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Article
Peer-Review Record

Fabrication of rGO/Fe3O4 Magnetic Composite for the Adsorption of Anthraquinone-2-Sulfonate in Water Phase

Water 2021, 13(17), 2315; https://doi.org/10.3390/w13172315
Reviewer 1: Anonymous
Reviewer 2: Anonymous
Water 2021, 13(17), 2315; https://doi.org/10.3390/w13172315
Received: 19 July 2021 / Revised: 20 August 2021 / Accepted: 20 August 2021 / Published: 24 August 2021
(This article belongs to the Section Wastewater Treatment and Reuse)

Round 1

Reviewer 1 Report

The manuscript presents results from a binary magnetic rGO/Fe3O4 absorbent and its removal of AQ2S from the water. The main finding is the elemental and phase composition, and material properties of rGO/rGO/Fe3O4 absorbent including numerical model analysis. Moreover, the manuscript included regeneration studies for the potential usage as an application. 

However, the study requires updates and revision in order to fulfill the suitability of the work to be published in Water.

  1. The author should describe options of methods for a binary magnetic absorbent, reduced graphene oxide-Fe3O4. And among those methods, the advantages of a one-pot hydrothermal method should address to highlight the technique in the introduction.
  2. Please check reference 7. The author did not indicate [7] in the manuscript. 
  3. Please review thoroughly regarding the units (particularly, lines 88-104, °C). And be consistent with the formats (superscript, subscript) of the unit and chemical presentation. Place the space before the unit (line 120, 129, 130 ...), please proofread. 
  4. Line 112, should be Nicolet "iS50"
  5. Line 142, should be rGO/Fe3O4.
  6. Figures 4,5,6 need to be larger including letters. 
  7. From Figure 2c, the author mentioned the aggregation of particles has not been shown. The author should add guidelines in Figure 2c to help the reader to understand what is aggregation-free particle. It is hard to clearly see the properties of particles including d-spacing measurement. 
  8. The author should define the reason to pick the temperature from 288 K to 308 K for absorption studies. 
  9. The article covers various characterization analyses for material verifications; however, the surface study has not been included to understand the surface of the absorbent at the saturation point. The author can add surface analysis corresponding to the absorption process. 

General comments: Please review the manuscript thoroughly for typo/template/unit/format issues. 

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

I have read your manuscript entitled:Fabrication of rGO/Fe3O4 magnetic composite for the adsorption of Anthraquinone-2-sulfonate in water phase, with great interest.

The paper contains research, which is worthy of publication, including the investigation of  a binary magnetic adsorbent, reduced graphene/Fe3O4 (rGO/Fe3O4), synthesis and characterized by TEM, XRD, FTIR, Raman spectra and TGA and the use of the system as removal of Anthraquinone-2-sulfonate (AQ2S) from water. The reusability and stability of the adsorbent were evaluated under the optimized conditions performing five consecutive adsorption/regeneration cycles. The result reveals that the rGO/Fe3O4 composite maintains its adsorption capacity at 85.7% after 5 cycles, indicating good stability of this composite. The results are presented clearly, but some important features are missing. This article can be considered as an interesting piece of research, after some major and important improvements, presented below point-by-point.

 

  1. Explain the possible mechanism of Anthraquinone-2-sulfonate (AQ2S) adsorption.
  2. Compare the adsorption capacities of rGO/Fe3O4 with literature results for Anthraquinone-2-sulfonate (AQ2S) removal from water.
  3. What was the reaction pH for rGO/Fe3O4 synthesis before adjusting it to 10. Did you tried also at different pH values? If yes, please detailed.
  4. Eq 4 should be corrected.
  5. Please check one again all the references and homogenize it:

- Some are having one page number as example reference 1, 11

- Some are having no page number as example Reference 2, 7

- Reference nr 4 is wrong, the correct reference is” Hans-Dieter Scharf, Jörg Fleischhauer, Hans Leismann, Ingrid Ressler, Wolfgang Schleker, Robert Weitz, Criteria for the Efficiency, Stability, and Capacity of Abiotic Photochemical Solar Energy Storage Systems, Angew. Chem. 1979, 91, 696–707; Angew. Chem. Int. Ed. Engl. 1979, 18, 652–662”

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The manuscript has improved after revision. The experimental data are clearly presented and discussed and the inserted references are appropriate, therefore the manuscript can be accepted in its present form.

Author Response

Thank you for your valuable advise!

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