Corrosion Inhibition of Mild Steel in Hydrochloric Acid Medium Using Schiff Base Synthesized by Green Approach

Abstract

The (1E)-benzylidene hydrazine was tested as a corrosion inhibitor for mild steel in 0.5 M HCl by using polarization and electrochemical impedance spectroscopy measurements at temperatures 303, 313, 323, and 333 K. The data obtained from those two methods were in good agreement with each other. The effect of an increase in temperature and a change in the concentration of the inhibitor were studied. The inhibition efficiency was found to increase with an increase in the inhibitor concentration. The maximum inhibition efficiency of 92% was observed for 500 ppm of the inhibitor at 323 K. Polarization measurements showed that the Schiff base acts as a mixed type of inhibitor involving both physisorption and chemisorption. Temperature studies revealed that the inhibition efficiency increased at temperatures up to 323 K, but, beyond that, the inhibitor efficiency decreased due to the desorption of the inhibitor. The adsorption of (1E)-benzylidene hydrazine on a mild steel surface is an endothermic process and was best described by the Langmuir adsorption isotherm. Both kinetic and thermodynamics adsorption parameters were calculated and discussed. The surface morphology of the uninhibited and inhibited mild steel samples was analyzed using scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results obtained from the quantum chemical analysis are well correlated with other experimental ones.