Synergistic effects of halide ions and Acacia senegal gum on the corrosion inhibition of mild steel in sulfuric acid solution

Abstract

The synergistic effects of halide ions, Br– and I– and Acacia senegal gum exudates on the corrosion inhibition of mild steel in 0.5 M sulfuric acid solution has been investigated by potentiodynamic polarization measurements and electrochemical impedance spectroscopy techniques. Results showed that Acacia senegal gum exudate moderately reduces the corrosion rate of mild steel. The inhibition efficiencies on mild steel electrodes increased with increase in gum exudate concentrations up to 300 ppm, corresponding to the inhibition efficiency of about 43% and its inhibition efficiency increased up to 81.6% with addition of halide ions due to synergistic effects. The enhancement effect of the halide ions was higher with iodide than with bromide ions. The synergism parameter, S1, evaluated was greater than unity, consistent with synergistic effect. The adsorption of Acacia senegal gum on the mild steel surface obeyed Langmuir’s adsorption isotherm. The results obtained, i.e., corrosion rates of mild steel, inhibition efficiencies of Acacia senegal gum exudates and the synergistic effects of Acacia senegal gum exudates and halides from polarization and impedance measurements were in good agreement.

Keywords: corrosion, inhibition, mild steel, synergistic effect, Acacia senegal, gum exudate.