Influence of organic compound structure on brass corrosion inhibition efficiency

In this study the influence of organic compounds with different structures on the inhibition of brass corrosion in sodium chloride solutions of 0.9%, 2% and 3.5% is investigated. The experimental work includes the evaluation of the inhibition efficiency of 2-mercapto-1-methylimidazole (MMI), 2-amino-5-ethyl1,3,4-thiadiazole (AETDA) and N-acetyl-L-leucine at various concentrations using electrochemical methods, including open circuit potential (OCP), cyclic voltammetry (CV), and potentiodynamic measurements (PD). The results show that all tested inhibitors reduce the corrosion currents and potentials, with the highest efficiency observed in solutions with the lowest sodium chloride concentration of 0.9%, where AETDA exhibited the highest inhibition efficiency of 92.93%, while MMI showed an efficiency of 88.78% at the same inhibitor concentration of 10-2 M. Compared to AETDA and MMI, N-acetyl-L-leucine at a concentration of 10-3 M showed the lowest inhibition efficiency of 44.21%, while AETDA and MMI achieved inhibition efficiencies of 76.12% and 72.16%, respectively. Adsorption isotherms were used to evaluate the binding mechanisms of inhibitors on the brass surface, and physisorption was found to be the most likely mechanism for all tested compounds. These findings provide insight into the potential application of the investigated inhibitors to prevent brass corrosion under corrosive conditions.