The synergistic effects of propargyl alcohol and potassium iodide on the inhibition of mild steel in 0.5 M sulfuric acid solution

The corrosion and inhibition behaviors of mild steel in aerated sulphuric acid in the presence of propargyl alcohol (PA) and potassium iodide (KI) were investigated using electrochemical methods. It was found that the inhibition efficiency increased with PA concentration, but the potential of unpolarizability (E-u), which indicates the commencement of desorption of adsorbed propargyl alcohol on the electrode, remained unchanged with increasing PA concentration. The addition of potassium iodide in the solution increased the value of E-u. A synergistic effect was observed between KI and PA with an optimum mass ratio of [PA]/[KI]= 1/1. The experimental results suggest that the presence of iodide ions in the solutions stabilized the adsorption of PA molecules on the metal surfaces and, therefore, improved the inhibition efficiency of PA. In the solutions containing propargyl alcohol (PA), the E-u values remained unchanged with increasing immersion times, indicating that there was less possibility of polymerization of PA molecules. An adsorption mechanism was favored for the inhibition of PA. (C) 1999 Elsevier Science Ltd. All rights reserved.