THE INHIBITION OF MILD-STEEL CORROSION IN HYDROCHLORIC-ACID BY 2,2'-PYRIDIL AND ALPHA-PYRIDOIN

The effect of closely related alpha-pyridoin and 2,2'-pyridil on the c orrosion behaviour of mild steel in hydrochloric acid solution has bee n studied. Weight loss and hydrogen evolution measurements reveal that alpha-pyridoin gives a better inhibition effect than 2,2'-pyridil. Th e inhibition effect is more pronounced with increasing temperature as well as inhibitor concentration. Chemical adsorption mechanism has bee n proposed for the two inhibitors. alpha-Pyridoin and 2,2'-pyridil obe y the Freundlich adsorption isotherm equation at all concentrations an d temperatures. The higher efficiencies of the alpha-pyridoin have bee n explained in terms of high solubility of the compound facilitated by hydrogen bonding with solvent molecules. alpha-Pyridoin is also consi dered to form a more stable bond with mild steel. (C) 1997 Elsevier Sc ience S.A.