School of Physical Sciences

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Browsing School of Physical Sciences by Subject "adsorption isotherm"

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    Evaluation of anticorrosion properties of Chrysophyllum albidum leaves extract for mild steel protection in acidic media
    (Springer Open, 2016-03) Akalezi, Chris O.; Oguzie, Emeka E.
    Background: The inhibition efficiency of Chrysophyllum albidum extract in controlling corrosion of mild steel in 1 M HCl has been evaluated by weight loss, potentiodynamic polarization and electrochemical impedance techniques at 303 K. The effect of immersion time and temperature on inhibition efficiency of the extract was also studied. Results: Inhibition was found to increase with increasing concentration of the extract but decrease with increasing time and temperature. Data from electrochemical measurements suggest that the extract functioned by adsorption of the organic matter on the metal/corrodent interface, inhibiting both the anodic and cathodic half reactions of the corrosion process. The increase in concentration of the inhibitor causes an increase in the activation energy and a decrease in the exponential factor k. Conclusion: The plant extracts follow Langmuir adsorption isotherm. Moreover, the process of adsorption is spontaneous, stable and considered to be physical adsorption. the thermodynamic properties recorded suggest that the process of film formation is higher than the destruction of the metal surface and that the adsorption process is exothermic.
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    ItemOpen Access
    Inhibitory mechanism of mild steel corrosion in 2M sulphuric acid solution by methylene blue dye
    (Elsevier Ltd, 2005) Oguzie, E. E.; Onuoha, G. N.; Onuchukwu, A. I.
    Methylene blue dye (MB) was investigated as a corrosion inhibitor for mild steel in 2M sulphuric acid solution using gravimetric and thermometric techniques. The inhibition efficiency of MB increased with concentration and synergistically increased in the presence of the halide additives, namely KCl, KBr and KI. The trend of inhibition efficiency with temperature suggests that inhibitor molecules are physically adsorbed on the corroding metal surface at lower concentration (0.01–0.5mM), and chemically adsorbed at higher concentration (1.0–5.0 mM). These results were further corroborated by kinetic and activation parameters for corrosion and adsorption processes evaluated from experimental data at the temperatures studied. MB was found to obey Langmuir and Frumkin adsorption isotherms in the concentration range investigated