New synthesised diamine derivatives as corrosion inhibitors of steel in 0.5Â M H2SO4

The effect of addition of diamine derivatives on the corrosion of steel in 0.5 M H2SO4 solution is studied using weight loss measurements, electrochemical polarisation and impedance spectroscopy (EIS) methods. This study permits to follow the evolution of the inhibitive effect of diamine derivatives on steel in 0.5 M H2SO4. Polarisation measurements show that the diamines act as mixed inhibitors. The cathodic curves indicate that the reduction of proton at the steel surface happens within a pure activating mechanism. The inhibitors are adsorbed on the steel surface according to the Frumkin adsorption isotherm model. We note a good agreement between gravimetric, electrochemical polarisation and impedance spectroscopy methods.