Removal of Per- and Polyfluoroalkyl Substances by Adsorption on Innovative Adsorbent Materials

Round 1

Reviewer 1 Report

Manuscript is good work however, some concerns are there.

 

·       PFPnA, PFHxA and some other words are there without full abbreviation at least once. Its full form is mandatory once.

·       Conclusion is not up to the mark. It should be rewritten.

·       Self citation is not good like….

Collivignarelli, M.C.; Canato, M.; Abbà, A.; Carnevale Miino, M. Biosolids: What Are the Different Types of Reuse? J. Clean. 645 Prod. 2019, 238, 117844, doi:10.1016/j.jclepro.2019.117844. 

 Bertanza, G.; Capoferri, G.U.; Carmagnani, M.; Icarelli, F.; Sorlini, S.; Pedrazzani, R. Long-Term Investigation on the Removal 558 of Perfluoroalkyl Substances in a Full-Scale Drinking Water Treatment Plant in the Veneto Region, Italy. Sci. Total Environ. 2020, 559 734, 139154, doi:10.1016/j.scitotenv.2020.139154

 Pistocchi, A.; Andersen, H.R.; Bertanza, G.; Brander, A.; Choubert, J.M.; Cimbritz, M.; Drewes, J.E.; Koehler, C.; Krampe, J.; 522 Launay, M.; et al. Treatment of Micropollutants in Wastewater: Balancing Effectiveness, Costs and Implications. Sci. Total 523 Environ. 2022, 850, 157593, doi:10.1016/j.scitotenv.2022.157593.

 

Remove this.

·       Some recent work may be added to this manuscript.

https://www.sciencedirect.com/science/article/abs/pii/S0045653523010913

https://www.sciencedirect.com/science/article/abs/pii/S0269749123008679

https://www.sciencedirect.com/science/article/abs/pii/S0304389423007215

·       Language needs to be revised. And the discussion should be written with good comparision.

·       In future research it will be advisable to devote efforts towards the reuse of sewage 500 sludge and biochar adsorbent materials for PFAS removal.

Write it is advisable…..

·       Conclusions—In this section, writing in pointwise fashion is not recommended.

·       An effective discussion section tells the reader what your study means and why it is important. This is missing in discussion section.

·       The effects of PFAS’ exposure on human health have been extensively studied. This line may be supported with some examples.

 

 

Language related corrections are still to be improved.

Author Response

Reviewer #1

 

The authors are very grateful to the Reviewer for the valuable comments, recommendations, and suggestions on the manuscript “Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials”. Revisions have been implemented accordingly.

Please find here in the following the detailed answers to the Reviewer’s and the reference to the related changes in the manuscript. Furthermore, additional changes (including syntax and grammar edits) were made to the manuscript (in “Track changes mode”).

 

 

Comment 1:  PFPnA, PFHxA and some other words are there without full abbreviation at least once. Its full form is mandatory once.

 

Reply: We added the full name to the abbreviations, including: “PFPnA (perfluoropentanoate)” and PFHxA “(perfluorohexanoic Acid)”

 

 

Comment 2:  Conclusion is not up to the mark. It should be rewritten.

 

Reply: We have improved the conclusions by better summarizing the content and providing some recommendations that derive from the analysis carried on in the paper.

 

Comment 3:  ·Self citation is not good like….

Collivignarelli, M.C.; Canato, M.; Abbà, A.; Carnevale Miino, M. Biosolids: What Are the Different Types of Reuse? J. Clean. 645 Prod. 2019, 238, 117844, doi:10.1016/j.jclepro.2019.117844. 

 Bertanza, G.; Capoferri, G.U.; Carmagnani, M.; Icarelli, F.; Sorlini, S.; Pedrazzani, R. Long-Term Investigation on the Removal 558 of Perfluoroalkyl Substances in a Full-Scale Drinking Water Treatment Plant in the Veneto Region, Italy. Sci. Total Environ. 2020, 559 734, 139154, doi:10.1016/j.scitotenv.2020.139154

 Pistocchi, A.; Andersen, H.R.; Bertanza, G.; Brander, A.; Choubert, J.M.; Cimbritz, M.; Drewes, J.E.; Koehler, C.; Krampe, J.; 522 Launay, M.; et al. Treatment of Micropollutants in Wastewater: Balancing Effectiveness, Costs and Implications. Sci. Total 523 Environ. 2022, 850, 157593, doi:10.1016/j.scitotenv.2022.157593.

Remove this.

 

 

Reply: We have worked on the citations, retaining only those that are essential for the full understanding of the content of the paper, including the reference to previous work and experiences of the authors. In particular, we have eliminated one citation  ( Bertanza, G.; Capoferri, G.U.; Carmagnani, M.; Icarelli, F.; Sorlini, S.; Pedrazzani, R. Long-Term Investigation on the Removal 558 of Perfluoroalkyl Substances in a Full-Scale Drinking Water Treatment Plant in the Veneto Region, Italy. Sci. Total Environ. 2020, 559 734, 139154, doi:10.1016/j.scitotenv.2020.139154).

 

 

Comment 4:  Some recent work may be added to this manuscript.

https://www.sciencedirect.com/science/article/abs/pii/S0045653523010913

https://www.sciencedirect.com/science/article/abs/pii/S0269749123008679

https://www.sciencedirect.com/science/article/abs/pii/S0304389423007215

 

 

Reply: We thank the reviewer for the recommendations. We have included references of two of the three recommended articles.

 

Comment 5:   Language needs to be revised. And the discussion should be written with good comparision.

 

Reply: The English of the paper has been carefully revised. As already mentioned, conclusions and discussion were revised to made them more effective for the reader.

 

Comment 6:   In future research it will be advisable to devote efforts towards the reuse of sewage 500 sludge and biochar adsorbent materials for PFAS removal.

Write it is advisable…..

 

Reply: We changed the sentence as recommended.

 

 

Comment 7:   ·       Conclusions—In this section, writing in pointwise fashion is not recommended.

 

Reply: We have modified the conclusions by eliminating the pointwise description.

 

Comment 8:   An effective discussion section tells the reader what your study means and why it is important. This is missing in discussion section.

 

Reply: Thank you for raising this point. Introduction, Discussion and conclusion sections now better clarify the meaning of the study and its overall importance.

 

Comment 9:   ·       The effects of PFAS’ exposure on human health have been extensively studied. This line may be supported with some examples.

 

Reply: We have made better reference to the available knowledge on the effects of PFAS on human health. In the introduction we have added two sentences, reported below:

 

“The effects of PFAS’ exposure on human health have been extensively studied. As reported by the National Institute of Environmental Health Sciences of NIH [11] (niehs.nih.gov/health/topics/agents/pfc), the concerns about PFAS is related to their widespread occurrence, numerous exposures, growing number and in particular bioaccumulation.”

 

“PFAS derivatives have been widely used in various industries due to their water- and oil-repellent properties. However, these derivatives have raised concerns regarding their impact on the environment and human health. Here are some of the main effects associated with PFAS derivatives: environmental persistence; bioaccumulation; toxicity; endocrine disruption; impact on wildlife; concerns for drinking water [15].”

 

 

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

The paper entitled " Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials: a mini review" is submitted for review for possible publication. 

So here are my comments:

1 TITLE: The "mini-review" portion of the title does not make the paper convincing at all. Why will I read a mini review while I can red a full review from other papers.  First time readers may connote this as a waste of time since this may not even represent the general current trend.

2. There is very little discussion on the occurrence of PFAs in WW, its source is still not clearly established. There should be at least discussion of their derivatives that is equally detrimental to the environment.

3. Datas are all presented textually. There is no effective data handling that was implemented for this paper.  

4. The conclusions cannot communicate well the recommendations since there is no clear trending presented that my substantiate the inferences generated from this paper.

5. There is no concrete recommendation as hoe everything will lead like policy recommendation or development of standards.

 

 

Author Response

Reviewer #2

 

The authors are very grateful to the Reviewer for the valuable comments, recommendations, and suggestions on the manuscript “Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials”. Revisions have been implemented accordingly.

Please find here in the following the detailed answers to the Reviewer’s and the reference to the related changes in the manuscript. Furthermore, additional changes (including syntax and grammar edits) were made to the manuscript (in “Track changes mode”).

 

 

Comment 1:    TITLE: The "mini-review" portion of the title does not make the paper convincing at all. Why will I read a mini review while I can red a full review from other papers.  First time readers may connote this as a waste of time since this may not even represent the general current trend

 

Reply: In accordance with the comment, the title of the paper has been changed by deleting "mini-review" in order to avoid misunderstandings. Further citations have also been added and the paper expanded in content and overall message for the readers.

 

 

Comment 2:  There is very little discussion on the occurrence of PFAs in WW, its source is still not clearly established. There should be at least discussion of their derivatives that is equally detrimental to the environment.

 

Reply: We thank the reviewer for the comments. We have added a sentence to the text (line 106) that reads as follows:

 

“PFAS derivatives have been widely used in various industries due to their water- and oil-repellent properties. However, these derivatives have raised concerns regarding their impact on the environment and human health. Here are some of the main effects associated with PFAS derivatives: environmental persistence; bioaccumulation; toxicity; endocrine disruption; impact on wildlife; concerns for drinking water [15].”

 

Comment 3:  Datas are all presented textually. There is no effective data handling that was implemented for this paper.  

Reply:

Our choice has been related to the difficulty of graphically summarizing the scattered experiences that have been synthesized in our work. However, we have now added to pie charts, related to the temporal and spatial distribution of the published papers.

 

Comment 4:  The conclusions cannot communicate well the recommendations since there is no clear trending presented that my substantiate the inferences generated from this paper.

 

Reply: We have now clarified the trend and evidence emerging from the paper. It is now possible from introduction, discussion, and conclusion to better understand the overall message of the paper.

 

Comment 5: There is no concrete recommendation as how everything will lead like policy recommendation or development of standards.

 

Reply: We have improved the conclusions by providing some recommendations that derive from the analysis carried on in the paper.

 

Author Response File: Author Response.docx

Reviewer 3 Report

Authors have compiled a research article entitled “Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials: a mini review” The topic chosen seems to have a little to readers and the article does not suit the journal ‘Sustainability’. After careful evaluation and critical insight, it is of the opinion that the manuscript does not suit well for publication in current state. It needs rigorous modifications before it can be accepted in any good journal.

1.        Authors have just compiled little above 60 papers and among which nearly half do not connect with the topic of the article. Moreover, most of the references are old and are out dated. Authors should look into how this articles is suitable for  the journal ‘Sustainability’??

2.        It is suggestive that there must be around 200 papers which must be compiled with critical evaluation using tables, figures, statistics, etc. that will help reader understand the concepts better.

3.        In section ‘Methods: Analysis of Literature’, the methodologies remained undescribed. There is no description about biochar and virgin adsorbent material in text. Also, literature data is not analysed.

4.        In Figure 1, the results of the literature search and the number of studies included according to PRISMA guidelines are presented. The authors haven’t explained figure 1. What does this flow diagram indicate?

5.        The section ‘Mechanism of PFAS removal’ should be elaborated and separated accordingly. Author should include anionic exchange, ligand exchange, hydrophobic interactions, electrostatic interactions mechanism for the adsorption of PFAS.

6.        The authors have included a section as ‘applications of adsorbent materials’ and described various adsorbent materials as adsorbent in the text. What is the purpose for naming this section as applications as the title of the manuscript is Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials: a mini review.

7.        The author should focus more on the mechanistic sights for the removal of PFAS.

8.        Section 3.1.3 is dedicated to metal organic and metal inorganic adsorbents but in table 1, Zeolites are classified under the metal organic adsorbent category.

9.        There are many grammatical and typographical errors in the manuscript.

10.    In section 3.1 the authors have written conventional adsorbent materials but not described in the main text.

Thus, it is not suitable for publication at this stage.

Authors have compiled a research article entitled “Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials: a mini review” The topic chosen seems to have a little to readers and the article does not suit the journal ‘Sustainability’. After careful evaluation and critical insight, it is of the opinion that the manuscript does not suit well for publication in current state. It needs rigorous modifications before it can be accepted in any good journal.

1.        Authors have just compiled little above 60 papers and among which nearly half do not connect with the topic of the article. Moreover, most of the references are old and are out dated. Authors should look into how this articles is suitable for  the journal ‘Sustainability’??

2.        It is suggestive that there must be around 200 papers which must be compiled with critical evaluation using tables, figures, statistics, etc. that will help reader understand the concepts better.

3.        In section ‘Methods: Analysis of Literature’, the methodologies remained undescribed. There is no description about biochar and virgin adsorbent material in text. Also, literature data is not analysed.

4.        In Figure 1, the results of the literature search and the number of studies included according to PRISMA guidelines are presented. The authors haven’t explained figure 1. What does this flow diagram indicate?

5.        The section ‘Mechanism of PFAS removal’ should be elaborated and separated accordingly. Author should include anionic exchange, ligand exchange, hydrophobic interactions, electrostatic interactions mechanism for the adsorption of PFAS.

6.        The authors have included a section as ‘applications of adsorbent materials’ and described various adsorbent materials as adsorbent in the text. What is the purpose for naming this section as applications as the title of the manuscript is Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials: a mini review.

7.        The author should focus more on the mechanistic sights for the removal of PFAS.

8.        Section 3.1.3 is dedicated to metal organic and metal inorganic adsorbents but in table 1, Zeolites are classified under the metal organic adsorbent category.

9.        There are many grammatical and typographical errors in the manuscript.

10.    In section 3.1 the authors have written conventional adsorbent materials but not described in the main text.

Thus, it is not suitable for publication at this stage.

Author Response

Reviewer #3

 

The authors are very grateful to the Reviewer for the valuable comments, recommendations, and suggestions on the manuscript “Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials”. When appropriate, revisions have been implemented accordingly.

Please find here in the following the detailed answers to the Reviewer’s and the reference to the related changes in the manuscript. Furthermore, additional changes (including syntax and grammar edits) were made to the manuscript (in “Track changes mode”).

 

Comments:    Authors have just compiled little above 60 papers and among which nearly half do not connect with the topic of the article. Moreover, most of the references are old and are out dated. Authors should look into how this articles is suitable for  the journal ‘Sustainability’??

 

It is suggestive that there must be around 200 papers which must be compiled with critical evaluation using tables, figures, statistics, etc. that will help reader understand the concepts better.

 

In section ‘Methods: Analysis of Literature’, the methodologies remained undescribed. There is no description about biochar and virgin adsorbent material in text. Also, literature data is not analysed.

 

In Figure 1, the results of the literature search and the number of studies included according to PRISMA guidelines are presented. The authors haven’t explained figure 1. What does this flow diagram indicate?

 

Reply: We have performed a careful analysis of the literature following a standard methodology, internationally and widely known as PRISMA guidelines. As now further explained in the paper (from line 153), the original search found 206 papers corresponding to the search conditions presented above (rows 132-135 of the paper). The first screening excluded papers related to reviews, papers not written in English and the articles related to water purification. Papers were further limited to treatments already applied to existing plants and thus do not present relevant implementation problems, either in terms of complexity or cost. Of the final 55 papers, only 53 were fully available.

 

Comment :  The section ‘Mechanism of PFAS removal’ should be elaborated and separated accordingly. Author should include anionic exchange, ligand exchange, hydrophobic interactions, electrostatic interactions mechanism for the adsorption of PFAS

 

Reply: We thank the reviewers for the comment. This part of the paper was fully rewritten (now lines 172-257) adding a Figure (Figure 2).

 

Comment:   The authors have included a section as ‘applications of adsorbent materials’ and described various adsorbent materials as adsorbent in the text. What is the purpose for naming this section as applications as the title of the manuscript is Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials: a mini review.

 

Reply: We agree with the reviewer and we have modified the text accordingly.

 

 

Comment 7:  The author should focus more on the mechanistic sights for the removal of PFAS.

 

Reply: We thank the reviewers for the comment. As already mentioned, this part of the paper was fully rewritten in lines 172-257.

 

 

Comment 8:   Section 3.1.3 is dedicated to metal organic and metal inorganic adsorbents but in table 1, Zeolites are classified under the metal organic adsorbent category.

 

 

Reply: We have changed the title of the section in order to include also Zeolites.

 

Comment 9:   There are many grammatical and typographical errors in the manuscript.

 

Reply:  We have fixed the grammatical and typographical errors and carefully revise the text of the document.

 

Comment 10:   In section 3.1 the authors have written conventional adsorbent materials but not described in the main text.

 

Reply: This is now better explained in Section 3.1.

 

Author Response File: Author Response.docx

Reviewer 4 Report

The authors should improve this review article per the following 

suggestions 

1. First of all draw the chemical structures of different per- and poly-fluoroalkyl substances.

2. There are different adsorption mechanisms explained in detail with their mechanisms also including suitable illustrations for it.

3. Describe the limitations of each adsorbent material and explain how can overcome that limitation.

4. Compare adsorption with other methods in detail and give a conclusion about where adsorption stands in it.

5.Discuss about techniques which currently industry utilizing 

NA

Author Response

Reviewer #4

 

The authors are very grateful to the Reviewer for the valuable comments, recommendations, and suggestions on the manuscript “Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials”. When appropriate, revisions have been implemented accordingly.

Please find here in the following the detailed answers to the Reviewer’s and the reference to the related changes in the manuscript. Furthermore, additional changes (including syntax and grammar edits) were made to the manuscript (in “Track changes mode”).

 

Comment 1:    First of all draw the chemical structures of different per- and poly-fluoroalkyl substances.

Reply: In accordance with the comment, the structure of some PFAS has been depicted in figure 2.

 

Comment 2:  There are different adsorption mechanisms explained in detail with their mechanisms also including suitable illustrations for it.

 

Reply: Thanks for the comment. In the paragraph related to the removal mechanism and in Figure 2, in addition to the structure of PFAS, the adsorption of perfluoroalkyl molecules is explained.

 

Comments:  Describe the limitations of each adsorbent material and explain how can overcome that limitation. Compare adsorption with other methods in detail and give a conclusion about where adsorption stands in it.

 

Reply: Conclusions have been modified reporting the PFAS removal/transfer mechanism and what their limits are. Conclusions also reports more considerations about the implications of this paper.

 

Comment 5: Discuss about techniques which currently industry utilizing. 

Reply: We have now better clarified this aspect. The text now reads as follows:

“PFAS derivatives have been widely used in various industries due to their water- and oil-repellent properties. However, these derivatives have raised concerns regarding their impact on the environment and human health. Here are some of the main effects associated with PFAS derivatives: environmental persistence; bioaccumulation; toxicity; endocrine disruption; impact on wildlife; concerns for drinking water [15].”

 

 

 

 

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Hi Authors, 

 

I would like to comment you for the revisions made, but the conclusion still seems off.   You have discussed the use of biochar as one better adsorbent for PFA while you never presented a clear reaction mechanism of how it addresses, degrades or removes PFAs? Are they really removed or just converted into lesser toxic pollutants? 

The conclusion in line 563 - 568 is never new to water treatment and is not a conclusion at all. Conversion of pollutants to a more concentrated from is addressed by flocculation and coagulation - from liquid to solid, this will clog your adsorbent, so what is really the aim of adding this to your conclusion. 

In addition the practice reduction of any pollutant at source or production is never new to water treatment and management.  

Generate a sound conclusion based on the data that you have presented. 

Also, fix your pie graphs.  The current state and quality is not for international peer-reviewed publication. 

Hi Editor, 

The conclusion must be fixed to provide insightful ideas about what are presented.  An original insight and not copied or patterned one. 

 

The resolution and form of the graph is also awful.  They should have presented a better looking graphic. 

 

Thanks

Author Response

 

The authors are very grateful to the Reviewer for the valuable comments, recommendations, and suggestions on the manuscript “Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials”. Revisions have been implemented accordingly.

Please find here in the following lines the detailed answers to the Reviewer and the reference to the related changes in the manuscript. Furthermore, additional changes (including syntax and grammar edits) were made to the manuscript (in “Track changes mode”).

 

 

Comment 1:    Hi Authors, 

 

I would like to comment you for the revisions made, but the conclusion still seems off. You have discussed the use of biochar as one better adsorbent for PFA while you never presented a clear reaction mechanism of how it addresses, degrades or removes PFAs? Are they really removed or just converted into lesser toxic pollutants?

The conclusion in line 563 - 568 is never new to water treatment and is not a conclusion at all. Conversion of pollutants to a more concentrated from is addressed by flocculation and coagulation - from liquid to solid, this will clog your adsorbent, so what is really the aim of adding this to your conclusion. 

In addition the practice reduction of any pollutant at source or production is never new to water treatment and management.  

Generate a sound conclusion based on the data that you have presented.

Also, fix your pie graphs.  The current state and quality is not for international peer-reviewed publication. 

 

Reply: An entire section called “Mechanism of PFAS removal” explains the reaction mechanisms (lines 176-332), please make reference to the new version of the manuscript.

 

As conclusions are concerned, they now read: “In conclusion, since the C-F bond is hardly biodegradable, the only treatment with high performance is the removal with adsorbent materials. All in all, this is only a transfer from a liquid to a solid matrix, achieved by flocculation and coagulation, thus obtaining a more concentrated form. The solid matrix is more easily manageable and storable, but it is not a real degradation of the micropollutants. Therefore, as a recommendation, at least on the long run, the main strategy should be to reduce or eliminate the PFAS from the production line of the different industrial processes. Even if this recommendation is certainly not a novelty, it is still actual and needs to be transferred from theory to practice in real scale plants.” Therefore, we clearly stated that the adsorbent materials remove C-F but do not perform any degradation. We should note, however, that this is a review of the current treatment strategies in real plants, and therefore we are not aiming at proposing new solutions.

Pie charts have been redrawn, too.

 

Comment 2:  Hi Editor, 

The conclusion must be fixed to provide insightful ideas about what are presented.  An original insight and not copied or patterned one. 

 

The resolution and form of the graph is also awful.  They should have presented a better looking graphic. 

 

 

Reply: This comment has been fixed in the revised version.

 

Author Response File: Author Response.docx

Reviewer 3 Report

Comments for major revision : 

1.      Authors have just compiled little above 80 papers and among which nearly half do not connect with the topic of the article. Moreover, most of the references are old and are out dated. Authors should look into how this articles is suitable for the journal ‘Sustainability’?? It is suggestive that there must be around 200 papers which must be compiled with critical evaluation using tables, figures, statistics, etc. that will help reader understand the concepts better.

2.      In section ‘Methods: Analysis of Literature’, the methodologies remained undescribed. There is no description about biochar and virgin adsorbent material in text. Also, literature data is not analysed.

3.      In Figure 1, the results of the literature search and the number of studies included according to PRISMA guidelines are presented. The authors haven’t explained figure 1. What does this flow diagram indicate?

4.      Authors suggest the use of ‘PRISMA guidelines’. Are these guidelines approved by MDPI or Scopus or Web of Science ? What makes you follow ‘PRISMA guidelines’?

5.      When you search the database from Scopus or web of science, you can find 1000’s of articles. Then why was that database not used for review compilation? Use Scopus or web of science database with papers from last 5-6 years.

6.      There are many grammatical and typographical errors in the manuscript which have not been removed.

After this paper may be reconsidered

Comments for major revision : 

1.      Authors have just compiled little above 80 papers and among which nearly half do not connect with the topic of the article. Moreover, most of the references are old and are out dated. Authors should look into how this articles is suitable for the journal ‘Sustainability’?? It is suggestive that there must be around 200 papers which must be compiled with critical evaluation using tables, figures, statistics, etc. that will help reader understand the concepts better.

2.      In section ‘Methods: Analysis of Literature’, the methodologies remained undescribed. There is no description about biochar and virgin adsorbent material in text. Also, literature data is not analysed.

3.      In Figure 1, the results of the literature search and the number of studies included according to PRISMA guidelines are presented. The authors haven’t explained figure 1. What does this flow diagram indicate?

4.      Authors suggest the use of ‘PRISMA guidelines’. Are these guidelines approved by MDPI or Scopus or Web of Science ? What makes you follow ‘PRISMA guidelines’?

5.      When you search the database from Scopus or web of science, you can find 1000’s of articles. Then why was that database not used for review compilation? Use Scopus or web of science database with papers from last 5-6 years.

6.      There are many grammatical and typographical errors in the manuscript which have not been removed.

After this paper may be reconsidered

Author Response

Reviewer #3

 

The authors are very grateful to the Reviewer for the valuable comments, recommendations, and suggestions on the manuscript “Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials”. When appropriate, revisions have been implemented accordingly.

Please find here in the following lines the detailed answers to the Reviewer and the reference to the related changes in the manuscript. Furthermore, additional changes (including syntax and grammar edits) were made to the manuscript (in “Track changes mode”).

 

Comments:  Authors have just compiled little above 80 papers and among which nearly half do not connect with the topic of the article. Moreover, most of the references are old and are out dated. Authors should look into how this articles is suitable for the journal ‘Sustainability’?? It is suggestive that there must be around 200 papers which must be compiled with critical evaluation using tables, figures, statistics, etc. that will help reader understand the concepts better.

In section ‘Methods: Analysis of Literature’, the methodologies remained undescribed. There is no description about biochar and virgin adsorbent material in text. Also, literature data is not analysed.

In Figure 1, the results of the literature search and the number of studies included according to PRISMA guidelines are presented. The authors haven’t explained figure 1. What does this flow diagram indicate? Authors suggest the use of ‘PRISMA guidelines’. Are these guidelines approved by MDPI or Scopus or Web of Science? What makes you follow ‘PRISMA guidelines’?

When you search the database from Scopus or web of science, you can find 1000’s of articles. Then why was that database not used for review compilation? Use Scopus or web of science database with papers from last 5-6 years.

 

 

Reply to all comments: We have performed a careful analysis of the literature following a standard methodology, internationally and widely known as PRISMA guidelines. PRISMA guidelines are an internationally recognized methodology to deal with systematic reviews, and it has been widely adopted internationally by all Publishers. Since the methodology is so well accepted, we think that is redundant to specifically report a motivation for its usage. Anyway, we have clarified this is in the text. We report here the web site and some reference papers.

 

http://www.prisma-statement.org/PRISMAStatement/PRISMAStatement

 

BMJ (OPEN ACCESS) Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021;372:n71. doi: 10.1136/bmj.n71

PLOS Medicine (OPEN ACCESS) Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. PLOS Medicine 2021;18(3):e1003583. doi: 10.1371/journal.pmed.1003583

Journal of Clinical Epidemiology (OPEN ACCESS) Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Journal of Clinical Epidemiology 2021

Systematic Reviews (OPEN ACCESS) Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Systematic Reviews 2021;10:89

International Journal of Surgery (OPEN ACCESS) Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. International Journal of Surgery 2021;88:105906. doi: 10.1016/j.ijsu.2021.105906

 

As explained in the paper (from line 153), the original search found 206 papers corresponding to the search conditions presented above (rows 132-135 of the paper). The exact string search is reported from row 135 to 138. We decided to limit the search from 2015 to now. The first screening excluded papers related to reviews, papers not written in English and the articles related to water purification. Papers were further limited to treatments already applied to existing plants and thus do not present relevant implementation problems, either in terms of complexity or cost. Of the final 55 papers, only 53 were fully available.

 

Comment 9:   There are many grammatical and typographical errors in the manuscript which have not been removed.

 

Reply: we have checked again the English of the text

 

 

Author Response File: Author Response.docx

Reviewer 4 Report

The AUthors have revised all suggested points 

Author Response

Thanks to the reviewer for the important work!

Round 3

Reviewer 2 Report

Hi Authors, 

 

Significant revisions were already made, however, there is really a dire need tp correct your conclusions:

"In conclusion, since the C-F bond is hardly biodegradable, the only treatment for PFAS contaminated waters having high performance is the removal of the molecules with adsorbent materials.

My comment: This is just one method in removing the PFAS and not the "only treatment".  Your claims are too conclusive which will confuse the scientific community. 

 

All in all, this is only a transfer from a liquid to a solid matrix, achieved by flocculation and coagulation, thus obtaining a more concentrated form. The solid matrix is more easily manageable and storable, but it does not perform a real degradation of the micropollutants.    To what grounds you have said that there is no real degradation?  Did you studied the reaction mechanism pathway of the process? 

 

Therefore, as a recommendation, at least on the long run, the main strategy should be to reduce or eliminate the PFAS from the production line of the different industrial processes. Even this recommendation is certainly not a novelty, it is still actual and needs to be transferred from theory to practice in real scale plants. So why do we need to read this paper if there is no novelty in it? 

 

Author Response

The authors are very grateful to the Reviewer for the valuable comments, recommendations, and suggestions on the manuscript “Removal of per- and polyfluoroalkyl substances by adsorption on innovative adsorbent materials”. Revisions have been implemented accordingly.

Please find here in the following the detailed answers to the Reviewer’s and the reference to the related changes in the manuscript. Furthermore, additional changes (including syntax and grammar edits) were made to the manuscript (in “Track changes mode”).

 

 

Comment:   

Hi Authors, 

 

Significant revisions were already made, however, there is really a dire need tp correct your conclusions:

"In conclusion, since the C-F bond is hardly biodegradable, the only treatment for PFAS contaminated waters having high performance is the removal of the molecules with adsorbent materials.

My comment: This is just one method in removing the PFAS and not the "only treatment".  Your claims are too conclusive which will confuse the scientific community. 

 

All in all, this is only a transfer from a liquid to a solid matrix, achieved by flocculation and coagulation, thus obtaining a more concentrated form. The solid matrix is more easily manageable and storable, but it does not perform a real degradation of the micropollutants.    To what grounds you have said that there is no real degradation?  Did you studied the reaction mechanism pathway of the process? 

 

Therefore, as a recommendation, at least on the long run, the main strategy should be to reduce or eliminate the PFAS from the production line of the different industrial processes. Even this recommendation is certainly not a novelty, it is still actual and needs to be transferred from theory to practice in real scale plants. So why do we need to read this paper if there is no novelty in it? 

 

Reply:

 

We thank the reviewer for the useful comments. We have improved the conclusions by providing some recommendations that derive from the analysis carried on in the paper. We have eliminated some overly strong claims such as the uniqueness of the adsorption treatment for PFAS removal. We have specified that the transfer reaction between the solid matrix and the liquid matrix does not lead to degradation especially for the short-chain molecules of PFAS.

 

“In conclusion, since the C-F bond is difficult to biodegrade, the treatment really applicable to already existing wastewater treatment plants for high performance PFAS-contaminated water is the removal of the molecules with adsorbent materials. All in all, this is a transfer from a liquid to a solid matrix, achieved by flocculation and coagulation, thus obtaining a more concentrated form. The solid matrix is easier to manage and store but does not carry out a real degradation of the micropollutants especially in relation to the short chain molecules of the perfluoroalkyl substances. Therefore, as a recommendation, at least on the long run, the main strategy should be to reduce or eliminate the PFAS from the production line of the different industrial processes. Even this recommendation is certainly not a novelty, it is still actual and needs to be transferred from theory to practice in real scale plants.”

Author Response File: Author Response.docx

Reviewer 3 Report

article can be accepted in current form

Author Response

Thanks you for the usefull work 

Best regards