School of Physical Sciences

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Browsing School of Physical Sciences by Subject "acid inhibition"

Now showing 1 - 3 of 3
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    Effect of hexamethylpararosaniline chloride (crystal violet) on mild steel corrosion in acidic media
    (Elsevier Ltd, 2008) Oguzie, E. E.; Njoku, V. O.; Enenebeaku, C. K.; Akalezi, C. O.; Obi, C.
    The corrosion inhibition of mild steel in 0.5 M H2SO4 and 1 M HCl by hexamethylpararosaniline chloride (HMPC) was investigated using the gravimetric technique in the temperature range 303–333 K. The results indicate that HPMC inhibited the corrosion reaction in both acid media at all temperatures and inhibition efficiency increased with HMPC concentration. The inhibiting action is attributed to general adsorption of protonated and molecular HPMC species on the corroding metal surface. Adsorption followed a modified Langmuir isotherm and the Temkin isotherm, with very high negative values of the free energy of adsorption (DG0ads). An increase in temperature reduced the inhibition efficiency of HPMC in 0.5 M H2SO4 but increased efficiency in 1 M HCl. Activation parameters such as activation energy (Ea), activation enthalpy (DH*) and activation entropy (DS*) as well as the adsorption heat (Qads) were evaluated from the effect of temperature on corrosion and inhibition
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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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    Potentials of hyppocratea pallens planch leave extract as inhibition towards the corrosion of mild steel in acidic media
    (Der Pharma Chemica, 2012) Akalezi, C.; Enenebaku, C.; Okolue, B.; Oguzie, E.
    The inhibiting effect of leaf extracts of Hyppocratea pallens planhc.ex oliv on the corrosion of mild steel in 1.0 M HCl and 0.5 M H2SO4 solutions has been investigated by weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. The effect of temperature on the corrosion and inhibition processes was studied in the temperature range 303-333K. The presence of this plant extract reduced considerably the corrosion rate of mild steel in acidic media and the corrosion inhibition efficiency increased with extract concentration up to 1000 mgL-1. The results suggest that the extract inhibited the corrosion reaction via adsorption of the organic matter on the metal surface, following the Langmuir isotherm and inhibited both the anodic and cathodic partial reactions.