THE EFFECT OF TRIAZOLE THIONE DERIVATIVE ON THE CORROSION OF IRON IN HYDROCHLORIC ACID SOLUTIONS

Surfactant; N-(sodium-2–hydroxy-3-sulphato propyl)-5-stearyl-1,3,4-triazole-2-thione (18PTT) was tested as a corrosion inhibitor for iron electrode in hydrochloric acid media using potentiodynamic polarization measurements. Results obtained show that the corrosion rate (CR) increases with increasing of free acid concentration. In the presence of the inhibitor, the magnitude of Cris suppressed as its tendency to increase with acid concentration. The changes in the electrochemical parameters with concentration of surfactant studied are indicative of the adsorption of surfactant leading to the formation of a protective layer on the surface of iron. The inhibition efficiency (IE %) increases with an increase in concentration of surfactant and hydrochloric acid but decreases with temperature. This surfactant suppressed both cathodic and anodic processes of iron corrosion in HC1 solution by adsorption on iron surface according to Langmuir adsorption isotherm but affecting more the anodic reaction than the cathodic one. Thus, it can be classified as mixed-type inhibitor. The thermodynamic parameters for the dissolution of the metal and for the adsorption of the inhibitor on the metal surface were calculated and discussed. In the range of 20-60 °C corrosion rates were found to increase with increasing temperature for inhibited and uninhibited acid solutions, while corrosion potential (Ecorr) was unchanged. The associated apparent activation corrosion energy (Ea) has been determined and found to be higher in presence than in absence of the inhibitor. The calculated thermodynamic parameters (∆G°), (∆H°) and (∆S°) showed that the inhibition process is spontaneous and exothermic in nature.