CORROSION INHIBITION STUDIES USING 4-[(4DIMETHYLAMINO) BENZYLIDENE) AMINO] BENZOIC ACID ON ZINC IN 0.1M SOLUTION OF H2SO4

Abstract

In this study, the inhibition performance of Schiff base, 4-[(4-dimethylamino) benzylidene) amino] benzoic acid, (4DAB) on the corrosion of zinc has been investigated using weight loss method at temperatures of 303 K to 343K. Results obtained revealed that this compound is a fairly good inhibitor. It was observed that the inhibition efficiency increased with increase in the concentrations of the Schiff base and with decrease in temperature. The efficiencies of the inhibitor, 4DAB at the temperatures of study ranged from 42.8% to 38.8% at inhibitor concentrations of 5.0 g/l. The kinetic data obtained showed that the corrosion process followed first-order kinetics. The activation energy, Ea, values obtained for the inhibited (and uninhibited) solutions were less than 80 kJ/mol, indicating that physical adsorption was the predominant mechanism of the inhibition process. This was also supported by the fact that free energies of adsorption were less than -40 kJ/mol, which is required for physisorption. The calculated free energies of adsorption ranged from - 3,594.51 J/mol to -4,129.54 J/mol. The result of heat of adsorption, ΔH0ads, showed that the adsorption process was endothermic. The adsorption of the inhibitor compound on zinc surface obeyed the Langmuir adsorption isotherm and the thermodynamic calculations revealed that the adsorption of the inhibitor was of physical nature.   Key Words: Adsorption isotherm, Corrosion Inhibitor, inhibition efficiency, Schiff base, weight loss