Corrosion behavior and inhibition of nickel in sulfuric acid solutions using triazole derivatives: insights from electrochemical and surface analysis.

3-Amino-1,2,4-triazole (AT), 3,5-diamino-1,2,4-triazole (DT), and 5-(4-pyridyl)-1H-1,2,4-triazole-3-thiol (PTT) were investigated as inhibitors towards the general and pitting corrosion of Ni in dilute sulfuric acid solutions contaminated with Br- ions. The utilized techniques are open circuit potential, galvanostatic polarization, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization supplemented by surface analysis using SEM. The galvanostatic polarization curves in 0.01 M H2SO4 indicate various oxidation regions followed by the passive region and O2 evolution. Additions of Br- ions initiate the pitting corrosion at Eb. The presence of the triazole compounds inhibits pitting corrosion by shifting Eb into the more positive potential with a decrease in the consumed electricity, Q. The potentiodynamic polarization proved that the triazole inhibitors behave as mixed inhibitors. The inhibition efficacy is raised with higher additions of triazole concentrations to follow the order AT < DT < PTT. The protection performance is illustrated by blocking the active sites on the Ni metal via an adsorption mechanism that obeys the Langmuir isotherm. The free energy of adsorption, ∆[Formula: see text] was computed to be -36.92, -36.18, and - 35.99 kJ. mol-1 for PTT, DT, and AT suggests a mixed adsorption mechanism.