Adsorption Of Imidazole Research Articles

In-depth study of a newly synthesized imidazole derivative as an eco-friendly corrosion inhibitor for mild steel in 1 M HCl: Theoretical, electrochemical, and surface analysis perspectives

The present study is concerned with the corrosion inhibition and adsorption behaviour of a series of novel imidazole derivatives. The compounds under investigation are 5,5-diphenyl-3-propyl-2-(propylthio)-3,5-dihydro-4 H-imidazol-4-one (AM3) and 3-allyl-2-(allylthio)-5,5-diphenyl-3,5-dihydro-4 H-imidazol-4-one (AM6). The objective of this study is to evaluate the efficacy of 5,5-diphenyl-3,5-dihydro-4 H-imidazol-4-one (AM6) as a corrosion inhibitor on mild steel immersed in a 1.0 M hydrochloric acid medium. This comprehensive study assesses the efficacy of these derivatives through a range of electrochemical and spectroscopic analysis techniques. Additionally, polarisation curves, electrochemical impedance spectroscopy and advanced computer simulations were employed to evaluate the efficacy and inhibition mechanism of imidazole derivatives, thereby facilitating a more profound understanding of their anticorrosive capacity. The results obtained from potentiodynamic polarisation (PDP), electrochemical frequency modulation (EFM) and electrochemical impedance spectroscopy (EIS) measurements demonstrate that the inhibition efficiency increases with increasing imidazole derivative concentration. Conversely, an inverse relationship is observed between inhibition efficiency and temperature. The thermodynamic parameters ΔG°_ads and ΔH°_ads corroborate the conclusion that the adsorption process is predominantly chemical in nature. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) were employed to characterise the surface morphology. The maximum protection afforded by imidazole derivatives was 95.2 % and 93 % for compounds AM3 and AM6, respectively. Polarisation curves indicated that imidazole derivatives exhibited mixed inhibition behaviour. Surface analysis demonstrated that imidazole derivatives were effectively adsorbed onto the carbon surface, thereby significantly reducing acid damage. This finding was corroborated by DFT calculations, as well as Monte Carlo (MC) and molecular dynamics (MD) simulations. These simulations provided a comprehensive insight into the adsorption of imidazole and its protonated form onto the carbon surface, offering valuable insight into the corrosion inhibition mechanism.

Ionic bond in hydrogen transferring of the ferrous and/or ferric human/mouse verdoheme oxygenase.

Formation of five coordinated ferric (ferrous) verdoheme oxygenase complexes have been investigated at ωB97X-D/6-31G(d) level of theory. This process was carried out by adsorption of imidazole and human/mouse verdoheme oxygenase (VO) compounds. Global reactivity indexes show electrophile and nucleophile roles of the VO complexes and Imidazole, respectively. This result confirms their interaction, molecular electrostatic potential (MEP) maps, and low HOMOFRVMO-LUMOImidazole gap. These interactions can cause in adsorption and five coordinated of the VO complexes. More negative value (-64.3kJmol-1) of adsorption energy (Eads) in the FRVMO complex shows better adsorption strength and stable configuration. Significant point of this interaction is hydrogen transfer from imidazole to the nearest oxygen of the VO complexes; this issue is approved using quantum theory of atom in molecule (QTAIM) and natural bond orbital (NBO) analysis. QTAIM calculations confirm ionic bonding between the transferred hydrogen and the oxygen atom of the VO. The 312.2-kcalmol-1s order stabilization energies in this complex are confirmation for strong donation and better formation of five coordinated complex in electron view point.

DFT Study of Azole Corrosion Inhibitors on Cu2O Model of Oxidized Copper Surfaces: II. Lateral Interactions and Thermodynamic Stability

The adsorption of imidazole, triazole, and tetrazole—used as simple models of azole corrosion inhibitors—on various Cu 2 O(111)- and Cu 2 O(110)-type surfaces was characterized using density functional theory (DFT) calculations with the focus on lateral intermolecular interactions and the thermodynamic stability of various adsorption structures. To this end, an ab initio thermodynamics approach was used to construct two-dimensional phase diagrams for all three molecules. The impact of van der Waals dispersion interactions on molecular adsorption bonding was also addressed. Lateral intermolecular interactions were found to be the most repulsive for imidazole and the least for tetrazole, for which they are usually even slightly attractive. Both non-dissociative and dissociative adsorption modes were considered and although dissociated molecules bind to surfaces more strongly, none of the considered structures that involve dissociated molecules appear on the phase diagrams. Our results show that the three azole molecules display a strong tendency to preferentially adsorb at reactive coordinatively unsaturated (CUS) Cu surface sites and stabilize them. According to the calculated phase diagrams for Cu 2 O(111)-type surfaces, the three azole molecules adsorb to specific CUS sites, designated as Cu CUS , under all conditions at which molecular adsorption is stable. This tentatively suggests that their corrosion inhibition capability may stem, at least in part, from their ability to passivate reactive surface sites. We further comment on a specific drawback due to neglect of configurational entropy that is usually utilized within the ab initio thermodynamics approach. We analyze the issue for Langmuir and Frumkin adsorption models and show that when configurational entropy is neglected, the ab initio thermodynamics approach is too hasty to predict phase-transition like behavior.

Surface-Enhanced Raman Scattering and Electrochemical Investigations on the Adsorption of Imidazole: Imidazolium Couple and Its Implications on Copper Corrosion Inhibition

The adsorption dynamics of Imidazol (Imid) and Imidazolium (ImidH+) on copper was investigated by Surface-Enhanced Raman Scattering (SERS) as a function of the applied potential and pH. Although both species adsorb on metal surfaces the neutral molecule changes the orientation from tilted to perpendicular as the potential is made more negative. On the other hand, the cation remains parallel over the whole studied potential window. Imid is the major species on copper electrode, although ImidH+ can be identified even in alkaline solutions. Cyclic voltammetry and chronoamperometry measurements show good correlation with SERS data in terms of CuCl (CuCl2− as well) and Cu2O formation. Initially, a chemisorption mechanism is proposed at cathodic potentials, which changes to physisorption near the copper corrosion potential and finally a soluble complex is formed at more positive potentials. Such findings indicate that Imid is a good cathodic inhibitor, but its inhibition efficiency is very low at anodic potentials.

Formation and structure of inhibitive molecular film of imidazole on iron surface

Adsorption of imidazole on clean Fe(100) was addressed by DFT calculations. It is shown that even though the imidazole in protonated form binds stronger to the surface than the neutral form, it is prone to deprotonation (dehydrogenation) resulting in neutral form, which further dehydrogenates due to the breaking of the C2–H bond. Thermodynamically the stablest identified structures thus consist of strongly bound and densely packed C2 dehydrogenated imidazole molecules, which may act as a thin protective film. On the other hand, the polymerization of imidazole molecules upon adsorption has been found improbable.

Surface-enhanced Raman scattering of imidazole adsorbed on an iron surface

The adsorption of imidazole on a roughened polycrystalline iron electrode was investigated by the SERS technique at pH values of neutral, 11 and 14 and compared with those from each solution. The results indicated that imidazole was adsorbed as mainly the neutral form and/or a certain amount of ylide form on the Fe surface in a neutral solution. The molecules have maximum adsorption at −0.9 V potential with tilted or perpendicular orientation with respect to the Fe surface, whereas a face-on orientation of imidazole was favored at both more cathodic and anodic potentials. In a weaker basic solution imidazole was also adsorbed on the Fe surface as the neutral form, and took a face-on orientation with respect to the Fe surface at all measured potentials because of its weaker adsorption than that in a neutral solution. Neutral and anionic forms of imidazole on the Fe surface were indicated by SERS at pH 14. Copyright © 2002 John Wiley & Sons, Ltd.

Surface‐enhanced Raman scattering of imidazole adsorbed on an iron surface

AbstractThe adsorption of imidazole on a roughened polycrystalline iron electrode was investigated by the SERS technique at pH values of neutral, 11 and 14 and compared with those from each solution. The results indicated that imidazole was adsorbed as mainly the neutral form and/or a certain amount of ylide form on the Fe surface in a neutral solution. The molecules have maximum adsorption at −0.9 V potential with tilted or perpendicular orientation with respect to the Fe surface, whereas a face‐on orientation of imidazole was favored at both more cathodic and anodic potentials. In a weaker basic solution imidazole was also adsorbed on the Fe surface as the neutral form, and took a face‐on orientation with respect to the Fe surface at all measured potentials because of its weaker adsorption than that in a neutral solution. Neutral and anionic forms of imidazole on the Fe surface were indicated by SERS at pH 14. Copyright © 2002 John Wiley & Sons, Ltd.

The electrosorption of imidazole on a gold electrode as studied with spectroelectrochemical methods

The adsorption of imidazole on a polycrystalline gold electrode has been studied with electrochemical methods (cyclic voltammetry, tensammetry) and Surface Enhanced Raman Spectroscopy (SERS). The results indicate a strong physisorption of the molecule when adsorbed from a neutral solution (Δ G 0 ad = −35.5 ± 0.5 kJ mol −1). SERS data indicate a molecular adsorption with a perpendicular orientation from solutions of 0.1 M KClO 4. From acidic solution a deprotonated imidazolate is adsorbed in a perpendicular orentation.

The use of Surface Enhanced Raman Scattering (SERS) to probe the interaction of imidazole with the silver electrode surface

The adsorption of imidazole on a roughened polycrystalline silver electrode has been studied using the SERS and impedance methods. The SERS results have indicated that different forms of imidazole (anionic, neutral and probably ylide ones) can be observed at the Ag surface. The relative amounts of these forms depend on the electrode potential and on the pH of the solution. The electrode surface facilitates deprotonation of neutral imidazole and a remarkable amount of the anionic form adsorbs at the Ag surface in spite of its small equilibrium content in the bulk.