Inhibitive effect of some Schiff base ligands for corrosion of mild steel in acidic media

Department of Post Graduate Studies in Chemistry, Sahibganj College, Sahibganj-816 109, Jharkhand, India E-mail : sanyalsom@yahoo.co.in, anilkumar_ism@yahoo.com Manuscript received 17 August 2009, accepted 18 December 2009 Schiff bases are widely used in complex formation as organic ligands. The effectiveness of some Schiff bases as corrosion inhibitors for mild steel in acid media has been studied by both weight loss and electro-chemical methods. Studies on the effect of Inhibitor concentration and temperature on the corrosion of mild steel have been made. The inhibitor appears to function through adsorption following Langmuir adsorption isotherm. The thermodynamic parameters such as activation energy and free energy of adsorption were calculated. With the addition of methyl group in the ligand, +I effect Increases, causing Increase In the -electron density on the azomethene group giving Increased Inhibitive effect. More effective Inhibition was found due to increased adsorption caused by greater -electron cloud when a phenyl group Is added to the ligand. The polarization studies show that the Inhibitors act as mixed inhibitors blocking both anodic and cathodic sites