INVESTIGATION OF CORROSION INHIBITOR ADSORPTION ON STAINLESS STEEL USING BENZALDEHYDE SEMICARBAZONE

The influence of benzaldehyde semicarbazone on corrosion through stainless steel in 11% HCl has been studied using weight loss measurements and scanning electron spectroscopy. The inhibition efficiency of benzaldehyde semicarbazone was found to vary with concentration, temperature and immersion time. The inhibition efficiency increases with increasing of inhibitor concentration. Good inhibition efficiency (IE) was evidenced in acid solutions, the inhibition efficiency was found to be 81.56% in 11% HCl of the 0.04 inhibitor concentration at 45°C for 5 days. Adsorption of inhibitor on the steel surface follows Langmuir adsorption isotherm. The mechanism of physical adsorption is proposed from the inhibitory action of benzaldehyde semicarbazone is satisfactorily explained by thermodynamic and kinetic parameters such as ΔH°, ΔS°, ΔG° and Ea are calculated. All the experiments show good agreements. Scanning electron spectroscopy technique is used to observe the surface morphology of mild steel samples in the presence and absence of benzaldehyde semicarbazone at optimum conditions. In the presence of benzaldehyde semicarbazone, scanning electron microscope exposes the formation of a smooth and dense protective layer on surface of mild steel. The values of activation energy and free energy of adsorption indicated chemisorption adsorption on 304 stainless steel surface.