Studies of corrosion inhibitors for zinc-manganese batteries: quinoline quaternary ammonium phenolates

Three compounds, hydroxyethyl quinoline quaternary ammonium phenolate, hydr oxyethyl quinoline quaternary ammonium para-methyl phenolate and hydroxyeth yl quinoline quaternary ammonium para-nitro phenolate were synthesized and tested as corrosion inhibitors for zinc-manganese batteries. Such quaternar y ammonium salts derived from heterocylic molecule containing N atoms posse ss a higher density electron cloud around the functional groups and provide a larger projective area. From the analysis of bi-directional polarization curves and the electrochemical impedance spectra of zinc electrode measure d in 26% NH4Cl solutions containing one of these compounds, we demonstrated that the first two compounds exhibit good inhibiting effects toward zinc c orrosion as the result of adsorption on zinc surface at open-circuit condit ions. These compounds desorb from the surface and will no longer hinder the dissolution of zinc once the zinc electrode is anodically polarized to cer tain extent. This property is desirable for corrosion inhibitor to be used in chemical batteries. (C) 2001 Published by Elsevier Science Ltd.