Abstract

OKENIYI, Joshua O.; LOTO, Cleophas A.  and  POPOOLA, Abimbola P. I.. Electrochemical Performance of Phyllanthus Muellerianus on the Corrosion of Concrete Steel-reinforcement in Industrial/Microbial Simulating-environment. Port. Electrochim. Acta [online]. 2014, vol.32, n.3, pp.199-211. ISSN 0872-1904.  https://doi.org/10.4152/pea.201403199.

Electrochemical monitoring techniques were employed in this study to assess anticorrosion performance of Phyllanthus muellerianus leaf-extract on concrete steel- reinforcement in 0.5 M H₂SO₄, used for simulating industrial/microbial environment. For this, steel-reinforced concretes admixed with different concentrations of the natural plant leaf-extract were partially immersed in the acidic test-solution and subjected to electrochemical monitoring of corrosion potential, corrosion current and corrosion rate. Test responses analysed as per ASTM G16-95 R04, showed that the corrosion rate correlated, r = 84.93%, ANOVA p-value = 0.0403, with the leaf-extract concentration admixed in concrete and the ratio of the standard deviation of potential to the standard deviation of current. These identified the 0.3333% Phyllanthus muellerianus (per weight of cement) with optimum effectiveness at inhibiting steel-reinforcement corrosion both by the experimental model, η = 91.66 & pm;2.51%, and by the prediction from the correlation fitting model, η = 85.54 & pm;14.44%. Fittings of both the experimental and the predicted data followed the Flory-Huggins and the Frumkin adsorption isotherms which suggest prevalent mechanism of physical adsorption (physisorption) of the extract on steel-rebar surface. These support the use of Phyllanthus muellerianus as environmentally-friendly admixture for inhibiting concrete steel-reinforcement corrosion in the industrial/microbial service-environment.

Keywords : steel-rebar corrosion in acidic environment; environmentally-friendly inhibitor; correlation fitting analysis; inhibition efficiency; adsorption isotherm.

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