The inhibition efficiency (IE) of various concentrations of a caffeine-Zn2+ system in controlling corrosion of mild steel immersed in an aqueous solution containing 60 ppm of Cl– was evaluated by a weight-loss study. The formulation consisting of 50 ppm of caffeine and 50 ppm of Zn2+ showed 91% IE. A synergistic effect was noticed between caffeine and Zn2+. The influence of sodium sulfite (Na2SO3), sodium dodecyl sulphate (SDS)—an anionic surfactant—pH, and a period of immersion on the IE of the caffeine-Zn2+ system has been evaluated. The transport of inhibitors toward the metal surface plays a major role in controlling corrosion of mild steel. Formation of micelles by surfactants changes the IE. The caffeine-Zn2+ system has better IE in the acidic medium than in the basic medium. The IE decreased as the period of immersion increased. The protective film was analyzed by Fourier transform infrared spectroscopy. The film consisted of Fe2+-caffeine complex and zinc hydroxide (Zn[OH]2). The film was found to be UV-fluorescent.

Subject
Stretching, Metal surfaces, Synergistic effect, Protective films, Bulk solution, Acidity, Fourier transform infrared spectrography, Anodic reactions, Film formation, Cathodic sites, Corrosion inhibitors, Immersion, Chlorides
Keywords:
caffeine, corrosion inhibition, inhibitor transport, mild steel, synergistic effect
NACE International
2003
You do not currently have access to this content.