Anti-corrosive properties of S. tinctoria and G. ouregou alkaloid extracts on low carbon steel

The effect of alkaloid extracts from two Amazonian trees (Guatteria ouregou and Simira tinctoria) on low carbon steel corrosion was investigated in acidic solutions by using electrochemical techniques. All of these plant extracts inhibit the corrosion of low carbon steel in 0.1 M HCl solutions. As their concentration increases to 250 mg/L, the inhibition efficiencies of S. tinctoria and G. ouregou alkaloid extracts reach approximately 92% in 0.1 M HCl solutions. The adsorption of the inhibitor molecules was in accordance with the Langmuir adsorption isotherm. The results obtained show that these plant extracts could be serve as an effective inhibitor for the corrosion of low carbon steel in hydrochloric acid media. Furthermore, harmane was identified as the main component of S. tinctoria extract and that suggests that it is the active ingredient against corrosion of low carbon steel.

Research highlights
► The effect of alkaloid extracts from two Amazonian trees (Guatteria ouregou and Simira tinctoria) on low carbon steel corrosion was investigated in acidic solutions by using electrochemical techniques.
► Total alkaloid extract from G. ouregou leaves, S. tinctoria barks can act as a natural sources and eco-friendly corrosion inhibitors for low carbon steel in 0.1 M HCl solutions.
► NMR analysis revealed the presence of harmane as major compound of S. tinctoria alkaloid extract.