2,5-Disubstituted 1,3,4-Oxadiazole Derivatives as Effective Inhibitors for the Corrosion of Mild Steel In 2M H3PO4 Solution

The influence of three oxadiazole derivatives on the corrosion inhibition of steel in 2M H3PO4 solution is studied using weight-loss and electrochemical polarisation measurements. The results show that 2,5-bis(4-methoxyphenyl)-1,3,4-oxadiazole (P4) is the best inhibitor and its inhibition efficiency increases with the increase of concentration to attain 76% at 5×10-4 M. Potentiodynamic polarisation studies clearly reveal that the oxadiazole derivatives act essentially as cathodic inhibitors. The inhibition efficiency of the studied oxadiazoles decreases with the rise in temperature in the range 298-348 K. E% values obtained from weight-loss and electrochemical methods were in good agreement. Adsorption of P4 on steel surface has an S-shaped adsorption isotherm.