Synergistic inhibition effect of imidazoline derivative and potassium iodide on carbon steel corrosion in amidosulfuric acid solution

Abstract

AbstractThe mixture of 2-undecyl-N-carboxymethyl-N-hydroxyethly imidazoline (UHCI) with potassium iodide (KI) as a corrosion inhibitor for carbon steel in 8% amidosulfuric acid solution was investigated by weight loss test and electrochemical methods. Results show that the combined inhibitor strongly inhibits the corrosion of 20# carbon steel in amidosulfuric acid solution, and the mixture with the mass ratio (UHCI:KI) of 9:1 has the best corrosion inhibition at a total concentration of 0.4%. The impedance spectra of carbon steel electrodes change from one time constant into two time constants when the mixture inhibitor adds into the blank solution, while the polarization curves indicate that the mixture behaves as a mixed type inhibitor. The mixture is found to follow the Langmuir adsorption isotherm, and the mechanism is chemisorption.