Inhibition of steel corrosion by some new triazole derivatives in boiling hydrochloric acid

Abstract

Some new triazole derivatives, namely 4-aminobenzylidene-3-propyl-5-mercapto-1,2,4-triazole, 4-aminocinnamalidene-3-propyl-5-mercapto-1 ,2, 4-triazole (ACPMT), 4-aminosalicylidene-3-propyl-5-mercapto-1,2,4-triazole (ASPMT), 4-aminovanillidene-3-propyl-5-mercapto-1,2,4-triazole, and 4-aminodimethylamino-benzylidene-3-propyl-5-mercapto-1,2,4-triazole (ADPMT), have been synthesised. Their inhibiting action on the corrosion of mild steel in 15%HCl under boiling conditions has been studied by the weight loss method. With the exception of ADPMT, all the triazole derivatives tested showed an inhibitor efficiency of > 98%. Triazole compounds ACPMT and ASPMT showed an efficiency of >99%. Their efficiency has been found to be comparable with that of propargyl alcohol, a standard corrosion inhibitor for mild steel in boiling HCl. Potentiodynamic polarisation studies revealed that all the triazoles investigated are mixed type inhibitors inhibiting the corrosion of mild steel by blocking the active sites of the metal surface. The adsorption of these compounds on mild steel from 15%HCl has been found to obey Temkin's adsorption isotherm.