An interesting and efficient organic corrosion inhibitor for mild steel in acidic medium

The effect of nicotinic acid (pyridine 3-carboxylic acid) on mild steel dissolution in H2SO4 is investigated by electrochemical methods: steady state galvanostatic and potentiostatic polarisation measurements. The dissolution parameters, such as corrosion currents, passive current, flade potential, open circuit potential, cathodic and anodic Tafel slopes and inhibition efficiencies, are determined. The adsorption and corrosion rates based on heat of adsorption and activation energies are calculated from Langmuir's adsorption isotherm. The inhibition efficiency range of 94-99% is obtained for a concentration range of 10(-1) to 10(-7) mol L-1. Passivating parameters revealed that these are strongly passivating additives. Synergistic effects of I- have a strong impact on the performance of these additives. These results are verified by the weight loss method. The surface analysis studies carried out by SEM supplement the galvanostatic results.