Corrosion inhibition of copper in chloride media by 2-mercapto-4-(p-methoxyphenyl)-6-oxo-1,6-dihydropyrimidine-5-carbonitrile: Electrochemical and theoretical study

AbstractElectrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization have been used to investigate the inhibition effect of a new pyrimidine heterocyclic derivative, namely 2-mercapto-4-(p-methoxyphenyl)-6-oxo-1,6-dihydropyrimidine-5-carbonitrile (MPD) on copper corrosion in 3.5% NaCl solutions at 25±1°C. The electrochemical investigations showed that MPD gives sufficient inhibition against copper corrosion in 3.5% NaCl solutions. Potentiodynamic polarization measurements have shown that the MPD inhibit both the cathodic and anodic processes and thus it classified as mixed-type inhibitor. EIS measurements indicate that the values of constant phase elements (CPEs) tend to decrease and both charge-transfer resistance and inhibition efficiency tend to increase by increasing the inhibitor concentration. Electrochemical kinetic parameters obtained using EFM methods were comparable with that calculated from traditional measurements (EIS and potentiodynamic polarization). Molecular simulation technique was used to investigate the adsorption configuration of MPD on copper surface. Number of electrons transferred from MPD to the copper surface was calculated by semi-empirical quantum chemical calculations

Can Taxpayers Stand Discrimination?: Lack of Standing and the Religious Freedom Restoration Act Permits the Executive Branch to Fund Discrimination Within Religious Organizations

The Density Functional Theory (DFT) and ab initio (HF and MP2) calculations were performed on the quinoline molecule (QL) and its derivatives, namely quinaldine (QLD) and quinaldic acid (QLDA) to investigate their possible role as corrosion inhibitors for mild steel in acidic medium. Calculations were done for non-protonated and protonated forms in vacuo and in water. Some quantum chemical parameters were calculated and discussed in order to provide insight into the reactivity and selectivity of the molecules. The performance of the different calculation methods were also compared with available experimental data. The results show that DFT/B3LYP basis set is adequate in describing the geometry and quantum chemical parameters of the studied systems. Both experimental and theoretical results established that QLDA has the highest inhibition efficiency. A comparison in the trends of the quantum chemical parameters in water solution and in vacuo shows minimal influence of the solvent effects

Electrochemical investigation of corrosion and corrosion inhibition of iron in hydrochloric acid solutions

AbstractThe inhibition effect of 1-methyl pyrazole (MPA) on the acidic corrosion of iron in 1.0M HCl was studied at different concentrations (10−3–10−2M) by potentiodynamic polarization and electrochemical impedance spectroscopy, and EIS measurements. It is found from the polarization studies that methyl pyrazole (MPA) behaves mainly as anodic inhibitor in HCl. Values of polarization resistance (Rp) and double layer capacitance (Cdl) in the absence and presence of MPA in 1.0M HCl are determined. The adsorption of MPA on iron surface from HCl is found to obey Temkin adsorption isotherm