Etude électrochimique et théorique de l'inhibition de la corrosion aqueuse de l'acier doux par quelques porphyrines et leurs complexes métalliques

The influence of porphyrin-derived compounds, such as 5,10,15,20- tetraphenylporphyrin (TPPH2), 5,10,15,20-tetra-p-tolylporphyrin (TPPH2(p-Me)), and 1,1',1'',1'''-(porphyrin-5,10,15,20-tetrayltetrakis(benzene-4,1-diyl))tetrakis(ethan- 1-one) (TAcPPH2), on the aqueous corrosion of mild steel XC52 in 0.5M sulfuric acid has been examined. This study utilized electrochemical impedance spectroscopy
and potentiodynamic polarization. Parameters considered included concentration and temperature. The electrochemical results showed that these three inhibitors exhibit a mixed nature and are highly effective in protecting XC52 steel against corrosion in the presence of a 0.5M H2SO4 solution. Notably, TAcPPH2 proved to be the most effective inhibitor, and the protective effect was directly linked to the electron- donating nature of the substituent. The mechanisms of action of these inhibitors were examined through thermodynamic studies, and calculations of parameters such as ?Gʻads, Ea, ?Ha, and ?Sa confirmed that all inhibitors are effectively adsorbed through a physisorption process. This adsorption was found to be spontaneous and followed the Langmuir adsorption isotherm. Additionally, a surface analysis conducted via UV-Visible confirmed the electrochemical and thermodynamic results. Quantum calculations performed using DFT and MDS also corroborated the experimental findings.