New bipyrazole derivatives as corrosion inhibitors for steel in hydrochloric acid solutions

The influence of some new bipyrazole derivatives synthesized in the laboratory on the corrosion inhibition of mild steel in 1 M HCl solution is studied using weight loss and electrochemical polarization techniques. The inhibition efficiency of all compounds tested increases with increase of concentration. The polarization measurements indicate that the inhibition efficiency of bipyrazolic compounds depends upon electrode potential without changing the mechanism of the cathodic hydrogen evolution reaction. It is found that ethyl 4-[bis(3,5-dimethyl-1H-pyrazol-1-yl)methyl)] amino benzoate (bipyrazol-4) is the best inhibitor. The effect of temperature indicates that the inhibition efficiency of bipyrazol-4 decreases with increasing temperature in the range 308-353 K. © 2005 Elsevier B.V. All rights reserved.