Adsorption Mechanism of Eco-Friendly Corrosion Inhibitors for Exceptional Corrosion Protection of Carbon Steel: Electrochemical and First-Principles DFT Evaluations (original) (raw)
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Three thiosemicarbazides, namely 2-(2-aminophenyl)-N phenylhydrazinecarbothioamide (AP4PT), N,2-diphenylhydrazinecarbothioamide (D4PT) and 2-(2-hydroxyphenyl)-N-phenyl hydrazinecarbothioamide (HP4PT), were investigated as corrosion inhibitors for mild steel in H 2 SO 4 solution using gravimetric and gasometric methods. The results revealed that they all inhibit corrosion and their % inhibition efficiencies (%IE) follow the order: AP4PT > HP4PT > D4PT. The %IE obtained from the gravimetric and gasometric experiments were in good agreement. The thermodynamic parameters obtained support a physical adsorption mechanism and the adsorption followed the Langmuir adsorption isotherm. Some quantum chemical parameters were calculated using different methods and correlated with the experimental %IE. Quantitative structure activity relationship (QSAR) approach was used on a composite index of some quantum chemical parameters to characterize the inhibition performance of the studied molecules. The results showed that the %IE were closely related to some of the quantum chemical parameters, but with varying degrees. The calculated/theoretical %IE of the molecules were found to be close to their experimental %IE. The local reactivity has been studied through the Fukui and condensed softness indices in order to predict both the reactive centers and to know the possible sites of nucleophilic and electrophilic attacks.
Corrosion of carbon steel is a major problem that destroys assists of industries and world steel installations; the importance of this work is to introduce new heterocyclic compounds as effective and low-cost corrosion inhibitors. Three compounds of carbohydrazide derivatives, namely: 5-amino-N 0-((2methoxynaphthalen-1-yl)methylene)isoxazole-4-carbohydrazide (H4), 2,4-diamino-N 0-((2-methoxynaphthalene-1-yl)methylene) pyrimidine-5-carbohydrazide (H5) and N 0-((2-methoxynaphthalen-1-yl) methylene)-7,7-dimethyl-2,5-dioxo-4a,5,6,7,8,8a-hexahydro-2H-chromene-3-carbohydrazide (H6) were used to examine the efficacy of corrosion of carbon steel in 1 M hydrochloric acid solution. This corrosion efficacy was detected by utilizing various methods including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), weight loss measurements (WL), surface morphology analyses by atomic force microscopy (AFM), quantum chemical computations based on density functional theory (DFT) and molecular dynamics (MD) simulation. The results indicated that these compounds act as mixed type inhibitors i.e. reduce the corrosion rate of carbon steel due to the formation of a stable protective film on the metal surface and reduce the cathodic hydrogen evolution reaction. As confirmed from impedance, carbohydrazide derivatives molecules are adsorbed physically on metal surface with higher corrosion efficacy reached to (81.5-95.2%) at 20 Â 10 À6 M concentration at room temperature. Temkin isotherm model is the most acceptable one to describe the carbohydrazide derivative molecules adsorption on the surface of carbon steel. Protection mechanism was supported by quantum chemical analyses and Monte Carlo modeling techniques. The theoretical calculations support the experimental results obtained. This proves the use of carbohydrazide derivatives as a very effective inhibitors against the corrosion of carbon steel in acidic media.
Journal of Molecular Structure, 2010
The corrosion inhibition characteristics of two synthesized Schiff bases, namely N, N´-bis(2-hydroxy-6-nitrobenzaldehyde) benzidine and N, N´-bis(salysylaldehyde) benzidine, on the mild steel corrosion in 2.0 M hydrochloric acid have been investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy techniques. These studies were carried out at different concentrations, temperatures and durations. Polarization measurements indicate that the two inhibitors act as mixed type inhibitors. The adsorption of inhibitors obeys the Langmuir adsorption isotherm and the thermodynamic parameters (E a , K ads , ΔG 0 ads ) were calculated and discussed. Quantum chemical calculations were performed to provide further insight into the inhibition efficiencies determined experimentally.
2020
The adsorption behavior of Benzimidazol-2-one (Bz), 5-Methylbenzimidazol-2-one(CH3Bz) and 5-Chlorobenzimidazol-2-one (ClBz) as inhibitors for mild steel corrosion in HCl 1M have been studied computationally using density functional theory (DFT) calculations with the hybrid B3LYP functional. The calculations were focused on the protonated forms of the molecules under study, seeing that these classes of inhibitors can easily be protonated in acidic medium. The most preferred protonation centers were determined proton affinity (PA). Fukui indices have been computed to evaluate the nucleophilic and electrophilic sites of atoms in the molecule. The interaction of the inhibitors with the iron surface was studied by calculating the combined energy (Ecom) and the free energy of adsorption ( ΔG°ads ). Observable correlation was found between experimental corrosion inhibition efficiency and the theoretical data. The molecular dynamics (MD) and Monte Carlo (MC) simulations used show that all i...
Bulletin of Materials Science, 2019
The theoretical and electrochemical performance of a novel organic corrosion inhibitor 3,4-dihydro-3-[2mercaptothiazolidine]indol-2-one (DMI), for API 5L Grade B carbon steel in 3.5% NaCl, was evaluated by potentiodynamic polarization (Tafel), electrochemical impedance spectroscopy (EIS) and density functional theory (DFT) for quantum chemical studies. Potentiodynamic studies confirmed that DMI was a mixed organic corrosion inhibitor type which specially affects the cathodic branch. The inhibition efficiencies of reactants, DMI and acetylcysteine followed the following order at 25 • C and 200 ppm: DMI (87%) > isatin (71%) > 2-thiazoline-2-thiol (62%) > acetylcysteine (54%). EIS measurements illustrated the charge transfer controlled corrosion process. The Langmuir adsorption isotherm model of DMI was adopted. Surface studies were performed using scanning electron microscopy. Activation and adsorption thermodynamic parameters of DMI were computed. The magnitude of G • ads and the sign of H • ads concluded that the adsorption occurred through chemisorption. Quantum chemical calculations of four corrosion inhibitors were used for investigating the molecular structure effect on inhibition efficiency.
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.
Scientific Reports
The present work aims to study 6-amino-4-aryl-2-oxo-1-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile derivatives namely: 6-Amino-2-oxo-1,4-diphenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-H), 6-Amino-2-oxo-1-phenyl-4-(p-tolyl)-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-Me) and 6-Amino-4-(4-hydroxyphenyl)-2-oxo-1-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PdC-OH) as corrosion inhibitors to provide protection for carbon steel in a molar hydrochloric acid medium. Chemical measurements such as (weight loss) and electrochemical techniques such as (Potentiodynamic polarization, electrochemical impedance spectroscopy, and Electron frequency modulation) were applied to characterize the inhibitory properties of the synthesized derivatives. The adsorption of these derivatives on the carbon steel surface was confirmed by Attenuated Total Refraction Infrared (ATR-IR), Atomic Force Microscope (AFM), and X-ray Photoelectron Spectroscopy (XPS). Our findings revealed that the tested derivat...
Jurnal Teori dan Aplikasi Fisika, 2022
Steel is a material that has low resistance to corrosion when interacting with a corrosive environment. The application of natural extracts as green inhibitors is able to provide good performance in inhibiting corrosion of steel with high inhibition efficiency. Natural extracts that are effective and efficient as corrosion inhibitors on steel are those which in their compound structure contain heteroatom groups (such as O, N, S, P) and aromatic rings. This work provides an important comparative overview for the development of green inhibitor natural extracts in steel. The results of theoretical studies based on quantum mechanics with the DFT method at the atomic level based on molecular orbitals, chemical quantum parameters, and adsorption characteristics show results that are in accordance with experimental studies. The frontier molecular orbital (FMO) plot shows the distribution of electron density in the HOMO-LUMO region as a predictor of the active site of the inhibitor molecule interacting with the steel surface. Quantum chemical parameters such as ionization potential (I), electron affinity (A), absolute electronegativity (χ), hardness (η), softness (σ), fraction of electrons transferred (ΔN), electrophilicity (ɷ), and electron backdonation (ΔEback-donation) was calculated to obtain a correlation between the electronic properties of the inhibitor molecule and the corrosion inhibition potential. The results of the calculation of the quantum chemical parameters show the reactivity of the inhibitor molecule which has a very good potential to interact and bind strongly to the steel surface. This has the potential to make the inhibitor molecule have a high inhibition efficiency. Chemical adsorption and/or physical adsorption by forming complex compounds between inhibitor molecules and the steel surface are corrosion inhibition mechanisms to protect steel from a corrosive environment.The development of future studies should be able to display the mechanism of interaction and inhibition of inhibitor molecules in more detail and systematically at the atomic level on several metal surfaces such as Fe, Al, Cu, and others.
Theoretical Investigations on Thiadiazole Derivatives as Corrosion Inhibitors on Mild Steel
Advanced Journal of Chemistry-Section A, 2023
Experimental methods have been employed to elucidate the corrosion inhibition mechanism, but they are often expensive and time-consuming, necessitating the search for more alternatives. The development of computer hardware and software engineering has allowed the effective use of theoretical modeling tools that successfully correlate the inhibition efficiency of the inhibitors with their molecular structure and properties. In this study, computational methods were used to further explain the mode and mechanism of the thiadiazoles inhibition on Fe surface whose studies were reported in the literature as Thiadiazoles-A potential class of heterocyclic inhibitors for prevention of mild steel corrosion in hydrochloric acid solution. Parameters including quantum chemical through DFT and molecular dynamic simulations of studied molecules on Fe surfaces were performed. Results obtained by calculating these thiadiazoles' adsorption or binding energies were in good agreement with the experimentally reported results elsewhere. Concerning the calculated adsorption or binding energies, their relatively low values inferred that the compounds are weakly adsorbed onto the surface of Fe through Van der Waals forces and therefore obey the mechanism of physical adsorption. Fukui indices values revealed that the active sites were found to be located on the molecules heteroatoms (Sulphur and Nitrogen). It was also established that the reference molecule thiadiazole (TDA) was the least adsorbed when compared to the other four molecules of its derivatives. The order of the inhibition efficiency as determined is as follows: PAT > EAT > MAT > AT > TDA