Corrosion Inhibition of Mild Steel via Ethanol Extracts of Phyllanthus mellerianus

What is it about?

The corrosion of mild steel is a problem in industrial processes based on its deterioration on exposure to acids, alkalis, and salt solutions. This issue has prompted an increase in research interest in order to mitigate the harmful effects of corrosion on metals and their alloys. The thermodynamic and adsorption analysis of mild steel in 0.5M hydrochloric acid solutions via ethanol leaf extract of Phyllanthus mellerianus was investigated using weight loss and hydrogen evolution techniques. The powdered sample was extracted with ethanol and concentrated with a rotary evaporator. The phytochemical analysis reveals the presence of tannins, flavonoids, phenols, and terpenoids at reasonable percentages. The inhibition efficiency, enthalpy, enthropy, activation energy, Gibbs free energy, and adsorption isotherms were extrapolated with some models. The inhibition efficiency increased with an increase in the concentration of the extract. The values of change in Gibbs free energy obtained at 303K, 313K, and 323K were negative, indicating that the leaf extract of Phyllanthus mellerianus was strongly adsorbed on mild steel surfaces and stable at high temperatures. The enthalpy of activation ranges from 43.08kJ/mol to 80.64kJ/mol. An increase in activation energy with inhibitor concentration confirmed the physical (physisorption) adsorption mechanism for the corrosion of mild steel surfaces. The R2 values obtained from the linear regression are strongly fitted to the Langmuir and freundlich isotherms. The inhibitory effectiveness of extracts has been attributed to the presence of the hetero atoms N, O, and S present in their phytochemical composition.

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Why is it important?

it explains corrosion inhibition using environmentally benign Phyllanthus mellerianus, This work also explains the thermodynamic and adsorption variable as related to corrosion.

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