engleski

AMINO ACIDS AS CORROSION INHIBITORS FOR TIN IN SALT SOLUTION

In this paper the effect of some amino acids on the electrochemical and corrosion behaviour of tin in sodium chloride solution was investigated. For this purpose, model salt solutions containing sodium chloride (3 - wt -per cent) and added amino acids at the concentrations from 10^-3 to 10^-1 wt -per cent, were prepared. As a control electrolyte 3-wt -per cent sodium chloride solution was used. From the potentiostatic polarisation data (using the standard three-electrode system) corrosion current (i_corr.), corrosion potential (E_corr.) and polarisation resistance (R_p) were calculated. Redox potential (rH), pH and conductivity values of model solutions were also investigated. Inhibition efficiency of methionine and lysine ranged from 88.7 -per cent to 98.1 -per cent while the lowest was in cysteine (15 -per cent) at the concentration of 10^-2 -per cent. The presence of cysteine, at the highest concentration (10^-1 -per cent) in sodium chloride solution acted as corrosion accelerator. Generally, a suitable well fitting linear correlation between amino acids concentration and physico-chemical (pH, rH, conductivity) and electrochemical (i_corr., E_corr., R_p) parameters was obtained.

corrosion inhibitors; cysteine; lysine; methionine; sodium chloride; tin

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