei-Qi Hung, Veeraraghavan Vishnu Priya,
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1-Please improve the English grammar and writing skills for this paper.
Author Reponses:
As suggested, we have thoroughly checked through the English grammar to make it more readable.
2-Your abstract didn’t begin with a brief but precise statement of the problem or issue only it has a description of the research. In addition, you should add the significant findings, and the conclusions reached to your abstract.
Author Reponses:
Thanks for your comments and suggestions. We have revised the abstract in the revised manuscript.
3-Provide some references to support the XRD, Raman and FTIR study results.
Author Reponses:
As per your suggestions, we have cited the references in the XRD, Raman and FTIR studies in the revised manuscript.
4-The prepared material exhibited good surface area and adsorption abilities, but during dye degradation study the adsorption study is missing?
Author Reponses:
Thanks for your comments. We are not performed adsorption study.
5-The authors claimed”, the 0.6 mg of catalyst showed the highest reduction 586 rate of 0.2473 min−1 among the dosages at 25 °C, exhibiting the best catalytic activity”.? What about the catalyst dose > 0.6 mg?
Author Reponses:
Thanks for your comments. The kapp values increased from 0.0685 to 0.2473 min-1 when catalyst dosage increased from 0.1 to 1.4 mg. This behavior is obvious, because by increasing the catalyst dosage more active sites are available for the reaction kinetics. The higher dosage of catalyst (1.4 mg) results in more number of active sites present in the reaction system with surplus surface‐to‐volume ratio and availability of lot of active sites for the reactants (BH4− and MB) to be adsorbed easily onto the surface of the nanocatalyst followed by the faster relay of electrons between BH4− and MB. Therefore, the reduction of MB occurs fast with the higher kapp.
6-From the degradation contours from Figure 8 (a-c), the degradation of dyes is not 100%, since the absorption peaks are existing not touching the zero on x-axis?
Author Reponses:
Thanks for your comments. Figure 8 (a-c) shows the visible absorption spectra of mixed dye solution during the degradation process. The absorption peak obviously decreased with increasing exposure time, indicating the dye molecules were degraded. Almost all the mixed cationic dye molecules were decomposed after certain time intervals. Furthermore, an increase in reaction intermediates could be produced by the higher concentration of dye mixtures in the solution.
7-Write down the conditions and light source for dye reduction experiment.
Author Reponses:
Thanks for your comments. We have provided the reaction conditions for dye reduction experiment in the revised manuscript.
8-The introduction and results and discussion method can be enriched by citing some recent works (10.3390/catal12111388, doi.org/10.1002/slct.202201913, doi.org/10.1016/j.optmat.2022.112211).
Author Reponses:
As per your suggestions, we have included the above references in the revised manuscript.
9-There are some typo mistakes, especially in subscripts and supersubscripts.
Author Reponses:
Thanks for your comments. The mistake has been corrected in the revised manuscript.
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Academic Editor Comments
*Please move "Materials and Methods" section after "Results and Discussion" section.*
Author Response:
As per your suggestions, we have moved Materials and Methods section after "Results and Discussion" section in the revised manuscript.
(I) Please check that all references are relevant to the contents of the manuscript.
Author Response:
Yes. We have checked carefully the cited all the references.
(II) Any revisions to the manuscript should be marked up using the “Track Changes” function if you are using MS Word/LaTeX, such that any changes can be easily viewed by the editors and reviewers.
Author Response:
Yes. As per your suggestions, we have uploaded the marked copy of the revised manuscript.
(III) Please provide a cover letter to explain, point by point, the details of the revisions to the manuscript and your responses to the referees’ comments.
Author Response:
As suggested, we have provided in details of the referees’ comments in the revised manuscript.
(IV) If you found it impossible to address certain comments in the review reports, please include an explanation in your appeal.
Author Response:
Thanks for your suggestions.
(V) The revised version will be sent to the editors and reviewers.
Author Response:
As suggested, we have provided revised version of manuscript and referees’ comments.
(VI) If one of the referees has suggested that your manuscript should undergo extensive English revisions, please address this issue during revision. We propose that you use one of the editing services listed at https://www.mdpi.com/authors/english or have your manuscript checked by a native English-speaking colleague.
Author Response:
As suggested, we have thoroughly checked through the grammar to make it more readable. The manuscript has also been improved by an experienced colleague.
(VII) We found that the Graphical Abstract you submitted is same as the Scheme 1 in the main text of your manuscript. Just a gentle reminder that, according to our rules, the graphical abstract is not allowed to be same as any figures in the main text. You could revise the Graphical Abstract or the Scheme 1.
Author Response:
As per your suggestions, we have provided a new Graphical Abstract in the revised manuscript.
Reviewer 2 Report
1- The manuscript must be improved by checking once again English grammar and technical writing.
2- The introductory sentence in the abstract is long.
3- The abstract should be revised in English grammar and technical writing.
4- Main methods and findings should be concisely mentioned in the abstract. Authors should consider the following;
a) Introduce the research problem, then highlight the research gap.
b) Add some results regarding the optimum conditions and highlight the novel findings of the study.
c) Highlight the study future recommendations.
5- Maximum adsorption capacity must be stated and clarified.
6- The opening sentence in the introduction part should be revised to be more attractive.
7- Photocatalysis is affordable and most widely used for the effective treatment of heavy polluted wastewaters. The authors can follow the following references for improving the introduction part by discussing some recent studies considering the efficacy and limitation of this treatment method. (https://doi.org/10.1016/j.ceramint.2022.05.151); (https://doi.org/10.1016/j.colsurfa.2021.127554) (https://doi.org/10.1016/j.seppur.2021.119791)
8- The reference style of the manuscript must be revised to meet the journal standards [1=3].
9- The authors should indicate a clear gap in knowledge which this study seeks to bridge, and potentially contribute to knowledge. Highlight this at the end of the introduction part.
10- Scheme 1 should be moved to section 2.3.
11- Mention the country of origin of the instruments used in the study.
12- The authors should repeat experiments to evaluate reproducibility of the work.
13- Equation (2) should be mentioned in the context.
14- Capitalize the eqns abbreviation in the context.
15- The use of NaBH4 in the preparation process is totally harm the environment as it considered a toxic material. These concerns should be highlighted.
16- How many cycles can this catalyst do?
17- Do the authors recommend using the investigated catalysts in large scale for real wastewater treatment? What about the ease of operation and cost evaluation? These concerns should be highlighted.
18- What about the spent catalyst in this work? The authors should compare the results with the WHO standards.
19- The authors should identify the limitations of this study and the recommended future studies in the conclusion part.
20- Bibliography part must be updated.
Author Response
Response to Reviewers Comments
Manuscript ID: catalysts-2200396
TITLE: Heteroatoms-doped porous carbons for reduction of toxic organic dyes
Authors: Pitchaimani Veerakumar, Shih-Tung Hung, Pei-Qi Hung, Veeraraghavan Vishnu Priya,
Comments and Suggestions for Authors
1-The manuscript must be improved by checking once again English grammar and technical writing.
Author Reponses:
As suggested, we have thoroughly checked through the English grammar to make it more readable.
2-The introductory sentence in the abstract is long.
Author Reponses:
As suggested, we have reduced the sentences and revised the abstract.
3-The abstract should be revised in English grammar and technical writing.
Author Reponses:
Thanks for your comments. We have checked the English grammar and technical writing thought the manuscript.
4-Main methods and findings should be concisely mentioned in the abstract. Authors should consider the following;
- a) Introduce the research problem, then highlight the research gap.
- b) Add some results regarding the optimum conditions and highlight the novel findings of the study.
- c) Highlight the study future recommendations.
Author Reponses:
As per your comments and suggestions. We have revised in the main text.
5-Maximum adsorption capacity must be stated and clarified.
Author Reponses:
Thanks for your comments. The maximum adsorption capacity of MB (321.51 mg g-1), CV (217.33 mg g-1), and NB (197.16 mg g-1) could reach quickly within 30 min via the mechanism of electrostatic interactions or hydrogen bonds interactions, due to the large SSA (1000.8 m2 g-1), the availability of heteroatoms (N,B,P), and plentiful oxygen-containing functional groups.
6-The opening sentence in the introduction part should be revised to be more attractive.
Author Reponses:
Thanks for your comments. We have revised sentences in the introduction part.
7-Photocatalysis is affordable and most widely used for the effective treatment of heavy polluted wastewaters. The authors can follow the following references for improving the introduction part by discussing some recent studies considering the efficacy and limitation of this treatment method. (https://doi.org/10.1016/j.ceramint.2022.05.151); (https://doi.org/10.1016/j.colsurfa.2021.127554) (https://doi.org/10.1016/j.seppur.2021.119791)
Author Reponses:
As per your suggestions we have included the references in the introduction section in the revised manuscript.
8-The reference style of the manuscript must be revised to meet the journal standards [1=3].
Author Reponses:
Thanks for your comments. We have checked the all the references and revised to meet the journal standards.
9-The authors should indicate a clear gap in knowledge which this study seeks to bridge, and potentially contribute to knowledge. Highlight this at the end of the introduction part.
Author Reponses:
As per your suggestions, we have included the highlight this at the end of the introduction part.
10-Scheme 1 should be moved to section 2.3.
Author Reponses:
Thanks for your comments. The Scheme 1 is moved to section 3.3.
11-Mention the country of origin of the instruments used in the study.
Author Reponses:
As suggested, we have included the country of origin of the instruments used in the revised manuscript.
12-The authors should repeat experiments to evaluate reproducibility of the work.
Author Reponses:
As suggested, we had repeated all experiments and to evaluate reproducibility of the work.
13-Equation (2) should be mentioned in the context.
Author Reponses:
Thanks for your comments. We have mentioned Equation (1) in the revised manuscript.
14-Capitalize the eqns abbreviation in the context.
Author Reponses:
The mistake has been corrected in the revised manuscript.
15-The use of NaBH4 in the preparation process is totally harm the environment as it considered a toxic material. These concerns should be highlighted.
Author Reponses:
Thanks for your comments. We have provided in detail in the revised manuscript.
16-How many cycles can this catalyst do?
Author Reponses:
Thanks for your comments. We have recycled the catalyst for 5 cycles.
17-Do the authors recommend using the investigated catalysts in large scale for real wastewater treatment? What about the ease of operation and cost evaluation? These concerns should be highlighted.
Author Reponses:
Thanks for your comments. We have discussed the prepared catalysts in large scale for real wastewater treatment, ease of operation and cost evaluation were also highlighted in the revised manuscript.
18-What about the spent catalyst in this work? The authors should compare the results with the WHO standards.
Author Reponses:
Thanks for your comments. In recent years, the research is devoted to the development of new methods that allow a good separation and recycling of catalysts. The separation process should follow a procedure economically and technically feasible with a minimal loss of the solid catalyst. In this work, we separated the spent catalyst and recycled for five times. In addition, we have included the WHO standards in the revised manuscript.
19-The authors should identify the limitations of this study and the recommended future studies in the conclusion part.
Author Reponses:
Thanks for your comments. In the conclusion section, we have listed the work's limitations.
20-Bibliography part must be updated.
Author Reponses:
Thanks for your suggestions. We have updated the bibliography of all authors.
Reviewer 3 Report
The manuscript has been checked and some corrections required before publication:
1. Improve the grammatical errors, need extensive revision.
For e.g. line 56, contamination of water
Line 65 , metal-free
Line 66, presence
Correct such errors throughout the manuscript.
2. Title of manuscript needs to be revised. It is very general. Specify the research work in the title.
3. In sec 2.3, mention the process for insertion of Mg, Fe, Zn .
4. Conclusion should be revised .
5. Can the as prepared catalyst , be applied on a large scale process.
Author Response
Response to Reviewers Comments
Manuscript ID: catalysts-2200396
TITLE: Heteroatoms-doped porous carbons for reduction of toxic organic dyes
Authors: Pitchaimani Veerakumar, Shih-Tung Hung, Pei-Qi Hung, Veeraraghavan Vishnu Priya,
Comments and Suggestions for Authors
The manuscript has been checked and some corrections required before publication:
Improve the grammatical errors, need extensive revision.
For e.g. line 56, contamination of water
Line 65 , metal-free
Line 66, presence
Correct such errors throughout the manuscript.
Author Reponses:
Thanks for your comments. We have corrected the errors and mistakes in the revised manuscript.
2.Title of manuscript needs to be revised. It is very general. Specify the research work in the title.
Author Reponses:
As suggested, we have revised the manuscript title.
3.In sec 2.3, mention the process for insertion of Mg, Fe, Zn.
Author Reponses:
As suggested, we have insertion of Mg, Fe, Zn in the section 3.3 in the revised manuscript.
4.Conclusion should be revised.
Author Reponses:
As suggested, we have revised the conclusion.
5.Can the as prepared catalyst, be applied on a large scale process.
Author Reponses:
Thanks for your comments. Generally, fruit peel is mostly discarded as waste in juice or jam-processing industries. Seriously, it can cause a series of environmental problems and the wastage of pomelo resources. In addition, Red dragon fruit has a fibrous and contains abundant cellulose and hemicellulose. Therefore, using Red dragon fruit as a raw material to prepare porous carbon material is worth considering. Red dragon fruit peel-derived porous carbon with large specific surface area and abundant pore structures were prepared by a facile method. The porous carbon had high adsorption capacity and excellent reusability toward reduction of MB. We believed that this work opened a new approach for fruit peel utilization for large scale process and also this catalyst used as a potential candidate for wastewater treatment, catalysis, and other sustainable applications.
Round 2
Reviewer 2 Report
Accept.
Author Response
Author Response:
Many thanks to the reviewer’s comments.
