Synergistic effect of KI and urea on the corrosion protection of mild steel in 0.5 M H2SO4: Experimental and computational insights

Abstract

Electrochemical impedance spectroscopy (EIS), gravimetric measurement, scanning electron microscopy (SEM), and Fourier transfer infrared spectroscopy (FTIR) studies have been used to examine the synergistic effect of KI on the corrosion inhibition efficacy of urea on mild steel (MS) in 0.5 M sulphuric acid solution, the findings demonstrate that mild steel inhibition efficiencies improve with increasing inhibitor concentrations, and that synergistic improvements in inhibition efficiencies were seen upon adding potassium iodide, the urea and urea + KI adsorptions on the surfaces of the corroding metal follow the Langmuir isotherm as well as functions as a physisorption inhibitor, the adsorption of the inhibitor on the metal surface and subsequent protection from corrosion were confirmed by scanning electron microscopy investigations, the mechanism of the corrosion inhibition process and the interpretation of the experimental results at the atomic and molecular levels were also understood using density functional theory (DFT) calculation and Monte Carlo simulation.