Estudo do 1,2,4-triazolanilina como inibidor de corrosão do aço carbono 1020 em meio ácido

Abstract

The objective of this study was to study the efficacy of the 1,2,4-triazolaniline organic compound as corrosion inhibitor of 1020 carbon steel in 0.1 moldm−3HCl medium by linear polarization of −0.7 V and −0.1 V at 1 mV s−1, Electrochemical Impedance Spectroscopy under open circuit potential perturbation with frequency between 10 kHz and 4 mHz and sinusoidal amplitude of 10 mV and mass loss.In the electrochemical analysis, the 1020 carbon steel with 2 cm2 was used as a working electrode, while a platinum electrode with an area of 2.2 cm2 was used as an auxiliary electrode and as reference electrode was used the Ag/AgCl/Cl− in saturated potassium chloride solution.Concentration effects of 1,2,4-triazolaniline, 0 to 5×10−3moldm−3, immersion time, 30 to 180 min, and temperature, 298 to 338 K, were evaluated. Electrochemical analyzes revealed that the molecule acts as a mixed inhibitor and that increasing the concentration of the inhibitor provided an inhibiting efficiency of up to 98%, whereas for mass loss only 58%.The immersion time did not influence the results obtained by electrochemical analysis. In the study by mass loss the efficiency of inhibition showed always increasing with the time of immersion.It has been suggested that the adsorption process in the molecule is exothermic, as the increase in temperature decreased the adsorption efficiency of the inhibitor. The isotherms employed, Langmuir, El-Awady and Flory-Huggins, showed that the concentration of the inhibitor influences the mechanism of inhibition. For the higher concentrations, it was suggested the formation of multilayers. The adsorption free energy presented a value close to −30 kJmol−1 indicating chemical and physical adsorption.