INHIBITION OF THE CORROSION OF IRON BY OXYGEN AND NITROGEN-CONTAININGCOMPOUNDS

Corrosion inhibition by quinine, ephedrine, brucine, cinchonine, codei ne, and harmaline with respect to the dissolution of iron in 2 M sulph uric acid was measured using electrochemical methods. Polarization cur ves indicated that these compounds act as mixed-type inhibitors, i.e. both the cathodic and anodic curves are affected. The observed effect follows the Temkin adsorption isotherm. The effect of the different st ructural features of these compounds on their inhibition efficiency ha s been studied. Results indicate that the rate of corrosion of iron in creases with increasing temperature over the range 30-50 degrees C bot h in the absence and in the presence of inhibitors. Some thermodynamic functions were also computed and are discussed.