Evaluation of Co-Inhibition Characteristics of caffeine-Zn2+ system in preventing Carbon Steel Corrosion.

摘要

The inhibition efficiency of Caffeine-Zn2+ system in controlling the corrosion of carbon steel in 120 ppm chloride solution has been evaluated by mass los method, potentiodynamic polarization study and AC impedance spectra. A formulation consisting of 200ppm of caffeine and 75 ppm of Zn2+ has inhibition efficiency (IE) of 75% at pH7. However IE decreases sharply at low and high pH. Polarization studies show that the caffeine - Zn2+ system functions as a mixed inhibitor. AC impedance spectra and AFM studies reveal the formation of a protective film on the metal surface. FTIR spectrum shows the presence of Fe2+- caffeine complex and Zn(OH)2 in the film.