Synergistic Inhibition Effect of 10-(3-Quinuclidinyl-Methyl) Phenothiazine and Potassium Iodide on Carbon Steel Corrosion in Sulfuric Solution

The inhibition effect of 10-(3-quinuclidinylmethyl) phenothiazine (QMPT), Potassium iodide and their synergistic effect on the corrosion of carbon steel in 0.5 M H2SO4 solution was studied by different electrochemical techniques. The inhibition efficiency increases with QMPT and KI concentration and increase further in presence of QMPT/KI mixtures. The adsorption of QMPT and KI on the metal surface in 0.5 M H2SO4 solution obeys the Langmuir adsorption isotherm. The probable inhibitory mechanism is proposed from the viewpoint of adsorption theory. The synergism parameter suggests that there is a cooperative mechanism between the iodide anion and QMPT cations.