ITUEN, Ekemini    UMOREN, I. S.. Solvent Effect and Adsorption Study of Mild Steel Protection from Acid Corrosion Using Eco-friendly Formulations of Annatto Extract. []. , 35, 1, pp.27-37. ISSN 0872-1904.  https://doi.org/10.4152/pea.201701027.

Annatto extract (dye) was investigated as a cheap and ecologically friendly alternative corrosion inhibitor. The corrosion process was monitored with mild steel coupons in 1.0 M hydrochloric acid at temperatures between 30 °C to 90 °C by weight loss and spectroscopic techniques. The dye effectively inhibited the corrosion of mild steel in the acid at the studied temperatures. Inhibition efficiency obtained was found to vary with temperature and concentration of the dye. Adsorption models were used to predict the nature of the dye-steel surface interaction. Thermodynamic models provided evidence of spontaneous physical and chemical adsorption mechanism with the evolution of heat. Kinetic studies revealed a deepening effect on the activation potential in the presence of the dye. The effect of solvent and synergistic intensifiers on the effectiveness of the dye was also assessed. Heavy metal ion composition in the formulation was determined and was within the limit of environmental and health safety.

: adsorption; annatto; corrosion inhibitor formulation; inhibition effectiveness; intensifier; solvents.

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