Investigation of Corrosion Inhibition Property of Triazole-Based Schiff Bases on Maraging Steel in Acid Mixtures

Abstract

Triazole-based Schiff bases, 4-{[4-(dimethylamino)benzylidene]amino}-5-methyl-4H-1,2,4-triazole-3-thiol [DBAMTT] and 5-methyl-4-[(thiophene-2-ylmethylidene)amino]-4H-1,2,4-triazole-thiol [MTATT], were studied for their corrosion inhibitory action on maraging steel in the temperature range 30–45 °C in a 2:1 mixture of HCl and H2SO4. Both the inhibition efficiencies increased with temperature rise as well as the concentration of inhibitors. The anti-corrosion potential of these molecules was further validated by kinetic and thermodynamic analyses. Both DBAMTT and MTATT demonstrated inhibitory action of a mixed form by chemisorption on the metal surface obeying Langmuir isotherm adsorption. SEM–EDX analysis was conducted to confirm inhibitor adsorption onto the labeling steel surface. Experimental data indicated better corrosion inhibition property of MTATT over DBAMTT, whereas theoretical studies predict DBAMTT as a better inhibitor over MTATT. This may be due to the difference in the conditions of both studies: experimental studies carried out in acid solutions and theoretical studies in the gas phase. Different quantum chemical parameters were assessed using DFT calculations using the B3LYP/6-311++(d, p) basis set to gain insight into the relationship between the molecular structure and the efficiency of corrosion inhibition.