Corrosion inhibition of low-alloy carbon steel by gum Arabic and zinc acetate in neutral chloride-containing environment

Abstract

In this work, we investigated the inhibitory properties of an eco-friendly composition based on polysaccharide (gum Arabic) and zinc acetate for corrosion resistance enhancement of low-alloy carbon steel in a neutral environment. Electrochemical results showed that the inhibitory efficiency of the composition increases with increasing its concentration and reaches its maximum at 2.0 g/l of each component. The inhibitory efficiency of the composition, calculated from impedance dependences after 24 hours immersion of steel in a 0.1% NaCl solution, was 98%. The protective effect of the composition is associated with the adsorption of zinc acetate and gum Arabic due to the presence of hydroxyl and carboxyl groups in them, and the ability of Zn2+ cations to interact with OH– anions with the formation of zinc hydroxides, which block cathode areas and slow down corrosion. The adsorption of zinc acetate and gum Arabic on the steel surface was described by the Langmuir isotherm most completely. Electrochemical impedance spectroscopy results indicate the formation of a protective film, which probably consists of Fe2+-Zn2+-gum Arabic-acetate complexes. The formation of a protective film on the steel surface in inhibited solutions was confirmed by scanning electron microscopy and energy dispersive X-ray analysis results.