Corrosion mitigation of carbon steel using triazole Mannich base derivatives: Correlation of electrochemical studies with quantum chemical calculations

The study investigated the corrosion-inhibitory properties of three synthetic triazole Mannich bases on C1018 carbon steel using various electrochemical techniques. The inhibitors, namely 4-amino-2-[(4-methylpiperazin-1-yl)methyl]-5-(pyridin-4-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (4MPT), 4-amino-2-[(piperidin-1-yl)methyl]-5-(pyridin-4-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (PPT) and 4-amino-2-[(morpholin-4-yl)methyl]-5-(pyridin-4-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (MPT), demonstrated the high inhibition efficiencies of 92.8%, 93.3% and 92.6%, respectively, and adhered to the Langmuir adsorption isotherm. The inhibitors also functioned as mixed-type inhibitors and improved the protective layer on the metal surface. The study also utilized scanning electron microscopy - energy dispersive x-ray (SEM-EDX) analysis to examine the surface morphology of the uninhibited and inhibited carbon steel specimens. Furthermore, density functional theory (DFT) was utilized for theoretical calculations, which corroborated with experimental measurements.