Investigation of inhibition effect of some aminoacids on aluminium in acidic media

In this study, it is aimed to prevent corrosion arising from the pickling processes undergone with acids in the systems that contains aluminum, which is light, durable and highly resistant to corrosion. Amino acid inhibitors were used to prevent corrosion on aluminum. The corrosion rate was determined by Tafel extrapolation and linear polarization methods and inhibitor efficiencies were calculated. The efficiencies of highly efficient inhibitors, selected among inhibitors in 1%HCI solution at 2000 ppm and 20°C, were analyzed with respect to the concentrations and temperature in the 1 % HCl solution. The highest efficiencies were calculated 91,4%, 92,7%, 84,5%, 91%, 92%, 93% and 97% for L-Aspartic Acid, DL-Aspartic Acid, L-Cysteine Hydrochloride Monohydrat, D(-) Mandelic Acid, Oxalic Acid, N-Acetyl-L-Cysteine and D-Phenylalanine at 3000 ppm respectively; 95% for Glycolic Acid at 2500 ppm; 86% for L-Arginine at 2000 ppm; 85% and 82% for L-Histidine and L-Methionine at 5000 ppm respectively. The effects of inhibitors having high efficiencies on the corrosion of aluminum in 1% H2SO4 solution is investigated with respect to concentration and temperature. The highest efficiencies were found for L-Aspartic Acid, D-Phenylalanine and Glycolic acid at 20°C temperature and 5000 ppm as 51%, 48.5% and 28.5% respectively. As a result of experiments, it was observed that the efficiency of inhibitor improves by increase in concentration of inhibitor. Considering that amino acids acted as adsorbent on metal surfaces, Langmuir, Freundlich, Temkin and Frumkin adsorption isotherms were drawn. Activation energies (Ea) of inhibitors are calculated and the protection of inhibitor was also supported by activation energy.