Control of 1050 steel corrosion with amino acids in acidic solutions

In this study, the aim was the prevention of corrosion of systems working with acids which was made 1050 steel. For prevention of 1050 steel corrosion in wt %0.5 of HCl solution used aminoacids. Some which were L-Cysteine Hydrochloride Monohydrat, N-Acetyl-L-Cysteine,L-Cystine(L-Cys2), L-Arginine, D-Alanine, L-Methionine, L-Aspargine Monohydrate, Glycolic Acid, D-Valine, D-Phenylalanine, L-Aspartic Acid, DL-Aspartic Acid, D(-)-Mandelic Acid, L-Leucine (L-Lue), Oxalic Acid Dihydrate . The inhibition efficiencies and corrosion rate were calculated with the use of Tafel extrapolation method and Linear polarization method.Various inhibitors were used in wt %0.5 of HCl solution at 25ºC and 1000 ppm. Among them L-Cysteine Hydrochloride Monohydrat, N-Acetyl-L-Cysteine, L-Cystine (L-Cys2), L-Methionine were provided high inhibitor efficiency. Inhibitor efficiency was found %91, %90.3, %88.4 and %86.1 respectively. The experiments were made which was high inhibitor efficiency at 25C, on the purpose of how effective these inhibitors at high temperatures, there were an some other experiments at 30C, 40C and 50C, it was found that these inhibitors which were again most effective at high temperatures according to other inhibitors. After that, the experiments were made with inhibitors which have a point of above some efficiency at concentrations between 500 ? 3000 ppm at 25C. High inhibitor efficiency was obtained for L-Cysteine Hydrochloride Monohydrat and L-Cystine (L-Cys2) at 3000ppm at 25C which were %94 ve %91.7, respectively; for N-Acetyl-L-Cysteine and L-Methionine which were % 90.3 (30C at 2000 ppm ) and % 86.1 (25C at 1000 ppm).In wt %0,5 of H2SO4 solution, the experiments were made with inhibitors which have high efficiency which were L-Cystine (L-Cys2), L-Cysteine Hydrochloride Monohydrat and N-Acetyl-L-Cysteine at 1000 ppm at 25°C, 30°C, 40°C and 50°C and 25°C at 2000 ppm and 3000 ppm. For L-Cystine, L-Cysteine Hydrochloride Monohydrat and N-Acetyl-L-Cysteine, the maximum inhibitor efficiency was found % 88.6, %83.0, %82.7 at 3000 ppm at 25C.To be thougt of the aminoacids affect with adsorption at the metal surface. So, adsorption isoterms plotted. Generally Adsorption izoterms obeys Langmuir and Freundlich isotherms.With the intention of calculating Activation Energy (Ea), there were plotted Lni - 1/T graphs for absence or presence of inhibitor at constant inhibitor consantration. The activation energy of the solution without inhibitor were lower than the activation energies of solutions with inhibitor. This result indicates that dissolution of metal becomes harder at the presence of inhibitor, corrosion reaction becomes harder and consequently corrosion rate decrease. Thus, protection effect was supported with activation energy, too.Keywords : Inhibitors, amino acids, corrosion, 1050 steel