Novel Perimidine Derivatives as Corrosion Inhibitors of HRB400 Steel in Simulated Concrete Pore Solution

Round 1

Reviewer 1 Report

The results have significance for enhancing the durability of concrete structures. Below are a few comments to be addressed:

 

1. Several works will be available on naphthalene and pyrimidine derivative-based corrosion inhibitors in different applications. The authors shall cite a few more relevant works/reviews in the introduction and emphasize the present study's novelty. More specific references for the remarkable rust-resisting effect of the corrosion inhibitors shall be added (10.1016/j.porgcoat.2019.105511)

2. Why weight loss experiments were not conducted to evaluate the inhibitor performance.

3. English need to be improved, for example.... ‘This study demostrates that add perimidine derivatives’, .. ‘corrosion of chlorine ion’ ....etc.

 

 

Author Response

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

The Ag/AgCl represents the redox couple of the reference electrode that is immersed in KCl solution (mostly saturated), therefore the symbol is Ag/AgCl, KCl_sat (line 89)

In the evaluation of the results, it must be stated from what the given conclusion can be drawn and which clauses of the references support it. (Lines 161, 168)

The I_corr values can be read from the table, it is not necessary to mention them separately. (Lines 175-177)

Since the inhibitory effect increases as the concentration of the inhibitor increases, why wasn't a higher concentration than 0.12 mM also used? Anyway, there is usually an optimal concentration of the inhibitor, at which the inhibitory effect reaches a maximum.

It is usually tested at 5 different concentrations (but there can be more).

The calculation formula for the surface coverage must be specified or its relation to the inhibition efficiency.

It is customary to fit a straight line through at least 5 points. (Fig 5)

The quality of the EIS fitting represented by χ² must be specified (Table 2)

I suggest the revision of results presentation.

Author Response

1. The Ag/AgCl represents the redox couple of the reference electrode that is immersed in KCl solution (mostly saturated), therefore the symbol is Ag/AgCl, KClsat (line 89)

Response: According to the good advice, The Ag/AgCl was modified.

2. In the evaluation of the results, it must be stated from what the given conclusion can be drawn and which clauses of the references support it. (Lines 161, 168)

Response:  According to the good advice, the Ref 27 was replaced with the more relevant Ref.

“It can be seen from Table 1 that with the increase of inhibitor concentration, the corrosion potential gradually shifts positively, and the corrosion potential shifts more than 85 mV after adding the inhibitor, the results indicate that the two perimidine derivatives PMD and SPMD are anodic corrosion inhibitors [24-26].”

“This can be attributed to perimidine derivative molecules and chloride ions compete on the surface of the specimens, the inhibitor is adsorbed on the surface of the steel to prevent the adsorption of chloride ions onto steel surfaces, thereby inhibiting the corrosion of the steel [27,28].”

[27] Y. Zhao, T. Pan, X. Yu, D. Chen. Corrosion inhibition efficiency of triethanolammonium dodecylbenzene sulfonate on Q235 carbon steel in simulated concrete pore solution[J]. Corrosion Science, 2019, 158:108097-108109.

 

3. The Icorr values can be read from the table, it is not necessary to mention them separately. (Lines 175-177)

Response: The manuscript has been deleted Lines 175-177.

“The Icorr value of the blank SCP solution was 23.69 μA/cm², and the Icorr value of the SCP solution containing PMD and SPMD inhibitors decreased to 3.68 μA/cm2 and 2.94 μA/cm2, respectively. The inhibition efficiency of PMD and SPMD were 84.4 % and 87.61 % respectively.”

 

4. Since the inhibitory effect increases as the concentration of the inhibitor increases, why wasn't a higher concentration than 0.12 mM also used? Anyway, there is usually an optimal concentration of the inhibitor, at which the inhibitory effect reaches a maximum.

Response: In the paper, 0~0.12mM was used as the concentration range for the study of perimidine derivatives, which was determined by a large number of experiments, firstly through wet and dry cycle experiments, and within a certain range, each group of concentrations corresponds to 3 parallel experiments, and then electrochemical experiments were conducted. Due to the high electrochemical sensitivity, a large number of repeated experiments and parallel experiments were needed. At least 3 parallel experiments were conducted in each group to determine the study range of concentration in this paper.

 

5. It is usually tested at 5 different concentrations (but there can be more).

Response: In this paper, 0~0.12mM was used as the concentration range for the study of perimidine derivatives, which was determined by a large number of experiments, firstly through wet and dry cycle experiments, and within a certain range, each group of concentrations corresponds to 3 parallel experiments, and then electrochemical experiments were conducted. Due to the high electrochemical sensitivity, a large number of repeated experiments and parallel experiments were needed. At least 3 parallel experiments were conducted in each group to determine the study range of concentration in this paper.

 

6. The calculation formula for the surface coverage must be specified or its relation to the inhibition efficiency.

Response: The surface coverage (θ) is equal to inhibition efficiency (IE%) obtained from the electrochemical measurements.

7. It is customary to fit a straight line through at least 5 points. (Fig 5)

Response: According to the good advice, but it is to fit a straight line through 4 points in more papers. (Fig 5)

such as:

[1] D. Alokdut, S. K. Sourav, B. Priyabrata, et al. Correlating electronic structure with corrosion inhibition potentiality of some bis-benzimidazole derivatives for mild steel in hydrochloric acid: Combined experimental and theoretical studies[J]. Corrosion Science, 2015, 98:541-550.

[2] X. Zhou, H Yang, F. Wang. Investigation on the inhibition behavior of a pentaerythritol glycoside for carbon steel in 3.5% NaCl saturated Ca(OH)2 solution[J]. Corrosion Science, 2012, 54:193-200.

[3] D. Dhaybia,  E. Hicham, E. Anouar, et al. Anti-corrosion performance of 8-hydroxyquinoline derivatives for mild steel in acidic medium: Gravimetric, electrochemical, DFT and molecular dynamics simulation investigations[J]. Journal of Molecular Liquids, 308-317.

[4] Z. Zhang, H Ba, Z. Wu. Sustainable corrosion inhibitor for steel in simulated concrete pore solution by maize gluten meal extract: Electrochemical and adsorption behavior studies[J]. Construction and Building Materials, 2019, 277:117080-117089.

8. The quality of the EIS fitting represented by χ2 must be specified (Table 2)

Response: According to the good advice, the standard deviation of the parameters were presented in Table 2.

Table 2. EIS parameters of reinforced steel steel in SCP in the absence and presence of inhibitors.

Cinh/(mM)		Rs	CPE1		Rf	CPE2			Rct	IE
		Ω cm2	Y0 (μΩ-1S-ncm-2)	n1	kΩ cm2	Y0 (μΩ-1S-ncm-2)		n2	kΩ cm2	%
	Blank	9.89±1.01	410.9±3.5	0.89±0.03	0.41±0.04	1 378.1±10.5	0.61±0.05		6.94±0.52	/
PED	0.02	30.05±2.25	306.5±3.0	0.93±0.05	0.59±0.03	783.5±10.8	0.65±0.03		11.95±0.69	41.92
	0.04	64.03±2.53	247.1±2.2	0.84±0.07	1.32±0.05	512.2±6.2	0.59±0.04		17.01±0.83	59.20
	0.08	75.18±2.45	179.8±2.3	0.88±0.08	2.01±0.02	405.6±8.5	0.56±0.05		25.28±0.75	72.55
	0.12	82.95±2.54	105.2±2.0	0.90±0.04	5.64±0.03	150.8±7.2	0.62±0.03		35.77±0.66	80.60
SPED	0.02	37.81±1.97	279.6±1.8	0.82±0.07	1.05±0.06	660.9±5.6	0.67±0.02		15.12±0.72	54.10
	0.04	70.23±2.66	198.5±1.9	0.85±0.03	3.09±0.02	435.7±4.8	0.66±0.04		22.94±0.35	69.75
	0.08	81.23±2.74	109.1±2.0	0.87±0.06	6.07±0.05	278.5±3.9	0.59±0.03		29.14±0.46	76.18
	0.12	96.16±2.83	65.7±1.3	0.88±0.05	9.01±0.06	99.4±4.3	0.65±0.06		48.85±0.58	85.79

 

9. I suggest the revision of results presentation

Response: We think this is an excellent suggestion, the results presentation has been modified.

such as:

 “It can be seen from Table 1 that with the increase of inhibitor concentration, the corrosion potential gradually shifts positively, and the corrosion potential shifts more than 85 mV after adding the inhibitor, the results indicate that the two perimidine derivatives PMD and SPMD are anodic corrosion inhibitors [24-26].”

“This can be attributed to perimidine derivative molecules and chloride ions compete on the surface of the specimens, the inhibitor is adsorbed on the surface of the steel to prevent the adsorption of chloride ions onto steel surfaces, thereby inhibiting the corrosion of the steel [27,28].”

Author Response File: Author Response.pdf

Reviewer 3 Report

The present manuscript reports the “Novel perimidine derivatives as corrosion inhibitors of RB400 steel in simulated concrete pore solution”. The results are in line with the information already available in the literature. In last few decades, several corrosion inhibitors already developed.  There is no novelty of this work. The following remarks may be useful for further revise the manuscript:

1. The introduction needs to be succinctly written focusing on the problem addressed in the manuscript. It is not clear what additional information was sought during the investigation. Why it is important to analyses 1H-perimidine (PMD) and 1H-perimidine-2-thiol (SPMD) as corrosion inhibitors.

2. In the last few decades, several ecofriendly corrosion inhibitors having efficient corrosion inhibition efficiency (~ 98%) were developed. In this present manuscript authors also evaluated 1H-perimidine (PMD) and 1H-perimidine-2-thiol (SPMD) as corrosion inhibitors for HRB400 steel using already established techniques like potentiodyanmics polarization, EIS, SEM, DFT and so on. What is the novelty of this work. Why it is necessary another piece of corrosion inhibitor in this domain.

3. Authors should also provide standard deviation of the parameter presented in Table 1 and Table 2.

4. Authors stated that “PMD and SPMD were synthesized through a modified procedure reported previ-ously [14,15], as shown in Fig. 1”. Also, they mentioned the values of NMR and IR. Although, I am unable to found FTIR and NMR spectra in the manuscript. Authors should be provided all the corresponding spectra.

5. Change of open circuit potential (OCP) as a function of immersion time should be provided. It suggests steady state potential was reached or not.

6. Authors should carry out molecular dynamics simulation (MD) for better understood the corrosion inhibition mechanism.

7. There are several syntax errors as well as grammatical mistakes. The authors should read the manuscript very carefully and improve the entire manuscript accordingly.

8. The authors defined the diameter of Nyquist plots as charge transfer
resistance (R_ct). In real practice it is not a charge transfer resistance, it is polarization resistance. Please see valuable literature references [Appl. Surf. Sci. 236 (2004) 155; Corrosion Science 52, 2010, 3321–3330; Materials Chemistry Frontiers, 2018, 2, 1674-1691].

9. Reference 18 and reference 51 is same.

Author Response

1. The introduction needs to be succinctly written focusing on the problem addressed in the manuscript. It is not clear what additional information was sought during the investigation. Why it is important to analyses 1H-perimidine (PMD) and 1H-perimidine-2-thiol (SPMD) as corrosion inhibitors.

Response: Perimidine derivatives as corrosion inhibitors of reinforced steel in simulated concrete pore solution medium were not paid full attention to previously. In fact, these compounds can be easily prepared by the reaction. In this manuscript, two perimidine derivatives, 1H-perimidine (PMD) and 1H-Perimidine-2-thiol (SPMD), were synthesized and investigated as corrosion inhibitors of reinforced steel in simulated concrete pore solution. From the two perimidine derivatives, the sole difference in structure is the structure of sulfur atom segment. For SPMD, it has 2-position sulphydryl group in the structure. However, SPMD exhibits better inhibition effectiveness than PMD at the same concentration. The result from computational chemistry demonstrate that the sulfur atom is mainly responsible for the enhanced corrosion inhibition of SPMD since the segment can donate electrons to and accept electrons from iron surface to form adsorptive bonds resulting in the strong interaction between SPMD and iron surface. These results and conclusions are in favour of the structural design and development of new perimidine inhibitors in future.

 

2. In the last few decades, several ecofriendly corrosion inhibitors having efficient corrosion inhibition efficiency (~ 98%) were developed. In this present manuscript authors also evaluated 1H-perimidine (PMD) and 1H-perimidine-2-thiol (SPMD) as corrosion inhibitors for HRB400 steel using already established techniques like potentiodyanmics polarization, EIS, SEM, DFT and so on. What is the novelty of this work. Why it is necessary another piece of corrosion inhibitor in this domain.

Response: 1H-perimidine (PMD) and 1H-perimidine-2-thiol (SPMD) as corrosion inhibitors were developed for HRB400 reinforcing steel in simulated concrete pore (SCP) solution. This research can effectively solve the corrosion problem of steel bars in concrete structures. Therefore, this study demonstrates that add perimidine derivatives into concrete can improve durability of concrete structure.

 

3. Authors should also provide standard deviation of the parameter presented in Table 1 and Table 2.

Response: According to the good advice, The standard deviation of the parameters were presented in Table 1 and Table 2.

Table 1. Potentiodynamic polarization parameters for HRB400 reinforced steel in SCP solution with and without different concentrations of inhibitors.

inhibitors	Conc.	Ecorr	Epit	-βc	βa	Icorr	IE	θ
	mM	mv	mv	mV dec-1	mV dec-1	μA cm-2	%
	Blank	-658.81±5.50	-73.66±3.15	197.24±3.96	251.39±4.56	23.69±1.15	/	/
PMD	0.02	-486.62±4.75	-26.89±2.78	177.24±4.51	196.00±4.12	12.97±1.01	45.25	0.4525
	0.04	-415.19±6.23	55.69±1.96	168.08±3.62	194.10±4.37	9.28±1.37	60.84	0.6084
	0.08	-350.40±5.66	132.46±3.05	170.54±3.74	187.13±3.95	6.24±0.86	73.66	0.7366
	0.12	-330.47±4.97	-194.15±2.94	164.85±3.55	189.15±4.16	3.68±0.65	84.48	0.8448
SPMD	0.02	-435.85±7.32	53.94±1.75	167.17±4.09	187.31±5.03	10.43±1.27	55.99	0.5599
	0.04	-408.14±6.40	91.32±2.46	170.88±4.27	190.54±4.48	7.36±0.79	68.95	0.6895
	0.08	-343.98±5.73	130.06±3.54	166.43±3.05	193.39±3.72	5.07±0.93	78.60	0.7860
	0.12	-315.49±5.49	175.99±3.17	163.39±3.96	186.27±3.85	2.94±0.82	87.61	0.8761

Table 2. EIS parameters of reinforced steel steel in SCP in the absence and presence of inhibitors.

Cinh/(mM)		Rs	CPE1		Rf	CPE2			Rct	IE
		Ω cm2	Y0 (μΩ-1S-ncm-2)	n1	kΩ cm2	Y0 (μΩ-1S-ncm-2)		n2	kΩ cm2	%
	Blank	9.89±1.01	410.9±3.5	0.89±0.03	0.41±0.04	1 378.1±10.5	0.61±0.05		6.94±0.52	/
PED	0.02	30.05±2.25	306.5±3.0	0.93±0.05	0.59±0.03	783.5±10.8	0.65±0.03		11.95±0.69	41.92
	0.04	64.03±2.53	247.1±2.2	0.84±0.07	1.32±0.05	512.2±6.2	0.59±0.04		17.01±0.83	59.20
	0.08	75.18±2.45	179.8±2.3	0.88±0.08	2.01±0.02	405.6±8.5	0.56±0.05		25.28±0.75	72.55
	0.12	82.95±2.54	105.2±2.0	0.90±0.04	5.64±0.03	150.8±7.2	0.62±0.03		35.77±0.66	80.60
SPED	0.02	37.81±1.97	279.6±1.8	0.82±0.07	1.05±0.06	660.9±5.6	0.67±0.02		15.12±0.72	54.10
	0.04	70.23±2.66	198.5±1.9	0.85±0.03	3.09±0.02	435.7±4.8	0.66±0.04		22.94±0.35	69.75
	0.08	81.23±2.74	109.1±2.0	0.87±0.06	6.07±0.05	278.5±3.9	0.59±0.03		29.14±0.46	76.18
	0.12	96.16±2.83	65.7±1.3	0.88±0.05	9.01±0.06	99.4±4.3	0.65±0.06		48.85±0.58	85.79

 

4. Authors stated that “PMD and SPMD were synthesized through a modified procedure reported previ-ously [14,15], as shown in Fig. 1”. Also, they mentioned the values of NMR and IR. Although, I am unable to found FTIR and NMR spectra in the manuscript. Authors should be provided all the corresponding spectra.

Response: According to the good advice, the FTIR was added.

The peak at 3 425 cm^-1, 3 430 cm^-1 is the absorption peak generated by N-H stretching vibration. The absorption peak at 3 000~2 900 cm^-1 is mainly aromatic ring C-H stretching vibration peak. In addition, benzene ring C=C skeleton stretching vibration peak is near 1 600^-1, 1500 cm^-1, and the peak near 1 600 cm^-1 also contains the absorption peak generated by stretching vibration of -C=N. The peak near 1 380 cm^-1 is the stretching vibration peak of -C-N. The peak at 1042 cm^-1,1 039 cm^-1 is the absorption peak of -C-H vibration. The absorption peak at 2 543cm^-1 is generated by -S-H vibration in (b).

5. Change of open circuit potential (OCP) as a function of immersion time should be provided. It suggests steady state potential was reached or not.

Response: It is stated in Section 2.3. EIS measurements were performed at open-circuit potential and before EIS measurements the steel electrode was immersed in the test solutions under unstirred condition for three days until a steady potential.

According to the good advice, a figure with OCP as a function of time was added as follows:

6. Authors should carry out molecular dynamics simulation (MD) for better understood the corrosion inhibition mechanism.

Response: According to the good advice, Adsorption isotherm and thermodynamic calculation，surface free energy of reinforced steel specimen and Quantum chemical calculations have been studied in this paper. There is sufficient evidence to understand the mechanism of action of corrosion inhibitors. In addition, the solution in this paper is simulated concrete pore solution (SCP), which was 3.5% NaCl saturated Ca(OH)₂ solution. OH^- has passivation effect on reinforcement, and the system is relatively complex. The application of molecular dynamics simulation is controversial in the solution.

 

7. There are several syntax errors as well as grammatical mistakes. The authors should read the manuscript very carefully and improve the entire manuscript accordingly.

Response: According to the good advice, the manuscript has been modified.

 

8. The authors defined the diameter of Nyquist plots as charge transfer resistance (Rct). In real practice it is not a charge transfer resistance, it is polarization resistance. Please see valuable literature references [Appl. Surf. Sci. 236 (2004) 155; Corrosion Science 52, 2010, 3321–3330; Materials Chemistry Frontiers, 2018, 2, 1674-1691].

Response: The diameter of Nyquist plots as charge transfer resistance (Rct) in some paper. Such as literature references ( [1]; [2]; [3] ).

 [1] Y. Cubides, H. Castaneda, Corrosion protection mechanisms of carbon nanotube and zinc-rich epoxy primers on carbon steel in simulated concrete pore solutions in the presence of chloride ions, Corros. Sci. 109 (2016) 145-161.

[2] Yong Teck Tan, Sudesh L. Wijesinghe, Daniel J. Blackwood, The inhibitive effect of bicarbonate and carbonate ions on carbon steel in simulated concrete pore solution, Corros. Sci. 88 (2014) 152-160.

[3] Y. Zhao, T. Pan, X. Yu, D. Chen, Corrosion inhibition efciency of triethanolammonium dodecylbenzene sulfonate on Q235 carbon steel in simulated concrete pore solution, Corros. Sci. 158 (2019) 108097.

[4] X. Zhou, H. Yang, F. Wang, Investigation on the inhibition behavior of a pentaerythritol glycoside for carbon steel in 3.5% NaCl saturated Ca(OH)₂ solution, Corros. Sci. 54(2012) 193-200.

 

9. Reference 18 and reference 51 is same.

Response: According to the good advice, the Ref 18 was replaced 51.

• Masoud, M. Awad, M. Shaker, M. El-Tahawy, The role of structural chemistry in the inhibitive performance of some aminopyrimidines on the corrosion of steel, Corros. Sci. 52 (7) (2010) 2387-2396.
• Berdimurodov, A. Kholikovb, K. Akbarovb, L. Guo, Inhibition properties of 4,5-dihydroxy-4,5-di-p-tolylimidazolidine-2-thione for use on carbon steel in an aggressive alkaline medium with chloride ions: Thermodynamic, electrochemical, surface and theoretical analyses, J. Mol. Liq. 327 (2021) 114813-114830.
• Verma, E. Ebenso, M.A. Quraishi, K. Rhee, Phthalocyanine, naphthalocyanine and their derivatives as Corrosion Inhibitors: A review, J. Mol. Liq. 334 (2021) 116441-116449.

 

Author Response File: Author Response.pdf