Inhibitive effect of new nitrogen and sulfur containing azole derivatives on mild steel corrosion in HCl solution: Electrochemical, SEM and AFM studies

Abstract

Abstract Twoazole-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, were synthesized and applied as corrosion inhibitors for mild steel, MS, in 0.5 M hydrochloric acid medium based on investigations with weight loss, potentiodynamic polarization, and electrochemical impedance measurements. Electrochemical impedance study showed that in the presence of TIB and BTPthe corrosion of MS in acidic medium was reduced significantly through a charge transfer mechanism. Tafel polarization revealed that the TIB and BTP behaved as mixed-type inhibitors, predominantly of cathodic type. The MS surface has been blocked by inhibition action of TIB and BTP molecules following Langmuir adsorption isotherm. The formed protective layer on MS surface was verified using scanning electron microscopy (SEM) and X-ray spectroscopy (EDX) techniques. Furthermore, atomic force microscopic (AFM) study revealed that the current inhibitors increase the surface smoothness of AFM micrographs by adsorbing on the metallic surface. Experimental results declared that the optimum concentration of TIB and BTP for coverage of MS surface are 600 µM and 400 µM, respectively. In addition, TIB is a more effective corrosion inhibitor than BTPfor MS in 0.5 M HCl medium. Furthermore, atomic force microscopic (AFM) study revealed that the current inhibitors increase the surface smoothness of AFM micrographs by adsorbing on the metallic surface.