Investigation on some Schiff bases as HC1 corrosion inhibitors for copper

The inhibiting action of some Schiff bases on the corrosion of copper in hydrocholoric has been studied. The Schiff bases N,N'-p-phenylen-bis(3-methoxy-salicylidenimine) (V-pphV), N,N'-o-phenylen-bis(3-methoxy-salicylidenimine) (V-oph-V), and N'-histidine-3-methoxysalicylidenimine (V-his) were synthesized by reacting 3-methoxy-salicylaldehyde with aromatic amines and histidine. The inhibiting action of these Schiff bases has been studied on the corrosion of copper in 5% HCl solution. The potentiostatic polarization and AC impedance studies reveal that all the studied Schiff bases inhibit the corrosion of copper in the solution and that the inhibiting efficiency increases with a decrease in temperature or an increase in concentration of the Schiff base. The Schiff base of V-pph-V at a concentration of 10(-3) mol/dm(3) can give 99.4% inhibition efficiency at 20 degrees C. (C) 1999 Elsevier Science Ltd. All rights reserved.