Synthesis, Characterization, and Anti-corrosion Behavior of Novel Mono Azo Dyes Derived from 4,5,6,7-Tetrahydro-1,3-benzothiazole for Mild Steel in Acid Solution

Abstract

The present study describes the use of 4,5,6,7-tetrahydro-1,3-benzothiazole incorporated azo dyes as anti-corrosive agents and dissolution protection of mild steel from 1 M HCl solution. The inhibition efficiency of the azo dyes is determined by potentiodynamic polarization technique and electrochemical impedance spectroscopic studies. Based on these experimental results, it is noted that, the azo dye T1 is an effective inhibitor and the inhibition efficiency of the azo dyes is found to be in the following order T1 > T2 > T3. From the polarization measurements, it is noted that, these azo dyes are mixed type of inhibitors in 1 M HCl. The inhibition efficiency was increased as the concentration of the inhibitors increased and attains a maximum value of 83.81% for T1 at 2.5 ppm concentration. The quantum chemical study was used to explain better about the structural and electronic effects in relation to the inhibition efficiencies. Further, the surface morphology of the tested mild steel samples was examined by scanning electron microscopy and energy-dispersive X-ray analysis with and without inhibitors in 1 M HCl solution. The results of the analysis showed the effective corrosion inhibition properties after the deposition of the inhibitors on to the metal surface.