Study of the mechanism and inhibiting efficiency of 3,5-bis(4-methylthiophenyl)-4H-1,2,4-triazole on mild steel corrosion in acidic media

The efficiency of a new triazole derivative, namely, 3,5-bis(4-methylthiophenyl)-4H-1,2,4-triazole (4-MTHT) has been studied for corrosion inhibition of mild steel in I M hydrochloric acid (HCI) and 0.5 M sulphuric acid (H2SO4). Corrosion inhibition was studied using electrochemical methods and weight loss measurements. These studies have shown that 4-MTHT was a very good inhibitor. 4-MTHT behaved better in 1 M HC1 than in 0.5 M H2SO4 and inhibition efficiencies up to 99% and 80% can be obtained in 1 M HC1 and 0.5 M H2SO4, respectively. Activation energies (E-a) in the presence and absence of 4-MTHT were obtained by measuring the temperature independence of the corrosion current. The potential of zero charge of mild steel was studied by ac impedance method, and the mechanism of adsorption has been discussed. The adsorption of 4-MTHT followed Langmuir's adsorption isotherm in both acids. (C) 2002 Elsevier Science Ltd. All rights reserved.