Assessing the Performance of Environmentally Friendly-Produced Zerovalent Iron Nanoparticles to Remove Pharmaceuticals from Water

Round 1

Reviewer 1 Report

The manuscript by Panagou and co-workers discusses the preparation and adsorption performance of a new composite material. The work has some merits and somewhat fits into the scope of the selected journal. However, there are multiple points to meet the high standards of the journal and complete the study before further consideration.

1. The abstract needs to mention the novelty of the work. The need and the general interest are clear. However, the novel aspects, what the authors achieved for the first time, is unclear. How has the field been advanced?
2. The introduction is too short and does not provide a sufficient background and context to the work.
3. What was the rationale for the selection of the feed concentration range? It seems to be much higher than the practically relevant concentrations in real world samples. The authors should elaborate on this and provide justification in the manuscript.
4. A figure summarizing the synthesis and preparation steps should be added at the beginning of the manuscript. This will help to understand the nanomaterials fabrication.
5. In general, there is a growing concern about the faith of nanoparticles and any nanomaterial in nature. Given that the publication is intended for a sustainable-oriented audience, have the authors considered this aspect? The authors should mention a white paper on this concern dealing with the sustainability aspect of the topic (10.1016/B978-0-12-814681-1.00001-1).
6. Is this an isolated case study, or can be applied for any non-steroidal anti-inflammatory drugs (NSAIDs)? Can it also be extended to other drug or non-API pollutants?
7. What is the effect of the matrix on the performance? The intended application has a complex matrix and a very low NSAID concentration. The authors should elaborate on this.
8. Error bars are provided in the manuscript, which is appreciated. However, their derivation is not mentioned. The authors should explicitly write how many independent batches of nanomaterials were prepared and used independently to obtain the set of data, which resulted in the averages and standard deviations.
9. The introduction focuses on the materials aspects only. Add one or two paragraphs on the sustainability aspects as well, given the journal selected for the publication. A better context should be set. Mention the use of leave extracts (line 70) in general, what are the recent work on their sustainable utilization (10.1039/D1GC00675D; 10.1021/acssuschemeng.9b04245; 10.1021/acsapm.1c01242)?
10. Cyclic studies should be performed. What is the estimated lifetime and reuse potential of these nanoparticles? How can they be most efficiently recovered? Data and discussions should be provided on these points. For the intended application, it is crucial to be able to recycle efficiently the nanoparticles. How can they be recovered from real samples?
11. Materials chemistry and morphological characterization of the nanoparticles should be provided in the manuscript.
12. The main research findings should be summarized in quantitative statements in the Conclusion part. Mention the potential but also the limitations and drawbacks of the proposed materials and methodologies.

Author Response

Please see the attachment below

Author Response File: Author Response.pdf

Reviewer 2 Report

This is an interesting read, with a good methodology and discussion. However, the novelty if the study was not well articulated and supported. Furthermore, please see below some suggestions that may contribute to add value to the text:

Key results should be provided in the abstract, such as the values of the removal efficiencies, the duration of the contact time with the targeted compounds, and the dose of R-nFe. 

Line 40: I guess you meant "they can interact with ... "

Line 42: What are the adverse effects on the fauna and human life you mentioned? Listing these effects could add value to this paragraph.

Line 59: Acronyms (TCEs here) should be defined before being used in the text

Line 71: please re-phrase this sentence

Line 140: what were the flasks agitated with?

Line 150: Please re-phrase this sentence

Line 178: please explain the C/Co ratio before using its acronym

Line 180: why was the experiment initially set up for 180 minutes?

The error bars in figure 2 look cropped, do they represent the standard deviation or a certain confidence interval? Also, it could have been more descriptive to use a line plot instead of a scatter plot to represent the decrease of the concentration of targeted compounds with time, for both figure 2 and 3. This also will show whether equilibrium was reached or not.

Line 179: Why was the removal of KFP as low?

Sub-headings 3.2 and 3.3 have the same title, maybe providing more details for each section could distinguish them.

Figure 3.a is missing a legend. 

Figure: It doesn't look obvious that the equilibrium was reached after 48 hours of contact time for NPX, and DCF. Why was the experiment limited to 48 hours?

The effect of pre-treated R-nFe on the removal of KTP is clearly illustrated in Figure 3.b. Why was the difference more pronounced in this case as compared to other targeted compounds?

It looks like figures 4.a, 4.b, 5.a, and 5.b were cropped at a C/Co of 1. The use of the original figures could have been better to properly display the error bars. Here again, what do the error bar represent? This specification should be added to the text. 

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript presents the results of a study on the application of nZVI for the degradation or removal (which is not clear based on the original results presented in the manuscript) of some pharmaceutical compounds. My specific comments are as below:

1. What do you mean by green produced? I think there is a grammatical error in here?
2. Abstract: “Non-steroidal anti-inflammatory drugs (NSAIDs) are pharmaceutical compounds that are 14 used on a large scale all over the world to treat inflammatory diseases and pain. These compounds 15 are known to be recalcitrant and conventional wastewater treatment plants are typically not de- 16 signed to remove them, thus allowing their entry to the environment and putting aquatic life and 17 human health at great risk. Nano Zero Valent Iron (nZVI) has been employed for removing a wide 18 range of complex compounds from water and soil, offering a promising alternative method towards 19 the elimination of NSAIDs.” Almost half of the abstract without any direct relation to the methodologies and results of the present study. Also, almost no results have been presented in the abstract.
3. Introduction: “The main advantages of ZVI nanoparticles are the small particle size, large specific area, and high reactivity”. These are the specifications of nano zero valent iron not zero valent iron.
4. Charazterization of the materials: “The morphology of resin beads was studied using a scanning electron microscope 132 (SEM), JEOL6380LV. The elemental microanalysis of observed surfaces was carried out by 133 an energy dispersive system (EDS). The resin samples were prepared by incorporating 134 them in a cylindrical epoxy matrix which was cut and abraded to obtain a cut section of 135 the incorporated resin beads.”. The most important characterization is XRD which is missing here. How do you prove the formation of zero valent iron, not iron oxides?
5. The authors need to justify the novelty of the work in the discussion section. Which results differ your paper from those that have been already published in the literature?
6. The conclusion does not include any numerical value. Furthermore, the future outlook is missing. Also, it has not been discussed which structural changes will happen to nZVI and whether they can be recovered and re-used?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The manuscript has improved and the comments have been addressed.

Reviewer 3 Report

I do believe that the authors have applied the comments/concerns raised by the reviewers.