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The corrosion inhibition effect of di[(4-phenylimino)-4-diethyl salicylaldehyde] ether (L1) and di[(4-phenylimino)-2,6-diacetyl pyridine] ether (L2) as Schiff bases on carbon steel X48 in 1 M HCl were examined with gravimetric measurement, Tafel polarization and electrochemical impedance spectroscopy (EIS). It was observed that the two compounds L1 and L2 act as greatly corrosion inhibitors. The potentiodynamic polarization results indicate that they act as anodic and cathodic type. The adsorption of each inhibitor on the mild steel surface obeys Langmuir isotherm. The associated activation parameters together with the thermodynamic data are evaluated and discussed. The characterization of the adsorbed molecules (L1 and L2) formed on the metal surface was carried out by SEM and AFM. The improvement in corrosion resistance was related to the presence of different substituent groups, apparently due to the easiness of the electron acceptance as confirmed by the quantum chemical calculations. Additionally, the molecular dynamic simulations were used to clarify the inhibition mechanism, especially, the adsorption modes and configurations of the studied inhibitor molecules. [ABSTRACT FROM AUTHOR]

{(1Z)-2-oxo-N′-phenyl-N-quinolin-8-ylpropanehydrazonamide (H2L-H) and (1Z)-N′-(4-bromophenyl)-2-oxo-N-quinolin-8-ylpropanehydrazonamide (H2L-Br)} have been studied as corrosion inhibitors of carbon steel in 1 M HCl medium by the weight loss method, potentiodynamic polarization, electrochemical impedance spectroscopy EIS, scanning electron microscopy SEM coupled with Energy Dispersion X-Ray Spectroscopy EDS, Atomic Force Microscopy AFM, IR and UV-visible spectroscopy. The inhibition efficacy has been shown to increase with increasing inhibitor concentration. The corrosion of the carbon steel is mainly controlled by a charge transfer process. The temperature effect was evidenced and the thermodynamic parameters were calculated. The adsorption of the inhibitors on the metal surface obeyed the Langmuir adsorption isotherm. The hydrodynamic effect and the synergetic effect have been implemented. Inhibitory efficiency decreases with increasing rotation speed and the used additives adsorb cooperatively to form a protective layer on the metal surface. The results obtained by the experimental measurements and those of the theoretical calculations (DFT and MD simulation) are in good correlation. Equilibrium adsorption configurations of H2L-Br on Fe (1 1 0) surface obtained by molecular dynamic simulations [ABSTRACT FROM AUTHOR]

The inhibition effect of a new Schiff base, namely, 4,4′-thio bis{N-[ (E ) -phenol-3-ylmethylidene]aniline}(SB), on the corrosion of mild steel (MS) in a 1M HCl solution was investigated under both hydrodynamic flow and a stagnant environment at different temperatures and concentrations. To assess the inhibition effect, different characterization techniques have been used including the measurement of weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). It was found that the inhibition efficiency increases with the increase of the inhibitor concentration and decreases when the temperature increases. The adsorption of the inhibitor on the surface of MS obeys the Langmuir isotherm. The surfaces of MS, after being exposed to test solutions, were examined by atomic force microscopy (AFM). [ABSTRACT FROM AUTHOR]

New di-, tri-, and tetraphosphonic acids were synthesized starting from four o-hydroxymethyl phenol derivatives and obtained in three steps in good overall yield. The phosphonic acids were isolated and purified using semi-preparative C18 HPLC column. The new compounds were characterized using different spectroscopic methods (1H, 13C, and 31P NMR; ESI MS; and MSn, IR). GRAPHICAL ABSTRACT[image omitted] [ABSTRACT FROM AUTHOR]