Adsorption-Reduction of Cr(VI) with Magnetic Fe-C-N Composites

Round 1

Reviewer 1 Report

The paper reports on utilization of an iron containing sludge processed at elevated temperatures for sorptive removal of Chromium(VI). There are no new important scientific findings presented, and the study seems to contain a series of tests for a new kind of material, which may not have been used in the past. Yet, the results can be of certain interest for the readers, and potentially useful for possible applications in technology of waste processing and environment remediation.

1. Abstract should fully describe the preparation of the material.

2. In the characterization methods, write the atmosphere type used for TGA measurements.

3. Figure 3, correct the title and the units of the horizontal axis.

4. Figure 5, check whether some graphs are not repeated in Figure S3.

5. Various studies for inorganic and magnetic sorbents for Cr removal should be added for comparison. e.g.

https://doi.org/10.1007/s11814-020-0675-2

https://doi.org/10.3390/ma14030628

https://doi.org/10.3390/ijms232416186

6. line 111 spell the c PerkinElmer

7. References should be brought to the format of mdpi journals. Many of them should be checked for missing data. Thus, page number is missing from ref 6.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

 The authors reported the adsorption and reduction of Cr(VI) using Magnetic Fe-C-N composites. The submission can be accepted after revision taking into account the following points:-

1.      The title should be revised to be short, precise, and informative. Removed redundant words such as ‘Treatment’; ‘Composites’; and ‘Generated by Pyrolyzing Coagulation Sludge from Dyeing Wastewater’should be removed.

2.      Selectivity should be investigated.

3.      The mechanism of adsorption/reduction should be discussed and supported with experimental data.

4.      The abstract should be revised. All abbreviations, e.g.,  SEM, XRD, IR, XPS, and BET, should be fully defined.

5.      A comparison with previously published materials should be discussed and summarized in a Table.

6.      Adsorption of Cr(VI) should be updated using other materials citing these examples; Chemical Engineering Journal 2022, 446, 136614; Chemical Engineering Journal, 2023, 461, 141972; Chemical Engineering Journal 2022, 426, 131733.

7.      The language should be revised and typos should be corrected. 

The language should be polished by native speaker or profesional service.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf