Corrosion Inhibition of Azo Compounds Derived from Schiff Bases on Mild Steel (XC70) in (HCl, 1 M DMSO) Medium: An Experimental and Theoretical Study

The inhibitory activity of three prepared azo compoundsderivedfrom Schiff bases, namely, bis[5-(phenylazo)-2-hydroxybenzaldehyde]-4,4 '-diaminophenylmethane(C1), bis[5-(4-methylphenylazo)-2-hydroxybenzaldehyde]-4,4 '-diaminophenylmethane(C2), and bis[5-(4-bromophenylazo)-2-hydroxybenzaldehyde]-4,4 '-diaminophenylmethane(C3), against corrosion of steel type XC70 in (HCl, 1 M DMSO) mediumwas investigated experimentally by electrochemical measurements andtheoretically using density functional theory (DFT). The correlationbetween corrosion inhibition and concentration is direct. The maximuminhibition efficiency at 6 x 10(-5) M for thethree azo compounds derived from Schiff bases was 64.37, 87.27, and55.47% for C1, C2, and C3, respectively. The Tafel curves indicatethat the inhibitors follow a mixed but predominantly anodic inhibitorsystem and have a Langmuir isothermal adsorption process. The observedinhibitory behavior of compounds was supported by DFT calculation.It was also found that there was a strong correspondence between thetheoretical and experimental results.

Automated summary

This study investigates the inhibitory activity of three prepared azo compounds derived from Schiff bases on the corrosion of XC70 steel in (HCl, 1 M DMSO) medium using electrochemical measurements and density functional theory (DFT). The inhibition efficiency is directly related to the concentration. The three azo compounds derived from Schiff bases show maximum inhibition efficiency of 64.37%, 87.27%, and 55.47% for C1, C2, and C3, respectively. Tafel curves indicate that the inhibitors have a mixed but predominantly anodic inhibition system and follow a Langmuir isothermal adsorption process. DFT calculations support the observed inhibitory behavior of the compounds, and there is a strong correspondence between the theoretical and experimental results.