Search

Two novel bithienyl fluorobenzamidine derivatives namely, 4-([2,2':5',2''-terthiophen]-5-yl)-2-fluorobenzamidine hydrochloride salt (MA-1615), 5'-(4-amidino-3-fluorophenyl)-[2,2'-bithiophene]-5-carboxamidine dihydrochloride salt (MA-1740) were synthesized, characterized and their corrosion inhibition properties were evaluated by electrochemical methods for carbon steel (C-steel) in 1 M HCl. Experimental investigations revealed that the inhibition effectiveness of the investigated inhibitors (INHs) by the Tafel polarization method followed the order: MA-1740 (96.9%) MA-1615 (95.6%), demonstrating higher efficiency than inhibitors of similar structure reported in the literature. The investigated bithiophene derivatives exhibit mixed-type corrosion inhibition characteristics by blocking the active sites on the surface of C-steel. EIS study revealed that the INHs behave as interface-type corrosion inhibitors. UV-Visible spectrometric measurements confirmed a complex formation between the Fe

The adsorption action of polyethylene oxide (PEO) on copper surface in 3.5 wt.% NaCl solution was tested using electrochemical frequency modulation (EFM), atomic absorption spectrometry (AAS), UV- visible spectrometry and the morphology of copper surface was investigated by attenuated total reflectance spectroscopy (ATR-FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques. Results obtained show that PEO is effective in preventing the corrosion of copper in NaCl solution. The adsorption of PEO onto copper surface was found to follow Langmuir isotherm model. ATR-FTIR, SEM and EDX spectroscopy techniques confirmed the adsorption of protective film of PEO on copper surface. Further, quantum chemical calculations were in agreement with inhibition efficiency (%I) of PEO that were obtained experimentally.

Theeffect of 6-[5-(4-methoxyphenyl) furan-2-yl] nicotinonitrile (MA-1160) as a new corrosion inhibitor for carbon steel (CS) in hydrochloric acid (HCl) solution was investigated using weight loss (WL), atomic absorption spectroscopy (AAS) and electrochemical measurements. The surface morphology of CS was tested using: scanning electron microscopy, atomic force microscope, attenuated total reflection–Fourier transform infra-red and ultraviolet–visible spectroscopy methods. The adsorption of MA-1160 on CS surface obeyed the model of Langmuir isotherm. Polarization data revealed that this inhibitor behave as mixed-type inhibitor. The spectroscopic measurements revealed the formation of a protective adsorbed layer on CS surface. Quantum chemical calculations were calculated and discussed using density functional theory method. The inhibition efficiency (% €) was 84% in WL, 86.4% in AAS, 86.0% in potentiodynamic polarization and 84.8% in EIS 86% at 21 µM. Thus, all the test methods gave good agreement with each other in % €.

The inhibitive action and adsorption behavior of cefotaxime drug on corrosion of copper in 0.1 mol L−1 HCl solutions was discussed using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques. The results obtained from different electrochemical measurements revealed that the cefotaxime drug is a good inhibitor efficient in the studied concentration range. Polarization curves suggested that the inhibitor is a mixed-type inhibitor. EIS spectra showed that the addition of inhibitor increases the charge-transfer resistance of the corrosion process, and hence the inhibition performance improved. Results obtained from EFM method are shown to be in agreement with potentiodynamic and EIS measurements. The adsorption behavior of inhibitor on copper surface followed Langmuir adsorption isotherm. SEM and EDX examination of the copper surface revealed that cefotaxime drug prevented copper from corrosion by adsorption on its surface to form a protective film. Quantum chemical calculations were employed using DFT method to determine the possible active centers responsible for the adsorption of cefotaxime drug on the copper surface.

In this study, the effect of imidazole derivatives on the inhibition of aluminum corrosion in 0.5 M HCl has been studied using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) measurements. The results show that all imidazole derivatives are good inhibitors, and inhibition efficiency follows the order: B > A. Polarization curves demonstrated that the imidazole derivatives were of mixed-type inhibitors. The adsorption of each inhibitor on aluminum surface obeys Frumkin adsorption isotherm. Surface morphology studies were done using scanning electron microscopy (SEM) to characterize the film formed on aluminum surface. Quantum chemical calculations show that imidazole derivatives can adsorb on the aluminum surface through the nitrogen atoms as well as π-electrons in the imidazole ring.

Newly antipyrinyl derivatives 4 and 5 were synthesized from the reaction of enaminonitrile 3 with 1-nitroso-2-naphthol and salicyaldehyde, respectively, and used to protect mild steel dissolution in 1.0 M HCl solutions using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy measurements. It was shown that these inhibitors act as good corrosion inhibitors for mild steel protection. The inhibition efficiencies were attributed to the simple blocking effect by adsorption of inhibitor molecules on the mild steel surface. The results showed that inhibitors acts as a mixed-type inhibitor. Relationship between molecular structure and their inhibition efficiency was elucidated by quantum chemical calculations.

The influence of Cephapirin drug on the corrosion of carbon steel (CS) in 2 M HCl solutions has been examined by mass loss (ML), and electrochemical methods. The results demonstrated that Cephapirin drug acts as good inhibitor for CS corrosion. The inhibition efficiency increased as the concentration of the drug increases. Potentiodynamic polarization (PDP) studies showed that Cephapirin is mixed-type inhibitor. The electrochemical impedance spectra (EIS) studies reveal that the process of inhibition is through charge transfer. The adsorption of the drug on metal surface obeyed Temkin adsorption isotherm. The surface analysis of the CS was investigated using Attenuated total reflectance spectroscopy (ATR-FTIR) and UV–visible reflectance spectroscopy. Surface analysis of CS confirmed the existence of a protective adsorbed film of the drug on the metal surface. The quantum chemical calculations of the drug molecule in aqueous phase were done using density functional theory (DFT) method and discussed to correlate the theoretical and experimental data. The inhibition efficiency of Cephapirin drug obtained by chemical and electrochemical methods was in good correlation with each other.