Synthesis and Application of New Quinoline as Hydrochloric Acid Corrosion Inhibitor of Carbon Steel

New quinoline, namely 5-penthylaminomethyl-8-hydroxyquinoline (p-qn) has been synthesized and characterized by different spectral methods such as 1^h nmr and 13^c nmr. their inhibitive action against the corrosion of carbon steel in 1.0 m hydrochloric acid solution were investigated at different temperatures in the range from 25±2 to 55±2 °c by a series of known techniques such weight loss, electrochemical impedance spectroscopy (eis) and tafel polarization measurements. the obtained results show that compound (p-qn) is a very good inhibitor with efficiency of 93.3% at 10^-3 m additive concentration in 1.0 m hcl solution. generally the inhibition efficiency increased with increase of inhibitor concentration. changes in impedance parameters (rct and cdl) were indicative of adsorption of compound (p-qn) on the metal surface, leading to the formation of a protective film. tafel polarization measurements showed that the inhibitor (p-qn) is a mixed type. the adsorption of the inhibitor on the surface of carbon steel in 1.0 m hcl solution was found to obey longmuir’s adsorption isotherm. the kinetic and thermodynamic parameters for carbon steel corrosion and inhibitor adsorption, respectively, were determined and discussed. on the bases of thermodynamic adsorption parameters, comprehensive adsorption (physisorption and chemisorption) for the studied inhibitors on carbon steel surface was suggested.