L-METHIONINE METHYL-ESTER HYDROCHLORIDE AS A CORROSION-INHIBITOR OF IRON IN ACID CHLORIDE SOLUTION

Some aminoester organic compounds were tested as corrosion inhibitors for iron in molar hydrochloric acid (HCl) by mass-loss and electrochem ical polarization methods. Both techniques gave the same order of inhi bition. comparison of results among those aminoesters showed L-methion ine methyl ester (METOCH(3)) was the best inhibitor. Its inhibition ef ficiency (E%) reached a maximum value of 95% at 10(-2) M. Polarization measurements indicated METOCH(3) acted as a cathodic inhibitor withou t changing the mechanism of the hydrogen evolution reaction. METOCH(3) , was adsorbed on the iron surface according to a Frumkin isotherm mod el. The effect of temperature indicated that E% of METOCH(3) increased with increasing temperature in the range of 20 degrees c to 50 degree s C.