Electrochemical and physiochemical studies on the effects of thiadiazole derivatives in corrosion inhibition of Muntz metal in sulfide-polluted marine environment

Abstract

Abstract The influence of certain thiadiazole derivatives on the corrosion of Muntz metal (60Cu-40Zn) in sulfide-polluted artificial seawater was analyzed using chemical and electrochemical methods. The surface morphology was examined by SEM to determine this inhibition mechanism. Elemental composition of the corroded alloy specimens was investigated in the presence and absence of thiadiazole derivatives using energy dispersive X-ray analysis (EDX). Thiadiazole derivatives were found to successfully suppress Muntz metal corrosion. Adopting the weight-loss method, the optimum concentration of inhibiting thiadiazole derivatives was 2.32 mM owing to the thiadiazole surface coverage and adsorption with increasing concentration. Among the derivatives investigated, N-(5-(4-aminophenyl)-1,3,4-thiadiazole-2-yl)-2-diphenylamino) acetamide (ATPA) showed the highest corrosion protection efficiency. EIS studies showed that charge transfer resistance occurs because of the presence of an inhibitor. Moreover, increasing thiadiazole concentration decreased the double-layer capacitance (Cdl) value because less charged species were attracted to the metal surface. Potentiostatic current-time transient techniques showed that ATPA hindered the corrosion rate owing to the substituted thiadiazoles. Polarization measurements clearly showed that the inhibitors suppressed both anodic and cathodic reactions. Consequently, accelerated leaching studies showed concentrations of Zn and Cu released from the alloy reducing as concentrations of inhibitors increased, in addition to the corrosion protection efficiency (%) increasing. The highest value was obtained at 2.32 mM of inhibitor. In conclusion, this study demonstrates that these compounds inhibit corrosion via chemisorption of organic compounds. Among these compounds, ATPA was found to offer better corrosion inhibition than others.