Corrosion Inhibition of Mild Steel by Benzopyranone Derivative in 1.0 M HCl Solutions

A new corrosion inhibitor namely N-((7-acetoxy-2-oxo-2H-1-benzopyran-4-yl) methyl)-2- (acryloyloxy)-N,N-dimethylethanaminium bromide (AOBAB) has been synthesized and its influences on corrosion inhibition of mild steel in 1.0 M HCl solutions have been studied by weight loss measurement, electrochemical impedance spectroscopy (EIS), Tafel polarization technique and scanning electron microscope (SEM). According to all the experimental results, the inhibition efficiency increases with increase in the concentrations of AOBAB, and also increases with increase in temperature. Tafel polarization studies revealed that the AOBAB acts as a mixed inhibitor. Adsorption of AOBAB on the mild steel surface in 1.0 M HCl solutions follows the Langmuir isotherm model. The activation energy and the thermodynamic parameters, such as apparent activation energy (Ea), enthalpy of activation (ΔH*) and entropy of activation (ΔS*), adsorption equilibrium constant (Kads), standard free energy of adsorption (ΔGads) for the inhibition process were also calculated. SEM observations of the mild steel surface confirmed that inhibitor molecules strongly adsorbed onto the surface.