Electrochemical and X-ray structural study of corrosion inhibition and adsorption behavior for mild steel by a new Schiff-base cobalt complex in HCl

A new cobalt(III) Schiff base omplex (SBCC), [Co(L)(2)]Cl (where L = N-(2-(2-hydroxyethylamino)ethyl) 5-methoxysalicylideneimine), was synthesized and structurally characterized by X-ray single crystal structure analysis. Intramolecular C-Ha <-O hydrogen bonds stack molecules on 020 directions and intramolecular hydrogen bonding with the chloride ions is the result of stacking the molecules on c direction in unit cell and 011 crystallographic sheets. More available surface area collect from 020 sheets and these surfaces are useful for making a blocking layer of complex with adsorption on the surface of steel. Corrosion inhibition and adsorption behavior of mild steel in 0.5 M HCl by SBCC were investigated using electrochemical techniques. It was found that inhibition efficiency increased with SBCC concentration. The inhibition efficiency is 84% for 400 ppm concentration of the complex. Corrosion inhibition was afforded by adsorption of SBCC onto the metal following El-Awady kinetic-thermodynamic adsorption isotherm model. The results obtained show that SBCC acts as a mixed-type inhibitor and it could serve as an effective corrosion inhibitor of mild steel in aqueous solution.