Electrochemical and Quantum Chemical Studies of Adsorption and Corrosion Inhibition of Two New Schiff Bases on Carbon Steel in Hydrochloric Acid Media

摘要

The inhibiting effect of two newly synthesized Schiff bases was investigated on the corrosion ofcarbon steel in 1M hydrochloric acid solution under various conditions by weight loss, impedance, andpotentiodynamic polarization measurements. The Schiff bases used were 4,4’-bis (2-hydroxy-1-naphthaldehyde imine) diphenylether (L1) and 4,4’-bis(2-Hydroxy-1-naphthaldéhyde imine)diphenylmethane (L2). The inhibition efficiency of these compounds varied with concentration andimmersion time. Potentiodynamic polarization study indicated that the tested compounds are mixedtype (cathodic/anodic) inhibitors. Electrochemical impedance spectroscopy was also used toinvestigate the mechanism of corrosion inhibition, it showed that the charge transfer resistance (Rct)increased and double layer capacitance (Cdl) decreased with an increase in the inhibitor concentration.The inhibition efficiency was found to increase with increasing inhibitor concentration. The adsorptionof the inhibitor on the metal surface obeys Langmuir isotherm.