Comparison of inhibition efficiency of some azoles on corrosion of type 304 stainless steel in acidic solutions

Abstract

Abstract Inhibition efficiencies have been investigated for two types of azole, namely 2-mercaptobenzoazole (CBA) and 2-methylbenzoazole (MBA), containing nitrogen, sulphur, oxygen, or selenium atoms, on the corrosion of type 304 stainless steel in 2M sulphuric acid (H2SO4) and 3M hydrochloric acid (HCl). The study was conducted using weight loss, gasometry, and polarisation methods. It was shown that some of the compounds tested provide 90% inhibition efficiency at a concentration of 5 × 10-4M and that the efficiency depends on the heteroatom and decreases in the order Se > S > N > O. These inhibitors were more efficient in H2SO4 than in HCl whereas the opposite is true for inhibitors with nitrogen alone. Adsorption isotherms were fitted to the experimental findings and some thermodynamics functions were obtained.