A New Synthesized Corrosion Inhibitor for Mild Steel in 0.5 M H2SO4

The inhibition effect of a new synthesized organic inhibitor , namely 1-insert ignore into journalissuearticles values(3-Nitrobenzylidene); Thiosemicarbazide insert ignore into journalissuearticles values(A); on the corrosion of mild steel in 0.5 M sulphuric acid   have been investigated at room temperature using weight loss, electrochemical impedance spectroscopyinsert ignore into journalissuearticles values(EIS); and Tafel polarization   measurements. The inhibition efficiencies obtained from all methods employed are in good agreement with each other. The obtained results show that compound insert ignore into journalissuearticles values(A); is a very good inhibitor with efficiency of 98% at 100 ppm additive concentration in acid solution. Generally the inhibition efficiency increased with increase of inhibitor concentration. Changes in impedance parameters insert ignore into journalissuearticles values( R ct and C dl ); were indicative of adsorption of compound insert ignore into journalissuearticles values(A); on the metal surface, leading to the formation of a protective film. Tafel polarization measurements showed that the inhibitor insert ignore into journalissuearticles values(A); is a mixed type. The adsorption of the inhibitor on the surface of mild steel in 0.5 M sulphuric acid was found to obey Longmuir’s adsorption isotherm. Scanning electron microscopy insert ignore into journalissuearticles values(SEM); observation, confirmed the existence of an absorbed protective film on the metal surface. The free energy of adsorption process was calculated and discussed.   Key Words : inhibitor, mild steel, AC impedance, corrosion inhibition