Synergistic effect of methyl red dye and potassium iodide on inhibition of corrosion of carbon steel in 0.5 M H2SO4

Abstract

PurposeThis paper aims to show the effectiveness of methyl red (MR) alone and in combination with KI as corrosion inhibitor for carbon steel in 0.5 M H2SO4.Design/methodology/approachCorrosion rates charge transfer resistance values were determined using gravimetric and electrochemical techniques. The efficiency of inhibition was calculated by comparing corrosion rates and charge transfer resistance values in absence and presence of the inhibitor, while the mechanism of inhibition was proposed by considering temperature influence on corrosion and inhibition processes.FindingsThe inhibition efficiency of MR increased with concentration and synergistically increased in the presence of the KI. Polarisation curves reveal that MR is a mixed type inhibitor. Changes in impedance parameters were indicative of adsorption of MR on the metal surface. The trend of inhibition efficiency with temperature suggests that inhibitor molecules are physically adsorbed on the corroding metal surface in the absence of KI and chemically adsorbed in its presence. MR was found to obey Langmuir adsorption isotherm both with and without KI.Originality/valueElectrochemical techniques have been used for the first time to study synergistic effect of MR dye and potassium iodide on inhibition of corrosion of carbon steel in H2SO4.The results suggest that the mixture (MR + KI) could find practical application in corrosion control in aqueous acidic environment.