New bipyrazole derivatives as effective inhibitors for the corrosion of mild steel in 1M HCI medium

The inhibition of the corrosion of the mild steel in 1M HCl by new bipyrazolic compounds has been studied by weight loss, electrochemical polarisation and electrochemical impedance spectroscopy (EIS) measurements. Results obtained reveal that these compounds are very good inhibitors. The inhibition efficiency increases with the increase of inhibitor concentration and reached 94 at 10^–3M for the bipyrazoles studied. Potentiodynamic polarisation studies clearly reveal that the presence of the bipyrazoles does not change the mechanism of the hydrogen evolution reaction and they act essentially as cathodic inhibitors. The effect of temperature on the corrosion behaviour of mild steel in 1M HCl without and with the bipyrazoles at 10^–3M was studied in the temperature range from 298° to 343°K. EIS measurements show the increase of the transfer resistance with the inhibitor concentration.