Search

This paper addresses the prediction of the adsorption behavior as well as the inhibition capacity of non-toxic sulfonamide-based molecules, also called sulfa drugs, on the surface of mild steel. The study of the electronic structure was investigated through quantum chemical calculations using the density functional theory method (DFT) and the direct interaction of inhibitors with the iron (Fe) metal surface was predicted using the multiple probability Monte Carlo simulations (MC). Then, the examination of the solubility and the environmental toxicity was confirmed using a chemical database modeling environment website. It was shown that the presence of substituents containing heteroatoms able to release electrons consequently increased the electron density in the lowest unoccupied and highest occupied molecular orbitals (LUMO and HOMO), which allowed a good interaction between the inhibitors and the steel surface. The high values of EHOMO imply an ability to donate electrons while the low values of ELUMO are related to the ability to accept electrons thus allowing good adsorption of the inhibitor molecules on the steel surface. Molecular dynamics simulations revealed that all sulfonamide molecules adsorb flat on the metal surface conforming to the highly protective Fe (1 1 0) surface. The results obtained from the quantum chemistry and molecular dynamics studies are consistent and reveal that the order of effectiveness of the sulfonamide compounds is P7 > P5 > P6 > P1 > P2 > P3 > P4. [ABSTRACT FROM AUTHOR]

• Xanthene derivatives act as efficient and nontoxic corrosion inhibitors for mild steel. • Quantum chemical parameters and Monte Carlo simulation results are in good correlation with experimental results. • NAR2 molecules shows a high effective corrosion inhibition compared to NAR3. The synthesis, characterization, and evaluation of inhibiting performance of two xanthene derivatives, namely 3-oxo-3H-spiro[ isobenzofuran -1,9′- xanthene ]-3′,6′-diyl (3-dibenzoate) (NAR2) and 3-oxo-3H-spiro[ isobenzofuran -1,9′- xanthene ]-3′,6′-diyl (3-diacetate) (NAR3) on mild steel immersed in 1 M HCl solution are performed. The in vivo tests were carried out to confirm the non-toxicity of NAR2 and NAR3. The solutions corrosive was analyzed using UV visible Spectroscopy. The recorded spectra confirm the adsorption capacity of these molecules on the surface of iron and thereby a formation of Fe–inhibitor complex film. A combination of Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) Spectroscopy were performed to characterize the surface of mild steel, with and without the NAR2 or NAR3 inhibitors; and Electrochemical techniques were evaluated (EIS) to determine the corresponding corrosion inhibition efficiencies of NAR2 and NAR3. The Density Functional Theory (DFT)- based total energy calculations and Monte Carlo simulations were also performed to get further theoretical insights into the inhibition mechanism. The obtained results confirmed that both organic inhibitors exhibit non-toxicity, with an inhibition efficiency of 93% and 89% for NAR2 and NAR3 at 10−4 M concentrations, respectively. Also, the both inhibitor function as mixed (cathodic and anodic) type inhibitors, displace water molecules from mild steel, and form an heterogeneous films on the mild steel surface to protect against corrosion. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Benzimidazole AE1 and 2 were synthesized using 1,3-dipolar cycloaddition techniques. • AE1 inhibits corrosion by 97.2 %, and AE2 by 95.8 %. • Inhibitors follow Langmuir isotherms on MS surface. • DFT and MC simulations support AE1 and 2 adsorptions on MS surface. In this study, novel compounds, isoxazolyl-benzimidazolone (AE1) and isoxazolinylbenzimidazolone (AE2), were synthesized and characterized using various spectroscopic methods. This involved employing 1,3-dipolar cycloaddition techniques with 2,4,6-trimethoxylbenzonitrile N-oxide and mesitonitrile-oxide in combination with "1-cyclohex-1-en-1-yl-3-propargyl-benzimidazolone" or "1-cyclohex-1-en-1-yl-3-allylbenzimidazolone". The structural identification of these newly formed cycloadducts was achieved through comprehensive analytical and spectral analyses. The two heterocyclic compounds, AE1 and 2, have been investigated into their corrosion inhibition potential of mild steel (MS) in 1.0 M HCl, utilizing diverse analysis methods such as Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscopy (EIS), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) techniques. The outcomes revealed significant corrosion inhibition, with AE1 displaying the highest effectiveness (97.2 %), followed closely by AE2 (95.8 %) at 10−4M. The inhibitors were observed to adhere to the MS surface following Langmuir isotherms, and their adsorption and thermodynamic characteristics were thoroughly assessed. Moreover, Density Functional Theory (DFT) and Monte Carlo (MC) simulations corroborated the robust adsorption capability of these organic chemicals on the MS surface. [ABSTRACT FROM AUTHOR]

• Two pyrazole derivatives were used for the creation of a thin solid film on the metal surface. • [Pyr-(CH 3) 2 ] and [Pyr-H 2 ] show 85 % and 78 % corrosion inhibition efficiency at 10−3 M, respectively. • SEM and AFM show their visible surface adsorption on the metal surface. • Electrochemical outcomes suggest its mixed type of inhibitor nature. • DFT and MD simulations agree with the experimental results. The adsorption performance of 4-((1H-pyrazol-1-yl)methyl)-4-methyl-2-phenyl-4,5-dihydrooxazole [Pyr-H 2 ] and 4-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)-4-methyl-2-phenyl-4,5-dihydrooxazole [Pyr-(CH 3) 2 ] was evaluated for mild steel in 1 M HCl solution. The current examination was carried out using weight loss measurements, electrochemical techniques (polarization curves and electrochemical impedance spectroscopy), surface morphology analysis, and theoretical approach. Before the experimental test, in-silico environmental toxicity was evaluated, indicating the eco-friendly behavior of the concentration used as corrosion inhibitors. The experimental findings showed that these chemicals acting as mixed-type inhibitors, preventing both anodic and cathodic reactions. Moreover, the mild steel surface was also examined using scanning electron microscopy coupled with EDX analysis. These chemicals adsorbed onto the mild steel surface following Langmuir isotherm. In addition, DFT calculations at B3LYP 6-311G (d,p) was used to estimate the reactivity of these molecules by linking their electronic characteristics with their experimental outcomes, whereas Monte Carlo simulation confirms the parallel approach of the studied pyrazole into the steel surface. Finally, it can be concluded that the existence of two methyl group in [Pyr-(CH 3) 2 ] inhibitor augmented the covered surface area compared to [Pyr-H 2 ] molecule. [Display omitted] [ABSTRACT FROM AUTHOR]