Corrosion inhibition of mild steel in hydrochloric acid by some aromatic hydrazides

The influence of some organic acid hydrazides, namely salicylic acid hydrazide (SAH), anthranilic acid hydrazide (AAH), benzoic acid hydrazide (BAH) and cinnamic acid hydrazide (CAH) on the corrosion inhibition of mild steel in the presence of 1 N HCl was studied. The adsorption of all the hydrazides on mild steel surface in the acid solution were found to obey Temkin’s adsorption isotherm. The values of activation energy and free energy of adsorption of all the hydrazides were also calculated. The potentiodynamic polarization studies indicated that all the hydrazides except SAH are mixed inhibitors.