Synthesis and characterization of 4-[(E)-(-2,5- dimethoxybenzylidene)amino] benzoic acid Schiff base and evaluation as corrosion inhibitor of steel in 2.0 M H2SO4.

The synthesis of 4-[(E)-(-2,5- dimethoxybenzylidene)amino] benzoic acid Schiff base, SBDAB was carried out inorder to determine its inhibitory efficiency at higher temperature using weight loss and gasometric techniques. The results showed that the inhibition efficiency of the studied Schiff base increased with increase in temperature for the corrosion of mild steel which suggests chemisorption reaction mechanism. The negative free energy of adsorption obtained confirms a spontaneous adsorption of the Schiff base on the metal surface. The positive values of the heat of adsorption suggest an endothermic reaction. The positive values of the entropy of adsorption suggest a disordered system. The Langmuir adsorption Isotherm result showed a deviation from an ideal Langmuir adsorption isotherm equation, this is due to the interaction of the inhibitor molecules with one another. The inhibition efficiency of 35.20% and 35.31% was obtained for the weight loss and gasometric techniques respectively. The plots of log(wi - & #916;w) against time gave linear graph which confirms a first order reaction mechanism.

Keywords
Schiff base; corrosion; chemisorption; weight loss and gasometric technique