Résumé:
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.
