A Comparison Study between Wood Flour and Its Derived Biochar for the Enhancement of the Peroxydisulfate Activation Capability of Fe3O4
Round 1
Reviewer 1 Report
A comparison study between wood flour and its derived biochar for the enhancement of peroxydisulfate activation capability of Fe3O4
This work focused on PDS activation by two catalysts. The effects of various factors have been studied. The design of manuscript was very good. However, some points should be conducted.
*As Important issue, please check Figs, 4, 5 and 6. There are no results.
1. In introduction, please add to toxic effect of BPA. Please see https://doi.org/10.1016/j.envres.2022.114789
https://doi.org/10.1016/j.jhazmat.2022.130626
2. Please add the rate constants for all equations
3. Please add a control experiment for the reaction of FFA with PDS.
4. Please add a table to compare the results with other studies based on recent catalytic SR_AOPs for the degradation of BPA. Please see (https://doi.org/10.1016/j.cej.2022.139556) ( https://doi.org/10.1016/j.jenvman.2022.115851) (https://doi.org/10.1016/j.jclepro.2020.124246)
5. Conclusion, I think that conclusion could be based on your opinion about future of this catalyst and its application in various fields.
6. Iron leaching could have been studied. (is not mandatory)
Author Response
A comparison study between wood flour and its derived biochar for the enhancement of peroxydisulfate activation capability of Fe3O4
This work focused on PDS activation by two catalysts. The effects of various factors have been studied. The design of manuscript was very good. However, some points should be conducted.
*As Important issue, please check Figs, 4, 5 and 6. There are no results.
Thank you for the comment. This may be due to the format problem of the submission platform when converting the word file to pdf file. We have changed these figures to other format.
- In introduction, please add to toxic effect of BPA. Please see
https://doi.org/10.1016/j.envres.2022.114789
https://doi.org/10.1016/j.jhazmat.2022.130626
Thank you for the comment. References have been added in the last paragraph of Introduction.
- Please add the rate constants for all equations
Thank you for the comment. The rate constants of homogeneous reactions have been added (Eqs. 2, 3, 6) for your further evaluation.
- Please add a control experiment for the reaction of FFA with PDS.
Thank you for the comment. Due to the Covid-19, our university took an early winter vocation and the laboratory has been closed. We cannot complete the experiments at this stage. But this is a commonly seen control experiment in the references (e.g., DOI: 10.1021/acs.est.8b04669), in which hardly any reaction could happen between PDS and FFA.
- Please add a table to compare the results with other studies based on recent catalytic SR_AOPs for the degradation of BPA. Please see (https://doi.org/10.1016/j.cej.2022.139556) ( https://doi.org/10.1016/j.jenvman.2022.115851) (https://doi.org/10.1016/j.jclepro.2020.124246)
Thank you for the comment. Table 1 has been added for your further evaluation.
- Conclusion, I think that conclusion could be based on your opinion about future of this catalyst and its application in various fields.
Thank you for the comment. The conclusion has been revised for your further evaluation.
- Iron leaching could have been studied. (is not mandatory)
Thank you for the comment. The iron leaching results were provided in Fig. 8(a).
Reviewer 2 Report
Comments on the manuscript entitled A comparison study between wood flour and its derived biochar for the enhancement of peroxydisulfate activation capability of Fe3O4 by Yu Han and Lijie Xu (catalysts-2159366)
The authors will have to make it clear in their response and the revised paper what the novelty of this work is as compared to the state of the art in the literature of other adsorption systems of these contaminants. This must include text related to either: 1) a novel material that has distinct advantages with respect to selectivity or capacity, 2) a novel theoretical treatment, and/or 3) an application that has not been addressed to date. It is not sufficient to describe another adsorbent for another "standard application".
Other remarks
(1) How is the reproducibility of the samples?.
(2) In figure 4,5. 6a,b, the data are missing.
(3) Figures, any error bars for the results? Error bars are missing for all the results.
(4) The cost calculation would be a better choice for convening audiences.
(5) Has the synthesis process been optimized? Such as the FeCl3, FeSO4, WF/Fe3O4 and WFB/Fe3O4 ratio and so on?
(6) How about the product yield for catalysts?
(7) A comparison table of BPA removal by other processes compared to the present work would need to be included.
(8) I recommend a full revision of the language in order to avoid further editorial work.
This paper needs a major revision.
Author Response
Comments on the manuscript entitled A comparison study between wood flour and its derived biochar for the enhancement of peroxydisulfate activation capability of Fe3O4 by Yu Han and Lijie Xu (catalysts-2159366)
The authors will have to make it clear in their response and the revised paper what the novelty of this work is as compared to the state of the art in the literature of other adsorption systems of these contaminants. This must include text related to either: 1) a novel material that has distinct advantages with respect to selectivity or capacity, 2) a novel theoretical treatment, and/or 3) an application that has not been addressed to date. It is not sufficient to describe another adsorbent for another "standard application".
Thank you for the comment. The novelty of this work is to compare the efficiency of two cost-effective biomass-based supports for Fe3O4 to enhance the catalytic performance of Fe3O4, which have not yet been considered in other studies. During scale application, Fe3O4 has to be attached on a good support to prevent agglomeration. Based on the results in this study, although WF does not need pyrolysis, it demonstrated lower efficiency than WFB when compositing with Fe3O4.
Other remarks
(1) How is the reproducibility of the samples?
The catalytic activation of the samples prepared from different batches has certain differences due to the unhomogeneity of the biomass. Therefore, we have prepared enough amount of catalysts from several batches, grounded and mixed the samples thoroughly to conduct all the experiments to make sure that all the samples have almost the same property during the investigation.
(2) In figure 4,5. 6a,b, the data are missing.
Thank you for the comment. This may be due to the format problem of the submission platform when converting the word file to pdf file. We have changed these figures to other format.
(3) Figures, any error bars for the results? Error bars are missing for all the results.
Thank you for the comment. In our first version of manuscript, we only added the description of “The batch experiments were conducted in duplicates at least until the errors were below 5%, and the average values obtained were used for plotting.” In part 3 “Materials and Methods”. In this revised version, we have carefully revised the figures including the values of error bar for your further evaluation.
(4) The cost calculation would be a better choice for convening audiences.
Thank you for the comment. Since the iron salts and biomass that we selected are relatively cost-effective, if this process can be in scale application, we think it has the advantage in catalyst cost.
(5) Has the synthesis process been optimized? Such as the FeCl3, FeSO4, WF/Fe3O4 and WFB/Fe3O4 ratio and so on?
Thank you for the comment. We have optimized the mass ratio of biomass and iron salt as shown in Figure 4, but we did not optimize the source of iron salt, which we will investigate in the future.
(6) How about the product yield for catalysts?
Thank you for the comment. The yield is around 25%.
(7) A comparison table of BPA removal by other processes compared to the present work would need to be included.
Thank you for your comment. Table 1 has been added for your further evaluation.
(8) I recommend a full revision of the language in order to avoid further editorial work.
Thank you for your comment. The language has been carefully revised, and the revised parts have been highlighted in red.
This paper needs a major revision.
Reviewer 3 Report
In the article, the authors wood flour and wood flour-derived biochar were used as the supports for Fe3O4. Peroxodisulfate is effectively used for the degradation of various organic compounds (model compound: Bisphenol A) , the sulfate radical anion formed from it is an effective oxidizing agent. The researchers tried to increase the efficiency of this process with Fe3O4 catalysts. The produced catalysts and the processes taking place during the degradation were also qualified in detail.
Some of my comments and questions:
1. „ This was consistent with the pore size distribution results. Moreover, compared with Fe3O4 (41.32 m2/g), the WF20/Fe3O4 (76.25 m2/g) and WFB20/Fe3O4 (78.65 m2/g) had larger specific surface areas (SSAs) and more micropores, which might provide abundant active sites for the catalytic reactions and facilitate the adsorption of the pollutant.”- I don't think the difference between the specific surface area of the two catalysts is very significant, it can even be considered a measurement error. Has the reproducibility of the production of the catalysts been investigated
2. Unfortunately, figures 4, 5 and 6 lack measurement data. I think the reason for this is some kind of technical error.
3. Equation 4 needs to be improved, the charge balance is not good.
Author Response
In the article, the authors wood flour and wood flour-derived biochar were used as the supports for Fe3O4. Peroxodisulfate is effectively used for the degradation of various organic compounds (model compound: Bisphenol A) , the sulfate radical anion formed from it is an effective oxidizing agent. The researchers tried to increase the efficiency of this process with Fe3O4 catalysts. The produced catalysts and the processes taking place during the degradation were also qualified in detail.
Some of my comments and questions:
- „ This was consistent with the pore size distribution results. Moreover, compared with Fe3O4 (41.32 m2/g), the WF20/Fe3O4 (76.25 m2/g) and WFB20/Fe3O4 (78.65 m2/g) had larger specific surface areas (SSAs) and more micropores, which might provide abundant active sites for the catalytic reactions and facilitate the adsorption of the pollutant.”- I don't think the difference between the specific surface area of the two catalysts is very significant, it can even be considered a measurement error. Has the reproducibility of the production of the catalysts been investigated.
Thank you for the comment. The small difference may be due to the small mass ratio of either WF or WFB in the prepared composites. We conducted duplicated measurement and used the average value.
The properties of the samples prepared from different batches have certain differences due to the unhomogeneity of the biomass. Therefore, we have prepared enough amount of catalysts from several batches, and then we grounded and mixed the samples thoroughly to obtain the mixture to conduct all the experiments, which can make sure that all the samples have almost the same property during the investigation.
- Unfortunately, figures 4, 5 and 6 lack measurement data. I think the reason for this is some kind of technical error.
Thank you for the comment. This may be due to the format problem of the submission platform when converting the word file to pdf file. We have changed these figures to other format.
- Equation 4 needs to be improved, the charge balance is not good.
Thank you for the comment. Equation 4 has been revised for your further evaluation.
Round 2
Reviewer 1 Report
All questions have been well addressed. The revision has been well prepared.
Author Response
Thank you.
Reviewer 3 Report
I accept the corrections, but unfortunately the measurement curves are still missing from Figs 3 and Figs 4 in the supplementary. This needs to be fixed.
Author Response
Dear Reviewer,
Thank you for the comment. We tried to replace the figure format for your further evaluation.
Author Response File: 
Author Response.pdf
