Inhibition of Copper Corrosion with Schiff Base Derived from 3-Methoxysalicylaldehyde and O-Phenyldiamine in Chloride Media

The inhibiting effect of Schiff base N,N´-o-phenylen-bis (3-methoxysalicylaldenimine), designated as V-ph-V, on corrosion of copper in 1.0 M hydrochloric acid (HCl) or 1.0 M sodium chloride (NaCl) solutions under various conditions was studied using the potentiostatic polarization method and the alternating current (AC) impedance technique. Results showed a remarkable decrease in the corrosion rate in the presence of V-ph-V (concentration = 10−4 M) in 1.0 M NaCl solution at 40°C. To study the nature of the solid products formed under free corrosion conditions or with the additive V-ph-V, the surface morphology at the end of the immersion tests was examined using scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) also was used to identify the spectra of the adsorbed complex. The surface film was identified as a polymeric Cu(II)-(V-ph-V)-H2O. Cu(II)-(V-ph-V)-H2O complex totally covered the copper surface, exhibiting strong corrosion inhibition. Formation of Cu(II)-(V-ph-V)-H2O was accomplished after adsorption of V-ph-V on the copper surface. The complex also was synthe-sized from V-ph-V with Cu(II), and its single crystal structure was determined using a diffractometer.