CNDO STUDY OF THE TAUTOMERIC STRUCTURE OF URACIL AND ITS EFFECT ON THE ELECTROCHEMICAL CORROSION BEHAVIOR OF MILD-STEEL IN ACID-MEDIA

The effect of uracil compound on the electrochemical corrosion behavio ur of mild steel in 1 M sulphuric and hydrochloric acid solutions, as corrosive media, has been studied. Weight loss measurements and potent iostatic polarization scanning were included. The anodic and cathodic parameters (e.g., Tafel slopes, charge transfer coefficients, corrosio n currents and corrosion potentials), values of activation energies an d the cathodic protective current in the absence and presence of diffe rent uracil concentrations revealed that this compound has an anticorr osive character. The corrosion potential E(corr.) of steel was affecte d by increasing uracil concentration. The slight shift in E(corr.) and the increase in activation energies due to addition of the investigat ed compound, together with the shift of the potentiostatic anodic pola rization curves to slightly higher potential regions denoted a mixed-t ype inhibitor. The electronic energies and charge densities for the di fferent tautomeric forms of uracil were calculated by the CNDO/SCF met hod. The obtained results together with the polarization studies indic ate that the inhibition occurs by simple blocking of both cathodic and anodic sites on the steel electrode surface through the adsorption pr ocess.