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The present paper was designed to investigate an original synthesized ionic liquid (ILs) named 1-phenethyl-3-(3-phenoxypropyl)-1H-imidazol-3-ium bromide [Imid-3PE] Br, and 1-phenethyl-3-(4-phenoxybutyl)-1H-imidazol-3-ium bromide [Imid-4PE] Br as corrosion inhibitors. These inhibitors were evaluated against mild steel corrosion in 1 M hydrochloric acid medium using electrochemical techniques. PDP experiments revealed that the [Imid-3PE] Br and [Imid-4PE] Br behaved as mixte type inhibitors. Electrochemical impedance spectroscopy (EIS) results indicated that the both compounds showed a good inhibition of the steel surface with an inhibition efficiency of 95.8% for [Imid-3PE] Br and 96.7% for [Imid-4PE] Br at the optimum concentration. According to Langmuir isotherm model and the activation parameters, these ILs can be adsorbed onto the mild steel surface through physical and chemical bonds. The theoretical approach confirms the adsorption behavior of the studied ILs based on DFT calculation and molecular dynamic simulation.

The corrosion inhibition behavior of sodium nitrite (NaNO2) towards pure copper (99.95%) in simulated cooling water (SCW) was investigated by means of electrochemical impedance spectroscopy (EIS) and dynamic electrochemical impedance spectroscopy (DEIS). NaNO2 interferes with metal dissolution and reduce the corrosion rate through the formation or maintenance of inhibitive film on the metal surface. Surface morphologies illustrated that the surface homogeneity increased on adding sodium nitrite. Sodium nitrite’s adsorption on copper surface followed the modified form of Langmuir, Freundlich and Frumkin isotherms. Physiosorption mode was involved in the corrosion protection. Electrochemical results revealed an corrosion resistance of copper increases on increasing the inhibitor concentration. The DEIS results indicated that copper corrosion mechanism could be hindered by 50% even after interval of 24 h by optimum concentration of sodium nitrite. The maximum inhibition was achieved with 2000 ppm of NaNO2. With this concentration, inhibition efficiency of up to 61.8% was achievable.

The action of solution's pH on the inhibition property of three linear α-amino acids, namely Glycine ( Gly ), Valine ( Val ) and Leucine ( Leu ), was examined against tin corrosion in 2 wt% NaCl solution using electrochemical techniques and SEM analysis. Density functional theory (DFT) calculations and Monte Carlo simulations have been used to shed more light into the inhibition process. The results showed that the pH variation had significantly influenced the rate and the mechanism of tin corrosion, as well as, the inhibition ability of all tested biomolecules. Higher inhibition efficiency was obtained for Val at near neutral (pH 5) solution compared with acidic one (pH 2). Furthermore, the inhibition efficiency of Val decreases with increase in temperature and physisorption mode is suggested as an inhibition mechanism of tin corrosion. The formation of protective film by Val on tin surface was revealed using SEM. Moreover, the relationship between the calculated molecular electronic structure parameters and observed inhibition property were discussed. Based on the obtained theoretical results, the formation of hydrogen bonds between amino acids and tin surface could be explained the higher inhibition efficiencies obtained at pH 5 in comparison with pH 2. Depending to the solution's pH, a mechanism of the corrosion inhibition process was proposed.

The influence of chitosan on the copper corrosion in sulfide polluted synthetic seawater (SSW) containing 20 ppm of sulfide has been investigated for the first time. Potentiodynamic polarization measurements, electrochemical impedance spectroscopy at the open circuit potential and weight loss measurements were employed to assess the corrosion inhibition ability of chitosan. The impedance studies revealed that in the presence of chitosan at various concentrations, the charge transfer resistance increases. At a concentration of 800 ppm, chitosan exhibited a corrosion inhibition efficiency of 89% following physical adsorption. The influence of temperature and immersion time was studied in sulfide-contaminated synthetic seawater and significant inhibition was observed even after 90 days. SEM-EDS studies confirm the absence of the deterioration products on copper surface.

Cysteine's action on 3003 aluminum alloy dissolution in a 2% NaCl solution, at different pH values, has been investigated. Weight-loss measurements, potentiodynamic polarization and electrochemical impedance at OCP were performed. The surface morphology was analyzed by SEM. The main results showed that the alloy underwent severe corrosion at 2 and 11 pH values, as compared to at 5 and 8 pH values. Furthermore, a duality effect of cysteine was noted, as it acted as a corrosion inhibitor or accelerator, depending on its concentration, and on the solution's pH value. This particular behavior can be related to the instability of the formed film adsorbed onto the metal surface. All these findings show the high complexity of cysteine action on 3003 aluminum alloy, under the investigated conditions.

Herein, new 2-oxo-1,2-dihydroquinoline-4-carboxylate derivatives (2a-5d) have been synthesized based on a developed systematic approach, only by esterification reactions of 2-oxo-1,2-dihydroquinoline-4-carboxylic acid with various kinds of alcohols, followed by an alkylation reactions using a different alkylating agents. All the generated compounds are characterized by NMR spectroscopy (1H and 13C). The structures of compounds (2b, 3c, 4a, and 4d) were confirmed using monocrystalline X-ray crystallography. The docking study of the developed derivatives and targets of protein database inhibitors (PDB: 1M17 -EGFR kinase) showed useful information on possible interactions. The experimental results and the expected spectral data using the DFT method at the B3LYP/6-31G(d,p) level of theory were compared. Bi- and three-dimensions Hirshfeld surface examinations have been realized to reveal the non-bond interactions in solid-phase crystal packing and to identify the neighboring inter-molecular contacts for the three molecules 3c, 4a, and 4d. Monte Carlo simulations in the aqueous phase were used to expect the affinity of these derivatives toward mitigation of iron and copper corrosion in acidic and neutral solutions. A proper protection property is anticipated for compounds 3c and 4d.

Three triazoles compounds used as corrosion inhibitors for copper in acidic medium, namely: 1,2,4 triazole (TR), 3-amino 1,2,4 triazole (3 ATR) and 3,5-diamino 1,2,4 triazole (3,5 DATR) have been studied theoretically in aim to investigate the correlation between its molecular reactivity indicators and the corresponding inhibition efficiency. All quantum chemical calculations at the B3LYP/6-31+G(d,p) method were performed with and without solvent effect. In the present paper, not only the neutral inhibitors has been studied, but also the first and the second protonation forms. A good correlation between theoretical and experimental data has been obtained both in gas and aqueous phases, notably for unprotonated inhibitors. Also, the interaction energy between inhibitors and copper has been calculated.

In the current study, the inhibition properties of three cyclic amino acids, namely Histidine (His), Tyrosine (Tyr) and Phenylalanine (Phe), have been investigated using electrochemical techniques for tin corrosion in stagnant 2% NaCl solution at different pH values. To shed more light on the inhibition mechanism, DFT-based computations and Monte Carlo-SAA simulations have been employed. The obtained data revealed that His and Phe compounds have shown the maximum of the inhibition effectiveness at pH 2 and 5, respectively. Besides, without exception, all studied inhibitors have exhibited higher prevention values at pH 5 as compared to pH 2, which was attributed to the ability of those compounds to form hydrogen bonds and interact effectively with the metal surface (SnO2) at pH 5. Furthermore, due to the complexity of the inhibition phenomena, the analysis of calculated intrinsic quantum parameters cannot be used to explain the almost observed inhibition behavior of the studied inhibitors set. On the other hand, agreeing with our results, the conjoint analysis of energetic and geometrical aspects of the adsorption of an inhibitor molecule onto the metal surface is required to get clear insights on the inhibition process.

An efficient synthesis of novel alkyl 2-oxo-1,2-dihydroquinoline-4-carboxylates (3a-3d) was developed, starting from 2-oxo-quinoline carboxylic acid 1a which successively undergoes esterification and alkylation reactions. The structures of all the obtained compounds were investigated and characterized by using 1H NMR and 13C NMR spectroscopic measurements. The molecular and crystal structures of four compounds (3a, 3b, 3c and 3d) have also been examined by single crystal X-ray crystallography. Furthermore, the experimental data and the predicted spectral data were also obtained using density functional theory (DFT) at the B3LYP/6–31G(d,p) level of theory. Also, the closest contacts between the active atoms of the four structures were identified through Hirshfeld surface analyses, molecular docking studies, and DFT calculations. The experimental results are correlated to the calculated ones and showed great compatibility. Finally, molecular docking studies are performed to investigate the binding patterns of the titled compounds with the Protein Data Bank (PDB:1M17-EGFR kinase) inhibitor targets and showed good insights on the possible interactions using the Auto-Dock Vina program.

Amino acids are naturally occurring, biodegradable, cheap, and easily available alternatives against the conventionally used toxic corrosion inhibitors. The structural features of the different amino acids play a crucial role in the adsorption and inhibition performance. The chemical functionalization of organic molecules using single-step protocol is an important strategy for improving the corrosion inhibition performance. The different functional groups present in the amino acid structures provide the choice of chemical modification of these amino acids. A number of derivatives such as Schiff bases, ionic liquid derivatives, surfactants, polymeric amino acids, etc. have been prepared using simple functionalization methods. This article presents an overview of the correlation of the experimentally obtained results of the amino acids and their derivatives with their structural features via computational techniques. The significance of amino acids as corrosion inhibitors, the importance of chemical modification, computational studies on amino acids, and the mechanism of adsorption and corrosion inhibition by amino acids are described herein.

Elevated concentrations of nutrient in wastewater discharge can lead to severe imbalance water-ecosystems due to eutrophication, therefore, efficient and cost-effectiveness remediation strategies are urgently required. This work reports the feasibility of using zirconium-modified Merlinoite (Zr@Merl) obtained from Mexican coal fly ash (CFA) for the removal of phosphate ions from aqueous solutions. Direct method and soft reaction conditions were employed to synthesis Merlinoite (Merl) in more than 100% yield related to CFA. Further, the Merl surface was modified by ZrO2+ through the microwave-assisted process at 130 °C for 5 min. Inductively coupled plasma confirmed the increase of Zr(IV) content up to 7.07 wt% while the potassium concentration decreased from 11.53 to 5.66 wt%, indicating the successful exchange in the Merl surface. The pristine Merl and its Zr@Merl were physicochemically characterized. X-ray photoelectron spectroscopy analysis before and after phosphate ions adsorption was done to elucidate the involved adsorption mechanism. The adsorption behavior was explained by pseudo-second-order and Freundlich models. The maximum adsorbed amount was 67.72 mg g−1. The results proved that the involved mechanisms for the phosphate sorption onto Zr@Merl were electrostatic attractions followed by coordination reactions. Further, a theoretical study using Monte Carlo/SA simulations was applied to get insight into the interaction between Merl and Zr@Merl surface groups and H2PO4− ions. The simulation results demonstrate the favorable adsorption, more stable and spontaneous, onto Zr@Merl than Merl. Overall, Zr@Merl could serve as a cost-effective and reusable adsorbent material for the phosphate recovery from aqueous effluents.

The bi-heterocyclic system, namely 2-[(5-methylpyrazol-3-yl) methyl] benzimidazole (MPMB) has been synthesized and characterized by 1H and 13C NMR methods. Its inhibitory property for carbon steel (C38) in 1 M HCl solution has been investigated using electrochemical impedance spectroscopy, potentiodynamic polarization, and weight loss measurements at 293 K. Besides, DFT/B3LYP-based calculations and Monte Carlo simulations are used under the solvation condition. The inhibition efficiency increases with the inhibitor concentration and attains a maximum value of 97.0% at 5 mM. The polarization curves show that the examined compound act as a mixed type inhibitor. The increase of temperature induces a decrease in the inhibition efficiency of the studied compound. Also, the adsorption of this compound obeyed the Langmuir adsorption isotherm. The carbon steel surface examination confirmed the presence of a protective adsorbed film of MPMB on the surface. According to the computational results, MPMB in its neutral and protonated forms exhibited an accurate affinity to adsorb onto the metal surface, which leads to the formation of a protective film.

Herein, four tetrazole derivatives namely 1,2,3,4-tetrazole (TZ), 5-amino-1,2,3,4-tetrazole (ATZ), 1-phenyl-1,2,3,4-tetrazole (PTZ) and 1-phenyl-5-mercapto-1,2,3,4-tetrazole (PMTZ) were investigated as corrosion inhibitors on Cu (111) surface in acidic medium. For this purpose, theoretical investigations were carried out preferentially with Density Functional Theory (DFT) at Lee–Yang–Parr correlation functional (B3LYP) using 6-31+g (2d, p) basis set. Numerous global and locale descriptors of reactivity such as EHOMO, ELUMO, energy gap, electronegativity (χ), hardness (η), frontier molecular orbitals repartitions were investigated to describe the reactivity of each molecule. On the other hand, Monte Carlo simulations were investigated on Cu (111) surface to understand the adsorption behavior of the as-studied inhibitors deeply. The adsorption energies (Eads) were also calculated; the results were as follows: PMTZ ˂ PTZ ˂ ATZ ˂ TZ. The experimental inhibition efficiencies were correlated with global descriptors, which confirm that this theoretical study is fruitful for the protection of copper metal in acidic medium.

International audience; In this work, three novel long-chain alkyl substituted 1,4-benzothiazine derivatives have been synthesized by alkylation reactions under phase transfer catalysis conditions. The obtained compounds (4, 5 and 6) obtained were characterized using 1H- and 13C- NMR spectroscopy and X-ray. Their molecular and crystal structures have been determined by single-crystal X-ray diffraction techniques. The experimental data, were compared with the predicted ones spectral data were also obtained using density functional theory (DFT) at the B3LYP/6-31G(d,p) level of theory. In addition, the closest contacts between the active atoms of the compounds were identified through Hirshfeld surface analyses. According to Monte Carlo simulations, the new compounds can act as good corrosion inhibitors for iron and as moderate ones for copper and aluminum metals.

Herein, the inhibition behavior of alginate biopolymer with different chain length (fragments) on corrosion of Fe (110), Cu (111), Al (111) and Sn (001) surfaces in acidic medium was investigated using quantum chemical calculations and molecular mechanic methods. Based on HSAB's theory, local and global reactivity indicators of different alginate fragments were calculated using DFT/B3LYP/3-21G method. Molecular mechanic simulations were employed to describe quantitatively and qualitatively the adsorption behavior of the bio-inhibitor on the metal surfaces. As a result, the chain length of alginate and metal nature were considerably affected magnitude and trend of alginate/metal interactions. Gradually as the chain length of the alginate molecule was increased, the binding energy increased. On the other hand, it found that the binding of alginate onto metal surfaces followed this order: Sn (001)

In the aim to understand the inhibition action of three 1,5-benzodiazepin-2-one derivatives (i.e. DMBD: 4,7-dimethyl-1,5-benzodiazepin-2-one, PBD: 3-phenyl-1,5-benzodiazepin-2-one, MPBD: 4-methyl-7-phenyl-1,5-benzodiazepin-2-one) against the dissolution of iron in acidic medium, both DFT-based calculations and Monte Carlo-SAA simulations were carried out. As a result, the protonation process was unfavorably affected the reactivity of investigated inhibitors. Further, the solvation free energy (∆GSolv) can be used as a parameter to inspect the inhibition performance of organic inhibitors. According to Monte Carlo-SAA simulations, the investigated inhibitors exhibited a great tendency to replace pre-adsorbed corrosive entities onto the iron surface and then forming a protective film via a parallel adsorption orientation. Finally, a predicting study pointed out that the MPBD compound is expected to act as a moderate inhibitor for aluminum and copper metals, while lower inhibition efficiency is anticipated in the case of tin in acidic environments.

Nowadays, theoretical calculation tools have become powerful in predicting the behavior of corrosion inhibitors on the surface of metals and, therefore, avoiding energy consumption and the cost of experimental tests. This work aims to predict the inhibitory power of some furan derivatives on Cu (111), Fe (110), Al (111) and Sn (111) surfaces in acidic media. For this purpose, three furan derivatives&mdash, furan-2-carbaldehyde (FF1), 5-(hydroxymethyl)furfural (FF2) and 5-(hydroxymethyl)furoic acid (FF3)&mdash, have been selected to compare their intrinsic properties against corrosion as well as their behavior on iron (Fe), copper (Cu), aluminum (Al) and tin (Sn) surfaces in acid medium. Typically, the anti-corrosive properties of FF1, FF2 and FF3 were studied by using quantum chemical calculations and Monte Carlo simulations. Density Functional Theory (DFT), lowest unoccupied (ELUMO) and highest occupied (EHOMO) molecular orbital energies, energy gap (∆E), chemical hardness (&eta, ), softness (&sigma, ), electronegativity (&chi, ), electrophilicity (&omega, ) and nucleophilicity (&epsilon, ) have been calculated and discussed. Theoretical vibrational spectra were also calculated to exhibit the functional groups in the selected chemicals. On the other hand, the adsorption behaviors of FF1, FF2 and FF3 were studied on the Fe(110), Cu(111), Al(111) and Sn(111) surfaces. As a result, the adsorption energies of all molecules are ordered as Fe(110) &lt, Cu(111) &lt, Al(111) &lt, Sn(111) and FF3 seems to be more effective as a corrosion inhibitor due to the existence of both carboxylic acid and hydroxyl groups, which consist of favorable sites of adsorption into the metal surface.

In this work, the effect of pH on the corrosion of tin in stagnant 2 wt.% NaCl solution without and with three functional side chain amino acids, namely Threonine (Thr), Asparagine (Asn) and Glutamine (Gln), was investigated. This study was carried out using potentiodynamic polarization and electrochemical impedance spectroscopy. The influence of solution's pH on protonation state of tested compounds and chemical nature of the metal surface (Sn or SnO2) was considered during the theoretical studies using DFT/B3LYP method and Monte Carlo/SA simulations. The obtained results revealed that the pH variation had affected significantly the speed and the corrosion mechanism of tin, as well as, the inhibitory performance of tested biomolecules. Higher inhibition efficiencies were obtained at pH 5 as compared to pH 2. The maximum value was obtained for Gln and Asn at pH 2 and at pH 5, respectively. Thr and Asn were shown a “duality” effect against the corrosion of tin, which can act as corrosion accelerators at pH 2 and as corrosion inhibitors at pH 5. The relationship between calculated molecular electronic structure parameters and observed inhibition efficiency was discussed. The capacity of tested compounds to form hydrogen bonds with metallic surface has explained the accurate inhibition effectiveness recorded at pH 5 against pH 2. A mechanism of the effect of tested amino acids against tin corrosion was proposed.