Degradation of Tetracycline Hydrochloride via Activation of Peroxymonosulfate by Magnetic Nickel–Cobalt Ferrite: Role of High-Valent Metal Species as Primary Reactive Agents
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this manuscript, the authors synthesized a novel ferrite (Co0.5Ni0.5Fe2O4) of varying particle sizes by modulating the calcination time, aiming to activate PMS for the removal of TCH from water. While the catalytic system showed high removal efficiency, some conclusions were drawn hastily. Overall, the manuscript can be acceptable by Water after some critical questions have been resolved. The specific suggestions are provided below:
(1) Please further explain the intrinsic relationship between the change in catalyst particle size and the generation of high-valent metal species.
(2) Please explain the role of Ni metal in the formation of active species.
(3) How to explain that both Fe(â…£)=O and Co(â…£)=O were generated instead of only Fe(â…£)=O or Co(â…£)=O?
(4) In 3.5.4, the presence of CO32- would make the system alkaline. Will this affect the stable existence of high-valent metal species?
(5) The scale in Figure 1 is too small. Please redraw the scale.
Comments on the Quality of English LanguageNo
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors1. In Figure 2b, data of 2h, 6h, and 24h are inconsistent, so it is recommended to complete or unify them.
2. In the FT-IR spectrum of Figure 2d, compared with the Fresh material, the Used material has two more functional group at the position of 2936.1cm-1 and 1133.2cm-1. Please explain the reason for this phenomenon.
3. The reaction performance lacks the reaction under dark state conditions, and the influence of light conditions on the reaction cannot be proved.
4. There are problems with the XPS component peak of Co metal in Figure 4c, and it is recommended to refer to the relevant literature on Co metal component peak for modification.
5. As shown in Figure 5c, there are reasons for the degradation of catalyst performance under high concentration Cl-, and what are the reasons for the improvement of catalyst performance under low concentration Cl-?
6. There is a lack of ICP tests to detect whether the amount of metal in the water after the reaction has an impact on the environment.
7. Some recent work is recommended to enrich the dicsussion of non-radical’ catalytic mechanism as well as high valent metal Co active sites, Applied Catalysis B: Environmental 325 (2023) 122387，Inorg. Chem. 2024, 63, 21260-21274.
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe present study evaluates the application of ferrite-based catalyst for the degradation of tetracycline through PMS activation. The manuscript is well constructed and details important aspects of the proposed system and its application. I believe that the manuscript may be accepted for publication after some revision.
1- The figures, especially in the materials characterization section, could be improved, with proper ranges that better display the main peaks and bands that need to be observed.
2- In most reactions, a concentration of 20 mg/L of TC is applied, which considering typical detected doses in WWTPs and surface water, is highly unrealistic, and even more recent studies apply much lower concentrations. Why the authors selected such high amounts of TC? I believe that at least in the evaluation of the effect of contaminants concentration, lower doses should be tested.
3- In the discussion of results, few comparisons are made between the results obtained and similar studies. As TC is a highly studied contaminant, I suggested adding comparisons with other relevant studies, or even adding a table comparing the kinetics and removals obtained.
4- The use of catalyst containing such transition metals may usually lead to some leaching, especially Fe. Did the authors evaluated this possibility? I believe that this data is crucial to understand the applicability of the proposed system.
5- In the characterization of used and fresh catalyst, some changes may be observed and are not properly addressed. Even with the observed stability of the material after 5 cycles, its possible poisoning may occur. Authors are encourage to further discuss this results.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsIt can be accepted at current states.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors sufficiently improved the manuscript according to my previous comments, although not all suggestions were incorporated, the authors justify it due to analytical equipment limitations and further evaluation in upcoming studies. I believe that the revised manuscript may be accepted.
