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Vol. 9. Issue 1.
Pages 727-748 (January - February 2020)
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Vol. 9. Issue 1.
Pages 727-748 (January - February 2020)
Original Article
DOI: 10.1016/j.jmrt.2019.11.014
Open Access
Electrochemical, surface and computational studies on the inhibition performance of some newly synthesized 8-hydroxyquinoline derivatives containing benzimidazole moiety against the corrosion of carbon steel in phosphoric acid environment
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Mohamed El Faydya, Brahim Lakhrissia, Charafeddine Jamab, Abdelkader Zarroukc, Lukman O. Olasunkanmid,e, Eno E. Ebensod,e, Fouad Bentissb,f,
Corresponding author
fbentiss@gmail.com

Corresponding author.
a Laboratory of Agricultural Resources, Polymer and Process Engineering, Ibn Tofail University, Department of Chemistry, B.P. 133, Kenitra, Morocco
b University Lille, CNRS, INRA, ENSCL, UMR 8207 – UMET – Unité Matériaux et Transformations, F-59000 Lille, France
c Laboratory of Materials, Nanotechnology and Environment, Faculty of Sciences, Mohammed V University, Av. Ibn Battouta, PO Box 1014, Agdal-Rabat, Morocco
d Department of Chemistry, School of Chemical and Physical Sciences, Faculty of Natural and Agricultural Sciences, North-West University, Private Bag X2046, Mmabatho 2735, South Africa
e Material Science Innovation & Modelling (MaSIM) Research Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Private Bag X2046, Mmabatho 2735, South Africa
f Laboratory of Catalysis and Corrosion of Materials, Faculty of Sciences, Chouaib Doukkali University, PO Box 20, M-24000 El Jadida, Morocco
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Tables (11)
Table 1. Abbreviation, molecular structure, spectral and analytical data of synthesized 8-hydroxyquinoline derivatives containing a benzimidazole moiety.
Table 2. Various extrapolated parameters of CS prior to and after adding different concentrations of 8-hydroxyquinoline derivatives in 2M H3PO4 electrolyte.
Table 3. EIS results for CS in 2M H3PO4 in the absence and presence of different concentrations of the synthesized 8-hydroxyquinoline derivatives at 303K.
Table 4. The corresponding EIS parameters at 303–333K range of CS in 2M H3PO4 including and excluding 10−3M of four 8-hydroxyquinoline derivatives.
Table 5. Activation parameters for CS substrate in 2M H3PO4 in the absence and presence of optimum concentrations of 8-hydroxyquinoline derivatives.
Table 6. Thermodynamic parameters for the adsorption of various synthesized 8-hydroxyquinoline derivatives in 2M H3PO4 on the CS at 303K.
Table 7. Binding energies (eV), relative intensity and their assignment for the major core lines observed of DCMBQ treated CS substrate.
Table 8. Shift binding energy values for N 1s component (N structure) of 8-hydroxyquinoline derivatives before and after immersion in 2M H3PO4 medium.
Table 9. Surface elemental concentrations (at.%) in DCMBQ powder and DCMBQ treated-steel.
Table 10. Quantum chemical parameters for the neutral and protonated forms of of 8-hydroxyquinoline derivatives obtained using the B3LYP/6-31+G(d,p)//IEFPCM model.
Table 11. Estimated energy values for the adsorption of 8-hydroxyquinoline derivatives on Fe(110) surface in the absence and presence of 60 molecules of H3O+ and 20 molecules of PO43− obtained from Monte Carlo simulation.
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Abstract

Four new 8-hydroxyquinoline derivatives, namely 5-((1H-benzimidazol-2-yl)methyl)quinolin-8-ol (BIMQ), 5-((5-methyl-1H-benzimidazol-2-yl)methyl)quinolin-8-ol (MBMQ), 5-((5-chloro-1H-benzimidazol-2-yl)methyl)quinolin-8-ol (CBMQ) and 5-((5,6-dichloro-1H-benzimidazol-2-yl)methyl)quinolin-8-ol (DCBMQ) were prepared in moderate to good yields through the condensation of 5-(carboxymethyl)-8-hydroxyquinoline and substituted o-phenylenediamine. 1H, 13C NMR and elemental analysis confirm the formation of the desired compounds. The anti-corrosive potential of these heterocyclic compounds has been studied on carbon steel in 2M phosphoric acid (H3PO4) electrolyte by means of electrochemical measurements. The inhibition efficiency of these heterocyclic compounds was strongly linked to the concentration and the structure of the molecules; reached a maximum of 94.7% for DCBMQ at 10−3M. Data generated from potentiodynamic revealed that the investigated 8-hydroxyquinoline derivatives are mixed type inhibitors. The influence of temperature on the corrosion behaviour was assessed. The four quinoline derivatives adsorbed according to the Langmuir's adsorption isotherm. Surface analysis (SEM and XPS) confirmed the formation of a protective layer adsorbed on the steel surface. DFT calculations suggested that 8-hydroxyquinoline derivatives adsorb on the metal via the 8-hydroxyquinoline ring and their corrosion inhibition potential have some linear correlation with the degree of co-planarity of the benzimidazole and hydroxyquinoline rings. Monte Carlo simulations showed that the molecules adsorbed on Fe(110) surface through the 8-hydroxyquinoline in a near-flat mode and the adsorption energies both in the absence and presence of aqueous phosphate ions agree with the observed trends of inhibition efficiencies.

Keywords:
8-Hydroxyquinoline
Carbon steel
Phosphoric acid
Corrosion inhibition
EIS
XPS
Theoretical calculations
Full Text
1Introduction

Carbon steel is by definition an alloy of iron that operates under various conditions in several industries where aqueous media, especially acids, are inevitably utilized for different advantageous purposes [1–3]. Hence, corrosion of carbon steel in acidic solution notably with regard to the use of organic inhibitors is a pioneering technical in the field of corrosion science [4–6]. In this context, several reviews about various types of organic inhibitors have been previously documented [7–16]. However, the existing data show that the more efficient organic compounds are suitable to contain heteroatoms such as nitrogen, sulphur, oxygen and also other parameters such as unsaturated bonds and plane conjugated systems comprising any kinds of aromatic rings [17–19]. Moreover, the organic inhibitors act by adsorption on the metal surface and the latter depends on the nature of the surface charge of metal, the allocation of charge on the entire inhibitor molecule [20].

Phosphoric acid (H3PO4) is largely used in several industrial sectors such as removal of oxide film, chemical and electrolytic polishing. In other words, phosphoric acid is known by its strong corrosiveness on iron-based materials, hence the need to protect or to limit the attack of metallic materials. However, little works have been done on the corrosion inhibition of steel in H3PO4 solution using organic molecules [21–34].

Quinoline derivatives are first actives ingredients in the anti-malarial drugs and have particular biological properties and who poses no significant risk to environment [34–36]. However, the literature uncovers that information with respect to the utilization of 8-hydroxyquinoline and its derivatives as corrosion inhibitor for steel in H3PO4 are extremely rare. To the best of our knowledge, 8-hydroxyquinoline and its derivatives have never been used as corrosion inhibitors for steel in H3PO4. In this context, the target of this work is to assess the anti-corrosive capability of newly synthesized 8-hydroxyquinoline derivatives, namely, 5-((1H-benzimidazol-2-yl)methyl)quinolin-8-ol (BIMQ), 5-((5-methyl-1H-benzimidazol-2-yl)methyl)quinolin-8-ol (MBMQ), 5-((5-chloro-1H-benzimidazol-2-yl)methyl)quinolin-8-ol (CBMQ) and 5-((5,6-dichloro-1H-benzimidazol-2-yl)methyl)quinolin-8-ol (DCBMQ) each representing two aromatic rings, 8-hydroxyquinoline ring fused to a heterocyclic (benzimidazol) ring on carbon steel in 2M H3PO4 by means potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) techniques. Theoretical density functional theory (DFT) calculations and Monte Carlo simulations were likewise performed on 8-hydroxyquinoline derivatives so as to associate the corrosion inhibition capacity with their molecular structures.

2Experimental2.1Inhibitors2.1.1General informations

All reagents and solvents are imported from Sigma-Aldrich. The kinetics of the reactions were examined by TLC. Melting points were defined through Fargo MP-2D. Flash column chromatography was carried out together with silica gel (0.040–0.063mm) by elution with hexane–acetone mixture. NMR spectra have been made by Bruker 300 WB spectrometer. C, H, N analyses were realized using a Perkin-Elmer Model 2400 CHNS/O Series.

2.1.2Chemical synthesis

The synthesis procedure of four kinds of 8-hydroxyquinoline derivatives containing benzimidazole moiety is described in Scheme 1. First, 8-hydroxyquinoline was converted to 5-chloromethyl-8-hydroxyquinoline hydrochloride as described by Burckhalter [37]; the 5-chloromethylquinolin-8-ol hydrochloride was transformed to 5-cyanomethyl-8-hydroxyquinoline (2) thereafter [38]. The acid hydrolysis of 5-cyanomethyl-8-hydroxyquinoline (2) leads to 5-(carboxymethyl)-8-hydroxyquinoline hydrochloride (3) [39], which was condensed with 4,5-substituted derivatives of o-phenylenediamine (4a–d) in HCl solution (37%) to give the desired hydroxyquinolines compounds (5a–d).

Scheme 1.

Synthesis of 8-hydroxyquinoline derivatives containing benzimidazole moiety.

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So, the general procedure for the synthesis of 8-hydroxyquinoline derivatives containing a benzimidazole moiety (5a–d) has been developed as follows; an equimolar mixture of 4-substituted derivative of o-phenylenediamine (4a–d), 5-(carboxymethyl)-8-hydroxyquinolin hydrochloride (3) was refluxed in 4N HCl for 8h, after cooling, the precipitate was obtained after addition of aqueous sodium hydroxide, the separated product was purified through Flash column chromatography. The structures of 8-hydroxyquinoline derivatives were identified by NMR and elemental analysis. Spectral and analytical data of synthesized 8-hydroxyquinoline derivatives containing a benzimidazole moiety are summarized in Table 1.

Table 1.

Abbreviation, molecular structure, spectral and analytical data of synthesized 8-hydroxyquinoline derivatives containing a benzimidazole moiety.

Compound  Abbreviation  Structure  Spectral and analytical data 
5a  BIMQ 
 
Yield 60%, M.P. 206°C, brown of solid. 1H NMR (300MHz, Me2SO-d6), δppm=5.0 (s, 2H, CH2); 7.0–8.89 (m, 9Harm); 12.15 (1s, 1H, NH). 13C NMR (300MHz, Me2SO-d6), δppm=37,18(HQCH2benzimidazole); 111.32–152.74 (CHarm and Carm). Elemental analysis for C17H13N3O: calcd.: C, 74.17; H, 4.76; N, 15.26; Found: C, 74.1 3; H, 4,75; N, 15.28%. 
5b  MBMQ 
 
Yield 70%, M.P. 211°C, brown of solid. 1H NMR (300MHz, Me2SO-d6), δppm=2.36 (s, 3H, CH3); 4.64 (s, 2H, CH2); 6.94–8.83 (m, 8 Harm); 12.27 (s, 1H, NH). 13C NMR (300MHz, Me2SO-d6), δppm=22.13 (CH3); 30.56 (CH2); 112.93–155.5 (CHarm and Carm). Elemental analysis for C18H15N3O: calcd.: C, 74.72; H, 5.23; N, 14.52; Found: C, 74.70; H, 5.26; N, 14.54%. 
5c  CBMQ 
 
Yield 72%, M.P. 195°C, brown of solid. 1H NMR (300MHz, Me2SO-d6), δppm=4,50 (s, 2H, CH2); 6.65–8.81 (m, 8 Harm); 12.20 (s, 1H, NH). 13C NMR (300MHz, Me2SO-d6), δppm=34,69(CH2); 110.84–154.01 (CHarm and Carm). Elemental analysis for C17H12N3OCl: calcd.: C, 65.92; H, 3.90; N, 13.57; Found: C, 65.85; H, 3.86; N, 13.59%. 
5d  DCBMQ 
 
Yield 80%, M.P. 180°C, brown of solid. 1H NMR (300MHz, Me2SO-d6), δppm=4.23 (s, 2H, CH2); 6.95–8.94 (m, 6Harm). 13C NMR (300MHz, Me2SO-d6), δppm=30,63(CH2);111.90–153.26 (CHarm and Carm). Elemental analysis for C17H11N3OCl2: calcd.: C, 59.32; H, 3.22; N, 12.21; Found: C, 59.36; H, 3.20; N, 12.23%. 
2.2Materials

The material, on which the review is based, is of the type carbon steel (CS), including its the composition (in wt%) of 0.02% P, 0.02% Al, 0.10% Si, 0.50% Mn, 0.36% C, 0.01% S, 0.2% Cr and the remainder iron (Fe). 1cm2 of working electrode was exposed at aggressive media, this surface area was abraded with different grit SiC paper. This one's was then washed with bi-distilled water and decreased with ethanol.

2.3Solutions

2M H3PO4 solutions were prepared by dilution of an analytical reagent grade HCl 85% H3PO4 with distilled water. The exposure concentrations ranged from 10−6M to 10−3M, these two extremes are used due to the solubility and the minimum protection.

2.4Electrochemical measurements

The 1cm2 of CS surface is employed as working electrode. A platinum wire was operated as a counter electrode; a saturated calomel electrode was employed as a reference electrode booster by Luggin capillary.

At the beginning, the exposed area of steel was immersed in electrolyte for half hour till you get steady state open circuit potential (Eocp), and that is when the electrochemical measurements were carried out. The electrochemical assays were carried out under aerated solution and thermostatic conditions. The EIS assays were realized in the frequency interval of 105Hz to 0.1Hz at Eocp with amplitude of 10mV. The ZView software was used to precede impedance spectra. The protection efficiency ηZ(%) of EIS is defined by the formula below:

where Rp and Rp(i) are the ac polarization resistance of CS electrode without and with synthesized molecules, respectively.

The Tafel curves were registered from cathodic to the anodic direction, with a scan rate of 0.5mVs−1 and analyzed by means of Voltamaster 4 software. The inhibition efficiency for three kinds of 8-hydroxyquinoline derivatives was also elaborated according to the Tafel curves:

where icorr and icorr(i) are the corrosion current densities in the absence and the presence of 8-hydroxyquinoline derivatives, respectively.

2.5Surface analyses

Scanning electron microscopy (JEOL 5300) was employed in assessing the surface quality of CS substrate without and with four kinds of 8-hydroxyquionline and after been immersed in 2M H3PO4.

X-ray photoelectron spectroscopy (XPS) spectra were registered using XPS KRATOS, AXIS UltraDLD spectrometer Thermo Scientific K-Alpha XPS system. The XPS test and treatment were made according to the same procedures previously described [40,41].

2.6Density functional theory calculations

Molecules of BIMQ, CBMQ, DCBMQ and MBMQ were modelled with GaussView 5.0 and subjected to geometry optimizations without symmetry constraints using the B3LYP/6-31+(d,p) model [42–44]. Since the experimental studies were carried out in aqueous phosphoric acid medium, all geometry optimizations were conducted in phosphoric acid medium, which was simulated by setting the solvent parameters of aqueous H3PO4 as 62.4 and 2.054 for static and optical dielectric constants respectively. The static dielectric constant was extracted from literature [45], while the optical dielectric constant was approximated as the square of refractive index (n20/D=1.433) of phosphoric acid as previously proposed in the literature [46,47]. All the calculations were carried out using Gaussian 09 [48] and the polarizable continuum model (PCM) using the integral equation formalism variant (IEFPCM) implemented in Gaussian 09 was used to treat the solvent. Relevant quantum chemical parameters were derived from the frontier molecular orbitals (FMOs) energies, that is, highest occupied molecular orbital energy (EHOMO) and lowest unoccupied molecular orbital energy (ELUMO) of the optimized structures based on the following relations [49]:

where ΦFe(110) and ηFe are the work function and hardness of Fe respectively, while χinh and ηinh are the electronegativity and hardness of the inhibitor molecule respectively. A value of 4.82eV for ΦFe(110) (previously reported for body centre cubic (bcc) crystal structure of Fe(110)) [50,51] and a value of 0eV/mol [52] for ηFe were used in Eq. (6) based on previous studies [49–52].

2.7Monte Carlo simulation

Adsorption of BIMQ, CBMQ, DCBMQ and MBMQ molecules on mild steel surface in phosphoric acid medium was using the adsorption locator module available in Materials Studio 2106. Mild steel is essentially iron, and thus, steel surface was represented by (110) cleaved plane of Fe, which has been adjudged the most reasonable crystal plane for the metal. The optimized structures of the inhibitor molecules obtained from the DFT study were used in the Monte Carlo simulations. To ensure that the simulation was as close as possible to the experimental study, the adsorption of each inhibitor molecule on Fe(110) was simulated in the presence of phosphoric acid solution, which was represented by H3O+ and PO43− ions.

Iron crystal was first cleaved into (110) plane, optimized and expanded into a 10×10 supercell having 6 layers of crystals in a 10Å vacuum slab. H3O+ and PO43− were optimized using the universal force field in forcite module. Adsorption of 60 molecules of H3O+ and 60 molecules of PO43− (since H+ and PO43− are in ratio 3:1 in one mole of the acid) on Fe(110) was first simulated in a simulated annealing using the COMPASSII force field. The simulation was carried out for 5 cycles at 50,000 steps per cycles. Thereafter the inhibitor molecule was adsorbed using the same computational details. The adsorption energy was calculated according to Eq. (7):

where Ecomplex2 is the total energy of the Fe (110)/inhibitor/20 PO43−/60 H3O+ complex and Ecomplex1 is the total energy of the Fe (110)/20 PO43−/60 H3O+ complex.

3Results and discussion3.1Corrosion inhibition studies3.1.1Polarization measurements

The cathodic and anodic Tafel curves for working electrode dipped in 2M H3PO4 including and excluding different concentrations of BIMQ, MBMQ, CBMQ and DCBMQ are illustrated in Fig. 1, it is clear that this is a significant decrease in the two cathodic and cathodic densities after addition of these four 8-hydroxyquinoline derivatives, which implies that the synthesized 8-hydroxyquinoline derivatives prevents both the iron dissolution and the cathodic hydrogen evolution. On the other hand, the prevention of the cathodic reaction is important in comparison that anodic reaction to cause a shift of corrosion potential towards the negative direction, The negative displacement of Ecorr after adding 8-hydroxyquinoline derivatives is ≤85mV, indicating that these 8-hydroxyquinoline derivatives are acting like mixed-type inhibitors with predominant cathodic effectiveness [53]. Various extrapolated parameters from Tafel curves are included in Table 2.

Fig. 1.

Tafel plots for CS in 2M H3PO4 prior to and after adding of various concentrations of BIMQ, MBMQ, CBMQ and DCBMQ.

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Table 2.

Various extrapolated parameters of CS prior to and after adding different concentrations of 8-hydroxyquinoline derivatives in 2M H3PO4 electrolyte.

Inhibitor  Cinh (M)  Ecorr (mV/SCE)  icorr (μA/cm2βc (mV/dec)  ηTafel (%) 
Blank  –  419  2132.0  219.6  – 
BIMQ10−3  477  156.2  137.3  93.0 
10−4  481  382.0  162.5  82.1 
10−5  490  420.0  168.6  80.3 
10−6  482  615.3  170.7  71.1 
MBMQ10−3  472  120.0  136.9  94.4 
10−4  476  184.5  138.2  91.3 
10−5  482  232.6  138.5  89.1 
10−6  483  521.4  161.8  75.5 
CBMQ10−3  469  112.0  146.8  94.7 
10−4  469  199.5  147.0  90.6 
10−5  479  382.0  156.8  82.1 
10−6  478  429.5  160.0  79.8 
DCBMQ10−3  467  51.0  127.2  97.6 
10−4  486  71.2  146.4  96.7 
10−5  505  161.7  158.7  92.4 
10−6  507  397.9  166.2  81.3 

Results in Table 2 indicate a significant reduction of icorr upon addition of four kind 8-hydroxyquinoline compared with that of the blank electrolyte. This large reduction is approximately forty-two times in case of DCBMQ at 10−3M, the increase in concentration causing a protective film covers the CS surface producing a decrease in corrosion current density. The values of βc are changed following the addition of four kinds of 8-hydroxyquinoline which suggests that this is an alteration of cathodic reaction [54,55].

The effectiveness ranking of four studied organic compounds at all concentrations is as per the following: DCBMQ>CBMQ>MBMQ>BIMQ, this order is assigned to the differences in the structures among the four 8-hydroxyquinoline derivatives. Additionally, it is clear that all the inhibitors tested have a similar structure with the exception of alkyl substituent carrying by the phenyl of benzimidazole. An extensively, it is found that the substitution of H in aromatic ring of benzimidazole moiety of compound BIPQ by methyl in MBMQ, chlorine in CBMQ and two chlorine atoms in DCBMQ change the protection efficiency. The presence of chlorine atoms which are donor by mesomeric effect (+M) in aromatic ring of CBMQ and DCBMQ increases the delocalization of electron density in the molecule, which makes the molecule more stable. This adsorption can be stabilized by participation of π-electrons of aromatic ring and free electron pair in the heteroatom.

3.1.2Electrochemical impedance spectroscopy studies (EIS)3.1.2.1Effect of inhibitor concentration

Nyquist diagrams of CS in H3PO4 electrolyte in the absence and presence diverse concentrations of 8-hydroxyquinoline derivatives are provided in Fig. 2. All diagrams showed two semicircles, one at the high frequency (HF) and the other at the low frequency (LF) region. The obtained semicircle at high frequency is allocated to the charge-transfer and double layer capacitance at the CS/electrolyte interface for the corrosion mechanism [56–58]. While that the inductive loop at low frequency may be assigned to the relaxation process achieved through adsorption of the chemical species like products of the corrosion reaction (exp. ferric phosphate), an oxidizable or reducible intermediate [59] or neutral or/and ionic forms of 8-hydroxyquinoline derivatives [60] on the CS surface.

Fig. 2.

Nyquist plots of the CS substrate in 2M H3PO4 with BIMQ, MBMQ, CBMQ and DCBMQ at different concentrations at 303K.

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The existing HF loops are slightly depressed in real axis and non-perfect semi-circles demonstrate the roughness and/or inhomogeneity of the CS surface [61]. As consequence, CPE was inserted in the equivalent circuit to substitute the double layer capacitance in order to obtain a good fit and which is defined through next formula [62–64]:

where A and n presents the constant and exponent of CPE, respectively. i is the imaginary number and ω (rads−1) is the radial frequency.

The selected equivalent circuit (Fig. 3) to fit the experimental EIS data consists of electrolyte resistance (Rs) in series with CPE in parallel with charge transfer resistance (Rct) in series with an inductive resistance RL in parallel with an inductance (L). However, the (Rct+RL) present the polarization resistance (Rp). These cited parameters are summarized in Table 3.

Fig. 3.

Equivalent circuit employed for adjusting the impedance data.

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Table 3.

EIS results for CS in 2M H3PO4 in the absence and presence of different concentrations of the synthesized 8-hydroxyquinoline derivatives at 303K.

Inhibitor  Cinh (M)  Rscm2Rctcm2RLcm2Rpcm2104A−1Sncm2n  L (Hcm−2Cdl (μFcm−2τd (ms)  ηZ (%)  θ 
2M H3PO4  –  5.21±0.02  9.71±0.06  2.01±0.08  11.72  2.43±0.09  0.880±0.005  0.19±0.02  109.2  1.22  –  – 
BIMQ10−6  7.27±0.07  19.58±0.27  5.83±0.37  25.41  0.75±0.07  0.898±0.010  0.14±0.17  36.8  0.94  53.8  0.54 
10−5  7.85±0.06  27.30±0.36  4.88±0.53  32.20  0.73±0.05  0.892±0.010  0.33±0.08  32.5  1.05  63.6  0.64 
10−4  8.40±0.06  28.41±0.38  6.40±0.48  34.81  0.62±0.04  0.901±0.009  0.38±0.13  30.0  1.10  66.3  0.66 
10−3  8.67±0.06  56.53±0.42  7.65±0.52  64.18  0.60±0.03  0.905±0.007  0.43±0.18  28.1  1.80  81.7  0.82 
MBMQ10−6  6.39±0.06  19.44±0.35  3.61±0.41  23.05  0.83±0.08  0.890±0.020  0.20±0.03  35.7  0.82  49.1  0.49 
10−5  6.43±0.05  32.97±0.53  3.99±0.63  36.96  0.78±0.07  0.898±0.010  0.41±0.03  35.1  1.29  68.3  0.68 
10−4  6.90±0.06  34.34±0.59  5.20±0.68  39.54  0.68±0.05  0.899±0.009  0.52±0.10  30.3  1.20  70.3  0.70 
10−3  6.92±0.06  67.05±0.62  15.77±0.73  82.82  0.62±0.03  0.908±0.006  2.31±0.40  26.0  2.15  86.0  0.86 
CBMQ10−6  6.63±0.06  22.71±0.29  5.67±0.39  28.38  0.66±0.05  0.897±0.001  0.77±0.12  29.4  0.83  60.5  0.60 
10−5  6.96±0.06  26.79±0.37  5.49±0.46  32.28  0.65±0.05  0.892±0.009  1.52±0.10  28.6  0.92  63.7  0.64 
10−4  7.04±0.06  41.25±0.43  10.80±0.64  52.05  0.59±0.03  0.896±0.008  2.16±0.30  28.2  1.46  77.4  0.77 
10−3  7.22±0.05  77.33±0.83  18.56±0.89  95.89  0.56±0.03  0.906±0.006  2.72±0.41  21.5  2.06  88.3  0.88 
DCBMQ10−6  7.22±0.05  32.02±0.61  2.22±0.61  34.24  0.68±0.04  0.894±0.008  0.71±0.47  33.1  1.13  65.7  0.66 
10−5  7.24±0.06  73.68±0.63  14.02±1.34  87.20  0.57±0.02  0.901±0.006  4.54±0.60  31.4  2.73  86.5  0.86 
10−4  7.46±0.06  176.00±0.59  32.61±0.30  208.61  0.33±0.01  0.920±0.005  11.75±0.65  21.4  4.46  94.4  0.94 
10−3  7.60±0.06  284.60±0.67  45.82±0.91  330.42  0.31±0.09  0.950±0.004  30.05±0.91  18.7  6.17  96.4  0.96 

These cited parameters are summarized in Table 3. From this table, there are also the values of Cdl which are derived from the CPE constant by virtue of the next formula [65,66]:

The collected value of Cdl and Rp are exploited to establish the relaxation time constant (τd) in line with to the following equation [67,68]:

The fits of our data using the present circuit are very satisfactory; a typical example of Nyquist and Bode diagrams fitted is presented in Fig. 4. Based on Table 3, the assembled values of A and Cdl are inversely proportionate to with inhibitor concentration, while Rp, RL, n, L, τd, ηZ(%) are diverse in the same manner with the concentration of four 8-hydroxyquinoline derivatives. The increasing Rp achieved 330.42 (Ωcm2) in case of DCBMQ involves the formation of the protective film [69]. Furthermore, the rise of the values of n after addition of synthesized compounds when compared with 2M H3PO4 could be explained away by certain decrease of the working electrode surface heterogeneity because of the occupation of most active adsorption sites by 8-hydroxyquinoline derivatives. The Cdl values in presence of studied molecules are lower than that of blank electrolyte could be through the reduction in local dielectric constant as a result of a substitution of H2O by inhibitors molecules at CS surface [70]. Moreover, the augmentation of the relaxation time constant (τd) with 8-hydroxyquinoline derivatives concentration suggests that the time of adsorption process gets slower. The corresponding L values for CS are observed to improve with addition of 8-hydroxyquinoline derivatives in 2M H3PO4 electrolyte that may be due to an increase of oxidizable or reducible intermediate of 8-hydroxyquinoline derivatives in the electrolyte. Considering the EIS results, it is obvious that the ηZ (%) with increases with concentration for four kinds of 8-hydroxyquinoline derivatives, this might be because the protonation of the heteroatoms (the aromatic amino group) presents in inhibitory molecules reducing the concentration of the hydrogen proton of electrolyte. From EIS findings, the sequence of inhibitor performance is DCBMQ>CBMQ>MBMQ>BIMQ. This is consistent with the obtained data by potentiodynamic polarization experiments. Obviously, the maximum effeteness corresponding at 10−3M for the four inhibitors and therefore, this optimum concentration was chosen to investigate the influence of temperature.

Fig. 4.

EIS Nyquist and Bode diagrams for CS/2M H3PO4+1×10−3M BIMQ, MBMQ, CBMQ and DCBMQ interface: (red line) experimental data and (green line) calculated.

(0.45MB).
3.1.2.2Effect of electrolyte temperature

Figs. 5 and 6 show Nyquist graphics for CS in 2M H3PO4 pre- and post-addition of 10−3M of DCBMQ, CBMQ, MBMQ and BIMQ at 303–333K range. A really good fit for all collected EIS data was obtained with the model proposed early.

Fig. 5.

Nyquist diagrams for CS substrate in 2M H3PO4 at different temperatures.

(0.09MB).
Fig. 6.

Nyquist plots for CS in 2M H3PO4 medium containing 10−3M of various synthesized 8-hydroxyquinoline derivatives at different temperatures.

(0.28MB).

The spectrum impedance in both prior to and subsequent to the addition of 8-hydroxyquinoline derivatives exhibit also two single, the first capacitive loop at a high-medium frequency and the second inductive loop at low frequency. The high-medium frequency capacitive semi-circle is connected to the charge transfer process. The low-frequency inductive semi-circle may be a result of the relaxation process brought about by the ions of the inhibitors. The size of the capacitive loop declines with increasing temperature in both inhibited and uninhibited electrolytes. The extracted corrosion parameters are collected in Table 4. The inspection of the latter demonstrated that, the temperature rise prompts a diminishing of Rp values, initially explained by the increase of the rate of metal dissolution, secondly by the displacement of the adsorption/desorption equilibrium verse the inhibitor desorption and consequently an abatement of surface coverage degree. Besides, the n value declined with temperature increasing, which construed as a proves for the surface inhomogeneity increase. Furthermore, the ηZ (%) for four synthesized 8-hydroxyauinoline derivatives reveals a smaller fall at 303–333K range (decreased to 90.8% for DCBMQ, 82.2% for both CBMQ/MBMQ and 77.2% for BIMQ at optimum concentration in 333K), indicating that the four synthesized 8-hydroxyauinoline derivatives keep their stability and their the inhibitive performance under these conditions.

Table 4.

The corresponding EIS parameters at 303–333K range of CS in 2M H3PO4 including and excluding 10−3M of four 8-hydroxyquinoline derivatives.

Inhibitor  Temp. (K)  Rscm2Rctcm2RLcm2Rpcm2104A−1Sncm2n  L (Hcm−2Cdl (μFcm−2τd (ms)  ηZ (%) 
2M H3PO4303  5.21±0.02  9.710±0.060  2.010±0.080  11.72  2.430±0.090  0.880±0.005  0.19±0.02  109.2  1.22  – 
313  4.28±0.01  5.590±0.044  0.560±0.049  6.15  3.689±0.360  0.879±0.066  0.037±0.036  159.6  0.98  – 
323  2.79±0.02  2.629±0.054  0.723±0.069  3.35  4.786±0.730  0.878±0.020  0.053±0.011  195.7  0.66  – 
333  3.79±0.01  1.855±0.019  0.416±0.019  2.27  6.068±0.270  0.875±0.011  0.037±0.004  236.0  0.54  – 
BIMQ303  8.67±0.06  56.530±0.420  7.650±0.520  64.18  0.600±0.030  0.905±0.007  0.43±0.18  28.1  1.80  81.7 
313  8.238±0.070  29.420±0.342  3.300±0.510  32.72  0.748±0.040  0.878±0.009  0.47±0.150  32.43  1.06  81.2 
323  7.617±0.050  14.360±0.317  2.250±0.380  16.61  0.908±0.090  0.873±0.013  0.034±0.01  35.28  0.58  79.8 
333  7.397±0.050  08.100±0.168  1.844±0.200  9.94  1.027±0.150  0.868±0.017  0.020±0.04  36.03  0.36  77.2 
MBMQ303  6.92±0.06  67.050±0.620  15.770±0.730  82.82  0.620±0.030  0.908±0.006  2.31±0.40  26.0  2.15  86.0 
313  7.010±0.062  36.430±0.520  06.710±0.710  43.14  0.736±0.050  0.850±0.008  0.93±0.13  26.67  1.19  85.7 
323  6.136±0.060  18.580±0.636  3.860±0.681  22.45  0.910±0.010  0.846±0.014  0.04±0.016  29.47  0.66  85.0 
333  7.169±0.060  09.960±0.247  2.839±0.310  12.80  1.000±0.020  0.845±0.016  0.03±0.006  29.49  0.37  82.2 
CBMQ303  7.22±0.05  77.330±0.830  18.560±0.890  95.89  0.560±0.030  0.906±0.006  2.72±0.41  21.5  2.06  88.3 
313  7.576±0.060  32.870±0.870  7.241±0.840  40.11  0.640±0.050  0.885±0.009  0.193±0.06  29.47  1.18  84.7 
323  6.703±0.060  16.000±0.420  4.100±0.456  20.01  0.749±0.080  0.883±0.013  0.077±0.02  31.66  0.64  83.3 
333  7.472±0.050  10.460±0.620  2.328±0.520  12.78  0.935±0.090  0.879±0.014  0.023±0.01  37.04  0.47  82.2 
DCBMQ303  7.60±0.06  284.60±0.67  45.82±0.91  330.42  0.310±0.090  0.950±0.004  30.05±0.91  18.7  6.17  96.4 
313  6.433±0.060  151.30±0.59  14.23±0.99  165.53  0.396±0.010  0.900±0.005  1.801±0.93  22.65  3.74  96.2 
323  6.770±0.060  73.12±0.58  10.15±0.94  83.27  0.683±0.040  0.858±0.007  0.587±0.22  29.03  2.41  95.9 
333  7.080±0.068  27.54±0.53  06.61±0.64  34.15  0.853±0.070  0.855±0.011  0.445±0.09  30.92  1.05  90.8 

Values of Rp were utilized to estimated values of the corrosion current density (icorr) at divers’ temperatures including and excluding of inhibitors using the next equation [49]:

where R is an ideal gas constant (R=8.314Jmol−1K−1), F is the Faraday constant (F=96,485C) and z is the valence of iron metal (z=2).

The icorr values are used to estimate the apparent activation energy Ea according to the according to the formula below [71].

where k is the Arrhenius pre-exponential factor. Additionally, the variation of apparent enthalpy (ΔHa) and apparent entropy (ΔSa) for the establishment of the activation complex in the transition state possibly determined through the above transition-state equation:
where N and h are the Avogadro's and the Plank's constants, respectively.

The variation of icorr as a function 1/T in both before and since the synthesized compounds match a straight line whose slope equal −Ea/R. A graphic of Ln (icorr/T) versus 1/T match a straight line whose slope of (−ΔHa/R) and intercept of (Ln R/Nh+ΔSa/R). Both graphics are illustrated in Figs. 6 and 7. The estimated values of Ea, ΔHa and ΔSa are summarized in Table 5. The estimated values of Ea for CS in the presence of four kinds of 8-hydroxyquinoline derivatives are superior to that of 2M H3PO4 electrolyte. Szauer et al. have clarified that the growing in Ea may be related to a reduced in the adsorption process with increasing temperature [71]. Additionally, the increase value of the Ea may be explained by the proceeding of specific interaction between inhibitor/electrode surface and with electrostatic adsorption, correspondingly. The organic molecules studied have weak basic properties, which promote their protonation in an acidic medium [72]. Mostly attacking the nitrogen atom (N) in the rings imidazole and pyridine moieties, subsequently, they become ionized, that are in equilibrium with the corresponding molecular form (Scheme 2):

Fig. 7.

Ln (icorr) versus 1/T in 2M H3PO4 without and with of optimum concentration of 8-hydroxyquinoline derivatives.

(0.09MB).
Table 5.

Activation parameters for CS substrate in 2M H3PO4 in the absence and presence of optimum concentrations of 8-hydroxyquinoline derivatives.

Medium  R2  Ea (kJmol−1ΔHa (kJmol−1ΔSa (Jmol−1K−1
Blank  0.993  48.14  45.50  −36.02 
BIMQ  0.998  55.32  52.68  −23.90 
MBMQ  0.999  55.13  52.49  −29.75 
CBMQ  0.984  59.39  56.75  −16.26 
DCBMQ  0.988  65.39  62.74  −07.92 
Scheme 2.

Protonation of DCMBQ molecule in 2M H3PO4 medium.

(0.04MB).

Therefore, the solution will contain both the molecular and the cationic forms of the compounds, Moreover, there are specifically adsorbed phosphate ions (they come from the supporting electrolyte, which are usually characterized by low adsorbability). Thus, he appears reasonable to suggest an electrostatic type of adsorption (Fig. 8).

Fig. 8.

Ln(icorr/T) versus 1/T in 2M H3PO4 without and with of optimum concentration of synthesized 8-ydroxyquinoline derivatives.

(0.1MB).

Based on the absolute value of ΔHa it is possible to differentiate between the chemisorption and the physisorption process. For a physisorption adsorption the enthalpy is equal to or lower than 40,100kJmol−1 while, a chemisorption it is equal to or higher than 100kJmol−1[72,73]. The obtained values of ΔHa for all synthesized compounds are superior 40 but lower than 100kJmol−1 suggest that the adsorption model is combination of physisorption and chemisorption [74]. The ΔSa values of DCBMQ, CBMQ, MBMQ, BIMQ, and 1M HCl electrolyte are negatives, which reveal that the activated complex in the rate-determining step stands for an association rather than dissociation. The values of the activation energy are superior for inhibited solutions than for uninhibited solution. This could be the result of the adsorption of four kinds of benzimidazole derivatives on the CS surface, which could be considered a replacement process of water molecules during adsorption of benzimidazole derivatives on the CS surface. This observation is in agreement with the findings of other workers [20,75].

3.2Adsorption phenomenon

The scanning electron microscopy (SEM) was realized so as to investigate the impact of different 8-hydroxyquinoline derivatives upon the steel surface morphology. The SEM observations (Fig. 9a–f) of the CS substrate surfaces were taken at same amplification (×1100) so as to see the progressions that occurred over corrosion process in the presence and non-attendance of the studied inhibitors in 2M H3PO4 electrolyte. The immerged metal surface in H3PO4 solution without inhibitor was emphatically harmed (Fig. 9b) compared to the slick and uniform metal surface with just little scratches by abrasive grains before the immersion (Fig. 9a). After added 10−3M of investigated compounds, the damage level of metal surface is astoundingly decreased, which justify the effect inhibitive of studied molecules. Besides, the metal surface in presence of DCBMQ is very smooth and less damaged than other inhibitors.

Fig. 9.

SEM micrographs of CS surface: (a) just after being polished, (b) after 6h immersion in 2M H3PO4 and after 6h of immersion in 2M H3PO4 containing 10−3M of (c) BIMQ, (d) MBMQ, (e) CBMQ and (f) DCBMQ.

(1.42MB).

The new synthesized 8-hydroxyquinoline derivatives containing benzimidazole moiety restrain corrosion of the CS by adsorbing onto the metal surface in a corrosive electrolyte. To clear up this adsorption process, various models of adsorption isotherms can be utilized, a better fit of EIS data was obtained through the Langmuir isotherm, which is defined by Eq. (14)[76]:

where Kads named the equilibrium constant for the adsorption process, θ is the surface coverage which is represented by next formula (15):

The Kads values are connected with free energy of adsorption (ΔGadso) according to the following equation [76]:

where R is defined as constant molar gas and 55.55 is the concentration of water in solution in molL−1.

The analysis of Fig. 10 shows that for all the compounds the variation of the ratio Cinh/θ as a function of Cinh is linear. This indicates that the adsorption of 8-hydroxyquinoline derivatives on the CS surface in phosphoric medium obeys the Langmuir adsorption isotherm. Therefore, the inhibition of corrosion is due to the formation of a single layer on the CS surface [77], limiting the access of the electrolyte. The regression coefficients (R2) are all close to 1 (R2>0.999), confirming the validity of the chosen model.

Fig. 10.

Langmuir isotherm adsorption model of various synthesized 8-hydroxyquinoline derivatives on the CS surface in 2M H3PO4.

(0.09MB).

From the intercepts of the straight lines Cinh/θ-axis, the Kads values were determined and given in Table 6. The great values of Kads are usually interpreted as an indicator of the adsorption strength between the inhibitor molecules and the CS surface [78]. The calculated ΔGadso values, using Eq. (16), were also listed in Table 6. The discrimination among chemisorption and physisorption depends on the estimated value of ΔGadso. For a physisorption mechanism the ΔGadso of adsorption ought to be equal to or under 20kJmol−1 while, for chemisorption it is equivalent to or superior to 40kJmol−1[79–81]. According to these informations, the obtained ΔGadso values indicate that the adsorption mechanism of 8-hydroxyquinoline derivatives on CS surface in phosphoric electrolyte is typical of chemisorption. The negative value of DCBMQ indicates its strong adsorption on the CS surface [82,83]. Moreover, |ΔGadso| of 8-hydroxyquinoline derivatives decreases in the order DCBMQ>CBMQ>MBMQ>BIMQ, this is in great concurrence with the ranking of inhibitive properties got from the electrochemical methods.

Table 6.

Thermodynamic parameters for the adsorption of various synthesized 8-hydroxyquinoline derivatives in 2M H3PO4 on the CS at 303K.

Inhibitor  R2  Kads (104M−1ΔSadso (kJmol−1Qads (kJmol−1ΔSadso (kJmol−1
BIMQ  0.999  9.08  −38.88  −7.64  103.10 
MBMQ  0.999  10.07  −39.14  −7.55  104.26 
CBMQ  0.999  14.47  −40.05  −11.89  92.94 
DCBMQ  1.000  76.25  −44.24  −25.35  62.34 

The estimation of the adsorption heat (−Qads) was assessed from the next equation [84,85]:

where q is a constant, Cinh is the inhibitor concentration, θ is the occupied, (1θ) is the vacant site not occupied by the inhibitor [86]. Fig. 11. illustrates the variation of Ln [θ/(1θ)] as a function of the inverse of the temperature for the different synthesized compounds. The lines obtained have a slope equal to (Qads/R). The negative values of Qads, given in Table 6, indicated that the adsorption of used inhibitors on the CS surface is exothermic. In other words, the negative Qads values exhibit that the rate of adsorption and the inhibition efficiency decreased with increase in temperature also supporting physical adsorption [87]. It is reported that the adsorption heat might be approximately considered as the standard enthalpy of adsorption (ΔGadso) under studied conditions [60,88]. Therefore, the standard adsorption entropy (ΔSadso) was obtained based on following thermodynamic basic equation [87,88]:

Fig. 11.

Ln (θ/(1θ)) vs. 1/T for adsorption of synthesized 8-hydroxyquinoline derivatives on the CS surface.

(0.08MB).

The obtained ΔSadso values in the presence of studied compounds are huge and positive (Table 6), uncovers that a decline in disordering during the passage of from reactant to the activated complex [89].

X-ray photoelectron spectroscopy (XPS) analysis was performed to provide insight to the adsorption mechanism of the 8-hydroxyquinoline derivatives and to investigate the composition of the organic adsorbed layer on the CS surface in the phosphoric acid medium. High-resolution XPS spectra (C 1s, N 1s, O 1s, Cl 2p, P 2p and Fe 2p), obtained from carbon-steel sample subsequent of immersion in 2M H3PO4 with 10−3M of inhibitor at 303K are shown in Fig. 12. Only XPS results of DCBMQ are presented. XPS spectra show complex forms, which were assigned to the corresponding species through a deconvolution fitting procedure using the CASA XPS software.

Fig. 12.

High-resolution X-ray photoelectron deconvoluted profiles of C 1s, N 1s, Cl 2p, O 1s, P 2p and Fe 2p3/2 for DCBMQ treated CS substrate.

(0.34MB).

The deconvolution of the C 1s spectrum may be fitted into four components, indicating different carbon environments, located at 285.0, 286.0, 288.8 and 290.2eV (Fig. 12 and Table 7). The first component, has the largest contribution (61%), can be assigned to the CC, CC and CH bonds in the DCBMQ molecule [90]. The second constituent is mainly ascribed to the CN, CN and CO bonds [91]. The third component can be associated to the carbon atom of the CN+ in 8-quinolinol and in benzimidazole moieties in the DCBMQ molecule [92], resulting probably from the protonation of the N structure, as described in Scheme 2, and/or the coordination of nitrogen with the iron of steel surface. The last and less intense component (2%) at binding energy (290.2eV) can be ascribed to shake-up satellite due to π(π* transitions in aromatic rings [93].

Table 7.

Binding energies (eV), relative intensity and their assignment for the major core lines observed of DCMBQ treated CS substrate.

Element  Position (eV)  Assignment 
C 1s285.0 (61%)  CH/CC/C
285.9 (25%)  CN/CN/C
288.8 (12%)  CN+ 
290.2 (2%)  π–π* shakeup satellite 
N 1s400.0 (79%)  N structure, N
401.9 (21%)  N+
O 1s530.1 (12%)  O2− in Fe2O3/OP in FePO4 
531.6 (84%)  OH in FeOOH/(PO in FePO4)/C
533.3 (4%)  Adsorbed H2
Cl 2p200.5 (83%)  ClC (Cl 2p3/2
202.0 (17%)  ClC (Cl 2p1/2 
P 2p133.4 (72%)  P 2p3/2 (PO43− in FePO4
134.3 (28%)  P 2p1/2 (PO43− in FePO4
Fe 2p3/2707.1 (4%)  Fe0 
710.9 (33%)  Fe3+ in Fe2O3 and in FeOOH 
711.6 (63%)  Fe3+ in FeOOH and in FePO4 

The high-resolution Cl 2p core-level of CS substrate covered with DCMBQ is best resolved with at least two spin–orbit-split doublets (Cl 2p1/2 and Cl 2p3/2) as illustrated in Fig. 12, with binding energy for Cl 2p3/2 peak lying at about 200.5eV [94]. This component can be associated to ClC bond of Cl2C6H2 group [94], belonging to the DCMBQ molecule.

The investigated bare CS is nitrogen free [95] and therefore, the adsorption of 8-hydroxyquinoline derivatives on the steel surface can be explained based especially on the N 1s signal presence. The surveyed spectrum for N 1s of protected carbon steel with DCBMQ in 2M H3PO4 can be fitted into two main components indicating therefore the presence of two chemical states of nitrogen (Fig. 12 and Table 7). The presence of the N species demonstrates that the investigated 8-hydroxyquinoline derivative (DCMBQ) molecules are adsorbed on the steel surface. Indeed, the first N 1s component, located at 400.0eV, has the largest contribution (79%) and can be attributed to the CN in the benzimidazole moiety and to the unprotonated N atom (N structure) in the 8-quinolinol and benzimidazole moieties [96]. It is significant that this component slightly shifted to higher binding energy side (ΔEb=0.51eV) compared to that one observed in the case of pure DCMBQ (Fig. 13). The same trend is shown in the case of the other 8-hydroxyquinoline derivatives (Table 8). This behaviour was explained by the coordination of the unprotonated N with the iron atom of steel surface, i.e. formation of N–Fe bond complex, which leads to a positive polarization of the nitrogen atom, and therefore a core-level chemical shift to higher binding energy is produced [97,98]. The second N 1s component, located at 401.9eV, component may be associated to the positively charged nitrogen, and could be related to protonated nitrogen atoms (N+H) in the 8-quinolinol and benzimidazole moieties in the DCBMQ molecule [99,100]. On the basis on the N 1s XPS results, we can conclude that the adsorption occurs through chemical chelation of the vacant d orbitals of iron with the lone sp2 electron pairs present on the N atom (N structure) in the 8-quinolinol and in benzimidazole moieties of the investigated inhibitors.

Fig. 13.

High-resolution X-ray photoelectron deconvoluted profile of N 1s for a-pure DCBMQ and b-DCBMQ treated CS substrate in 2M H3PO4 medium.

(0.18MB).
Table 8.

Shift binding energy values for N 1s component (N structure) of 8-hydroxyquinoline derivatives before and after immersion in 2M H3PO4 medium.

Inhibitor  ΔEb (eV) 
BIMQ  0.70 
MBMQ  0.63 
CBMQ  0.32 
DCBMQ  0.51 

The O 1s spectrum for CS surface after immersion in 2M H3PO4 solution containing DCMBQ can be resolved into three components (Fig. 12 and Table 7). The first one, at 530.1eV, is attributed to oxygen double bonded to Fe3+ in the iron oxide (Fe2O3) [101] and non-bridging oxygen in the phosphate group (PO) [94]. The second component, located at. 531.6eV, is the most intense one (80%), can be assigned to combined effects of singly bonded oxygen (O) in FeO, in PO and in COH groups. Indeed, this component can be partly ascribable to OH of hydrous iron oxides, such as FeOOH [102] and to OP in the adsorbed phosphate group (PO43−) [103] and partly assigned to singly bonded oxygen (O) in CO and in OH which are present in the DCMBQ molecules [104]. However, the separation of inorganic (O in FeOOH, phosphates) and organic oxygen (O in carbonyl groups) contributions since O 1s signal is not possible [105]. The latest at 533.3eV can be attributed to oxygen of adsorbed water [106], which remained on the surface after drying the sample.

The P 2p spectrum of CS surface after immersion in 2M H3PO4 solution containing DCMBQ was fitted into two asymmetric main components ∼0.9eV apart, assigned to P 2p3/2 at 133.5eV and P 2p1/2 at 134.4eV, due to spin splitting, as given in Fig. 12. This is attributed to PO43− in agreement with the presence of the FePO4 as detected in the O 1s spectrum [103].

From the Fe2p signal in Fig. 12 for the CS surface covered with DCMBQ, two characteristic peaks Fe2p1/2 at 725eV (not given) and Fe2p3/2 at 711 due to spin splitting are evident. The deconvolution of the high resolution Fe 2p3/2 XPS spectrum consists in three main components, as shown in Fig. 12 and Table 7, corresponding to the same groups combining oxygen to iron, observed in the case of the O 1s signal: Fe2O3, FeOOH and FePO4. The first one, at 707.1eV, was attributed to metallic iron [92]. The second one at 710.9eV may be associated to ferric oxide species such as Fe2O3 (i.e., Fe3+ oxide) and/or to ferric hydroxide species such as FeOOH [92]. The latest, at 711.6eV, presents the highest contribution (62%), can be associated to the presence of FeOOH and FePO4[92,107].

XPS surface elemental analyses of DCMBQ extract and DCMBQ-treated steel samples were also performed and given in Table 9. In both cases, the sum of the atom concentrations was normalized to 100% in order to easily compare surface concentrations for the different elements. Inspection of the obtained results shows the presence of N atom (3.72%) on the steel surface probably due to the DCMBQ adsorption through chemical chelation of the lone sp2 electron pairs present on the N atom of the hetercocyclic ring of 8-hydroxyquinoline derivative with the vacant d orbitals of iron. The atom concentration of oxygen is high in the case of DCMBQ-treated steel sample (38.25%) compared to that of DCMBQ powder (13.51%) (Table 8). This difference is normally due to the formation of oxidized species (Fe2O3, FeOOH and FePO4) in 2M H3PO4 and therefore DCMBQ molecules are incorporated into the oxide/hydroxide iron layer formed on the CS surface. The appearance of phosphorus element (4.56%) on the steel surface confirms the formation of FePO4 due to the testing medium (2M H3PO4).

Table 9.

Surface elemental concentrations (at.%) in DCMBQ powder and DCMBQ treated-steel.

Element  DCMBQ powder  DCMBQ treated-steel 
72.66  49.05 
13.51  38.25 
7.71  3.72 
Fe  –  4.41 
–  4.56 
Cl  6.12  – 

The above XPS detail analyses (qualitative and quantitative) demonstrate that the presence of chemical (chemisorption) interactions between surface steel ions and DCMBQ and confirm the adsorption isotherm findings. The addition of this 8-hydroxyquinoline derivative in the corrosive solution promotes the formation of the stable metal-organic complex (DCMBQ/Fe) and an insoluble oxide layer leading to reduce the attack of acid ions as well as restraining the corrosion process simultaneously.

3.3Quantum chemical calculations

DFT/B3LYP/6-31+G(d,p) optimized structures of BIMQ, CBMQ, DCBMQ and MBMQ are shown in Fig. 14. It was observed that the quinolin-8-ol ring and benzimidazole ring are not on the same plane as the two rings have a torsion angle of about 79–82° depending on the molecule. In other words, there is a need to identify the ring moiety that has the maximum overlap with mild steel in the adsorption process. Though the variation in the dihedral angles (listed in Fig. 14) does not follow a particular trend, it is noteworthy that BIMQ with the largest torsion angle, −81.50° (between the two rings) has the lowest inhibition efficiency, while DCBMQ with the lowest torsion angle, 79.24° has the highest inhibition efficiency recorded from the experiments. This suggests that planarity of the molecules might influence their corrosion inhibition efficiency [108–110].

Fig. 14.

Optimized structures of the neutral and protonated forms of the studied 8-hydroxyquinoline derivatives.

(0.32MB).

The frontier molecular orbitals electron density isosurfaces are shown in Fig. 15. The distribution of highest occupied molecular orbital (HOMO) electron density for the molecules revealed that the major orbitals that contribute to the HOMO are those of the quinolin-8-ol moiety. Surprisingly the electron density of the lowest occupied molecular orbitals are also distributed over the quinolin-8-ol ring. These observations could lead one to assume that the inhibitor molecules would preferably interact with mild steel via the quinolin-8-ol. The adsorption of the inhibitor molecules on mild steel surface might be through the plane of quinolin-8-ol ring.

Fig. 15.

HOMO and LUMO electron density isosurfaces of the investigated 8-hydroxyquinoline derivatives (isosurfave value=0.02).

(0.27MB).

Selected quantum chemical parameters or reactivity indices of the studied inhibitor molecules (both neutral and protonated) are listed in Table 10. The studied compounds are more prone to protonation on the sp2 benzimizalole nitrogen since benzimidazole is more basic (having a smaller pKb) than quinoline [111]. Therefore, the protonated species were considered as those in which the proton is attached to the benzimidazole sp2 nitrogen. For a conventional corrosion inhibitor whose reactivity is governed by its frontier molecular orbitals behaviour, higher HOMO energy (EHOMO) and lower LUMO energy (ELUMO) are associated with higher tendency to donate electron to vacant metallic orbital, and hence higher corrosion inhibition efficiency [112]. Few instances of lower ELUMO as an indication of possible back-donation from occupied orbitals of the metal to the anti-bonding orbitals of the inhibitor and a drive for improved adsorption of the inhibitor molecules on the metal surface have also been documented [113,114].

Table 10.

Quantum chemical parameters for the neutral and protonated forms of of 8-hydroxyquinoline derivatives obtained using the B3LYP/6-31+G(d,p)//IEFPCM model.

Inhibitor  Parameters
  EHOMO (eV)  ELUMO (eV)  ΔE (eV)  η (eV)  χ (eV)  ΔN  Dipole moment (Debye) 
Neutral species
BIMQ  −6.116  −1.835  4.281  2.140  3.975  0.197  5.031 
CBMQ  −6.130  −1.842  4.288  2.144  3.986  0.195  3.767 
DCBMQ  −6.141  −1.850  4.291  2.145  3.995  0.192  5.309 
MBMQ  −6.107  −1.830  4.277  2.139  3.969  0.199  5.218 
Protonated species
IMQ-H+  −6.319  −1.978  4.341  2.171  4.148  0.155  13.364 
CBMQ-H+  −6.328  −2.288  4.040  2.020  4.308  0.127  8.947 
DCBMQ-H+  −6.338  −2.282  4.055  2.028  4.310  0.126  6.545 
MBMQ-H+  −6.311  −1.972  4.339  2.169  4.142  0.156  12.352 

The trend of EHOMO values in Table 10 when compared with the order of inhibition efficiencies does not support increasing inhibition efficiency with increasing EHOMO. However, a near linear correlation was observed for the ELUMO values in comparison with the order of inhibition efficiencies recorded from the experiments (DCBMQ>CBMQ>MBMQ>BIMQ) such that DCBMQ with the lowest ELUMO has the highest inhibition efficiency.

Furthermore, electronegativity is a measure of the ability of a molecule to retain its pairs of electrons. The order of electronegativity of the inhibitors is DCBMQ>CBMQ>MBMQBIMQ, which suggests than the corrosion inhibition potentials of the molecules might be related with the tendency of the molecules to accept electrons from occupied metallic orbitals. The dipole moments for the neutral inhibitor molecules do not correlate with the observed trend of inhibition efficiencies. However, the dipole moments for the protonated species suggest that a protonated molecule with lower dipole moment is better disposed to accumulation in the surface layer of the metal and therefore has higher corrosion inhibition efficiency [112,115,116].

3.4Monte Carlo simulations

Adsorption of the studied inhibitor molecules on mild steel surface was modelled in the absence and presence of phosphoric acid ions. The equilibirium configurations for the adsorption the molecules on Fe(110) both in isolation and in the presence of 60 H3O+ and 20 PO43− are shown in Fig. 16. It is evident from BIMQ/Fe(110), CBMQ/Fe(110), DCBMQ/Fe(110) and MBMQ/Fe(110) that the inhibitor molecules adsorb on Fe(110) surface via the plane of the quinolin-8-ol moiety as the plane of the ring lies nearly flat to the metallic surface. Since the inhibitor molecules would compete with acidic ions (H3O+ and PO43−), the adsorption of inhibitor molecules in the presence of these ions was also examined and the equilibirium configurations in Fig. 16 revealed that the studied inhibitor molecules have good tendency of displacing the corrosive acidic ions from the metallic surface. Adsorption energies of the optimized inhibitor-Fe(110) complexes without and with acidic ions are listed in Table 11. The order of increasing magnitude of the adsorption energy (Eads) for the adsorption of isolated inhibitor molecule (in the absence of corrosive acidic ions) is DCBMQ (Eads=−666.99kJ/mol)>CBMQ (Eads=−646.24kJ/mol)>MBMQ (Eads=−642/77kJ/mol)>BIMQ (Eads=−621.11kJ/mol). Similar trend was obtained for the adsorption of inhibitor molecules in the presence of acidic ions. The simulation results are in good agreeement with the experimentally observed trend of corrosion inhibition efficiencies.

Fig. 16.

Adsorbed inhibitor molecules on Fe(110) surface in absence and presence of 60 molecules of H3O+ and 20 molecules of PO43− obtained from Monte Carlo simulation.

(0.98MB).
Table 11.

Estimated energy values for the adsorption of 8-hydroxyquinoline derivatives on Fe(110) surface in the absence and presence of 60 molecules of H3O+ and 20 molecules of PO43− obtained from Monte Carlo simulation.

System  Eads (kJ/mol) 
BIMQ/Fe(110)  −621.11 
CBMQ/Fe(110)  −646.24 
DCBMQ/Fe(110)  −666.99 
MBMQ/Fe(110)  −642.77 
BIMQ+60 H3O++20 PO43−/Fe(110)  −775.38 
CBMQ+60 H3O++20 PO43−/Fe(110)  −856.85 
DCBMQ+60 H3O++20 PO43−/Fe(110)  −831.08 
MBMQ+60 H3O++20 PO43−/Fe(110)  −808.74 
4Conclusions

Four new the 8-ydroxyquinoline derivatives containing benzimidazole moiety were synthesized and identified by 1H, 13C NMR and elemental analysis. The impact of these four heterocyclic compounds on the corrosion inhibition for carbon steel in 2M H3PO4 solution was investigated using experimental and theoretical techniques. The experimental results showed that the chemical structure of the 8-ydroxyquinoline derivatives containing benzimidazole moiety impairs the inhibitory efficiency, generally they are good to excellent protection for steel corrosion. At the concentrations studied, inhibition performance follows the sequence DCBMQ>CBMQ>MBMQ>BIMQ. The results obtained from potentiodynamic polarization data indicate that the investigated compounds are mixed type inhibitors. Impedance studies were analyzed using an equivalent circuit for effects of concentration and temperature for all tested inhibitors. All 8-ydroxyquinoline derivatives are adsorbed on the metal surface according to Langmuir adsorption isotherm model and the corresponding values of ΔGadso revealed that their adsorption mechanism on steel surface is mainly due to chemisorption. XPS results confirm the thermodynamic findings and reveal the formation of protective film on the carbon steel surface in 2M H3PO4 medium, composed by an iron oxide/hydroxide/phosphates layer, in which the 8-hydroxyquinoline molecules are incorporated. Both the computational DFT calculations and Monte Carlo simulations results revealed that the inhibitor molecules adsorb on mild steel surface through the 8-hydroxyquinoline ring plane and the theoretical parameters correlate reasonably with the trend of experimental inhibition efficiencies.

Conflicts of interest

The authors declare no conflicts of interest.

References
[1]
M. El Faydy, F. Benhiba, B. Lakhrissi, M. Ebn Touhami, I. Warad, F. Bentiss, et al.
J Mol Liq, 295 (2019), pp. 111629
[2]
D.S. Chauhan, M.A. Quraishi, A.A. Sorour, S.K. Saha, P. Banerjee.
RSC Adv, 9 (2019), pp. 14990-15003
[3]
W. Guo, S. Chen, Y. Feng, C. Yang.
J Phys Chem C, 111 (2007), pp. 3109-3115
[4]
N.O. Eddy, E.E. Ebenso.
Afr J Pure Appl Chem, 2 (2008), pp. 107-115
[5]
M. El Faydy, M. Galai, R. Touir, El Assyry, B. Touhami, B. Lakhrissi, et al.
J Mater Environ Sci, 7 (2016), pp. 1406-1416
[6]
I.B. Obot, S.A. Umoren, N.O. Obi-Egbedi.
Int J Electrochem Sci, 7 (2012), pp. 10215-10232
[7]
H. Zarrok, S.S. Al-Deyab, A. Zarrouk, R. Salghi, B. Hammouti, H. Oudda, et al.
Int J Electrochem Sci, 7 (2012), pp. 4047-4063
[8]
A. Zarrouk, B. Hammouti, H. Zarrok, M. Bouachrine, K.F. Khaled, S.S. Al-Deyab, et al.
Int J Electrochem Sci, 6 (2012), pp. 6353-6364
[9]
H. Zarrok, K. Al Mamari, A. Zarrouk, R. Salghi, B. Hammouti, S.S. Al-Deyab, et al.
Int J Electrochem Sci, 7 (2012), pp. 10338-10357
[10]
A.K. Singh, M.A. Quraishi.
Mater Chem Phys, 123 (2010), pp. 666-677
[11]
M. El Faydy, M. Galai, A. El Assyry, A. Tazouti, R. Touir, B. Lakhrissi, et al.
J Mol Liq, 219 (2016), pp. 396-404
[12]
A.K. Singh, B. Chugh, S.K. Saha, P. Banerjee, E.E. Ebenso, S. Thakur, et al.
Results Phys, 14 (2019), pp. 102383
[13]
H. Zarrok, H. Oudda, A. El Midaoui, A. Zarrouk, B. Hammouti, M. Ebn Touhami, et al.
Res Chem Intermediat, 38 (2012), pp. 2051-2063
[14]
A. Ghazoui, A. Zarrouk, N. Bencaht, R. Salghi, M. Assouag, M. El Hezzat, et al.
J Chem Pharm Res, 6 (2014), pp. 704-712
[15]
H. Zarrok, A. Zarrouk, R. Salghi, H. Oudda, B. Hammouti, M. Assouag, et al.
J Chem Pharm Res, 4 (2012), pp. 5056-5066
[16]
M.A. Hegazy, M. Abdallah, M.K. Awad, M. Rezk.
Corros Sci, 81 (2014), pp. 54-64
[17]
M.H.M. Hussein, M.F. El-Hady, H.A.H. Shehata, M.A. Hegazy, H.H.H. Hefni.
J Surf Deterg, 16 (2013), pp. 233-242
[18]
V.V. Torres, R.S. Amado, C.F. de Sá, T.L. Fernandez, C.A.S. Riehl, A.G. Torres, et al.
Corros Sci, 53 (2011), pp. 2385-2392
[19]
M.A. Hegazy, A.M. Badawi, S.S. Abd El Rehim, W.M. Kamel.
Corros Sci, 69 (2013), pp. 110-122
[20]
I.B. Obot, N.O. Obi-Egbedi.
Curr Appl Phys, 11 (2011), pp. 382-392
[21]
M.E. Belghiti, Y. Karzazi, A. Dafali, I.B. Obot, E.E. Ebenso, K.M. Emran, et al.
J Mol Liq, 216 (2016), pp. 874-886
[22]
H. About, M. El Faydy, F. Benhiba, Z. Rouifi, M. Boudalia, A. Guenbour, et al.
J Bio Tribo Corros, 5 (2019), pp. 50
[23]
X.H. Li, S.D. Deng, H. Fu.
Corros Sci, 53 (2011), pp. 3704-3711
[24]
X.H. Li, S.D. Deng, H. Fu.
Corros Sci, 53 (2011), pp. 664-670
[25]
H. Zarrok, A. Zarrouk, R. Salghi, B. Hammouti, M. Elbakri, M. Ebn Touhami, et al.
Res Chem intermediat, 40 (2014), pp. 801-815
[26]
Y.J. Yang, Y.K. Li, L. Wang, H. Liu, D.M. Lu, L. Peng.
Int J Electrochem Sci, 14 (2019), pp. 3375-3392
[27]
E.G. Ebrahimi, J. Neshati, F. Rezaei.
Prog Org Coat, 105 (2017), pp. 1-8
[28]
T. Poornima, J.A. Nayak, N. Shetty.
Corros Sci, 53 (2011), pp. 3688-3696
[29]
M. Benabdellah, R. Touzani, A. Dafali, B. Hammouti, S. El Kadiri.
Mater Lett, 61 (2007), pp. 1197-1204
[30]
D. Ben Hmamou, A. Zarrouk, R. Salghi, H. Zarrok, E.E. Ebenso, B. Hammouti, et al.
Int J Electrochem Sci, 9 (2014), pp. 120-138
[31]
D. Ben Hmamou, R. Salghi, A. Zarrouk, H. Zarrok, B. Hammouti, S.S. Al-Deyab, et al.
Int J Electrochem Sci, 8 (2013), pp. 11526-11545
[32]
M. Belayachi, H. Serrar, H. Zarrok, A. El Assyry, A. Zarrouk, H. Oudda, et al.
Int J Electrochem Sci, 10 (2015), pp. 3010-3025
[33]
M.A. Hegazy.
J Mol Liq, 208 (2015), pp. 227-236
[34]
R.S. Keri, S.A. Patil.
Biomed Pharmacother, 68 (2014), pp. 1161-1175
[35]
P. Singh, V. Srivastava, M.A. Quraishi.
J Mol Liq, 216 (2016), pp. 164-173
[36]
W. Zhang, R. Ma, H. Liu, Y. Liu, S. Li, L. Niu.
J Mol Liq, 222 (2016), pp. 671-679
[37]
N. Du, Q. Mei, M. Lu.
Synth Met, 149 (2005), pp. 193-197
[38]
B. Himmi, S. Kitane, A. Eddaif, J. Joly, F. Hlimi, F. Soufiaoui, et al.
J Heterocycl Chem, 45 (2008), pp. 1023-1026
[39]
V.D. Warner, J.N. Sane, D.B. Mirth, S.S. Turesky, B. Soloway.
J Med Chem, 19 (1976), pp. 167-169
[40]
M. Tourabi, K. Nohair, M. Traisnel, C. Jama, F. Bentiss.
Corros Sci, 75 (2013), pp. 123-133
[41]
D.A. Shirley.
Phys Rev B, 5 (1972), pp. 4709-4714
[42]
A.D. Becke.
J Chem Phys, 98 (1993), pp. 5648-5652
[43]
A.D. Becke.
Phys Rev A, 38 (1988), pp. 3098-3100
[44]
C. Lee, W. Yang, R.G. Parr.
Phys Rev B, 37 (1988), pp. 785-789
[45]
J.H. Christensen, A.J. Smith, R.B. Reed, K.L. Elmore.
J Chem Eng Data, 11 (1966), pp. 60-63
[46]
H.P.R. Frederiske.
Dielectric measurements.
Electr. Prop. Solids, first ed., pp. 85-147
[47]
K.O. Sulaiman, A.T. Onawole.
Comput Theor Chem, 1093 (2016), pp. 73-80
[48]
M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, et al.
Gaussian 09, revision D.01.
Gaussian, Inc., (2009),
[49]
M. El Faydy, R. Touir, M. Ebn Touhami, A. Zarrouk, C. Jama, B. Lakhrissi, et al.
Phys Chem Chem Phys, 20 (2018), pp. 20167-20187
[50]
A. Kokalj.
Chem Phys, 393 (2012), pp. 1-12
[51]
H. Lgaz, R. Salghi, I.H. Ali.
Int J Electrochem Sci, 13 (2018), pp. 250-264
[52]
R.G. Pearson.
Inorg Chem, 27 (1988), pp. 734-740
[53]
K. Marusic, H.O. Curkovic, H. Takenouti.
Electrochim Acta, 56 (2011), pp. 7491-7502
[54]
N.A. Negm, N.G. Kandile, I.A. Aiad, M.A. Mohammad.
Colloid Surf, 391 (2011), pp. 224-233
[55]
D.K. Yadav, M.A. Quraishi, B. Maiti.
Corros Sci, 55 (2012), pp. 254-266
[56]
A.A. Hermas, M.S. Morad, M.H. Wahdan.
J Appl Electrochem, 34 (2004), pp. 95-102
[57]
C.M. Palomar-Pardavé, M. Romero-Romo, H. Herrera-Hernández, M.A. Abreu-Quijano, N.V. Likhanova, J. Uruchurtu, et al.
Corros Sci, 54 (2012), pp. 231-243
[58]
S.S. Abdel Rehim, H.H. Hassan, M.A. Amin.
Appl Surf Sci, 187 (2002), pp. 279-290
[59]
M.A. Amin, S.S.A. El-Rehim, E.E.F. El-Sherbini, R.S. Bayoumi.
Electrochim Acta, 52 (2007), pp. 3588-3600
[60]
A.K. Singh, M.A. Quraishi.
Corros Sci, 52 (2010), pp. 152-160
[61]
R.S. Goncalves, D.S. Azambuja, A.M. Serpa Lucho.
Corros Sci, 44 (2002), pp. 467-479
[62]
D.S. Chauhan, K.R. Ansari, A.A. Sorour, M.A. Quraishi, H. Lgaz, R. Salghi.
Int J Biol Macromol, 107 (2018), pp. 1747-1757
[63]
M. Abdallah, M.A. Hegazy, M. Alfakeer, H. Ahmed.
Green Chem Lett Rev, 11 (2018), pp. 457-468
[64]
R. Macdonald, D.R. Franceschetti.
Impedance spectroscopy, pp. 96
[65]
D.A. Lopez, S.N. Simison, S.R. de Sanchez.
Electochim Acta, 48 (2003), pp. 845-854
[66]
S. Martinez, M. Metikoš-Huković.
J Appl Electrochem, 33 (2003), pp. 1137-1142
[67]
N. Labjar, M. Lebrini, F. Bentiss, N.E. Chihib, S. El Hajjaji, C. Jama.
Mater Chem Phys, 119 (2010), pp. 330-336
[68]
M. El Faydy, B. Lakhrissi, A. Guenbour, S. Kaya, F. Bentiss, I. Warad, et al.
J Mol Liq, 280 (2019), pp. 341-359
[69]
B. Chugha, A.K. Singh, S. Thakura, B. Panic, A.K. Pandeya, H. Lgaz, et al.
J Phys Chem C, (2019), pp. 22897-22917
[70]
M. El Faydy, M. Rbaa, L. Lakhrissi, B. Lakhrissi, I. Warad, A. Zarrouk, et al.
Surf Interfaces, 14 (2019), pp. 222-237
[71]
T. Szauer, A. Brandt.
Electrochim Acta, 26 (1981), pp. 1253-1256
[72]
A. Popova, M. Christov, A. Zwetanova.
Corros Sci, 49 (2007), pp. 2131-2143
[73]
A. Popova, E. Sokolova, S. Raicheva, M. Chritov.
Corros Sci, 45 (2003), pp. 33-41
[74]
C. Verma, A. Singh, G. Pallikonda, M. Chakravarty, M.A. Quraishi, I. Bahadur, et al.
J Mol Liq, 209 (2015), pp. 306-319
[75]
D.K. Yadav, M.A. Quraishi.
Ind Eng Chem Res, 51 (2012), pp. 14966-14979
[76]
F. Bentiss, M. Bouanis, B. Mernari, M. Traisnel, H. Vezin, M. Lagrenée.
Appl Surf Sci, 253 (2007), pp. 3696-3704
[77]
A.K. Singh, S. Thakur, B. Pani, E.E. Ebenso, M.A. Quraishi, A.K. Pandey.
ACS Omega, 3 (2018), pp. 4695-4705
[78]
R.K. Gupta, M. Malviya, K.R. Ansari, H. Lgaz, D.S. Chauhan, M.A. Quraishi.
Mater Chem Phys, 236 (2019), pp. 121727
[79]
F. Bentiss, M. Traisnel, H. Vezin, H.F. Hildebrand, M. Lagrenée.
Corros Sci, 46 (2004), pp. 2781-2792
[80]
F. Bentiss, M. Lebrini, M. Lagrenée, M. Traisnel, A. Elfarouk, H. Vezin.
Electrochim Acta, 52 (2007), pp. 6865-6872
[81]
I. Lukovits, A. Shaban, E. Kalman.
Electrochim Acta, 50 (2005), pp. 4128-4133
[82]
A.K. Singh, S. Thakur, B. Pani, G. Singh.
New J Chem, 42 (2018), pp. 2113-2124
[83]
M. El Faydy, M. Galai, M.E. Touhami, I.B. Obot, B. Lakhrissi, A. Zarrouk.
J Mol Liq, 248 (2017), pp. 1014-1027
[84]
F.H.M. Azahar, S. Mitra, A. Yabushita, A. Harata, B.B. Saha, K. Thu.
Appl Therm Eng, 143 (2018), pp. 688-700
[85]
E.E. Oguzie, V.O. Njoku, C.K. Enenebeaku, C.O. Akalezi, C. Obi.
Corros Sci, 50 (2008), pp. 3480-3486
[86]
E.A. Noor, A.H. Al-Moubaraki.
Mater Chem Phys, 110 (2008), pp. 145-154
[87]
G. Avci.
Colloid Surf A, 317 (2008), pp. 730-736
[88]
S.M.A. Hosseini, A. Azimi.
Corros Sci, 51 (2009), pp. 728-732
[89]
M. Sahin, S. Bilgic, H. Yılmaz.
Appl Surf Sci, 195 (2002), pp. 1-7
[90]
D. Briggs, M.P. Seah.
Practical surface analysis by Auger and X-ray photoelectron spectroscopy.
John Wiley & Sons Ltd., (1983),
[91]
H. Ouici, M. Tourabi, O. Benali, C. Selles, C. Jama, A. Zarrouk, et al.
J Electroanal Chem, 803 (2017), pp. 125-134
[92]
M. Bouanis, M. Tourabi, A. Nyassi, A. Zarrouk, C. Jama, F. Bentiss.
Appl Surf Sci, 389 (2016), pp. 952-966
[93]
A.M. Puziya, O.I. Poddubnaya, R.P. Socha, J. Gurgul, M. Wisniewski.
Carbon, 46 (2008), pp. 2113-2123
[94]
F. Moulder, W.F. Stickle, P.E. Sobol, K.D. Bomben.
Handbook of X-ray photoelectron spectroscopy,
[95]
F.Z. Bouanis, F. Bentiss, S. Bellayer, M. Traisnel, J.B. Vogt, C. Jama.
Mater Chem Phys, 127 (2011), pp. 329-334
[96]
O. Olivares, N.V. Likhanova, B. Gómez, J. Navarrete, M.E. Llanos-Serrano, E. Arce, et al.
Appl surf Sci, 252 (2006), pp. 2894-2909
[97]
O. Olivares, N.V. Likhanova, B. Gómez, J. Navarrete, M.E. Llanos-Serrano, E. Arce, et al.
Appl Surf Sci, 252 (2006), pp. 2894-2909
[98]
Y. Kharbach, F.Z. Qachchachi, A. Haoudi, M. Tourabi, A. Zarrouk, C. Jama, et al.
J Mol Liq, 246 (2017), pp. 302-316
[99]
G.A. Schick, Z.Q. Sun.
Spectroscopic characterization of sulfonyl chloride immobilization on silica.
Langmuir, 10 (1994), pp. 3105-3110
[100]
N. El Hamdani, R. Fdil, M. Tourabi, C. Jama, F. Bentiss.
Appl Surf Sci, 357 (2015), pp. 1294-1305
[101]
P. Bommersbach, C. Alemany-Dumont, J.P. Millet, B. Normand.
Electrochim Acta, 51 (2005), pp. 1076-1084
[102]
W. Temesghen, P.M.A. Sherwood.
Anal Bioanal Chem, 373 (2002), pp. 601-608
[103]
X. Wu, K. Gong, G. Zhao, W. Lou, X. Wang, W. Liu.
RSC Adv, 8 (2018), pp. 4595-4603
[104]
A.G. Kannan, N.R. Choudhury, N.K. Dutta.
Polymer, 48 (2007), pp. 7078-7086
[105]
A.R. González-Elipe, A. Martínez-Alonso, J.M.D. Tascón.
Surf Interface Anal, 12 (1988), pp. 565-571
[106]
K. Babić-Samardžija, C. Lupu, N. Hackerman, A.R. Barron, A. Luttge.
Langmuir, 21 (2005), pp. 12187-12196
[107]
G. Gunasekaran, L.R. Chauhan.
Electrochim Acta, 49 (2004), pp. 4387-4395
[108]
C. Verma, M.A. Quraishi, L.O. Olasunkanmi, E.E. Ebenso.
RSC Adv, 5 (2015), pp. 85417-85430
[109]
E.E. Ebenso, M.M. Kabanda, L.C. Murulana, A.K. Singh, S.K. Shukla.
Ind Eng Chem Res, 51 (2012), pp. 12940-12958
[110]
F. Bentiss, M. Lagrenée.
J Mater Environ Sci, 2 (2011), pp. 13-17
[111]
D.M. Smith, G. Tennant.
Benzimidazoles and cogeneric tricyclic compounds, Part 1 edited by P.N. Preston with contributions by.
John Wiley & Sons, (1981), pp. 582
[112]
L.O. Olasunkanmi, I.B. Obot, M.M. Kabanda, E.E. Ebenso.
J Phys Chem C, 119 (2015), pp. 16004-16019
[113]
Y. Karzazi, M. El Alaoui Belghiti, A. Dafali, B. Hammouti.
J Chem Pharm Res, 6 (2014), pp. 689-696
[114]
K. Barouni, A. Kassale, A. Albourine, O. Jbara, B. Hammouti, L. Bazzi.
J Mater Environ Sci, 5 (2014), pp. 456-463
[115]
N. Soltani, M. Behpour, E.E. Oguzie, M. Mahluji, M.A. Ghasemzadeh.
RSC Adv, 5 (2015), pp. 11145-11162
[116]
A. Popova, M. Christov, T. Deligeorigiev.
Corrosion, 59 (2003), pp. 756-764
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