Iron Carbon Catalyst Initiated the Generation of Active Free Radicals without Oxidants for Decontamination of Methylene Blue from Waters

Round 1

Reviewer 1 Report

The manuscript Iron carbon catalyst initiated the generation of active free radicals without oxidants for decontamination of methylene blue from waters by Yan Liu et al. describes the preparation of a new material capable of methylene blue removal from water. The study is well designed and fits the scope of the journal Catalysts.

However, there are some issues that need to be clarified:

1. Abstract should be changed to reflect on the actual findings on the study. You mention the “ultra-efficient spontaneous degradation of MB within 10 min” (lines 18-19), while MB was removed and not fully degraded, which you discuss in the recycling testing.
2. Ecotoxicity of the post-degradation solutions should be performed. It is necessary as the material is designed to be used in environmental applications.
3. You mention the adsorption-desorption equilibrium (line 274). If the decomposition of MB occurs simultaneously, shouldn’t it be degradation/removal equilibrium?
4. How many repetitions were there performed for each experiment? There are error bars in some figures, in some – not. Please add such information.
5. You mention figures S2 and S3 but there is no supporting information for the submitted manuscript.
6. “And finally, it will be converted for CO₂ and H₂O and other inorganic compounds. Since then, Fe/NG catalysts can spontaneously degrade MB in aqueous solutions, reducing the burden on the water treatment process.” (lines 427-430). To include such statement the TOC should be performed to monitor the carbon content in the degraded solutions. Otherwise it is an overstatement.
7. What happens to the Fe²⁺ that is produced in the process? Is it released to the medium? This could be a concern similar to the one in the Fenton process.
8. Experimental section: provide more information on the sonication applied – what equipment was used (ultrasonic bath/ultrasonic probe, power of the ultrasounds). Add the details of the muffle furnace used.
9. You do not mention the particle size of the Fe/NG, yet the catalyst is removed by filtration with the 0.45 µm filters. What was the size of the catalyst particles?
10. There should be references added in the results and discussion in the paragraphs in lines 246-260 and 353-363.
11. English used in the paper is of poor quality and should be improved.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

1. The main findings (values) are recommended to be highlighted in the abstract.
2. Equations 1-8 need to be supported with relevant references.
3. The correlation between structural and morphological findings and adsorption performance should be discussed.
4. A table of compassion should be provided to show the importance of using this catalyst among the available materials.
5. Pore size distribution (from BET) should be provided even as an inset of Fig. 5a.
6. What is the nonmenial ratio of Fe:C and how does it correlate with the EDX ratio.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Please see the file attached.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The authors have addressed most of the comments in the revised version. The current version could be accepted for publication.

Author Response

Thanks for your affirmation.