ANTI-CORROSION PROPERTIES OF BENZOTHIAZOLE DERIVATIVES FOR MILD STEEL IN 1M H2SO4 SOLUTION

Abstract

The corrosion inhibition performance of benzothiazole derivatives namely, 2-phenylbenzothiazole(PBT), 2-(4- methoxy-phenyl)benzothiazole(MPB) and 2-(3,4,5- trimethoxy-phenyl)benzothiazole(TPB) on mild steel in 1M H2SO4 has been studied by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy. The experimental results showed that the inhibition efficiency increases with increase in inhibitor concentration but decreases with increasing temperature. The inhibition has been assumed to occur via adsorption of inhibitors on mild steel surface. This is supported by the results obtained from scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Adsorption of inhibitors on mild steel surface follows Langmuir adsorption isotherm. The activation energy and free energy of adsorption for the inhibition reaction support the mechanism of physical adsorption. Potentiodynamic polarization measurements indicate that the studied benzothiazole derivatives act as mixed inhibitors. Quantum chemical calculations have been performed and quantum chemical indices were calculated to supplement the experimental results.