The synergistic inhibition behaviour of tannic acid and iodide ions on mild steel in H2SO4 solutions

The synergistic effect of tannic acid and I− in H2SO4 solution has been studied through electrochemical impedance spectroscopy, potentiodynamic polarization curves, immersion tests, weight loss tests, and scanning electron microscopy in present work. The results show that tannic acid and iodide ions have an obvious synergistic inhibiting effect in H2SO4 solution. SEM images indicate that the absorbed mixed inhibitors layer composed of tannic acid and I− can provide a long term protection for mild steel in 0.1 M H2SO4 solution. The mixed inhibitor composed of tannic acid and iodide ions is an effective inhibitor for mild in acid solution.