A study of corrosion behavior of copper in acidic solutions containing cetyltrimethylammonium bromide

The inhibitive effect of cetyltrimethylammonium bromide (CTAB) on copper corrosion in aerated H2SO4 solutions was investigated by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. CTAB inhibited copper corrosion more strongly than tetramethylammonium bromide (TMAB) under the same conditions due to the chemisorption of the n-cetyl group on the copper surface. The surface of the copper electrode was positively charged in sulfuric acid solution at the corrosion potential. The copper corrosion inhibition of CTAB and TMAB was attributed to the synergistic effect between bromide anions and positive quaternary ammonium ions. The C16H33N(CH3)(3)(+) and N(CH3)(4)(+) ions may electrostatically adsorb on the copper surface, which is primarily covered with adsorbed bromide ions. The inhibition efficiency of CTAB depended on the CTAB concentration and the immersion time for the copper electrode in corrosive solutions. Based upon the variation of impedance display of copper with the CTAB concentration and the immersion time, an adsorption model of CTAB on the copper surface was proposed. The C16H33N(CH3)(3)(+) ions adsorbed on the copper surface by horizontal binding to hydrophobic hydrocarbon chains at the low CTAB concentrations, whereas a perpendicular adsorption dominated as a result of an interhydrophobic chain interaction when the CTAB concentration increased. (C) 2001 The Electrochemical Society.