In this study, different concentrations of C6H5NH2 (Aniline) were employed for investigating its corrosion inhibition of stainless steel in 0.5 M HCl. Corrosion rate measurements at 28°C, 45°C and 60°C were obtained from a linear sweep voltametry instrument and analyzed for inhibition efficiency and apparent activation energy in the presence and absence of C6H5NH2. Results showed that C6H5NH2 generally exhibited excellent inhibition effects on stainless steel corrosion at the higher temperatures, i.e. the 45°C and 60°C, at which the self-protectiveness of the stainless steel metal appears to breakdown. In contrast, the stainless steel metal exhibited self protection in the presence and absence of C6H5NH2 at the low temperature of 28°C, such that very low inhibition effects of aniline appears to be required at this temperature. Thus, while maximum inhibition efficiency (η) = 23.13% at 28°C by the 0.086 M C6H5NH2, inhibition efficiency was as high as η = 96.00% by 0.043 M C6H5NH2 at 40°C and η = 95.58% by the 0.107 M C6H5NH2 at 60°C on stainless steel corrosion in the HCl test-medium. Apparent activation energy analyses showed that this thermodynamic quantity decreased in values from the uninhibited, Ea = 100.37 kJ/mol, to the excellently inhibiting 0.107 M C6H5NH2 for which Ea = 6.30 kJ/mol. The implications, of these results, on the temperature dependency of C6H5NH2 corrosion inhibition performance as well as on the dominance of chemisorption adsorption mechanism by this chemical inhibitor on the stainless steel metal were detailed in the study.
Key words: Aniline inhibitor, hydrochloric acid environment, stainless steel metal, linear sweep voltametry instrumentation, corrosion inhibition efficiency, activation energy modeling