Novel Collection Equipment Loaded with Superhydrophobic Sponge for Continuous Oil/Water Separation from Offshore Environments

Round 1

Reviewer 1 Report

The review of the manuscript entitled: “Novel collection equipment loaded with superhydrophobic sponge for continuous oil/water separation from offshore environments”. The work is interesting. By responding to the following comments and questions, the work can be ready for publication:

1.      The abstract is well written, however, it can be improved by adding the mechanisms of the obtained results. Why the possible recovery capacity is enhanced more than 4 times?

2.      At the end of the first paragraph; the authors mentioned the production recovery techniques. This sentence can be improved by presenting detailed techniques such as scale inhibitors and nanoparticle injection. For this purpose, the next papers can be used in the revision stage:

https://doi.org/10.1007/s13202-022-01583-1
https://doi.org/10.1016/j.molliq.2020.113250

3.      More literature review should be added in the introduction section by presenting the previous results

4.      Did the authors measure the porosity of 95.5%?

5.      What will be the results at temperatures higher than 22 C?

6.      The analysis of adsorption capacity by adsorption isotherm can provide predictive results. It can be a topic for future work.

7.      How is possible to consider the measurement of contact angle under oilfield conditions?

8.      The separation of oil and water can be predicted by developing models through RSM. It is recommended to add the results of the next studies to section 3.3. in the revised manuscript:

- https://doi.org/10.1016/j.fuel.2022.124270
- https://doi.org/10.1007/s11356-014-3511-6
- https://doi.org/10.1016/j.petrol.2019.106463

9.      Please add more details of the obtained results in the conclusion section.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Oil spill disasters occur every year around the world. In this regard, the manuscript "Novel Collection equipment loaded with superhydrophobic sponge for continuous oil/water separation from offshore environments" is very relevant. It demonstrates how to clean up such spills quickly, conveniently and safely. This development is very useful for society. Especially if it will be able to enter industrial production and use in the future. The manuscript is recommended for publication, but after a number of corrections.

1. I really like the introduction. It allows to understand the essence of the problem to the person who was not previously familiar with it. However, there is no part in it that reveals previous research on this topic. Please tell us about the world experience in the development of three-dimensional porous adsorbents. What materials are used for this? What are their advantages and disadvantages? What is the rationale for choosing your research subjects? Why do you use melamine sponge? Why do you use silicon oxide and aminopropyltriethoxysilane coupling agent to process it? Please answer these questions in the introduction in terms of hydrophilicity/hydrophobicity and previous research on the subject.

2. Please describe the sea water used in the section 2.1. It would be good to know its mineralization, or at least its density.

3. Figure 2 would be more logical to move to section 2.2.

4. If the method used for preparing the adsorbent has already been used in the literature, please provide the reference to this (section 2.2.)

5. The design of the equipment (section 2.4) is very interesting. Who is its author? Please indicate the creators of the equipment. If it has already been described in the literature, please provide the reference to it. In the event that this invention is new and made in the framework of this study, tell us about it. This will enhance the value of this manuscript.

6. Please indicate the material from which the equipment for collecting oil is made.

7. Please sign in Figure 5 the characteristic and important peaks that allow you to judge the changes that have occurred after the treatment of the melamine sponge (OH, O-Si-O and others)

8. What is the measurement error of adsorption capacity? Is there a big difference between the indicated values, taking into account the error for fresh and sea water (32.05 g/g and 31.45 g/g)?

9. What can be the reason for the sharp decrease in the adsorption capacity in water with pH=6? This is out of the ordinary. The maximum adsorption capacity is typical for neutral water (рН=7). The adsorption capacity decreases in water with an increase in pH to 8. With a straight-line pattern, the adsorption capacity in water pH = 6 should be maximum. However, on the contrary, it is minimal.

10. The conclusion says that the adsorption material was obtained by a green method. Should it be considered environmentally friendly if THF was used as a solvent?

Author Response

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Reviewer 3 Report

The article is devoted to the creation of superhydrophobic materials for the separation of water-oil mixture. The topic is relevant and has practical significance, but the authors failed to show the scientific component. The article requires significant revision and re-reviewing.

1) What is the science and scientific novelty of the research? What have the new authors done? The introduction is weak, there is no comparison with the results of other scientific groups (there are many articles on this topic in the literature). Why do we need PVC and silane (what is the principle of choice)?

2) The authors do not provide pore sizes for the sponge used.

3) Clause 2.2. Why are superhydrophobic sponges washed in water?

4) Superhydrophobicity and sorption capacity.

It is necessary to provide data on contact angles and sorption of water and oil for the original melamine sponge. Without this, it is impossible to compare and determine the effect upon transition to superhydrophobicity.

Unfortunately, the authors demonstrate a lack of understanding of the principle of using superhydrophobic materials for the manufacture of sorbents or filters. The sponge must be superhydrophobic and oleophilic, i.e. selectively not absorb water and absorb oil. There are no initial data on the sorption of water and oil by the original and modified sponge. From fig. 6, it is not clear what liquid the sponge absorbs, and the authors do not discuss the influence of pH and ionic strength of the solution on the amount of absorbed liquid. Why is sorption less in sea water?

There are similar works in the scientific literature, it is necessary to compare with the results obtained by the authors.

It is necessary to determine the amount of water in the adsorbed oil.

5) Fig. 3. The modified and original material have the same structure, what did the authors want to show?

6) Fig. 5 It is necessary to label the peaks in the figure. Check out the description and discussion of IR spectra.

7) Fig. 6. It is not clear from the caption and drawing what exactly the material absorbs (water or oil).

8) Fig. 5-9 Poor picture quality.

9) The conclusions are poorly written, there are no concrete scientific results.

Author Response

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Round 2

Reviewer 1 Report

The authors revised the work based on the comments. But, still, comments 2, 4, and 5 were not completely applied in the manuscript. 

# comment 2: please use both recommended references for the added text  of "It should be noted that adsorbents and device combination oil recovery technology can play a key role in reducing the impact of oil spill accidents, as well as protecting the environment"

- Khormali, A., Koochi, M.R., Varfolomeev, M.A. and Ahmadi, S., 2022. Experimental study of the low salinity water injection process in the presence of scale inhibitor and various nanoparticles. Journal of Petroleum Exploration and Production Technology, pp.1-14.

- Safari, M., Rahimi, A., Lah, R.M., Gholami, R. and Khur, W.S., 2020. Sustaining sulfate ions throughout smart water flooding by nanoparticle based scale inhibitors. Journal of Molecular Liquids, 310, p.113250.

# comment 4:  please add the used method of porosity determination to the manuscript. "We’ve measured the porosity of melamine sponge (MS) in our laboratory. The pristine sponge was firstly cut into cubes, then soaked into pure water. The sponge was then squeezed by several times to extrude air bubbles. The porosity was calculated as: ? = ?2−?1 ?? . Where M1 (g) and M2 (g) were the mass of MS before and after adsorption, respectively, p (g/cm3 ) represents the water density, and V is the sample volume"

# comment 6: you can add the response to this comment as follows: "The temperature effect is a topic for future works"

Author Response

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Reviewer 3 Report

Comments for author File: Comments.pdf

Author Response

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Round 3

Reviewer 3 Report

The authors did a good job and eliminated a number of comments. But I want to note that, despite the presented results on sorption, the article does not stand out in terms of novelty from a number of other “typical” articles.

1)      In the last paragraph of the introduction, the authors write that the main advantage of using PVC is its low cost, but what is the science in this? The question arises, how is the PVC attached to the surface of the melamine sponge? Also in this paragraph, the authors use the past tense: we prepared, we received ...., but these are not conclusions, it is necessary to show the idea of the work here.

The main feature of this article is the device designed by the authors, but in this case the article does not fit the subject of the journal.

2)      2) The authors do not want, or cannot, provide data on the sorption of water by the original and modified sponges. But this is very important, because when using a sponge to collect oil from the water surface, water can be captured. That's why it has to be waterproof.

3) L 270-276

In this formulation, the amino groups interact with sea water, i.e. its sorption is observed (see comment 2).

4) Remove the term "outstanding" (line 17, 277, 362).

I think that the material can be published after revision and the decision of the editor: it is necessary to correctly place the accents.

Author Response

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