Sample synthesis, characterization, experimental and theoretical study of the inhibitory power of new 8-hydroxyquinoline derivatives for mild steel in 1.0 M HCl

Article abstract of DOI:10.1016/j.molstruc.2020.128155

Some new compounds which are derived from 8-hydroxyquinoline were both prepared and characterized by IR, NMR spectroscopy and elemental analysis. After the successful synthesis, we tested these products as corrosion inhibitors of mild steel (MS) in 1.0 M HCl at 298 K ± 1. The anticorrosive property was achieved by electrochemical and theoretical methods such as potentiodynamic polarization (PDP), the spectroscopy impedance (EIS), density functional theory (DFT) calculations and the Monte Carlo simulation (MC). The experimental and theoretical results obtained show that these products have an excellent anticorrosive property for the MS. The thermodynamic parameters show that all the compounds adsorb to the metal surface by chemical bonds according to the Langmuir adsorption isotherm. The surface morphology was investigated using scanning electron spectroscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and the FT-IR analysis. The gravimetric solutions after 6 h of immersion were analyzed by the UV–Visible spectrometry.

Full text of DOI:10.1016/j.molstruc.2020.128155

Journal Pre-proof
Sample synthesis, characterization, experimental and theoretical study of the
inhibitory power of new 8-hydroxyquinoline derivatives for mild steel in 1.0￿ ꢀ HCl
ꢀ. Rbaa, F. Benhiba, Ashraf S. Abousalem, ꢀ. Galai, Z. Rouifi, H. Oudda, B.
Lakhrissi, I. Warad, A. Zarrouk
PII:
S0022-2860(20)30480-4
DOI:
https://doi.org/10.1016/j.molstruc.2020.128155
ꢀOLSTR 128155
Reference:
To appear in: Journal of Molecular Structure
Received Date: 14 October 2019
Revised Date: 27 ꢀarch 2020
Accepted Date: 28 ꢀarch 2020
Please cite this article as: ꢀ. Rbaa, F. Benhiba, A.S. Abousalem, ꢀ. Galai, Z. Rouifi, H. Oudda, B.
Lakhrissi, I. Warad, A. Zarrouk, Sample synthesis, characterization, experimental and theoretical study
of the inhibitory power of new 8-hydroxyquinoline derivatives for mild steel in 1.0￿ ꢀ HC Jl ,ournal of
Molecular Structure (2020), doi: https://doi.org/10.1016/j.molstruc.2020.128155.
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CRediT authorship contribution statement
M. Rbaa
: Conceived and designed the experiments- Performed the
experiments- Wrote the paper.
F. Benhiba: Conceived and designed the experiments- Performed the experiments-
Wrote the paper.
A.S. Abousalem: Conceived and designed the experiments- Contributed reagents,
materials- Wrote the paper.
M. Galai : Conceived and designed the experiments- Performed the experiments.
Z. Rouifi: Conceived and designed the experiments- Performed the experiments.
H. Oudda
: Analyzed and interpreted the data- Contributed reagents, materials,
analysis tools or data- Wrote the paper..
B. Lakhrissi : Analyzed and interpreted the data- Contributed reagents, materials,
analysis tools or data- Wrote the paper.
I. Warad
: Analyzed and interpreted the data- Contributed reagents, materials,
analysis tools or data- Wrote the paper.
A. Zarrouk : Analyzed and interpreted the data- Contributed reagents, materials,
analysis tools or data- Wrote the paper.
.

Graphical Abstract

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Sample Synthesis, characterization, experimental and
theoretical study of the inhibitory power of new
8-hydroxyquinoline derivatives for mild steel in 1.0 M HCl
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a
b,c
d,e
f
b
M. Rbaa , F. Benhiba
Ashraf S. Abousalem , M. Galai , Z. Rouifi , H.
,
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a
g
c
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Oudda , B. Lakhrissi , I. Warad , A. Zarrouk *
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Laboratory of Organic Chemistry, Catalysis and Environment, Faculty of Sciences, Ibn Tofail
University, PO Box 133, 14000, Kenitra, Morocco.
b
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Laboratory of Separation Procedure, Faculty of Sciences, Ibn Tofail University, PO Box 133, 14000,
Kenitra, Morocco.
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Laboratory of Materials, Nanotechnology and Environment, Faculty of Sciences, Mohammed V
University, Av. Ibn Battuta. P.O. Box 1014, Rabat, Morocco.
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Chemistry Department, Faculty of Sciences, Mansoura University, El-Mansoura 35516, Egypt.
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Quality Control Laboratory, Jotun, Egypt.
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Laboratory of Materials Engineering and Environment: Modeling and Application, Faculty of
Sciences, Ibn Tofail University BP. 133-14000, Kenitra, Morocco.
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Department of Chemistry and Earth Sciences, PO Box 2713, Qatar University, Doha, Qatar.
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* Corresponding author. Tel.: +212 665 201 397. Fax.: +212 537 774 261.
E-mail address: azarrouk@gmail.com (A. Zarrouk).
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ABSTRACT
Some new compounds which are derived from 8-hydroxyquinoline were both prepared and
characterized by IR, NMR spectroscopy and elemental analysis. After the successful synthesis,
we tested these products as corrosion inhibitors of mild steel (MS) in 1.0 M HCl at 298 K±1.
The anticorrosive property was achieved by electrochemical and theoretical methods such as
potentiodynamic polarization (PDP), the spectroscopy impedance (EIS), density functional
theory (DFT) calculations and the Monte Carlo simulation (MC). The experimental and
theoretical results obtained show that these products have an excellent anticorrosive property
for the MS. The thermodynamic parameters show that all the compounds adsorb to the metal
surface by chemical bonds according to the Langmuir adsorption isotherm. The surface
morphology was investigated using scanning electron spectroscopy (SEM) coupled with
energy dispersive spectroscopy (EDS) and the FT-IR analysis. The gravimetric solutions after
6 hours of immersion were analyzed by the UV-Visible spectrometry.
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Keywords: Synthesis; Corrosion inhibition; Mild steel; SEM/EDS; FT-IR analysis; Monte
Carlo simulation.
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1. Introduction
Steel is an alloy of iron used in metal construction, tool making, strengthening foundations,
and transporting water. A large amount of metals degraded by corrosion, in acidic media. So,
the use of corrosion inhibitors has become essential to extend the lifetime of metal part [1].
According to the literature, several authors have reported that the heterocyclic compounds
based on 8-hydroxyquinoline showing several applications in various fields such as:
Pharmaceutical field, Medicinal, Agrochemical, and analytical chemistry [2-4].
The 8-hydroxyquinoline is a good precursor for the synthesis of novel heterocyclic
compounds with multiple advantages such as the preparation of biologically active
compounds, metal complexes for use in the physical field and in medicine [5-7]. However,
The 8-hydroxyquinoline derivatives are good inhibitors of corrosion of steel in acidic
media.For this, today's researchers aim at synthesizing new compounds based on 8-
hydroxyquinoline [8-10].
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Our investigation in this work is the combination between two multifunctional heterocyclic
compounds based on 8-hydroxyquinoline by a simple synthesis. The pure products were
tested as corrosion inhibitors of mild steel in 1.0 M HCl at 298 K±1. The anticorrosive
property was achieved by electrochemical and theoretical methods such as potentiodynamic
polarization (PDP), the spectroscopy impedance (EIS), DFT calculations and the Monte-Carlo
simulation (MC). The surface morphology was investigated using scanning electron
spectroscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and the FT-IR
analysis. The gravimetric solutions after 6 hours of immersion were analyzed by the UV-
Visible spectrometry (UV-vis).
2. Experimental
2.1. Materials
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The materials used in the synthesized part have been published in another study [9]. The
corrosion solution (1.0 M HCl) is obtained by the decentralization of HCl (37%) with distilled
H O. The steel samples are prepared, before immersion in the solutions, by polishing with
2
sand paper until 1200.
2.2. Methods
2.2.1. Chemical synthesis
The two compounds derived from 8-hydroxyquinoline were synthesized by simple and
effective methods in two steps: the first step is the preparation of precursor 5-chloromethyl-8-
hydroxyquinoline hydrochloride (5-CMHQ) from a commercial product 8-hydroxyquinoline
(8-HQ). The second step consists in adding the binucleophile compounds to the compound 5-
1
1
1
1
CMHQ in tetrahydrofuran (THF) in the presence of triethylamine (Et N) at reflux for 8 hours
3
to obtain the two compounds, 5-(((2-aminoethyl) amino) methyl) quinolin-8-ol N-HQ and 5-
((2-aminoethoxy) methyl) quinolin-8-ol O-HQ.
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Scheme 1. Preparation of the products N-HQ and O-HQ
1
8
2.2.2. Electrochemical tests
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3
The inhibition yields of corrosion of mild steel of the compounds synthesized for the
potentiodynamic polarization study were calculated by equation 1. And the yields of corrosion
of mild steel for spectroscopy impedance were calculated by equation 2.

i

corr
°
4
ηPDP (%) = 1−
×100
(1)



i

corr
°
corr
5
6
i
and icorr represent the densities of the corrosion currents in the absence and in the
presence of the inhibitor
0
Rp − Rp
7
ηEIS (%) =
×100
(2)
Rp
0
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3
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9
0
1
2
R
and R are the values of the polarization resistance without and with inhibitor,
p p
respectively.
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2
2
2
Regarding the details for the two electrochemical methods used in this study were published
in another study [9].
2.2.3. Computional details
The computional chemical methods used in this work are DFT and MC simulation to
corroborate the experimental findings and make it possible to explain and give additional
information on the mode of action [10]. The chemical quantum study of N-HQ and O-HQ
molecules via DFT/ B3LYP was based on calculations of quantum chemical descriptors and
molecular orbital descriptors using 6-31G (d,p) and 6-311G ++ (d, p) basis sets [11]. The DFT
calculations were performed by the aid Gaussian 09 [11]. We used two basis sets for the
quantum calculations in order to obtain the appropriate correlation [11].
About Monte Carlo (MC) simulation, we will take into considerations all interactions possible
in the system studied (Surface Fe (110)/N-HQ and O-HQ compounds in an aggressive acid
+
-
environment with 5H O , 5Cl and 500H O). The MC simulation was performed using
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Materials Studio 2016 software package [12]. The parameters used to run the MC simulation
are detailed as follows:
3
Simulation cell details: Lattice parameter 3D Triclinic, (32.27*32.27*=30.13 Å ) unit cell
size, (13 × 13) unit cell and 40 Å vacuum.
Geometry optimization parameter: Algorithm Smart, quality convergence tolerance fine,
-4
-1
displacement convergence tolerance 10 kcal mol . All chemical species inserted in the
crystal system are optimized using GGA/DPN. The displacement of these species within
crystal systems is under the influence of COMPASS force fields [13]. The adsorption (E
adsorption) and binding (Ebinding) energies of N-HQ and O-HQ molecules on Fe (110) surfaces in
an aggressive acid medium are calculated according to the following two equations [13]:
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2
2
2
2
2
2
Eads = ET(system) - ET(inhibitor) - ET(iron) - ET(ions) - ET(water)
Ebinding = -E adsorption
(3)
(4)
3. Results and discussion
3.1. Chemical study
3.1.1. General procedure
We mix (0.01 mol) of 5-(chloromethyl) quinolin-8-ol hydrochloride (5-CMHQ) with (0.01
mol) of bi-nucleophilic in The THF, in the presence of Et N. The reaction mixture was
3
followed by CCM plate. After evaporation of tetrahydrofuran at 60 °C, the mixture is
extracted with chloroform (CHCl ). After the evaporation of the extraction solvent, a quantity
3
of the ether (C H O) is added to solidify the product obtained. The crude product was then
2
6
purified by column chromatography on silica gel and recrystallized from absolute ethanol
(scheme 1).
3.1.2. Spectral data
5-(((2-aminoethyl) amino) methyl) quinolin-8-ol N-HQ
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Yield: 50 %. Green solid, Melting Point: 131-133 °C, (Absolute Ethanol). ( FT-IR (KBr,
−
1
1
cm ) ν: 1624 (C=C), 3239 (OH), 1737 (CH ), 2362 (C=N). H NMR (DMSO-d ) (δppm):
2
6
2.16 (s, 2 H, CH -NH ), 1.76 (s, 2 H, CH -NH), 4.86 (s, 1 H, NH ), 4.86 (s, 1 H, OH), 7.05-
2
2
2
2
1
3
7.48--9.64 (m, 5 H, ArH). C NMR (DMSO-d ) (δppm):153.28 (C-OH), 62.04 (CH ), 30.89
6
2
(C-NH ), 110.55-128.20-129.98-139.22-148.10 (ArCH), 130.13-134.07 (ArC). Anal. Calcd
2
for C H N O in (%) (M = 231, 29 g/mol) predicted: C, 66.34; H, 6.96; N, 19.34. Found: C,
1
2
15
3
66.65; H, 6.38; N, 19.07.
5-((2-aminoethoxy) methyl) quinolin-8-ol O-HQ
Yield: 65 %. Green solid, Melting Point: 113-115 °C, (Absolute Ethanol). ( FT-IR (KBr,
−
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
cm ) ν: 1625 (C=C), 3238 (OH), 2033 (CH ), 2361 (C=N). H NMR (DMSO-d ) (δppm):
2 6
1
3
7.62 (s, 2 H, CH -NH ), 6.89 (s, 2 H, CH -O), 6.94 (s, 1 H, OH), 7.89-8.20 (m, 5 H, ArH). C
2
2
2
NMR (DMSO-d ) (δppm):198.47 (C-OH), 27.98 (C-NH ), 124.35-148.41 (ArCH of
6
2
quinoline), 131.15-140.72 (ArC of quinoline). Anal. Calcd for C H N O
2
in (%)
12
14
2
(M = 218.25 g/mol) predicted: C, 66.04; H, 6.47; N, 12.84. Found: C, 66.10; H, 6.83; N,
12.90.
3.2. Corrosion test
3.2.1. Potentiodynamic polarization
The potentiodynamic polarization (PDP) gives us permission to extract specific parameters on
the corrosion process [14-17]. The data obtained by this technique are summarized in Table 1
and Fig. 1.
The shape of the curves of Fig. 1 shows that of the two organic inhibitors is a mixed type
during the reaction with mild steel in 1.0 M HCl [18]. The addition of the two compounds
also causes the modification in the values of the anodic and cathodic slopes. This means that
the two compounds have been well adsorbed on the surface of the steel [19]. On the other
hand, the addition of the two compounds causes a decrease in the values of the current density
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(i). This can be explained by the formation of an organic film on the surface of the steel that
blocks the passage of electric current [19-21]. The decrease in current density values causes
an increase in the inhibitory efficiency values for the two compounds at different
concentrations (98.2 % for O-HQ and 98.5 % for N-HQ).
3.2.2. Electrochemical impedance spectroscopy
The stationary electrochemical technique remains insufficient to characterize the complex
mechanisms, involving several reaction stages and having different characteristic kinetics.
Moreover, many studies have shown that electrochemical impedance measurements are
capable of elementary steps involved in global corrosion and/or protection processes. The use
of transient techniques, then becomes essential to elucidate the mechanism of action of the
inhibitor. In our case, we carried out the electrochemical impedance measurements for the
steel/1.0 M HCl interfaces alone and with inhibitors [22, 23].
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We observe that these diagrams (Fig. 2) present a single capacitive loop in the form of a
semicircle having a phase shift with respect to the axis of the real (the semicircle center is
located below the axis of the real), characteristic of solid electrodes of heterogeneous and
irregular surface. The best fit of the parameters of the impedance spectroscopy is obtained by
the equivalent circuit shown in Fig. 3. The bode and phase diagrams show that there is a
single time constant (τ) which confirms the equivalent circuit pattern found [24, 25].
This circuit consists of the electrolyte resistance (R ), the polarization resistance (R ) and a
s
p
constant phase element (CPE).
From Table 2 the addition of the organic compounds caused an increase in the values of the
polarization resistance (R ), also a decrease in the values of the double layer capacity (C ).
p
dl
These results explain the presence of a film on the surface of the steel which confirms the
adsorption of the two compounds on the metal surface [26]. The study of the impedance
spectroscopy confirms the results of polarization in terms of efficiency (N-HQ > O-HQ). In
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acidic media, the nitrogen compounds is more effective than the compounds containing the
oxygen atom, which explains the good resistance of the N-HQ compound relative to the O-
HQ compound [24].
3.2.3. Influence of temperature and activation parameters
The Fig. S1 shows that the polarization curves vary in a non-symmetrical way in the anode
and cathode branches. The increase in temperature causes an increase in current density (i)
values, which leads to a decrease in the inhibitory efficiency values, but this decrease remains
low. In 328 K, the inhibitory efficiency is of the order of 83 % to compose N-HQ and 80 % of
the compound O-HQ (Table 3). However, Both compounds are profitable for the corrosion
inhibition of steel in high temperature molar HCl. Therefore, these compounds can be used in
the industrial field.
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1
1
Thanks to the effects of the temperature we were able to access the calculation of several
activations parameters such as [27]: The activation energy (E , Equation 5), The activation
a
enthalpy (ΔH , Equation 6) and activation entropy (ΔS Equation 6).
a
a,

−E 
RT 
a
1
1
5
6
icorr = Aexp
(5)



RT
 ∆S 
 ∆H 
a
a
icorr
=
exp
exp
(6)








Nh
R
RT
-
1
-1
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2
2
2
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3
R,
A
and
T
are, respectively, constant perfect gas (8.314
J
mol
K ),
pre-exponential factor and the temperature in Kelvin.
The values of the activation energies have been extracted from the figure S2 and the values of
the other two activation parameters ( H , Sa) were extracted from Figure S3. The results in
Δ
Δ
a
-3
Table 3 show that after the addition of 10 M of the inhibitors (N-HQ and
O-HQ) the activation energy (E ) values become larger relative to the blank solution (1.0 M
a
HCl). This result is explained by the creation of electrostatic interactions in the corrosive
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solution in the presence of organic inhibitors [27]. In this study, the corrosion process is
endothermic and spontaneous, because the value of the activation enthalpy is positive
(ΔH > 0) for the all inhibitors [28]. The very positive values of the activation entropy (ΔSa)
a
compared to the HCl only solution. This that the two organic compounds are well absorbed on
the surface of the steel [29].
3.2.4. Adsorption isotherm
The best description of the adsorption behavior of studied inhibitors was explained by
2
Langmuir adsorption isotherm (Fig. 3) as the average linear regression coefficient values (R )
obtained for N-HQ and O-HQ and slope are very close to unity. All the values are listed in
Table 4. The isotherm is given by the following equation (7).
1
1
Cinh
1
1
=
+ Cinh
(7)
θ
Kads
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1
1
1
1
1
2
3
4
5
6
7
where Cinh is the concentration of inhibitor,
θ
is the surface coverage degree, and Kads is the
adsorptive equilibrium constant. The linear relationships of Cinh/
Fig. 3
θ versus Cinh are depicted in
.
In each study of the corrosion, the only method to study the type of the interactions between
metal and inhibitor is the calculation of the thermodynamic adsorption parameters [30].
Among the adsorption parameters that have been calculated in this study is the adsorption
°
ads
1
1
8
9
energy ( ∆G , Equation 8).
°
∆G = −RT Ln
(
55.55Kads
)
(8)
ads
2
2
2
0
1
2
According to the literature, if the values of the free energy about -40 kJ/mol mean that there
are chemistry-like bonds between the metal and the inhibitor. From Table 4, the values of free
energy are about -40 kJ mol. This suggests that the two inhibitors are linked to the steel by
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chemical bonds, according to Langmuir adsorption isotherm (R close to unity, Fig. 3)
[31,32].
3.2.5. UV-visible spectrometry
To confirm the complexing property of the two compounds with iron we carried out a study
by UV-visible spectroscopy (Fig. 4) [33]. In the case of compounds in HCl alone, the
maximum wavelength values (λmax) are of the order of 262.29 nm for the compound N-HQ
and 256.32 nm for the compound O-HQ. On the other hand, in the case of the addition of steel
to the solution containing HCl molar and the two inhibitors after 6 h of submersion, the
maximum values of wavelengths (λmax) are moving of 262.29 nm at 314.48 nm for the
compound N-HQ and 256.32 nm at 264.36 nm for the compound O-HQ. These values
1
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1
1
1
1
1
2
2
2
2
2
2
(262.29 nm and 256.32nm) of the maximum wavelength (λmax) attributed to the band
This confirmed that our compound has a complexing property with ferrous ions [33,34].
3.2.6. Surface morphological
π-π *,
3.2.6.1. FTIR-analysis
The surface of the iron after six hours of submersion in acidic solution contains of the
quinoline substituted, analyzed by the infrared spectroscopy (Fig. 5.A-D). The observation of
the spectra after the addition of the inhibitors (Fig. 5.B,D) shows the presence of the
characteristic peaks corresponding to the CH , OH and C = N groups, this shows the presence
2
of the organic chemical substance on the surface of the iron. Moreover, in the spectra of the
adsorbed film (Fig. 5.B,D) the intensity of the alcohol (OH) groups of the two compounds is
decreased, this decrease signifies that the alcohol (OH) function has become occupied because
of complexation between quinoline substituted and of the iron ions [35].
3.2.6.2. SEM-EDS analysis
The morphology of the surface was characterized by scanning electron spectroscopy coupled
with energy dispersion microscopy (SEM-EDS) (Fig. 6.A-C). The surface of the steel in HCl
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alone was destroyed by the pitting corrosion (Fig. 6.C). After addition of the compounds N-
HQ and O-HQ for 6 hours of submersion (Fig. 6.A,B), the surface becomes well protected by
layers of the organic compounds. However, the EDS spectra show that there are carbon atoms,
nitrogen and oxygen in the metal surface, this confirmed the our compounds are well
adsorbed on the surface of the steel. The MEB-EDX studies confirm the results obtained
during infrared spectroscopy (FT-IR).
3.3. Theoretical calculations
3.3.1. DFT calculations
Quantum chemical calculations using the theory of DFT were carried out in order to find
relationship between quantum chemical properties and corrosion inhibition of the studied
molecules. In this context, the experimental study shows that inhibitors N-HQ and O-HQ are
effective against corrosion. While the chemical quantum study of DFT/ B3LYP was based on
calculations of quantum chemical descriptors and molecular orbital (energy) parameters using
the 6-31G (d,p) and 6-311G++ (d, p) basis sets. Frontier molecular orbital’s (FMO) namely
LUMO (lowest unoccupied molecular orbital) and HOMO (highest occupied molecular
orbital) are important for locating the reactive parts in a molecule. Fig. 7 visualizes the
different optimized geometry of the quinoline derivatives mentioned for the three studied
bases, the electron density distribution of the FMO and the molecular electrostatic potential of
surface (MEPS). In Fig. 7, the distribution of HOMO and LUMO is distributed on all the
atoms of the aromatic rings of the N-HQ and O-HQ inhibitors for 6-31G (d, p) and 6-311G++
(d, p) basis sets. This indicates that these atoms may be responsible for the reactivity of the
selected molecules. Non attendance of unreal frequency for the different optimized molecules
of N-HQ and O-HQ with the two selected basis sets.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
The quantum chemical descriptors (QCD) were extracted basing on electronic properties of
the ground state of the molecular structures. FMO energies such as the EHOMO, the ELUMO and
1
2

1
2
3
4
5
6
the energy gap (
the two selected inhibitors at the two used basis sets. In addition, the main parameters
describing the chemical reactivity of the tested molecules are global hardness ( ), global
electronegativity ( ), electrophilicity ( ) and nucleophilicity ( ) index and number displaced
electrons from occupied orbitals of the inhibitors to no-occupied orbitals of the metal surface
of the iron (110) ( N110) were determined using the following different equations [36-40].
ΔE = ELUMO – EHOMO) were calculated for all the inhibitors are calculated for
η
χ
ω
ε
Δ
ELUMO − EHOMO ∆Egap
7
8
ηinh
=
=
(9)
2
2
1
χinh = − (E
+ ELUMO
)
(10)
HOMO
2
2
χinh
9
0
1
ωinh
=
=
(11)
(12)
2
η
inh
1
1
1
εinh
ωinh
φ
−
χinh
φ
−
χinh
∆N110
=
=
(13)
2
η
(
+
ηinh
2
ηinh
Fe110
)
1
1
2
3
To calculate the
∆
N
, we introduced the job function (
φ
) which equals the 4.82 eV in the
lattice plane (110) of Fe. In addition, the hardness value of Fe (ηFe ) is zero for IP = EA which
1
1
1
1
1
1
2
2
4
5
6
7
8
9
0
1
corresponds the metallic bulk [41].
Usually, High value of EHOMO reflects high capacity of an inhibitor to offer its electron to a
vacant orbital of the metal. On the other hand, low value of ELUMO translates the great
possibility of receiving electrons. In addition, molecules have higher reactivity, they have a
lower energy gap (
the values of the calculated parameters at two basis sets for the two molecules studied, we
observed that the molecule N-HQ showed the lowest Egap, the highest EHOMO, the lowest
the highest and the highest , all indicating to greater electron donating ability and
ΔE). The results of these parameters are reported in Table 5. By looking at
Δ
η,
χ
ω
1
3

1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
molecular reactivity. All these elements justify the high inhibitory efficiency of N-HQ, as
observed from experimental studies. While the theoretical values of N110 are not adaptable
with the order of the experimental inhibition efficiencies. Concerning the lower values of
ELUMO and for the compound N-HQ in the two basis sets used indicate that the latter have
more available centers to accept electrons. This behavior appears in the selected two basis sets
selected, ie the N-HQ remains more reactive than O-HQ. The dipole moment ( ) is another
Δ
ε
µ
very important element used to support the experimental results. This could promote strong
electrostatic interactions between the tested structures and the metal surface, this type of
interaction contribute to better adsorption of N-HQ on the carbon steel surface than O-HQ
.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
All the calculation results obtained by the two basis sets show that the inhibitory molecule N-
HQ is more reactive than the inhibitory molecule O-HQ. The results of the calculation allow
us to judge that there is a correlation between the calculation of the QCD of the neutral
molecules N-HQ and O-HQ and the experimental results.
On another side, organic molecules having heteroatoms can be protonated in an acid medium
to form ammonium ions. For this, we followed the same procedure what we have previously
adopted for the quantum chemical calculation of the protonated forms. The main QCD of the
protonated molecules are shown in Table 6. Results presented in this table showed that values
of all the parameters are more modified after to the protonation of the studied molecules.
Indeed, the values of EHOMO and ∆N110 are shifted to more intense and less negative values.
This indicates that the protonated molecules can accept electrons in a more important way.
This result reflects that the proton forms behave like Lewis acids [42].
While, the decrease in the values of
∆E and the increase in the values of w show that the
reactivity of the protonated inhibitors is greater than that of the neutral forms. Meanwhile, the
higher values of the dipole moment of the protonated forms indicate that these molecules are
1
4

1
2
3
4
5
the most polarizable when they come into contact with the metal surface. These observations
are generalized for all the results obtained in the three phases mentioned.
3.3.2. Fukui functions
Fukui functions (FF) population analysis provides information about the number of active
centers (atoms) in an inhibitor. Table 7 collates the density values of Fukui functions
r
+
6
7
corresponding to the centers responsible for the electrophilic (
f
(
r
)
) or nucleophilic
r
−
f
( )
r
attack of each atom of the molecules mentioned in both forms: neutral and protonated.
r
+
r
−
8
9
0
The two FF of fi
(
r
)
and fi
(
r
)
are calculated using the following two equations 14 and 15
[43,44]:
r
+
1
1
fi
fi
(
(
r
)
)
= qi
= qi
(
(
N +1
)
− qi
(
N
)
)
(14)
(15)
r
−
1
r
N
)
− qi
(
N −1
1
1
2
3
Where the charge values of atom i for cation, neutral and anion are qi (N+1), qi (N) and qi (N-
1), respectively.
r
+
r
−
1
4
The values of the fi
(
r
)
and fi
(
r
)
of N-HQ and O-HQ are calculated by the of Materials
1
1
5
6
Studio 8 software from Biovia-Accelrys Inc., using a GGA exchange-correlation functional in
3
the Dmol module with the polarization function DNP
.
r
+
1
1
7
8
Inevitably, sites that are characterized by high values of fi
(
r
)
, so, these sites are considered as
r
−
electron acceptors. While, Sites with high values of fi
( )
r
are capable of releasing electrons.
1
2
2
2
2
9
0
1
2
3
Table 7 shows that the atoms that are responsible for the electrophilic attack for two neutral
substances N-HQ and O-HQ, we quote C2, C3, C6, O11 and C13. However, the N7, C8 and
C10 atoms of the neutral structures N-HQ and O-HQ are considered favorable sites for
receiving electrons. Concerning the protonated forms and according to Table 7, it is clear that
the centers that are responsible for the nucleophilic attack, they are found with lower densities
1
5

1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
for the two protonated molecules N-HQ and O-HQ. This indicates that the protonated form
behaves like LEWIS acid (cationic form). So, it's a good electron acceptor. Indeed, we justified
this observation by the existence of sites available for electron acceptance (as C2, N7, C8 and
C10) and the native values of electron transfer fraction ∆N110 (Table 6).
3.3.3. MC simulations
The objective of a Monte Carlo (MC) simulation is to generate an ensemble of representative
configurations under specific conditions for a macromolecular system. The application of
disturbance and the random dynamics of a system results in an end stable position. In this
study, we were more focused on studying the behavior of the system (Surface Fe (110) /
+
-
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
molecules (N-HQ and O-HQ) in a simulated aggressive acid environment with 5 (H O , Cl )
3
and 500 H O. The most stable optimized molecules of the investigated 8-hydroxyquinoline
2
derivatives (N-HQ and O-HQ) was incorporated in the simulation process on Fe (110)
surface. The orientations of compounds with the least energy in the simulated test solution are
displayed in Fig. 8. As evident from this figure, structures were adsorbed onto Fe (110)
surface in
a
parallel configuration involving the aromatic heterocyclic of
8-hydroxyquinoline. This type of interaction is due to the electronic cloud present in aromatic
nuclei. In addition, the studied molecules are also adsorbed by the functional groups namely
secondary amine function (-N-) for N-HQ and the ether function (-o-) for O-HQ, which was
justified by the presence of free lone pair electron of O and N heteroatom’s.
To explore the interactions of structures N-HQ and O-HQ with the Fe (110) surface of iron,
an appropriate analysis for the energy calculations namely the total energy, the adsorption
(
Eads) energy or interaction (Eint) energy (E - Eint), the reports of energies for the elements of
ads
the system being studied (dE /dNi). So, the different values of these energies are illustrated
ads
in Table 8. From these data, it obvious that the Eads and Etot energies of N-HQ and O-HQ
molecules are of large negative values. This indicates that the adsorption could occur readily
1
6

1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
and spontaneously on the corroding metal surface [44-46] The Eads of the molecule (N-HQ
)
)
(Eads -5530.897 kcal/mol) is higher than that of the inhibitor O-HQ
=
(
(Eads = 5521.463 kcal/mol), which means that the binding (Ebinding) of N-HQ molecule with Fe
(110) surface in the aggressive environment studies is stronger than O-HQ. As shown in Fig.
9, this result is in support of the highest inhibition efficiency of N-HQ as obtained from
experimental studies.
Further insights on the interaction of the investigated compounds with Fe surface was
dervived from analyzing pair correlation functions (PCF) g(r). This theoretical function is an
established method to measure the bond length between the interacting molecules and the
targeted surface substrate [47]. As previously reported in literature, the peaks occur at 1 Å–3.5
Å is related to chemisorption, by contrast the peaks appear further than 3.5 Å is associated
with electrostatic interaction [48]. PCF plots of S, N atoms in the investigated compounds are
displayed in Fig. 10 where it is clear that the highest peaks on both compounds with Fe-atoms
appear at distance less than 3.5 A indicating high probability of the formation of chemical
bonding between investigated molecules with Fe atom surface. Also, the highest peak of
N-HQ compound is obviously larger than the one of O-HQ, this means that the former
compound binds more strongly than the latter with the corroding metal surface.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
4. Conclusion
In summary, In this work, we have prepared and characterized two new compounds derived
from 8-hydroxyquinoline in one step by a simple synthesis. The two new compounds are
tested as corrosion inhibitors for steel in molar HCl by electrochemical (EIS and PDP) and
theoretical (DFT and MC) methods. The both studies show that both compounds are very
good corrosion inhibitors (98 % for the compound N-HQ and 96 % for the compound O-HQ).
1
7

1
2
3
4
5
6
7
The PDP study shows that both inhibitors act as inhibitors of the mixed type and also remain
effective at high temperature (328 K). However, the thermodynamic adsorption studies show
that the two inhibitors adsorb to the surface of the steel by chemical bonds following
isothermal adsorption of Langmuir. Infrared spectroscopy and SEM-EDX spectroscopy show
that the metal surface has been well protected after the addition of the two inhibitors.
Moreover, the analysis of gravimetric solutions by UV-visible spectroscopy (UV-vis) shows
that both compounds have a complexing property with ferrous ions.
8
9
References
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
[1] L.O. Olasunkanmi, M.M. Kabanda, E.E. Ebenso, Quinoxaline derivatives as corrosion
inhibitors for mild steel in hydrochloric acid medium: Electrochemical and quantum chemical
studies, Physica E 76 (2016) 109-126.
[2] M. Rbaa, A. Oubihi, M. Ouhssine, F. Almalki, T.B. Hadda, A. Zarrouk, B. Lakhrissi,
Synthesis of New Heterocyclic Systems Oxazino Derivatives of 8-Hydroxyquinoline: Drug
Design and POM Analyses of Substituent Effects on their Potential Antibacterial Properties,
Chem. Data Collect. 24 (2019) 100306.
[3] M. Rbaa, S. Jabli, Y. Lakhrissi, M. Ouhssine, F. Almalki, T.B. Hadda, S. M. Moumene,
A. Zarrouk, B. Lakhrissi, Synthesis, antibacterial properties and bioinformatics computational
analyses of novel 8-hydroxyquinoline derivatives, Heliyon 5(10) (2019) e02689.
[4] M. Rbaa, A.S. Abousalem, M.E. Touhami, I. Warad, F. Bentiss, B. Lakhrissi, A. Zarrouk,
Novel Cu (II) and Zn (II) complexes of 8-hydroxyquinoline derivatives as effective corrosion
inhibitors for mild steel in 1.0 M HCl solution: Computer modeling supported experimental
studies, J. Mol. Liq. 290 (2019) 111243.
[5] O. Fergachi, F. Benhiba, M. Rbaa, M. Ouakki, M. Galai, R. Touir, M.E. Touhami,
Corrosion Inhibition of Ordinary Steel in 5.0 M HCl Medium by Benzimidazole Derivatives:
Electrochemical, UV–Visible Spectrometry, and DFT Calculations, J. Bio-and Tribo-
Corrosion 5(1) (2019) 2-13.
[6] S. Indira, G. Vinoth, M. Bharathi, K. Shanmuga Bharathi, Synthesis, spectral,
electrochemical, in-vitro antimicrobial and antioxidant activities of bisphenolic mannich base
and 8-hydroxyquinoline based mixed ligands and their transition metal complexes, J. Mol.
Struct. 1198 (2019) 126886.
1
8

1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
[7] M. Rbaa, M. Galai, A.S. Abousalem, B. Lakhrissi, M.E. Touhami, I. Warad, A. Zarrouk,
Synthetic, spectroscopic characterization, empirical and theoretical investigations on the
corrosion inhibition characteristics of mild steel in molar hydrochloric acid by three novel 8-
hydroxyquinoline derivatives, Ionics 13(8) (2019) 1-20.
[8] S. K. Saha, P. Ghosh, A. Hens, N.C. Murmu, P. Banerjee, Density functional theory and
molecular dynamics simulation study on corrosion inhibition performance of mild steel by
mercapto-quinoline Schiff base corrosion inhibitor, Physica E 66 (2015) 332-341.
[9] M. Rbaa, B. Lakhrissi, Novel oxazole and imidazole based on 8-Hydroxyquinoline as a
Corrosion Inhibition of mild steel in HCl Solution: Insights from Experimental and
Computational Studies, Surf. Interfaces 15 (2019) 43-59.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
[10] O. Fergachi, F. Benhiba, M. Rbaa, R. Touira, M. Ouakki, M. Galaia, B. Lakhrissi, H.
Oudda, M. E. Touhami, Experimental and Theoretical Study of Corrosion Inhibition of Mild
Steel in 1.0
M
HCl Medium by 2(-4(hloro phenyl-1H- benzo[d]imidazol)-1-
yl)phenyl)methanone, Mat. Res. 6 (21) (2018) 1516-1439.
[11] A. Zarrouk, B. Hammouti, A. Dafali, M. Bouachrine, H. Zarrok, S. Boukhris, S.S. Al-
Deyab, A theoretical study on the inhibition efficiencies of some quinoxalines as corrosion
inhibitors of copperin nitric acid, J. Saudi Chem. Soc. 18 (2014) 450-455.
[12] M. Rbaa, F. Benhiba, I.B. Obot, H. Oudda, I. Warad, B. Lakhrissi, A. Zarrouk, Two new
8-hydroxyquinoline derivatives as an efficient corrosion inhibitors for mild steel in
hydrochloric acid: Synthesis, electrochemical, surface morphological, UV–visible and
theoretical studies, J. Mol. Liq. 12 (276) (2018) 120-133.
[13] A. Ramazani, M. Sheikhi, H. Yahyaei, Molecular Structure, NMR, FMO, MEP and NBO
Analysis of Ethyl-(Z)-3-phenyl-2-(5-phenyl-2H-1,2,3,4-tetraazol-2-yl)-2-propenoate Based on
HF and DFT Calculations, Chem. Methodol. 1 (2017) 28-48.
[14] M. Khattabi, F. Benhiba, S. Tabti, A. Djedouani, A. El Assyry, R. Touzani, I. Warad, H.
Oudda, A. Zarrouk, Performance and computational studies of two soluble pyran derivatives
as corrosion inhibitors for mild steel in HCl, J. Mol. Struct. 1196 (2019) 231-244.
[15] J. Cruz, T. Pandiyan, E. Garcia-Ochoa, J. Electroanal. Chem. 583 (2005) 8-16.
[16] L.M. Rodriguez-Valdez, A. Martínez-Villafañe, D. Glossman-Mitnik, J. Mol. Struct.
THEOCHEM 713 (2005) 65-70.
[17] I.B. Obot, N.O. Obi-Egbedi, N.W. Odozi, Acenaphtho [1,2-b] quinoxaline as a novel
corrosion inhibitor for mild steel in 0.5M H SO , Corros. Sci. 52 (2010) 923-926.
2
4
1
9

-
1
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
[18] A.Y. El-Etre, A.I. Ali, A novel green inhibitor for C-steel corrosion in 2.0 mol L
hydrochloric acid solution, Chin. J. Chem. Eng. 25(3) (2017) 373-380.
[19] H. Hamani, T. Douadi, M. Al-Noaimi, S. Issaadi, D. Daoud, S. Chafaa, Electrochemical
and quantum chemical studies of some azomethine compounds as corrosion inhibitors for
mild steel in 1 M hydrochloric acid, Corros. Sci. 88 (2014) 234-245.
[20] A. Yousefi, S. A. Aslanzadeh, J. Akbari, Experimental and DFT studies of 1-
methylimidazolium trinitrophenoxide as modifier for corrosion inhibition of SDS for mild
steel in hydrochloric acid, Anti-Corros. Methods Mater. 65 (1) (2018) 107-122.
[21] A. Zarrouk, H. Zarrok, Y. Ramli, M. Bouachrine, B. Hammouti, A. Sahibed-dine, F.
Bentiss, Inhibitive properties, adsorption and theoretical study of 3,7-dimethyl-1-(prop-2-yn-
1-yl)quinoxalin-2(1H)-one as efficient corrosion inhibitor for carbon steel in hydrochloric
acid solution, J. Mol. Liq. 222 (2016) 239-252.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
[22] K.R. Ansari, M.A. Quraishi, A. Singh, Schiff’s base of pyridyl substituted triazoles as
new and effective corrosion inhibitors for mild steel in hydrochloric acid solution, Corros.
Sci. 79 (2014) 5-15.
[23] T. Douadi, H. Hamani, D. Daoud, M. Al-Noaimi, S. Chafaa, Effect of temperature and
hydrodynamic conditions on corrosion inhibition of an azomethine compounds for mild steel
in 1 M HCl solution, J. Taiwan Inst. Chem. Eng. 71 (2017) 388-404.
[24] J. Yang, Y. Lu, Z. Guo, J. Gu, C. Gu, Corrosion behaviour of a quenched and partitioned
medium carbon steel in 3.5 wt.% NaCl solution, Corros. Sci. 130 (2018) 64-75.
[25] M. El Faydy, M. Galai, M. Ebn Touhami, I. B. Obot, B. Lakhrissi, A. Zarrouk,
Anticorrosion potential of some 5-amino-8-hydroxyquinolines derivatives on carbon steel in
hydrochloric acid solution: gravimetric, electrochemical, surface morphological, UV–visible,
DFT and Monte Carlo simulations, J. Mol. Liq. 248 (2017) 1014-1027.
[26] J. Yang, Y. Lu, Z. Guo, J. Gu, C. Gu, Corrosion behaviour of a quenched and partitioned
medium carbon steel in 3.5 wt.% NaCl solution, Corros. Sci. 130 (2018) 64-75.
[27] H. Tayebi, H. Bourazmi, B. Himmi, A. El Assyry, Y. Ramli, A. Zarrouk, A. Geunbour,
B. Hammouti, Eno E. Ebenso, An electrochemical and theoretical evaluation of new quinoline
derivative as a corrosion inhibitor for carbon steel in HCl solutions, Der Pharm. Lett. 6(6)
(2014) 20-34.
[28] B. Hirschorn, M.E. Orazem, B. Tribollet, V. Vivier, I. Frateur, M. Musiani,
Determination of effective capacitance and film thickness from constant-phase-element
parameters, Electrochim. Acta 55 (21) (2010) 6218-6227.
2
0

1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
[29] M. Rbaa, M. Galai, Y. El Kacimi, M. Ouakki, R. Touir, B. Lakhrissi, M.E. Touhami,
Adsorption Properties and Inhibition of Carbon Steel Corrosion in a Hydrochloric Solution by
2-(4, 5-diphenyl-4, 5-dihydro-1h-imidazol-2-yl)-5-methoxyphenol, Port. Electrochim. Acta 35
(6) (2017) 323-338.
[30] H. Zarrok, S.S. Al-Deyab, A. Zarrouk, R. Salghi, B. Hammouti, H. Oudda, M.
Bouachrine, F. Bentiss, Thermodynamic Characterisation and Density Functional Theory
Investigation of 1,1',5,5'-Tetramethyl-1H, 1'H-3,3'- Bipyrazole as Corrosion Inhibitor of C38
Steel Corrosion in HCl, Int. J. Electrochem. Sci. 7 (2012) 4047-4063.
[31] O. Dagdag, A. El Harfi, O. Cherkaoui, Z. Safi, N. Wazzan, L. Guo, R.T. Jalgham,
Rheological, electrochemical, surface, DFT and molecular dynamics simulation studies on the
anticorrosive properties of new epoxy monomer compound for steel in 1 M HCl solution,
RSC adv. 9 (8) (2019) 4454-4462.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
[32] I. Ahamad, R. Prasad, M.A. Quraishi, Thermodynamic, electrochemical and quantum
chemical investigation of some Schiff bases as corrosion inhibitors for mild steel in
hydrochloric acid solutions, Corros. Sci. 52 (2010) 933-942.
[33] E.A. Noor, A.H. Al-Moubaraki, Thermodynamic study of metal corrosion and inhibitor
adsorption processes in mild steel/1-methyl-4 [4′(-X)-styryl pyridinium iodides/hydrochloric
acid systems, Mater. Chem. Phys. 110 (2008) 145-154.
[34] Y. Abboud, A. Abourriche, T. Saffaj, M. Berrada, M. Charrouf, A. Bennamara, H.
Hannache, A novel azo dye, 8-quinolinol-5-azoantipyrine as corrosion inhibitor for mild steel
in acidic media, Desalination 237 (1-3) (2009) 175-189.
[35] M. Gopiraman, N. Selvakumaran, D. Kesavan, Adsorption and corrosion inhibition
behaviour of N-(phenylcarbamothioyl) benzamide on mild steel in acidic medium, Prog. Org.
Coat. 73(1) (2012) 104-111.
[36] C. Wang, C. Lai, B. Xie, X. Guo, D. Fu, B. Li, S. Zhu, Corrosion inhibition of mild steel
in HCl medium by S-benzyl-O, O'-bis (2-naphthyl) dithiophosphate with ultra-long lifespan,
Results Phys. 10 (2018) 558-567.
[37] L. Jiang, Y. Qiang, Z. Lei, J. Wang, Z. Qin, B. Xiang, Excellent corrosion inhibition
performance of novel quinoline derivatives on mild steel in HCl media: experimental and
computational investigations, J. Mol. Liq. 255 (2018) 53-63.
[38] F. Benhiba, H. Zarrok, A. Elmidaoui, M. El Hezzat, R. Touir, A. Guenbour, A. Zarrouk,
S.Boukhris, H.Oudda, Theoretical prediction and experimental study of 2-phenyl-1, 4-
2
1

1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
dihydroquinoxaline as a novel corrosion inhibitor for carbon steel in 1.0 HCl, J. Mater.
Environ. Sci. 6 (8)(2015) 2301-2314.
[39] R. Nabah, F. Benhiba, Y. Ramli, M. Ouakki, M. Cherkaoui, H. Oudda, R. Touir, I.
Warad, A. Zarrouk, Corrosion inhibition Study of 5, 5-diphenylimidazolidine-2, 4-dione for
Mild Steel corrosion in 1 M HCl solution: Experimental, theoretical computational and Monte
Carlo simulations studies, Anal. Bioanal. Electrochem. 10(10) (2018)1375-1398.
[40] D.V. Andreeva, E.V. Skorb, D.G. Shchukin, Layer-by-layer polyelectrolyte/inhibitor
nanostructures for metal corrosion protection, ACS Appl. Mater. Interfaces 2(7) (2010) 1954-
1962.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
[41] A. Zarrouk, I. El Ouali, M. Bouachrine, B. Hammouti, Y. Ramli, E. M. Essassi, I. Warad,
A. Aouniti, R. Salghi, Theoretical approach to the corrosion inhibition efficiency of some
quinoxaline derivatives of steel in acid media using the DFT method, Res. Chem. Intermed.
39 (2013) 1125-1133.
[42] Ş. Erdoğan, Z.S. Safi, S. Kaya, D. Ö. Işın, L. Guo, C. Kaya, A computational study on
corrosion inhibition performances of novel quinoline derivatives against the corrosion of iron.
J. Mol. Struct. 1134 (2017) 751-761.
[43] M. El Faydy, R. Touir, M. Ebn Touhami, A. Zarrouk, C. Jama, B. Lakhrissi, L. O.
Olasunkanmi, E. E. Ebenso, F. Bentiss, Corrosion inhibition performance of newly
synthesized 5-alkoxymethyl-8-hydroxyquinoline derivatives for carbon steel in 1 M HCl
solution: experimental, DFT and Monte Carlo simulation studies, Phys. Chem. Chem. Phys. 20
(2018) 20167-20187.
[44] H. Mi, G. Xiao, X. Chen, Theoretical evaluation of corrosion inhibition performance of
three antipyrine compounds, Comput. Theor. Chem. 1072 (2015) 7-14.
[45] A. Fouda, G. Elewady, K. Shalabi, H.A. El-Aziz, Alcamines as corrosion inhibitors for
reinforced steel and their effect on cement based materials and mortar performance, RSC
Adv. 5 (2015) 36957-36968.
[46] L. Guo, S. Zhang, W. Li, G. Hu, X. Li, Experimental and computational studies of two
antibacterial drugs as corrosion inhibitors for mild steel in acid media, Mater. Corros. 65
(2014) 935-942.
[47] A.S. Fouda, M.A. Ismail, A.S. Abousalem, G.Y. Elewady, Experimental and theoretical
studies on corrosion inhibition of 4-amidinophenyl-2, 2
media, RSC Adv. (2017) 46414-46430.
′-bifuran and its analogues in acidic
7
2
2

1
2
3
4
5
[48] A.S. Fouda, M.A. Ismail, G.Y. Elewady, A.S. Abousalem, Evaluation of 4-
amidinophenyl-2, 2 -bithiophene and its aza-analogue as novel corrosion inhibitors for CS in
′
acidic media: experimental and theoretical study, J. Mol. Liq. 240 (2017) 372-388.
6
7
8
9
0
1
1
1
Figures
0
-
-
-
-
-
-
-
1
2
3
4
5
6
7
Blank of solution
-3
10
10
10
10
M of N-HQ
M of N-HQ
M of N-HQ
M of N-HQ
-
4
-5
-
6
-0.8
-0.6
-0.4
-0.2
E (V/SCE)
1
2
2
3

0
1
2
3
4
5
6
-
-
-
-
-
-
Blank of solution
-3
1
0
M of O-HQ
-
4
10 M of O-HQ
-5
10
0
M of O-HQ
M of O-HQ
-6
1
-0.8
-0.6
-0.4
-0.2
E (V/SCE)
1
2
3
Fig.1. Curves obtenaid of M-steel in 1.0 M HCl without and with the addition of N-HQ and
O-HQ at 298 K.
7
Blank solution
500
blank solution
6
5
4
3
2
1
0
-3
1
0 M of N-HQ
-4
10 M of N-HQ
-5
10 M of N-HQ
400
-6
10 M of N-HQ
0
1
2
3
4
5
6
7
r
Z(ohm.cm²)
300
100 Hz
200
100 KHz
0.1 Hz
100
0
0
100
200
300
400
500
600
Z (Ω cm²)
re
4
2
4

500
400
300
200
100
0
7
6
5
4
3
2
1
0
Blank solution
blank solution
-3
1
0 M of O-HQ
-4
10 M of O-HQ
-5
10 M of O-HQ
-6
10 M of O-HQ
0
1
2
3
4
5
6
7
Z
r
(ohm.cm²)
100 Hz
1
00 KHz
0.1 Hz
0
100
200
300
400
500
Zre
(Ω cm²)
1
80
3
.0
.4
.8
.2
.6
.0
0.6
1.2
7
0
2
60
50
1
40
1
30
0
20
BlankSolution
0
-3
10
1
0 MOf N-HQ
-4
10 MOf N-HQ
-
-5
0
10 MOf N-HQ
-6
10 MOf N-HQ
-
-10
0
2
4
Logf (Hz)
2
2
5

3
.5
.0
.5
.0
.5
.0
.5
.0
0.5
1.0
80
70
3
2
60
2
50
1
40
1
30
0
20
-
3
1
0 MOf O-HQ
0
-
4
10
1
0 MOf O-HQ
-
5
-
10 MOf O-HQ
0
-
6
1
0 MOf O-HQ
-
BlankSolution
-10
0
2
4
Logf (Hz)
1
2
Rs
CPE
Rp
3
4
5
6
7
Fig. 2. Nyquist diagram of steel in 1.0 M HCl, the equivalent circuit used for the sizing of
impedance spectra and Bode-phase diagrams of steel after immersion in HCl solution at
different concentrations of inhibitor N-HQ and O-HQ at 298 K.
2
6

N-HQ
O-HQ
0.0012
0.0009
0.0006
0.0003
0.0000
0.0000
0.0003
0.0006
0.0009
0.0012
1
2
C
Fig. 3. The isotherm Langmuir adsorption quinoline derivatives studied on the surface of mild
3
steel at 298 K.
1
.4
.2
.0
.8
.6
.4
.2
.0
0.2
1
Fer + O-HQ/HCl 1M
O-HQ/HCl 1M
1
0
λ
= 314.48 nm
0
λ
= 262.29 nm
0
0
0
-
200
400
600
800
1000
1200
Wavelength (nm)
4
2
7