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.