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

The inhibitive effect of cetyltrimethylammonium bromide (CTAB) on copper co rrosion in aerated H2SO4 solutions was investigated by means of electrochem ical impedance spectroscopy (EIS) and potentiodynamic polarization techniqu es. 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. Th e copper corrosion inhibition of CTAB and TMAB was attributed to the synerg istic effect between bromide anions and positive quaternary ammonium ions. The C16H33N(CH3)(3)(+) and N(CH3)(4)(+) ions may electrostatically adsorb o n 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 u pon the variation of impedance display of copper with the CTAB concentratio n 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 b y horizontal binding to hydrophobic hydrocarbon chains at the low CTAB conc entrations, whereas a perpendicular adsorption dominated as a result of an interhydrophobic chain interaction when the CTAB concentration increased. ( C) 2001 The Electrochemical Society.