Benzimidazole derivatives as novel inhibitors for the corrosion of mild steel in acidic solution: Experimental and theoretical studies

Corrosion inhibition performance of benzimidazole derivatives for protection of carbon steel in hydrochloric acid solution

This paper presents a comprehensive study on the corrosion inhibition properties of new organic compounds, (1H-benzimidazol-2-yl)methanethiol (LF1) and 1-dodecyl-2-((dodecylthio)methyl)-1H-benzimidazole (LF2), have been examined for inhibiting of Carbon-Steel (C.S) in 1.0 M HCl. Numerous methods, such as potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis, atomic force microscopy (AFM), contact angle measurements, UV-visible spectroscopy, and theoretical calculations, were used to evaluate the effectiveness in preventing corrosion. The two benzimidazoles (LF1 and LF2)' inhibitory efficacy rose as their concentration increased, peaking at 88.2% and 95.4% respectively. The polarization graphs show a mixed behavior, with anodic predominance for LF1 and cathodic predominance for LF2. Thermodynamic investigations showed that the values of ΔG ads were -40.0 kJ mol-1 for LF1 and -43.1 kJ mol-1 for LF2, highlighting their strong adsorption onto the metal surface. Their adsorption process was in line with the Langmuir isotherm. Density Functional Theory (DFT) and Molecular Dynamics (MD) modeling have been utilized to examine and clarify the relationship between the inhibitor and carbon steel (C.S).

Prolonged corrosion protection via application of 4-ferrocenylbutyl saturated carboxylate ester derivatives with superior inhibition performance for mild steel

A series of 4-ferrcenylbutyl carboxylate esters with different alkyl chain length (C2-C4) of carboxylic acids were synthesized using Fe3O4@SiO2@(CH2)3-Im-bisEthylFc[I] nanoparticles as catalyst and have been characterized with FT-IR, 1H NMR, and 13C NMR. Ferrocenyl-based esters were used as corrosion inhibitors of mild steel in the 1M HCl solution as corrosive media. The corrosion inhibition efficiency of the synthesized ferrocenyl-based esters has been assessed by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The 4-ferrocenylbutyl propionate showed a more effective corrosion inhibition behavior among the studied esters with 96% efficiency after immersion in the corrosive media for 2 weeks. The corrosion inhibition mechanism is dominated by formation of passive layer of inhibitor on the surface of the mild steel by adsorption. Moreover, the adsorption characteristics of 4-butylferrcenyl carboxylate esters on mild steel were thoroughly explored using density functional theory calculations. It was found that the Fe atoms located around the C impurity in the mild steel are the most efficient and active sites to adsorb 4-butylferrcenyl carboxylate esters.

Experimental IR, Raman, and UV-Vis Spectra DFT Structural and Conformational Studies: Bioactivity and Solvent Effect on Molecular Properties of Methyl-Eugenol

Structural, conformational, and spectroscopic investigations of methyl-eugenol were made theoretically at the B3LYP-6-311++G**level. Experimental IR, Raman, and UV-vis spectra were investigated and analyzed in light of the computed quantities. Conformational analysis was carried out with the help of total energy vs. dihedral angle curves for different tops, yielding 21 stable conformers, out of which only two have energies below the room temperature relative to the lowest energy conformer. The effect of the solvent on different molecular characteristics was investigated theoretically. MEP and HOMO-LUMO analysis were carried out and barrier heights and bioactivity scores were determined. The present investigation suggests that the molecule has three active sites with moderate bioactivity. The solvent-solute interaction is found to be dominant in the vicinity of the methoxy moieties.

Experimental and Theoretical Tests on the Corrosion Protection of Mild Steel in Hydrochloric Acid Environment by the Use of Pyrazole Derivative

In this study, 1,5-diallyl-1H-pyrazolo [3,4-d] pyrimidin-4 (5H)-one (PPD) was evaluated as an anticorrosion agent for mild steel (MS) in 1 M HCl. The analysis was performed by weight loss (WL), potentiodynamic polarization measurement, and electrochemical impedance spectroscopy (EIS). The Tafel polarization showed that PPD is a mixed-type inhibitor and reaches 94% of the protective efficiency at 10^-3 M. EIS results indicated that the resistance to charge transfer increases with increasing inhibitor concentration and the corrosion of MS is controlled by a charge transfer process. The inhibitor adsorption on the MS surface obeyed the Langmuir's adsorption isotherm. Thermodynamic parameters were calculated to elaborate the corrosion inhibition mechanism. The micrographic analysis revealed the existence of a barrier layer on the electrode surface with the presence of PPD. Theoretical examinations performed by electronic/atomic computer simulations confirmed that the obtained results were found to be consistent with experimental findings.

Insights into the newly synthesized N-doped carbon dots for Q235 steel corrosion retardation in acidizing media: A detailed multidimensional study

N-doped carbon quantum dots (NCQDs) were synthesized by a hydrothermal method using folic acid and o-phenylenediamine as precursors. The inhibition behaviour of the NCQDs on Q235 steel in 1 M HCl solution was appraised through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves (PDP), and surface analysis. The results demonstrated that the synthesized NCQDs had an effective anticorrosion effect on Q235 steel, and the corrosion inhibition efficiency of 150 mg/L NCQDs reached 95.4%. Additionally, the analysis of the PDP corrosion potential changes indicated that the NCQDs acted as a mixed corrosion inhibitor. Moreover, the NCQDs adsorbed onto the surface of steel by coordinating its electron-rich atoms with the iron metal to form a protective film, which slowed the dissolution reaction of the anodic metal to achieve corrosion inhibition. The adsorption mechanism of the NCQDs was consistent with Langmuir adsorption, including physical and chemical adsorption. Therefore, this work can inspire and facilitate, to a certain extent, the future application of doped carbon quantum dots as efficient corrosion inhibitors in pickling solutions.

Experimental and computational investigations on the anti-corrosive and adsorption behavior of 7-N,N'-dialkyaminomethyl-8-Hydroxyquinolines on C40E steel surface in acidic medium

Two new 7-N,N'-dialkylaminomethyl-8-Hydroxyquinolines, namely 7-N,N'-dipropylaminomethyl-8-Hydroxyquinoline (DPQ) and 7-N,N'-dimethylaminomethyl-8-Hydroxyquinoline (DMQ), were synthesized and characterized using ¹H/¹³C NMR and Elemental analysis methods. Corrosion inhibition effect of DMP and DPQ for C40E steel in 1 M HCl was evaluated at different concentrations (10^-3 to 10^-6M) and temperatures (298 to 328 K) using several experimental and computational approaches. Weight loss and electrochemical studies showed that protection efficiencies (η_max) of DPQ and DMQ increase with increase in concentrations. The DPQ and DMQ showed maximum efficiencies of 96.1% and 94.4%, respectivelyat 10^-3 M. Polarization measurements showed that DMQ and DPQ act as mixed type corrosion inhibitors. Adsorption of DPQ and DMQ on C40E steel in 1 M HCl obeyed the Langmuir adsorption isotherm. Variation in surface morphology of corroded metallic surface with and without DMQ and DPQ was demonstrated using scanning electron microscopy. Molecular dynamics (MD) simulations studies showed that DPQ and DMQ acquire the flat or horizontal orientation over the C40E steel. DFT analyses revealed that both DPQ and DMQ interact with the C40E steelusing electron-sharing(donor-acceptor)mechanism. Computational analyses conducted using DFT and MD simulations well corroborate the experimental results.

Evaluation of 2-Mercaptobenzimidazole Derivatives as Corrosion Inhibitors for Mild Steel in Hydrochloric Acid

This research aimed to develop a better understanding of the corrosion inhibition of the mild steel in acidic medium by new organic molecules. For this purpose, two new compounds namely, 2,3-dihydrobenzo[4,5]imidazo[2,1-b]thiazole (2-BIT) and 3,4-dihydro-2H-benzo[4,5]imidazo[2,1-b]thiazole (3-BIT) were synthesized and evaluated for mild steel (MS) corrosion in HCl. Analyses were carried out using weight loss measurements, electrochemical techniques, and scanning electron microscope (SEM). The adsorption of inhibitors onto the steel surface follows the Langmuir adsorption model. Generally, results showed that the corrosion inhibition efficiency of the investigated molecules was found to increase with increased concentration of inhibitors. Electrochemical tests, i.e., electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques, showed that the addition of our investigated inhibitors decreases the dissolution of the metal and generally act as mixed-type inhibitors. In addition, the influence of temperature (from 303 to 333 K) on the corrosion inhibition was studied, and the results demonstrated that with an increase in temperature, the inhibition efficiency decrease. SEM results confirmed that the inhibition process is due to a protective film that prevents corrosion. Similarly, the results showed that the inhibitory efficiencies reach 93% at 5 × 10−3 M in the case of inhibitor 3-BIT. These results revealed that this compound could effectively control and reduce the corrosion rate of mild steel in the corrosion test solution.