Synergistic effect of potassium iodide with phthalazone on the corrosion inhibition of mild steel in 1.0 M HCl

The effects of phthalazone (PTO) and its synergistic effect with KI on the corrosion of mild steel in 1.0 M HCl solution were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The inhibition efficiency increases with the concentration of the inhibitor and increased further with the presence of 6.02 mM KI. The synergistic effect of 6.02 mM KI at different concentrations of PTO was determined by calculating the synergism parameters, which showed that a cooperative mechanism exists between the iodide anion and PTO cations.

► The inhibition of PTO with 6.02 mM KI was studied. ► The inhibition efficiency increase with the increase in inhibitor concentration. ► The inhibition efficiency further increase with presence of 6.02 mM KI. ► A co-operative mechanism exists between iodide anion and PTO cations. ► The adsorption of PTO with and without KI obeys the Langmuir adsorption isotherm.