Gravimetrical, theoretical, and surface morphological investigations of corrosion inhibition effect of 4-(benzoimidazole-2-yl) pyridine on mild steel in hydrochloric acid (original) (raw)
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Density Functional Theory (DFT) method was used to study the corrosion inhibition characteristics of 2-phenylimidazo[1,2-a]pyridine (2PIP) and 2-(m-methoxyphenyl)imidazo[1,2-a]pyrimidine (2MPIP) on mild steel. Quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), the energy gap, chemical hardness, softness, dipole moment, absolute electronegativity, electrophilicity index and the fraction of electron transferred were calculated and correlated to inhibition efficiency of the studied molecules. Low energy band gaps coupled with structural stabilities should favour the adsorption of protonated molecules on metal surface at low concentrations and before the adsorption equilibrium. However, at high concentrations and towards equilibrium desorption of the protonated would be rapid due charge repulsion and molecular distortion from planarity which would facilitate the adsorption of neutral molecules on metal surface at equilibrium.
Journal of the Turkish Chemical Society Section A: Chemistry, 2019
Density Functional Theory (DFT) calculation at B3LYP level of theory and 6-31G* basis set was applied on some triazole derivatives of pyrimidine which led to the optimization of their structures, generation of electronic and other important Quantum chemical descriptors such as the energy of the highest occupied molecular orbital (EHOMO), the energy of the lowest unoccupied molecular orbital (ELUMO), energy band gap (ΔE), Dip E), Dipole Moment (μ)), chemical hardness (η),), chemical softness (σ)), global electronegativity σ =1η = − (2 (EHOMO − E L U M O)) (χ) and number of transferred electrons (ΔE), Dip N) using SPARTAN'14 Software. The obtained results shows a good correlation between the chemical structures of the inhibitors and their experimental inhibition efficiencies (%IEs). The ranking of these efficiencies (%IEs) nicely matched with the order of a good number of the generated descriptors but with a varying degree of correlation as majority of the descriptors indicates that I-4 is the best inhibitor among the data set. Furthermore, molecular dynamic (MD) simulations were carried out to search the best adsorption configuration of the inhibitor on the steel (1 1 0) surface using Material Studio 8.0. The obtained results of MD simulations suggest that the interaction was as a results of the chemical adsorption on the steel surface, since the binding energy > 100 Kcalmol-1 for all the inhibitors and the best adsorption energy was found to be-488.07 Kcalmol-1 (I-4). This observation are in good agreement with the DFT results and the experiment findings. Thus; this study provides a valuable approach and new direction to novel steel corrosion inhibitor discovery.
Surface and Interface Analysis, 2014
The corrosion inhibition properties of synthesized pyridine derivatives, namely, 4-(4-methoxyphenyl)-5,6-dimethyl-2morpholinopyridine-3-carbonitrile and 4-(4-methoxyphenyl)-5,6-dimethyl-2-piperazinyl-pyridine-3-carbonitrile on N80 steel in 15% HCl solution were studied using gravimetric measurement, potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The inhibition efficiency was found to increase with increasing inhibitor concentration and decreases on increasing the temperature from 303 to 333K. Some thermodynamic and kinetic parameters were calculated and discussed. The adsorption of inhibitor on the N80 steel surface obeys the Langmuir adsorption isotherm. Polarization studies showed that both the inhibitors behave as a mixed-type inhibitor. Scanning electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy and atomic force microscopy were performed for the surface study of uninhibited and inhibited N80 steel samples. The density functional theory was employed for theoretical calculations.
Corrosion inhibition effect of pyrazole derivatives on mild steel in hydrochloric acid solution
Synthesized compounds, namely methyl 5-(4-Chlorobenzoyloxy)-1-phenyl-1H-pyrazole- 3-carboxylate (MCPPC) and 5-(4-methoxyphenyl)-3-(4-methylphenyl)4,5-dihydro- 1H-pyrazol-1-yl-(pyridin-4-yl)methanone (MMDPPM) were investigated as corrosion inhibitor for mild steel (MS) in 15% HCl solution using weight loss measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. Inhibition efficiency was found concentration-dependent and increased by increasing the concentration of MCPPC and MMDPPM. Both of inhibitors were efficient even at a very low concentration of 25 ppm. The inhibitors MCPPC and MMDPPM showed inhibition efficiency of 67.1 and 76.8%, respectively, at 25 ppm, whereas it was 92.0 and 95.9%, respectively, at 250 ppm concentration at 303 K. The potentiodynamic polarization curves showed that MCPPC and MMDPPM act as mixed-type inhibitor in 15% HCl solution. The Nyquist plots showed that charge transfer resistance increased and double-layer capacitance decreased on increasing the concentration of studied inhibitors due to adsorption of inhibitor molecules on MS surface. The adsorption of each inhibitor on MS surface obeys Langmuir adsorption isotherm. On the basis of thermodynamic adsorption parameters, mixed-type adsorption (physisorption and chemisorption) for the studied inhibitors on MS surface was suggested. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM) analyses confirmed the existence of a protective film of the inhibitor on MS surface. The density functional theory was employed for theoretical calculations, and the obtained results were found to be consistent with the experimental findings.
2012
The inhibition effect of a new imidazolpyridine derivative namely 2,6-bis(2,5-dimethyl-2H-imidazol-4-yl)pyridine (BDIP) on corrosion of mild steel in 1 M HCl was studied at 308 K. Weight-loss measurements, potentiodynamic polarisation and impedance spectroscopy (EIS) methods were used. Results showed that BDIP was a good inhibitor and its inhibiting efficiency reaches 97,4% at 10− 3 M. The values of the inhibition efficiency calculated from these techniques are reasonably in good agreement. Polarisation curves revealed that this organic compound acted predominately as a cathodic inhibitor. EIS measurements showed that the charge transfer resistance increases with the inhibitor concentration. The temperature effect on the corrosion behaviour of mild steel in 1 M HCl with and without BDIP at 10− 3 M was studied in the temperature range 308–353 K. The associated activation energy was determined. The adsorption of BDIP on the mild steel surface obeyed to the Langmuir's adsorption is...
Corrosion, 2005
Ab initio quantum chemical calculations at the density functional theory (DFT) level were performed on eight pyridine derivative molecules as corrosion inhibitors for iron in an acidic solution. In this regard, the geometry of the molecules were optimized using the B3LYP/6-31G** method fi rst, and then interactions of these optimized structures with the iron atom were explored using the B3LYP/LANL1MB method. Two modes of adsorption were considered, i.e., planar adsorption (P) via the pyridine ring and vertical adsorption (V) through a nitrogen atom. The interaction energy was minimized through the variation of the inhibitor molecule-iron atom distance. These minimum energy values, along with the values of induced charge on the iron atom, were used to compare the inhibition power of various pairs of pyridine derivatives under consideration. Compared with the experimental data, the P orientation seems to be more satisfactory, if the minimum energy values are considered alone. However, the V orientation is in accordance with the experiment, if the induced charge on iron is considered. This is attributed to the effect of the induced charge on reducing the original surface charge of iron. It may be concluded that the P orientation is more favorable at low coverage and the V orientation at high coverage because of the excessive diminishing of the charge on the iron surface and area releasing through the P → V reorientation.
2017
The inhibitive effect of three substituted pyrazoles, 1H-pyrazole (P1) and ethyl 5methyl-1H-pyrazole-3-carboxylate (P2) against the steel corrosion in phosphoric acid solution is investigated using density functional approach B3LYP/ 3-21G* calculations. Results obtained by weight loss in part 1, show that P2 is the best inhibitor.The kinetic and adsorption parameters obtained in part 2 indicated that these pyrazoles acted preferentially by chemical adsorption. The calculated quantum chemical parameters are the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the separation energy (∆E), dipole moment (µ), electronegativity (χ), electron affinity (A), global hardness (η), softness (σ), ionization potential (I), and the total energy. The obtained data are discussed according to the inhibition efficiencies (E %) obtained.
Journal of Physical & Theoretical Chemistry, 2017
The study examined corrosion inhibition of corrosion inhibition of 5-methyl-2H-imidazol-4carboxaldehyde and 1H-Indole-3-carboxaldehyde on mild steel in acidic medium using weight loss and Density Functional Theory (DFT) methods. DFT calculations were carried out at B3LYP/631+G** level of theory in aqueous medium on the molecular structures to describe electronic parameters. The values of thermodynamic parameters such as free energy of adsorption (ΔGoads), adsorption equilibrium constant (Kads), adsorption entropy (ΔSoads), adsorption enthalpy (ΔHoads) and activation energy (Ea) were calculated, analyzed and discussed. The adsorption process on mild steel surface showed that 4-methylimidazol-5-carboxaldehyde and Indole-3-carboxaldehyde obeyed Freundlich and Temkin adsorption isotherms respectively. Also, the molecular parameters associated with inhibition efficiency such as EHOMO, ELUMO, band gap energy (ELUMOEHOMO), softness (S), electron affinity (EA) and number of electrons transf...
Journal of Bio- and Tribo-Corrosion, 2019
In the present work, a new organic inhibitor, namely (2(-4(chloro phenyl-1H-benzo[d]imidazol)-1-yl)phenyl) methanone (CBIPM), that has an inhibitive effect on the ordinary steel corrosion in 5.0 M HCl has been studied using electrochemical measurements (potentiodynamic polarization and electrochemical impedance spectroscopy). The obtained results showed that the inhibition efficiency increased with concentration and reached 98.6% at 10 −3 M. In addition, the CBIPM takes its performance at the temperature range of 298-328 K. The adsorption of the inhibitor on the ordinary steel was well described by the Langmuir isotherm. On the other hand, the establishing of correlation between the molecular structures of quantum chemistry indices was carried out using the density functional theory.
Electrochimica Acta, 2010
The corrosion inhibition properties of a new class of oxadiazole derivatives, namely 3,5-bis(n-pyridyl)-1,2,4-oxadiazoles (n-DPOX) for C38 carbon steel corrosion in 1 M HCl medium were analysed by electrochemical impedance spectroscopy (EIS). An adequate structural model of the interface was used and the values of the corresponding parameters were calculated and discussed. The experimental results showed that these compounds are excellent inhibitors for the C38 steel corrosion in acid solution and that the protection efficiency increased with increasing the inhibitors concentration. Electrochemical impedance data demonstrate that the addition of the n-DPOX derivatives in the corrosive solution decreases the charge capacitance and simultaneously increases the function of the charge/discharge of the interface, facilitating the formation of an adsorbed layer over the steel surface. Adsorption of these inhibitors on the steel surface obeys to the Langmuir adsorption isotherm. X-ray photoelectron spectroscopy (XPS) and the thermodynamic data of adsorption showed that inhibition of steel corrosion in normal hydrochloric solution by n-DPOX is due to the formation of a chemisorbed film on the steel surface. Quantum chemical calculations using the Density Functional Theory (DFT) and the Quantitative Structure Activity Relationship (QSAR) approach were performed on n-DPOX derivatives to determine the relationship between molecular structure and their inhibition efficiencies. The results of the quantum chemical calculations and experimental inhibition efficiency were subjected to correlation analysis and indicate that their inhibition effect is closely related to E HOMO , E LUMO , and dipole moment ( ). (F. Bentiss). characteristics of strong chemical activity and low toxicity .