Reduction of Oxidizable Pollutants in Waste Water from the Wadi El Bey River Basin Using Magnetic Nanoparticles as Removal Agents
, Nedra Asses 2, Karima Horchani-Naifer 1, Mounir Ferhi 1, Gerardo F. Goya 4,5 and Jesús Antonio Fuentes-García 4,5,*Round 1
Reviewer 1 Report
1. This study selected actual polluted water to study the purification performance of MNPs. In order to better understand the pollution situation of water sources and predict the practical application value of MNPs, please supplement the basic water quality summary (COD, BOD, turbidity, etc.) of the water sample to fully understand the water source situation.
2. Considering the magnetic properties of MNPs, vibrating sample magnetometer (VSM) was supposed to be occupied to measure the saturation magnetization of materials and then draw the hysteresis loop to explore the magnetic separation potential of MNPs.
3. In order to ensure the scientific nature of the experimental results, please conduct parallel experiments in the nanomaterial efficiency experiment and represent them in the form of error lines in the figure.
4. Considering the practical application value of the MNPs, please study its recycling treatment ability for polluted water.
Author Response
Reviewer #1:
- This study selected actual polluted water to study the purification performance of MNPs. In order to better understand the pollution situation of water sources and predict the practical application value of MNPs, please supplement the basic water quality summary (COD, BOD, turbidity, etc.) of the water sample to fully understand the water source situation.
Response: Thank you for your comments. We have added a new paragraph (from 123 to 134 lines) in the revised manuscript that provides the relevant information on COD, BOD5, turbidity, and other parameters for each water sample tested. This additional information would allow for a more comprehensive understanding of the water source situation, as you suggested. We hope that you are satisfied with the changes.
- Considering the magnetic properties of MNPs, vibrating sample magnetometer (VSM) was supposed to be occupied to measure the saturation magnetization of materials and then draw the hysteresis loop to explore the magnetic separation potential of MNPs.
Response: Unfortunately, the magnetic properties of the presented materials were not studied. The VSM measurements for the materials used in our study are unavailable due to facilities issues and sample scarcity (from the same batch). However, the results point to the influence of magnetic separation in increasing the removal of pollutants by at least 10%. We have the theory that, in an experiment without magnetic field application, it is possible to remove a small amount of MNPs, while under magnetic field, the MNPs are attracted to the magnet and we only carry waste water.
- In order to ensure the scientific nature of the experimental results, please conduct parallel experiments in the nanomaterial efficiency experiment and represent them in the form of error lines in the figure.
Response: The authors apologize the methodology issue; it was addressed performing all measurements by triplicate. Also, as suggested, the errors bars have been added in the corresponding figures.
- Considering the practical application value of the MNPs, please study its recycling treatment ability for polluted water.
Response: We appreciate the reviewer's suggestion. As a result, we conducted an experiment of regeneration to evaluate the potential of MNPs in this regard. These results have been added to the revised manuscript (Figure 6 and Discussion).
Reviewer 2 Report
I have read the manuscript “Reduction of oxidizable pollutants in waste water from the 2
Wadi El Bey river basin using magnetic nanoparticles as removal agents” and think that this is an interesting work and can be considered for publication. These days the usage of MNPs as a decontaminant agent demands the development of new and efficient protocols, which is rather difficult to achieve. Nevertheless, the manuscript contains some errors in English and also it would require some accurate revision in the text format/organization due to lots of mistakes harming sometimes comprehension. If the authors can address the related issues in the manuscript, then it can be reconsidered for the press, in my opinion
1) The author should state the shortcomings of the current technology and the novelty of the author's method concretely
2) Provide more literature on the removal of drug contaminants to improve the feedback related to this work. To better representation of Results and Discussion, go through some recently published papers and improve:
https://doi.org/10.1007/s10924-022-02388-3
3) Units in all sections should be uniform, and significant figures and tables should be uniform accordingly.
4) The author should, if”s possible data regarding the magnetism properties of the MNPs and compare them with other magnetic materials
5) I consider the XRD spectra description of Fe3O4 lacking scientific rigor. Please refer to the new references.
6) The conclusions appear more like a summary of the study. In this part, it is expected that the authors would synthesize all the findings and draw conclusions vis-a-vis their implications. What are the major implications of the study findings on the practical applications of MNPs? etc
The manuscript contains some errors in English and also it would require some accurate revision in the text format/organization due to lots of mistakes harming sometimes the comprehension
Author Response
Reviewer #2:
- The author should state the shortcomings of the current technology and the novelty of the author's method concretely
Response: Thank you for your comment. For more clarity and readability, we have addressed the shortcomings of the current technology and the novelty of the employed methods in the revised manuscript.
2) Provide more literature on the removal of drug contaminants to improve the feedback related to this work. To better representation of Results and Discussion, go through some recently published papers and improve:
Response We agree with reviewer´s opinion is a relevant issue, but is not the focus of the report. In the revised version, we have provided a paragraph (lines 42-46) to include this suggestion in the framework.
3) Units in all sections should be uniform, and significant figures and tables should be uniform accordingly.
Response: We thank the reviewer for their observation. We have thoroughly reviewed our manuscript and made the necessary revisions to ensure that the units in all sections are uniform. We have also made sure that the significant figures and tables are uniform accordingly. We believe that these revisions will improve the presentation of our results and make them clearer and more concise.
4) The author should, if”s possible data regarding the magnetism properties of the MNPs and compare them with other magnetic materials
Response: We agree with the reviewer's comment that it would be helpful to provide data regarding the magnetism properties of the MNPs. We did not determine the magnetism properties of the MNPs because facilities issues and samples scarcity. However, we need to conduct further experiments to determine the exact nature of the magnetism and to compare the magnetism properties of the MNPs with other magnetic materials. We apologize for the limitations of this study. We hope that our future research will provide more information about the magnetism properties of MNPs.
5) I consider the XRD spectra description of Fe3O4 lacking scientific rigor. Please refer to the new references.
Response: We appreciate the reviewer's intention to improve the XRD discussion. We have expanded our analysis by including additional comparisons with relevant literature using and incorporating recent references (40, 41) that strengthen the interpretation and rigour of our results.
6) The conclusions appear more like a summary of the study. In this part, it is expected that the authors would synthesize all the findings and draw conclusions vis-a-vis their implications. What are the major implications of the study findings on the practical applications of MNPs? Etc
Response: We try to clarify the statements of the conclusions, the modifications were made in the revised version of the manuscript.
Reviewer 3 Report
The article entitled “Reduction of oxidizable pollutants in waste water from the 2 Wadi El Bey river basin using magnetic nanoparticles as removal agents” is an interesting research and the construction of the article is logical. Scientific merit is good. The work is relevant and practical. Clarity of expression and communication of ideas, readability and discussion of concepts is low.
More specific description or relevance to the Wadi Bay River Basin is needed as the article presents itself as an application/case study for the Tunisian region. How does the optimal parameters compare to other techniques currently used to reduce COD and BOD5? How does the optimal application pH of 8 relate to the basin's natural pH, or the wastewater pH? Will pH need to be adjusted for application? How will it be adjusted?
Authors say in the discussion that literature studies report optimal contact time between 20-120 min to justify their contact time of 80 min. However, in the discussion and cited texts, all contact times mentioned vary 20-60… Why is 80 minutes ok if comparable applications produce similar COD or BOD5 removal % at much shorter times?
More information is need on how the DC magnetic current was applied to the samples and ho it will be used in the ultimate application of reducing BOD5 and COD for the river basin influents.
Some corrections are needed:
1. Check all BOD5 are subscript.
2. There should be a brief summary of the material synthesis before presenting results
3. Make sure citations are clearly labeled within text
4. Check chemical formulas of ions to ensure superscript of charges
5. Further explain BET technique or cite it
6. Be consistent on how figures are references within the text. Check that the correct figure is being referred to in the text. (i.e., Line 275 references figure 4d when it should be 4b)
7. In the discussion there are references made to other works but there are no citations… Similarly, reference to findings of “many researchers” is stated but only one referenced presented.
8. Make sure all abbreviations are clearly defined in the text when they are first used
Double check the grammar throughout the text. At time it seems more than one person wrote the article and it is clear one has better writing skills than the other. Make sure the entire article flows well together
Some paragraphs throughout the text do not read well. The process to measure BOD5 can be better explained. Seems like several sentences jumbled together instead of a flowing paragraph. In discussion, the first paragraph is one long sentence, consider rewriting. Other paragraphs in the discussion need to be rewritten as several sentences instead of one long sentence
Lots of grammatical errors, misspellings, and missing words throughout text (specially in the results section)
Author Response
Reviwer#3
More specific description or relevance to the Wadi Bay River Basin is needed as the article presents itself as an application/case study for the Tunisian region. How does the optimal parameters compare to other techniques currently used to reduce COD and BOD5?
Response: We thanks the reviewer´s observations, we added a new paragraph (lines 123-134) in the revised manuscript that provides the relevant information on COD, BOD5, turbidity, and other parameters for each water sample tested. This additional information allows for a more comprehensive understanding of the water source situation, as suggested.
How does the optimal application pH of 8 relate to the basin's natural pH, or the wastewater pH? Will pH need to be adjusted for application? How will it be adjusted?
Response: We appreciate this observation. Regarding the optimal application pH of 8, it is noted that the natural pH of the Wadi Bay river basin is around 7.5, although the pH in those regions with high pollutants concentration can vary significantly depending on the water source and quality. We selected this pH value since a significant improvement in the method's efficacy, but we do not foresee the need to add a way to change the conditions (e.g. adding a base) of the proposed application, since the material works also at lower pH.
Authors say in the discussion that literature studies report optimal contact time between 20-120 min to justify their contact time of 80 min. However, in the discussion and cited texts, all contact times mentioned vary 20-60… Why is 80 minutes ok if comparable applications produce similar COD or BOD5 removal % at much shorter times?
Response: We agree with the reviewer that studies in the literature mention optimal contact times ranging from 20 to 60 minutes, and our selection of the contact time of 80 minutes in our study was motivated by several considerations. First, we conducted preliminary experiments to evaluate the kinetics of COD and BOD5 reduction using different contact times. These preliminary results showed that significant reduction efficiencies were achieved within the first 60 minutes, with decreasing efficiencies beyond this time. However, we opted for an extended contact time of 80 minutes to ensure that a substantial proportion of the pollutants were adsorbed and removed adequately.
Furthermore, although comparable applications in the literature may show similar percentages of COD or BOD5 reduction at shorter contact times, it is essential to take into account the specific conditions and target contaminants of each study. Factors such as the concentration and nature of the pollutants, the characteristics of the treatment materials and the desired level of reduction can influence the optimum contact time. In our case, given the characteristics of the Wadi Bay water and the targeted pollutants, we found that a contact time of 80 minutes provided satisfactory reduction efficiency.
We recognise that further investigation and optimisation of the contact time could be explored in future studies. These could involve assessing the balance between treatment efficiency and time, and taking into account the specific requirements and constraints of practical applications.
More information is need on how the DC magnetic current was applied to the samples and how it will be used in the ultimate application of reducing BOD5 and COD for the river basin influents.
Response: During our tests, we used permanent magnets with intensity magnetic field 0.33 Tesla (without current). The principle of action of the magnetic field to reduce BOD5 and COD for the river basin is detailed in the section (4) of the manuscript.
Some corrections are needed:
- Check all BOD5 are subscript.
Response: The modification is made to the manuscript.
- There should be a brief summary of the material synthesis before presenting results
Response: A brief summary of the material synthesis was added before presenting results.
- Make sure citations are clearly labeled within text
Response: The modification is made to the manuscript.
- Check chemical formulas of ions to ensure superscript of charges
Response: The chemical formulas of ions are checked
- Further explain BET technique or cite it
Response: The section explained the BET technique are added
- Be consistent on how figures are references within the text. Check that the correct figure is being referred to in the text. (i.e., Line 275 references figure 4d when it should be 4b)
Response: The modification is made to the manuscript.
- In the discussion there are references made to other works but there are no citations… Similarly, reference to findings of “many researchers” is stated but only one referenced presented.
Response: The modification is made to the original manuscript.
- Make sure all abbreviations are clearly defined in the text when they are first used
Response: we addressed the abbreviations suggestion.
Round 2
Reviewer 1 Report
The authors have adequately considered the comments of the referees and markedly improved the quality of the manuscript. I can now recommend publication after a few very minor editing of English language.
Reviewer 3 Report
Suggestions were incorporated. Article reads much better with sound scientific findings
