Influence of some multifunctional triazoles on corrosion of mild-steel in boiling hydrochloric acid solutions

Some new triazole based corrosion inhibitors namely, 4-benzylideneamino-3-hydrazino-5-mercapto -1,2,4-triazole, (BAHMT), 4-dimethylaminobenzylideneamino-3-hydrazino-5-mercapto-1,2,4-triazole (DAHMT), and 4-vanillideneamino-3-hydrazino-5-mercapto- 1,2,4-triazole (VAHMT) have been synthesized and their influence on corrosion inhibition of mild steel in 15% hydrochloric acid solution under boiling conditions has been studied using weight loss method. All the tested inhibitors except DAHMT showed > 90% inhibition efficiency. Potentiodynamic polarization measurements have been carried out at room temperature, which clearly reveal the fact that all investigated inhibitors are of mixed type and they inhibit corrosion of mild steel by blocking the active sites of the metal surface. The adsorption of these inhibitors on the mild steel surface from 15% HCl has been found to obey Temkin's adsorption isotherm.