Electrochemical studies on the inhibition behavior of copper corrosion in pickling acid using quaternary ammonium salts

Abstract

The inhibition effect of two quaternary ammonium salts namely: N1,N2-didodecyl-N1,N1,N2,N2-tetramethylethane-1,2-diaminium bromide (I) and N-(2-hydroxyethyl)-N,N-dimethyldodecan-1-aminium bromide (II) on the corrosion of copper in 1M HNO3 has been investigated by polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Polarization studies showed that these compounds are mixed-type inhibitors. The inhibition efficiency increases with increasing the inhibitor concentration and the maximum inhibition (93.9% and 90.8%) was obtained in the presence of 1×10−3M of I and II, respectively. The adsorption of these inhibitors on the copper surface obeys Langmuir isotherm. The results obtained from the different electrochemical techniques were in good agreement.