Inhibitiory effects of some imines on the corrosion of mild steel in hydrochloric acid solution

The inhibition effect of 4-[(E)-(phenylimino)methyl]phenol (PIP), 4-[(E)-(4-fluorophenylimino)methyl]phenol (FIP), 4-[(E)-(4-chlorophenylimino)methyl]phenol (CIP), 4-[(E)-(4-bromophenylimino)methyl]phenol(BIP) and 4-[(E)-(4-nitro-phenylimino) methyl]phenol (NIP) on the corrosion of mild steel in hydrochloric acid was investigated. The corrosion inhibiting action was studied through weight loss and electrochemical techniques. The corrosion parameters such as anodic and cathodic Tafel slopes (ba and bc), corrosion potential (Ecorr), corrosion current densities (Icorr), surface coverage (q) and corrosion inhibition efficiencies %IE were determined. The polarization measurements indicated that the inhibitors are of mixed type. The adsorption obeyed Langmuir adsorption isotherm. The inhibition efficiencies increased with increase in inhibitor concentration but decreased with increase in temperature and also with increase in acid concentration. The activation and thermodynamic parameters were calculated for different temperatures.