Corrosion inhibition of steel in hydrochloric acid solution by new bipyrazole derivatives

Abstract

Purpose

To study the effect of inhibition of new bipyrazole derivatives on the corrosion of steel in HCl media at various temperatures.

Design/methodology/approach

In this study, novel corrosion inhibitors, namely bipyrazoles were synthesised and tested as corrosion inhibitors for steel in 1 M HCl. The degree of corrosion was measured using various techniques including weight loss measurements, potentiodynamic polarisation, linear polarisation resistance (Rp) and impedance spectroscopy (EIS).

Findings

It was found that 1,5,5′‐trimethyl‐1H,2′H‐3,3′‐bipyrazole (P₁) gave the best inhibition effect. The inhibition efficiency increased with the concentration of P₁ to attain 79 per cent at 10⁻³ M. Good agreement between the various methods explored was observed. Polarisation measurements also showed that P₁ acted essentially as a cathodic inhibitor. The cathodic curves indicated that the reduction of proton at the steel surface was an activating mechanism. P₁ adsorbed on the steel surface according to Frumkin adsorption model.

Research limitations/implications

The synthesis route offers the possibility of other pyrazolic compounds to be tested in the future.

Practical implications

The inhibitory efficiency of P₁ increased with the increase of both the concentration and the temperature (in the 298‐353 K range). As such, P₁ can be used in chemical cleaning and pickling processes.

Originality/value

The originality of this work is the synthesis of new inhibitors based on pyrazolic organic compounds.

Citation

Bouklah, M., Hammouti, B., Benkaddour, M., Attayibat, A. and Radi, S. (2005), "Corrosion inhibition of steel in hydrochloric acid solution by new bipyrazole derivatives", Pigment & Resin Technology, Vol. 34 No. 4, pp. 197-202. https://doi.org/10.1108/03699420510609088