Electrochemical and Theoretical Study of Corrosion Inhibition on Carbon Steel in 1M HCl Medium by 1,10-Bis(4-Amino-3-Methyl-1,2,4-Triazole-5-Thioyl)Decane (original) (raw)
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2018
Experimental electrochemical methods, combined with Monte Carlo simulations, have been employed to investigate the possibility of usi ng 1-decyl-2-(decylthio)-1Hbenzimidazole (T2) as corrosion inhibitor for mild steel in a 1 M HCl medium. This inhibitor was found to be of the mixed type. The re sults derived from EIS indicate that the charge transfer resistance has increased with t he increase in the inhibitor concentration. The inhibitory mechanism was explore d by the potential of zero charge (Epzc) measurement at the solution/metal interface. The inhibitor adsorption has followed Langmuir adsorption isotherm. Surface morp h logy results showed the compound adsorbed film on a mild steel surface. The molecule interactions with the mild steel surface were simulated based on Monte Ca rlo simulation approach using Fe(111) crystal surface as a representative metalli c surface.
Metals
In the present work, we represent two thiazolidinediones, namely (Z)-5-(4-methoxybenzylidene) thiazolidine-2,4-dione (MeOTZD) and (Z)-5-(4-methylbenzylidene) thiazolidine-2,4-dione (MeTZD), as corrosion inhibitors for carbon steel (CS) in 1.0 M HCl solution. Techniques for gravimetric methods, electrochemical measurements, and morphological characterization were used to conduct experimental evaluations. Additionally, calculations based on the fundamental principles of Density Functional Theory (DFT) were employed to simulate inhibitor–iron interactions. Experimental results indicated that investigated inhibitors can significantly enhance the corrosion resistance of CS, reaching a performance of 95% and 87% at 5 × 10−3 mol/L of MeOTZ and MeTZD, respectively. According to gravimetric and electrochemical experiments, inhibitor molecules obstruct corrosion reactions by adhering to the CS surface, which follows the Langmuir isotherm model. On the other hand, the morphological analysis sh...
Quantum chemical calculations based on density functional theory (DFT) methods were performed on indigo blue (IB), methylene blue (MB), and crystal violet (CV) molecules as inhibitors for iron corrosion in acid media. DFT calculations were performed on the molecular structures to describe electronic parameters which are associated with inhibition efficiency such as the Homo values −4.981 eV, −4.518 eV, and −3.872 eV which increased in the order IB > MB > CV while LUMO values were −3.73 eV, −3.63 eV, and −2.87 eV for IB, MB, and CV, respectively. Quench molecular dynamics simulations performed at metal/vacuum interface were applied to find the equilibrium adsorption configurations and calculate the minima interaction energy between inhibitor molecules and iron surface Fe(110). The theoretical order of inhibition efficiency of these dye molecules had a linear relationship with experimentally observed inhibition efficiency on iron corrosion in acid media. The electronic structures as well as reactivity elucidate parameters which could be practical in designing novel high-efficiency, cheap, and eco-friendly inhibitors by quantitative structure-activity relationship (QSAR) method.
DFT study of the adsorption of the corrosion inhibitor 2-mercaptoimidazole onto Fe(100) surface
Electrochimica Acta, 2013
From quantum mechanical calculations, based on density functional theory and using the pseudopotentials planewave method, in the first part of this work, a set of iron surfaces namely: (110), (100), (111) and (311) have been modeled and their work functions and surface energies calculated. It was found that the Fe(100) surface displayed the highest surface energies (2.43 J m-2), the lowest work function (3.95 eV) and the lowest coordination number too, thus furnishing the conditions for the interaction with organic molecules. In the second part, the bonding structure for 2-mercaptoimidazole, 2MI, adsorbed onto Fe(100) surface has been studied and the geometry optimized; the adsorption energy (-1.26 eV), the Bader analysis and the bonding structure are presented and discussed. In these calculations, different adsorption sites of the Fe(100) surface, such as top, bridge and hollow were considered. The energetically-most favored adsorption geometry shows the aromatic 2MI ring in a parallel position with respect to the surface, the charge transfer flows from the metallic surface to the inhibitor mainly through the adsorbate's carbon and sulfur atoms. Two dissociation processes were found: one related to deprotonation of the thiol group, and the other to dropping the entire thiol group. They were lower in energy by about 0.33 eV and 1.42 eV, respectively, than the adsorption energy of the molecule as a whole.
Journal of Chemical Information and Modeling, 2015
The inhibition effect of N,N′-bis(1-(3,5-dihydroxyphenyl)ethylidene)propane-1,3-diamine was studied on steel corrosion in 1 M hydrochloric acid solutions. The density functional theory was applied to calculate quantum chemical parameters such as the highest occupied molecular orbital energy, the lowest unoccupied molecular orbital energy, electron affinity, global electrophilicity index, the fraction of electron transferred, global nucleophilicity index, and Mulliken charges. According to quantum calculation, the diamine compound showed high interaction and effective adsorption on steel surface and high inhibition efficiencies and therefore nitrogen atoms of inhibitor indicated more tendencies for the electrophilic effect in the adsorption. Electrochemical impedance and potentiodynamic polarization indicated that this material has excellent inhibiting features in very low concentrations. The influence of DC trend on the explanation of electrochemical noise data was evaluated by polynomial fitting and the optimum polynomial order m = 4 was obtained. Noise resistance and the inhibition efficiency was calculated and compared in different methods. The theory of shot noise in frequency domain was used to obtain the electrochemical event charge. The corroded surface of steel in the absence and existence of thiazole compound was studied by Atomic force microscopy.
Research on Chemical Intermediates, 2013
2-(6-Methylpyridin-2-yl)oxazolo [5,4-f][1,10]phenanthroline (MOP) was synthesized and characterized by elemental analysis and Fourier-transform infrared (FT-IR), 1 H nuclear magnetic resonance (NMR), and 13 C NMR spectra. MOP was evaluated as a corrosion inhibitor for carbon steel in 0.5 M H 2 SO 4 solution using the standard gravimetric technique at 303-333 K. Quantum chemical calculations and molecular dynamic (MD) simulations were applied to analyze the experimental data and elucidate the adsorption behavior and inhibition mechanism of MOP. Results obtained show that MOP is an efficient inhibitor for mild steel in H 2 SO 4 solution. The inhibition efficiency was found to increase with increase in MOP concentration but decreased with temperature. Activation parameters and Gibbs free energy for the adsorption process using statistical physics were calculated and discussed. The adsorption of MOP was found to involve both physical and chemical adsorption mechanisms. Density functional theory (DFT) calculations suggest that nitrogen and oxygen atoms present in the MOP structure were the active reaction sites for the inhibitor adsorption on mild steel surface via donor-acceptor interactions between the lone pairs on nitrogen and oxygen atoms together with the p-electrons of the heterocyclic and the vacant d-orbital of iron atoms. The adsorption of MOP on Fe (1 1 0) surface was parallel to the surface so as to maximize contact, as shown in the MD simulations. The experiments together with DFT and MD simulations provide further insight into the mechanism of interaction between MOP and mild steel.
International Journal of Electrochemical Science, 2011
The corrosion inhibition of cast iron in 1 M HCl by Phenanthroline (Phen) was investigated using potentiodynamic polarization (PDP) curves, electrochemical impedance spectroscopy (EIS), surface analysis and theoretical calculations. It is found that Phen exhibits high inhibition activity towards the corrosive action of HCl and its adsorption obeys the Langmuir adsorption isotherm model. The results showed that inhibition efficiency increases with Phen concentration up to a maximum value of 96% at 1.4 mM, and decreases slightly with the increase in temperature. The free adsorption energy value indicates that Phen adsorbs on cast iron surface in 1 M HCl via a simultaneous physisorption and chemisorption mechanism. Scanning electron microscopy (SEM) micrographs, atomic force microscopy (AFM) and FTIR analysis confirmed the formation of a protective film on cast iron surface, resulting in the improvement of its corrosion resistance in the studied aggressive solution. Quantum chemical calculations at the DFT level were achieved to correlate electronic structure parameters of Phen molecules with their adsorption mode.
The density function theory (DFT) is used to study the structural properties of two sulfa dimedine azo derivatives in aqueous phase in an attempt to understand their inhibition mechanism. The protection efficiencies of these compounds showed a certain relationship to highest occupied molecular orbital (HOMO) energy, Mulliken atomic charges and Fukui indices. Quantum chemical method was also employed to explore the relationship between the inhibitor molecular properties and its protection efficiency. The protection influence of two sulfa dimedine azo derivatives against C-steel corrosion was studied in 0.5 M H 3 PO 4 solutions at 25 o C. Measurements were conducted under various experimental conditions using Weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. These studies have shown that sulfa dimedine azo derivatives are very good " " green " , inhibitors. Corrosion rates obtained from both Tafel extrapolation and EIS methods are comparable with those recorded using Weight loss method, confirming validation of corrosion rates measured by the latter. The inhibitive action of these sulfa dimedine azo derivatives against C-steel corrosion in 0.5 M H 3 PO 4 solutions was discussed in terms of blocking the electrode surface by adsorption of the molecules through the active centers contained in their structures following Temkin adsorption isotherm.
Journal of the Turkish Chemical Society, Section A: Chemistry, 2021
One of the ways of reducing metal corrosion and its devastating effects is by using organic corrosion inhibitors. This is because of the π-conjugation in their moieties, their ability to donate electrons to the metal's vacant d-orbitals, and their low lying LUMO orbitals for accepting electrons as well from the metal, all these improve their adsorption on the metal surface. (E)-5-((4-benzoylphenyl)diazenyl)-2hydroxybenzoic acid (AD4) was synthesized via the coupling reaction of p-aminobenzophenone and Salicylic acid, characterized via FTIR, UV/Vis, 1 H-NMR, and 13 C-NMR spectroscopy. The melting point of AD4 is 103 o C-106 o C indicating that it is thermally stable and pure. Gravimetric and potentiodynamic polarization techniques were employed to obtain the corrosion rates (Cr) and percentage inhibition efficiency (%IE) at different concentrations of the inhibitor and at different temperatures. The thermodynamic parameters like Enthalpy, ∆H o ads, Entropy, ∆S o ads and free energy of adsorption (∆Gads) of Adsorption were calculated. The Langmuir adsorption isotherm was used to describe the adsorption of AD4 molecules on mild steel. Quantum mechanical calculations were employed to calculate the electronic properties and global reactivity descriptors of AD4. The theoretical results are broadly consistent with experimental results. From the results obtained AD4 could be used as a corrosion inhibition agent in the oil and gas industries.