Adsorption behavior and corrosion inhibition mechanism of a polyacrylamide on C–steel in 0.5 M H2SO4: Electrochemical assessments and molecular dynamic simulation

Abstract Anticorrosion activity and adsorption behavior of a polyacrylamide (PA) for C–steel corrosion in 0.5 M H2SO4 solution were analyzed by potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), scanning Electron Microscopy (SEM) and molecular dynamics (MD) simulations. PP curves indicated that PA behaved as a mixed–type inhibitor and its Inhibition efficiency increased with increasing PA concentration to attain 93% at 4 x 10–6 M and at 298 K. EIS data are analyzed and modeled by equivalent circuit adapted to a single time constant. Kinetic–thermodynamic parameters, were calculated and discussed, based on six linearized forms adsorption isotherms. Mixed and spontaneous mode of adsorption is proposed for the inhibition with repulsive lateral interactions in adsorbed inhibitory layer. MD simulations confirmed the better adsorption capacity of PA compared to corresponding monomer and dimer with a flat orientation on C–steel surface.