The Study of Corrosion Inhibition of Al-pure in HCl by Some New Organic Schiff Bases Using Chemical and Electrochemical Methods

The inhibiting effects of some newly synthesized Schiff bases on the corrosion of Al-Pure in 1.0 M HCl have been studied by means of the chemical and electrochemical methods. The Schiff bases m-Chloroaniline-N-benzylidene (m-CANB), p-Chloroaniline–N-benzylidene (p-CANB), Benzylamine-N-(p-methoxy benzylidene) (BANPMB) and 2-Phenylethylamine-N-(p-methoxy benzylidene) (2PANPMB) were synthesized from benzyldehyde or substituted benzyldehyde with the corresponding amines and characterized by IR studies. The corrosion inhibition properties of these compounds on Al-Pure in 1.0 M HCl were investigated by weight loss, galvanostatic polarization and electrochemical impedance techniques. The weight loss study showed that the inhibition efficiency increases with increase in the concentration of the inhibitor and was found to be inversely related to temperature. The values of activation energy (Ea ), free energy of adsorption (∆Gads) and heat of adsorption (Qads) were calculated from the temperature data. The adsorption of these compounds on aluminium surface follows the Langmuir adsorption isotherm. The galvanostatic polarization data show that these compounds studied are mixed type inhibitors with predominant effect on the cathode. The mechanism of corrosion inhibition is also proposed.