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    Evaluation of inhibitive and adsorption behavior of thiazole-4-carboxylates on mild steel corrosion in HCl
    (Elsevier, 2020) El aoufir, Y.; Zehra, S.; Lgaz, H.; Chaouiki, A.; Serrar, H.; Kaya, S.; Salghi, R.
    The present work describes the corrosion inhibiting properties of three synthesized thiazole-4-carboxylates namely, methyl (E)-5-(4-chlorophenyl)-2-(((E)-4-methylbenzylidene)hydrazono)-2,3-dihydrothiazole-4-carboxylate (T1), methyl (E)-5-(4-chlorophenyl)-2-(((E)-4-nitrobenzylidene)hydrazono)-2,3-dihydrothiazole-4-carboxylate (T2) and methyl (E)-2-(((E)-4-chlorobenzylidene)hydrazono)-5-(4-chlorophenyl)-2,3-dihydrothiazole-4-carboxylate (T3) towards corrosion of mild steel (MS) in 1.0 mol/L HCl. Various techniques like electrochemical measurements, SEM-EDX analysis, Density Functional Theory (DFT) and molecular dynamics (MD) simulations were employed to probe the effects of substituent groups on inhibition performances of investigated compounds. EIS studies indicated the adsorbed protective film's construction on the steel/electrolyte interface by tested molecules; its existence was affirmed by SEM-EDX analysis. Polarization studies revealed a mixed-type of corrosion inhibition activity. Their mode of adsorption was studied by using isotherm models, and the best match was found just in case of Langmuir adsorption isotherm. Electrochemical results showed that the polarization resistance was greatly increased, from an initial value for the MS (in 1.0 mol/L HCl) of 20.24 up to 256.7 Omega cm(2) for the inhibited solution (1.0 mol/L HCl with 5 x 10(-4) mol/L of T3). Tested compounds behaved as effective inhibitors for MS corrosion in HCl at all concentrations with better efficacy at an optimal concentration of 5 x 10(-4) mol/L. Among all the tested inhibitors, T3 exhibited the most effective performance with an inhibition of 92 %, and the order of the inhibition potency is found within the order of T3 > T2 > T1 by all utilized techniques. The morphological examinations of the surface of MS specimens were explored by using SEM/EDX analysis. DFT calculations were not in agreement with experimental results while MD simulations confirmed the dependence of inhibition performances on the molecular structure of tested compounds.
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    Performance evaluation and assessment of the corrosion inhibition mechanism of carbon steel in HCl medium by a new hydrazone compound: Insights from experimental, DFT and first-principles DFT simulations
    (Elsevier, 2023) En-Nylly, M.; Skal, S.; El Aoufir, Y.; Lgaz, H.; Adnin, Raihana J.; Alrashdi, Awad A.; Bellaouchou, A.
    In the present work, a new hydrazone compound, namely N'-[(Z)-(4-chlorophenyl)methy lidene]-2-(5-methoxy-2-methyl-1H-indol-3-yl)acetohydrazide, noted HTH, was selected to protect carbon steel against corrosion in 1.0 mol/L HCl. Different chemical, electrochemical, and surface characterization techniques such as scanning electron microscope coupled with X-ray energy disper-sion (SEM/EDX) were used to investigate the corrosion inhibition performance. Electrochemical data showed that the effectiveness of the inhibitor improved with increasing concentration, reaching 98% at the optimal concentration of 10-3 mol/L. The results of potentiodynamic polarization mea-surements showed that hydrazone acted as a mixed-type inhibitor. The EIS results showed an increase in polarization resistance accompanied by a noticeable decrease in Ceff,dl values. In the tem-perature range of 303 K-333 K, hydrazone protected carbon steel by 89%, showing high resistance to temperature effect. The analysis of the steel surface by SEM/EDX confirmed that the effective-ness of the hydrazone was attributed to the formation of a protective layer on the surface of the metal. Quantum chemical calculations revealed insights into the chemical reactivity of the tested hydrazone while first-principles density functional theory (DFT) and molecular dynamics (MD) simulation supported the experimental conclusions and showed outstanding adsorption ability of HTH on the Fe(1 10) surface. First-principles DFT simulations showed that the HTH molecule was more stable in a parallel adsorption mode. (c) 2023 Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).