Experimental, Monte Carlo and Molecular Dynamic Study on Corrosion Inhibition of Mild Steel by Pyridine Derivatives in Aqueous Perchloric Acid

The corrosion of mild steel in aqueous perchloric acid solution was studied in the presence and absence of four different pyridine derivatives. Electrochemical measurements point out that these molecules inhibit the corrosion of mild steel by acting as mixed inhibitors. The adsorbed molecules act as a barrier that prevents the oxidation of the metal and the hydrogen evolution reaction at the mild steel surface. Molecular insights vis-à-vis the corrosion process were acquired by the use of Density Functional Theory (DFT), Molecular Dynamics, and Monte Carlo calculations. Monte Carlo and Molecular Dynamic simulation were used to understand at the molecular level the adsorption ability of the studied molecules onto Fe(110) surface. The experimental results and theoretical calculations provided important support for the understanding of the corrosion inhibition mechanism expressed by the pyridine molecules.

Substrate Inhibition in Ruthenium(III) Catalyzed Oxidation of Propane-1,3-diol by Periodate in Acidic Medium: A Kinetic Study

Ruthenium(III) catalyzed oxidation of propane-1,3-diol by potassium periodate was studied in aqueous perchloric acid medium. Orders of reaction with respect to concentrations of oxidant, substrate, acid and catalyst were determined. First order in oxidant and catalyst concentrations, and inverse fractional order in acid medium were observed. In addition, substrate inhibition (i.e. a decrease in reaction rate with an increase in substrate concentration) was observed. Effect of addition of salt and solvent was studied. Based on the studies of temperature variation, Arrhenius parameters were calculated. Plausible mechanism was also proposed based on observed kinetics.

Analysis of acid-base properties of some p-substituted aromatic hydrazones in aqueous perchloric acid by spectrophotometric and semiempirical methods

<p>The acid-base properties of some <em>p</em>-substituted aromatic hydrazones were examined in aqueous perchloric acid medim by spectrophotometric methods. The possible site where the proton may take place and the stability of the protonated form was discussed using the values of the total energy, binding energy, heat of formation and proton affinity calculated according to the semiempirical methods AM1 and PM3. Furthermore, the stability of the protonated forms, as well as, the stability of the isomers (<em>E</em> and <em>Z</em>) was discussed. Electronic absorption studies were utilized for determination of the dissociation constants of the protonated form (p<em>K</em>_BH⁺), numerically and graphically, at different ionic strength (0.1, 0.25 and 0.5 mol/dm³), as well as, thermodynamic dissociation constants. The influence of the solvent on the appearance of the recorded spectra was compensated by the use of the method of characteristic vector analysis (CVA).</p><p> </p>