Electrochemical and Quantum Chemical Investigations of novel pyrazole derivatives as a Corrosion Inhibitor for Stainless Steel in 2M H2SO4 medium

Stainless steels play a crucial role in diverse industrial domains. However, due to their exposure to acidic environments, stainless steels undergo the corrosion phenomenon, leading to the deterioration of the material and its properties. Thus, the objective of this work is to study the corrosion inhibition of stainless steel in an H2SO4 2M medium by using two organic compounds, namely Py-3:{1-amino-5,10-dioxo-3-(p-tolyl)-5,10-dihydro-1H-pyrazolo[1,2-b] phthalazine-2-carbonitrile} and Py-4:{1-amino-3-(2-chlorophenyl)-5,10-dioxo-5,10-dihydro-1H-pyrazolo[1,2-b]phthalazine-2carbonitrile}. This study was conducted using transient electrochemical methods in conjunction with a theoretical approach. The obtained results demonstrate that the addition of pyrazole compounds in the corrosive medium H2SO4 exhibits excellent inhibitory power against steel corrosion, with an inhibitory efficiency reaching 98%. The tested inhibitors are adsorbed into the surface of the metal by chemical bonds, Moreover, the adsorption of these compounds follows the Langmuir adsorption model. Theoretical calculations based on the Density Functional Theory (DFT) provide a better understanding of the reactivity of tested inhibitor towards stainless steel which they are in good agreement with the experimental findings.