Inhibitive Effect of New Azole‐Azomethine Derivatives on Mild Steel Corrosion in HCl Solution: Electrochemical, Scanning Electron Microscopy and Atomic Force Microscopy Studies

Abstract

Two azole‐based Schiff bases, namely, 2‐(((1H‐1,2,4‐triazol‐3‐yl)imino)methyl)‐4‐bromophenol, TIB, and 4‐Bromo‐2‐((thiazol‐2‐ylimino)methyl)phenol, BTP, are synthesized and used as corrosion inhibitors for mild steel, MS, in acidic medium. The inhibitive effect of TIB and BTP, in 0.5 m hydrochloric acid, is investigated using weight loss, potentiodynamic polarization, and electrochemical impedance measurements. The optimum concentrations of TIB and BTP for coverage of metal surface are 600 and 400 μM, respectively. An electrochemical impedance study shows that the corrosion of MS is reduced through a charge transfer mechanism. The maximum inhibition efficiencies at optimum concentration of TIB and BTP are ≈83% and ≈81%, respectively. Tafel polarization reveals that the TIB and BTP behave as mixed‐type inhibitors, predominantly of cathodic type. The results indicate that the MS surface has been blocked by TIB and BTP molecules following the Langmuir adsorption isotherm. The formed protective layer on MS surface is verified using SEM and EDX techniques. Furthermore, atomic force microscopic study reveals that the current inhibitors increase the surface smoothness of MS by adsorbing on the metallic surface.