Novel and effective pyridyl substituted 1, 2, 4-triazole as corrosion inhibitor for mild steel in acid solution

Abstract

The corrosion inhibition effect of 4-amino-5-(pyridin-4-yl)-4H-1,2,4-triazol-3-thiol (APTT) was evaluated for mild steel in 1M HCl solution using gravimetric measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Inhibition efficiencies obtained ranged between 54.3 to 95.7% in the concentration range of 50 to 200 mgL-1. Double layer capacitance, Cdl, and charge transfer resistance, Rct, values were evaluated and discussed. Potentiodynamic polarization study clearly revealed the fact that APTT is a mixed-type inhibitor. The values of activation energy (Ea), adsorption equilibrium constant (ΔKads), free energy of adsorption (ΔGads), enthalpy of adsorption (ΔHads) and entropy of adsorption (ΔSads) were evaluated to corroborate the mechanism of inhibition. Langmuir adsorption isotherm was found to confirm the adsorption characteristics of inhibitor. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) examinations of metal surface confirmed the existence of thin protective film of inhibitor on metal surface. © 2012 by ESG.