Browsing by Author "Oguzie, Emeka E."

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    Application of aqueous extracts of coffee senna for control of mild steel corrosion in acidic environments
    (Springer, 2012-07-16) Akalezi, Chris O.; Enenebaku, Conrad K.; Oguzie, Emeka E.
    Background: The inhibitive effect of the aqueous extract of Coffee senna (CS) on the corrosion of mild steel in 1 MHCl and 0.5 M H2SO4 solutions was investigated by weight loss measurement as well as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. Result: The extract was found to efficiently inhibit the corrosion process in both environments and inhibition efficiency increased with extract concentration as well as rise in 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. Adsorption of the extract organic matter was approximated by the Langmuir isotherm. The adsorption behavior of selected organicconstituents of the extract on the metal surface was assessed at the molecular level, in the framework of the density functional theory. Conclusion: This study clearly shows the potentials of CS extract for control of mild steel corrosion in acidic environment.
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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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    Evaluation of the inhibitive effect of some plant extracts on the acid corrosion of mild steel
    (Elsevier Ltd, 2008) Oguzie, Emeka E.
    Corrosion inhibition of mild steel in 2M HCl and 1M H2SO4 by extracts of selected plants was investigated using a gasometric technique at temperatures of 30 and 60°C. The studied plants materials include leaf extracts Occimum viridis (OV), Telferia occidentalis (TO), Azadirachta indica (AI) and Hibiscus sabdariffa (HS) as well as extracts from the seeds of Garcinia kola (GK). The results indicate that all the extracts inhibited the corrosion process in both acid media by virtue of adsorption and inhibition efficiency improved with concentration. Synergistic effects increased the inhibition efficiency in the presence of halide additives. Inhibition mechanisms were deduced from the temperature dependence of the inhibition efficiency as well as from assessment of kinetic and activation parameters that govern the processes. Comparative analysis of the inhibitor adsorption behaviour in 2M HCl and 1M H2SO4 as well as the effects of temperature and halide additives suggest that both protonated and molecular species could be responsible for the inhibiting action of the extracts
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    Experimental and theoretical studies on the protective effect of a biomass corrosion inhibitor (vigna radiata) on mild steel in acidic medium
    (Wiley-VCH GmbH, 2020) Maduabuchi, Chidiebere A.; Njoku, Demian I.; Obike, I. Anthony; Nwanonenyi, Simeon C.; Akalezi, Christogonus; Adindu, Blessing; Oguzie, Emeka E.
    The scrutiny of the impeding properties of vigna radiata (VR) on mild steel corrosion in sour environs (1 M HCl and 0.5 M H2SO4) was done by means of gravimetric, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods (PDP). Polarization findings revealed that VR retarded the corrosion process in a mixed-mode manner. Adsorption of the active components of VR was found to be in line with Langmuir adsorption isotherm. The obtained PDP result was complemented by the EIS findings. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and the theoretical technique was used to complement the results.
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    Inhibition of copper corrosion in chloride solution by caffeine isolated from black tea
    (UP, 2014-05-02) Gudić, Senka; Oguzie, Emeka E.; Radonić, Ani; Vrsalović, Ladislav; Smoljko, Ivana; Kliškić, Maja
    Caffeine (1,3,7-trimethylxanthine) was isolated from black tea and characterized using different physical methods (determination of melting point, thin layer chromatography, FTIR spectroscopy and UV spectrophotometry). The corrosion inhibition performance of the caffeine isolate on copper corrosion in neutral 0.5 mol L-1 NaCl solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The obtained results show that caffeine effectively inhibited the corrosion reaction in the chloride solution with inhibition efficiency up to » 92 %. Furthermore, caffeine was found to function essentially as a cathodic inhibitor by adsorption on the copper surface according to the Langmuir adsorption isotherm. The adsorption free energy of » –37 kJ mol-1 indicates strong adsorption of the caffeine on the metal surface. Quantum chemical computations and molecular dynamics simulations were adapted to understudy the adsorption of a single caffeine molecule as well as a polymeric cluster of caffeine molecules on a model Cu surface at a molecular level and show good agreement with the experimental findings
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    Studies on the inhibitive effect of Occimum viridis extract on the acid corrosion of mild steel
    (Elsevier Ltd, 2006) Oguzie, Emeka E.
    Corrosion inhibition of mild steel in 2M HCl and 1M H2SO4 by leaf extracts of Occimum viridis (OV) was studied using the gasometric technique at temperatures of 30 and 60°C. The results indicate that the extracts inhibit the corrosion process in both acid media and inhibition efficiency increased with concentration. Synergistic effects increased the inhibition efficiency in the presence of halide additives namely KCl, KBr, KI. Temperature studies revealed a decrease in efficiency with rise in temperature and corrosion activation energies increased in the presence of the extract, probably implying that physical adsorption of cationic species may be responsible for the observed inhibition behaviour. Comparative analysis of the inhibitor adsorption behaviour in 2M HCl and 1M H2SO4 as well as the effect halide additives suggest that cationic species may not be the only constituents responsible for the inhibiting action of the extract