Review Reports - Single and Double Alkyl Chain Quaternary Ammonium Salts as Environment-Friendly Corrosion Inhibitors for a Q235 Steel in 0.5 mol/L H<sub>2</sub>SO<sub>4</sub> Solution

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The Authors have succeeded excellently two salt ionic liquids, namely octadecyl trimethyl ammonium chloride ionic liquids (OTAC) and dioctadecyl dimethyl ammonium chloride (DDAC), as environment-friendly corrosion inhibitors for Q235 steel in 0.5 M H2SO4 solution, in which the results showed that the steric hindrance effect of the double alkyl chain was not conducive to the adsorption of DDAC on the surface of steel electrodes.

Also, finally the authors has concluded professionally that these systematic studies not only provided an idea for the spatial structure of corrosion inhibitors, but also enriched their types.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The abstract needs to be corrected. It does not introduce the reader to the work, it contains a lot of names and abbreviations. It should indicate the purpose of the work, methodology and conclusions, but this is not there.

The materials are described very generally and in little detail. Few research methods have also been described. Some of the research methods from which the results are presented in the article are missing.

The description regarding contact angles does not clearly mention wetting with which liquid it is. You can guess that it is about water, but it is not indicated. If we want to say that the sample is hydrophobic, the water contact angle should be greater than 90 degrees. The description needs to be changed.

To sum up, only 2 substances were used in the research and, based on the results obtained, they were only compared with each other. No comparative use of other products would show the advantage of the two substances described.

The number of substances used should be increased, the methodology and the description of test results should be significantly improved.

Comments on the Quality of English Language

The language of the article is understandable. It should be read carefully again and some corrections made.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Comments to the authors

Manuscript Submission ID coatings-2632508

Title: Single and double alkyl-chain quaternary ammonium salts as environment-friendly corrosion inhibitors for Q235 steel in 0.5 M H2SO4 solution

General comments:

The study aimed the evaluation of OTAC as corrosion inhibitor for Q235 steel in sulfuric acid media. The manuscript is interesting and fits the journal goals. English revision is required. Some specific comments to the authors:

- The Abstract is too short and should contain the novelty and main results.

- I recommend the use of “mol/L” rather than “M”.

- I also recommend the authors to state the main corrosion inhibitors and ionic liquids reported in literature in Introduction section.

- Page 2 line 64: what is the unit “grits”?

- Equations 1 and 2: improve the quality.

- Page 5: the formatting needs improvement.

- Chapter 3.3: needs discussion.

- Chapter 3.4: why only Langmuir isotherms was evaluated? If it is “the most suitable mode to match the data of polarization curves” (line 247-248), why evaluate it?

- Conclusion section must be numbered.

- Comparison to the literature is missed.

Comments on the Quality of English Language

There are small mistakes and sentences repeated.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The study focuses on comparing the effectiveness of two quaternary ammonium salt ionic liquids, OTAC and DDAC, as corrosion inhibitors for Q235 steel in a sulfuric acid solution. It concludes that OTAC demonstrates superior anti-corrosion properties compared to DDAC. However, the discussion section of the study requires enhancement and further discussion of the results.

Comments on the Quality of English Language

Author Response

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Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

REPORTS ON: coatings-2632508

Although the proposed manuscript has Novelty and it is reasonably organized, there are certain weaknesses, which induce that a MAJOR REVISION is requested before its final publication, as follow:

1. Firstly, in the Abstract, a simple present tense should only be used. Also, English written style should be revised and improved.

2. Into the Introduction section, although in the last paragraph, the NOVELTY is implicit, it is hardly suggested that this be clarified. For this purpose, new sentence should be included to evidence the technological/scientific.

3. In section 2, all dimensions should be accompanied with their error ranges. Besides, all experimentations should be detailed concern to duplicate or triplicate to guarantee its reproducibility. This is rather and poorly detailed/described.

4. At line 77, it is mentioned that a scan rate of 1 mV/s is applied. It is remarked that potential scan rate has an important role in order to minimize the effects of distortion in Tafel slopes and corrosion current density analyses, as previously reported [AA-CC]. In this sense, it is suggested that the follow references be included.

[AA] Duarte T, Meyer Y.A. Osório W.R. The Holes of Zn Phosphate and Hot Dip Galvanizing on Electrochemical Behaviors of Multicoatings on Steel Substrates. Metals 2022, 12(5): 863; https://doi.org/10.3390/met12050863

[BB] Zhang X.L., Jiang Zh.H., Yao Zh.P, Song Y., Wu Zh.D. Effects of scan rate on the potentiodynamic polarization curve obtained to determine the Tafel slopes and corrosion current density. Corrosion Science. 2009, 51: 581-587.

[CC] E. McCafferty. Validation of corrosion rates measured by Tafel extrapolation method. Corr. Scie 47 (2005) 3202-3215.

5. When Tables 1, 2, 3 and 4 are depicted, it is also hardly suggested that icorr error values be included.

6. When EIS plots are shown and discussed, the follow sentences and references should be included:

“In order to determine the impedance parameters using simulations correlated with the experimental data obtained, a complex non-linear least squares (CNLS) simulation is utilized [AA;DD].

[DD] YA Meyer, I Menezes, RS Bonatti, AD Bortolozo, WR Osório. EIS investigation of the corrosion behavior of steel bars embedded into modified concretes with eggshell contentes. Metals 2022, 12(3), 417; https://doi.org/10.3390/met12030417

7. Tables 2 and 4 should be revised and the error ranges corresponding with “Rct” and “RL”, and “Y0” and “CDL” should obligatory be demonstrated.

8. A New FIGURE 9 should be included in the revised manuscript in order to depict the “post-mortem” SEM micrographs of each one of the examined samples.

9. In Fig. 9, that should be renumbered, as Fig. 10, the term “Tafel” should be replaced with another more appropriated. Although it is understood that “icorr” values by using Tafel extrapolation are used, it is hardly suggested to be replaced with other ones.

10. The conclusion section should be meticulously revised and improved. It is very summarized and bullets should be adopted.

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Comments on the Quality of English Language

No comments.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 5 Report

Comments and Suggestions for Authors

Based on the revised version of the proposed manuscript , in my frank opinion, it deserves its final publication.