Approach to corrosion inhibition by some green inhibitors based on oleochemicals

The need for developing green inhibitors is increasing day by day due to increasing awareness of environmental issues. In view of this we have synthesized three hydrazides namely, dodecanohydrazide (DDH), cis-9-octadecanohydrazide (ODH) and 10- undecanohydrazide (UDH) derived from long chain fatty acids to investigate their inhibiting actions on corrosion of mild steel (MS) in 1N hydrochloric acid (HCl) and 1N sulfuric acid (H2SO4) by weight loss and potentiodynamic polarization methods. All of these compounds have-shown good inhibition efficiency (IE) in both acids. IE of these compounds has been found to vary with the nature and concentration of the compounds, temperature, immersion time and nature of the acid solutions. The adsorption of these compounds on the steel surface from both acids has been found to obey Temkin's adsorption isotherm. The values of activation energy (E-a) and free energy of adsorption (DeltaG(ads)) indicated physical adsorption of these compounds on the steel surface. The potentiodynamic polarization experiments revealed that all the compounds are mixed type inhibitors. Electrochemical impedance spectroscopic (EIS) technique was also used to investigate the mechanism of corrosion inhibition.