Corrosion inhibition of mild steel in 1 M HCl using water soluble chitosan derivative of vanillin.

ABSTRACT

The water-soluble chitosan derivative (WSCD) was made by mixing chitosan with sodium hydroxide, treating the mixture with chloroacetic acid, and then forming a Schiff base with vanillin in an acidic medium. In this study, we examined the corrosion-inhibiting ability of a WSCD on mild steel surfaces in acidic environments. Weight loss, EIS, PDP, LPS, and OCP measurements were used to study the corrosion resistance on mild steel surfaces in 1 M HCl solutions with known concentrations of WSCD. The results show that WSCD functions effectively as a mixed-type anodic and cathodic inhibitor, providing 87 % corrosion inhibition efficiency at 75 ppm. Using SEM to investigate the morphology of corroded mild steel with and without varying amounts of WSCD, impedance measurements show the development of a thin film of inhibitor on the metal surface, the extent of which increases as the inhibitor concentration rises. The WSCD molecule first adsorbs on mild steel and follows Langmuir adsorption isotherm. It is found that the (∆Gads0)adsorption's free energy is -17.473 kJ/mol. The contact angle measurements confirm that the hydrophobicity of the metal surface has increased as a result of the inhibitor's thin film development.