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 ( R p) and impedance spectroscopy (EIS). Findings – It was found that 1,5,5&vprime;‐trimethyl‐1H,2&vprime;H‐3,3&vprime;‐bipyrazole (P 1 ) gave the best inhibition effect. The inhibition efficiency increased with the concentration of P 1 to attain 79 per cent at 10 −3 M. Good agreement between the various methods explored was observed. Polarisation measurements also showed that P 1 acted essentially as a cathodic inhibitor. The cathodic curves indicated that the reduction of proton at the steel surface was an activating mechanism. P 1 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 P 1 increased with the increase of both the concentration and the temperature (in the 298‐353 K range). As such, P 1 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.
Pigment & Resin Technology – Emerald Publishing
Published: Aug 1, 2005
Keywords: Steel; Inhibitors; Corrosion; Acid conditions