Etude de l'inhibition de la corrosion de l'acier en milieu acide par des composes de type dithioacetal de cetene.

Abstract

This work is devoted to the synthesis and evaluation of the inhibitory power of a category of heterocyclic organic compounds of the ketene dithioacetal family such as PDDY, ECDYA and DYMN. The inhibition ability of these synthesized compounds towards mild steel S9Mn28K corrosion in 1M HCl was examined at various concentrations and temperatures, using weight loss measurements, polarization curves, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) techniques. Gravimetric measurements showed that the studied compounds have a corrosion inhibiting character of mild steel in 1M HCl. The polarization curves revealed that these examined compounds are efficient mixed type corrosion inhibitors and there inhibition efficiencies increase with increasing concentration. The adsorption of these inhibitors on the metal surface obeys to the Langmuir isotherm. Thermodynamic parameters, such as: activation energy value, enthalpy and entropy of activation, adsorption constant, enthalpy, entropy and standard free energy adsorption were calculated and interpreted. The study of the surface morphology of S9Mn28K mild steel by scanning electron microscopy (SEM) showed the presence of a protective and adherent layer on the metal surface, which limits the penetration of the electrolyte.The theoretical study conducted using the DFT / B3LYP / 6-31G (d, p) software showed a good agreement with the experimental results.