Electrochemical and quantum-chemical study on newly synthesized triazoles as corrosion inhibitors of mild steel in 1 M HCl

Several newly synthesized triazoles including 1-(2″-nitrobenzyl)methenylideneamino-2-mercapto-5-(1′-(1′,2′,4′-triazol)) methenyl-1,3,4-triazole (NMTT), 1-(2″-methoxybenzyl)methenylideneamino-2-mercapto-5-(1′-(1′,2′,4′-triazol)) methenyl-1,3,4-triazole (MMTT), and 1-((4″-chlorobenzyl)methenylideneamino-2-mercapto-5-(1′-(1′,2′,4′-triazol)) methenyl-1,3,4-triazole (CMTT) were studied as corrosion inhibitors of mild steel in 1 M HCl by weight loss measurements, electrochemical experiments, and quantum-chemical calculations. The experimental results show that these compounds have high inhibition efficiency in the order CMTT > MMTT > NMTT. CMTT at concentration of 1.0 × 10−3 M showed the highest inhibition efficiency of 96.4 %. The adsorption of the inhibitors on the metal surface obeyed the Langmuir isotherm, and the basic adsorption mechanism is proposed based on quantum-chemical calculations.