Exploring the corrosion inhibition capability of FAP-based ionic liquids on stainless steel

Corrosion is clearly one of the more common causes of materials failure in stainless steel. To manage corrosion, chemical inhibitors are often used for prevention and control. Ionic liquids due to their hydrophobic and corrosion-resistant property are being explored as alternative protective coatings and anti-corrosion materials. In this particular study, ionic liquids containing functionalized imidazolium cations and tris(pentafluoroethyl)trifluorophosphate (FAP) anions were investigated for their ability to inhibit corrosion on stainless steel surfaces in acidic environment. Using surface characterization techniques, specifically scanning electron microscopy and energy-dispersive X-ray (EDX), the morphology and the elemental composition of the steel surfaces before and after corrosion were determined. Contact angle measurements were also performed to determine how these ionic liquids were able to wet the stainless steel surface. In addition, potentiodynamic studies were carried out to ensure that corrosion inhibition has occurred. Results show that these ionic liquids were able to inhibit corrosion on the stainless steel surfaces. This indicates promise in the use of these FAP-based ionic liquids for corrosion management in stainless steel.


Comments to the Author(s)
In the discussion of Figure 9, it should be stated what the regions a and b refer to.
In Table 3, there is no need to abbreviate what are presumably "without" and "with".

Review form: Reviewer 2
Is the manuscript scientifically sound in its present form? Yes

Recommendation?
Major revision is needed (please make suggestions in comments)

Comments to the Author(s)
The manuscript describes a study of FAP-based ionic liquids (ILs) as anti-corrosion reagents for stainless steel. The FAP anion is known to be stable against acids compared with BF4 and PF6 anions and therefore was used as the IL anion in the present study. Because the results are interesting I do not deny the publication of the manuscript to RSOS. The followings are major amendments before the publication.
Amide anions such as TFSA and BETI are also hydrophobic and acid-stable. Another good point is the cost; they are much cheaper than FAP. The authors should comment on why they used FAP in Introduction.
I cannot understand the discussion of Figs. 6 and 7 using "excess positive charge" and "excess negative charge" (p.5 4th paragraph). Is the "charge" located on the steel surface, the IL surface, or the steel/IL interface? Why and how did the positive charge generate at first? Why does the negative charge make IL spread on the surface? Also, they attributed the formation of 4 um size IL globules to micelle formation, but 4 um is too big (three orders of magnitude bigger) for micelles. I also do not understand "with EDX exposure and minus EDX exposure" in Fig.7 caption. Does "EDX exposure" mean electron beam irradiation? What is "minus EDX exposure"? They should clearly explain what they did.

Dear Dr Martinez:
Title: Exploring the Corrosion Inhibition Capability of FAP-based Ionic Liquids on Stainless Steel Manuscript ID: RSOS-200580 Thank you for submitting the above manuscript to Royal Society Open Science. On behalf of the Editors and the Royal Society of Chemistry, I am pleased to inform you that your manuscript will be accepted for publication in Royal Society Open Science subject to minor revision in accordance with the referee suggestions. Please find the reviewers' comments at the end of this email.
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In Table 3, there is no need to abbreviate what are presumably "without" and "with".

Reviewer: 2
Comments to the Author(s) The manuscript describes a study of FAP-based ionic liquids (ILs) as anti-corrosion reagents for stainless steel. The FAP anion is known to be stable against acids compared with BF4 and PF6 anions and therefore was used as the IL anion in the present study. Because the results are interesting I do not deny the publication of the manuscript to RSOS. The followings are major amendments before the publication.
Amide anions such as TFSA and BETI are also hydrophobic and acid-stable. Another good point is the cost; they are much cheaper than FAP. The authors should comment on why they used FAP in Introduction.
I cannot understand the discussion of Figs. 6 and 7 using "excess positive charge" and "excess negative charge" (p.5 4th paragraph). Is the "charge" located on the steel surface, the IL surface, or the steel/IL interface? Why and how did the positive charge generate at first? Why does the negative charge make IL spread on the surface? Also, they attributed the formation of 4 um size IL globules to micelle formation, but 4 um is too big (three orders of magnitude bigger) for micelles.
I also do not understand "with EDX exposure and minus EDX exposure" in Fig.7 caption. Does "EDX exposure" mean electron beam irradiation? What is "minus EDX exposure"? They should clearly explain what they did.

Miscellaneous
Please define PREN (Table 2) work has -> work, has (p.2, l.26) where -> were (p.2, l.40) by the group -> by our group (p.2, l.52) filliform -> filiform (p.4, l.19) approximately 3.85 um -> approximately 4 um (p.5, l.29) however were -> however, was (p.5, l.41) there was not -> there were not (p.5, l.42) are be -> are (p.5, l.59) lnJ -> ln(J/A cm^-2) ? (Fig.11  It is a pleasure to accept your manuscript in its current form for publication in Royal Society Open Science. The chemistry content of Royal Society Open Science is published in collaboration with the Royal Society of Chemistry. The comments of the reviewer(s) who reviewed your manuscript are included at the end of this email.
Thank you for your fine contribution. On behalf of the Editors of Royal Society Open Science and the Royal Society of Chemistry, I look forward to your continued contributions to the Journal.