School of Physical Sciences
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Browsing School of Physical Sciences by Author "Akalezi, C. O."
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Item Open Access Adsorption and corrosion-inhibiting effect of dacryodis edulis extract on low-carbon-steel corrosion in acidic media(Elsevier Inc, 2010-09-01) Oguzie, E. E.; Enenebeaku, C. K.; Akalezi, C. O.; Okoro, S. C.; Ayuk, A. A.; Ejike, E. N.The inhibition of low-carbon-steel corrosion in 1 M HCl and 0.5 M H2SO4 by extracts of Dacryodis edulis (DE) was investigated using gravimetric and electrochemical techniques. DE extract was found to inhibit the uniform and localized corrosion of carbon steel in the acidic media, affecting both the cathodic and anodic partial reactions. The corrosion process was inhibited by adsorption of the extracted organic mat ter onto the steel surface in a concentration-dependent manner and involved both protonated and molec ular species. Molecular dynamics simulations were performed to illustrate the process of adsorption of some specific components of the extractItem Open Access Adsorption and corrosion-inhibiting effect of dacryodis edulis extract on low-carbon-steel corrosion in acidic media(Elsevier Inc., 2010) Oguzie, E. E.; Enenebeaku, C. K.; Akalezi, C. O.; Okoro, S. C.; Ayuk, A. A.; Ejike, E. N.The inhibition of low-carbon-steel corrosion in 1 M HCl and 0.5 M H2SO4 by extracts of Dacryodis edulis(DE) was investigated using gravimetric and electrochemical techniques. DE extract was found to inhibit the uniform and localized corrosion of carbon steel in the acidic media, affecting both the cathodic and anodic partial reactions. The corrosion process was inhibited by adsorption of the extracted organic mat ter onto the steel surface in a concentration-dependent manner and involved both protonated and molec ular species. Molecular dynamics simulations were performed to illustrate the process of adsorption of some specific components of the extract.Item Open Access Corrosion inhibiting effect of aframomum melegueta extracts and adsorption characteristics of the active constituents on mild steel in acidic media(Taylor & Francis Group, LLC, 2013) Oguzie, E. E.; Iheabunike, Z. O.; Oguzie, K. L.; Ogukwe, C. E.; Chidiebere, M. A.; Enenebeaku, C. K.; Akalezi, C. O.The extract from the seeds of Aframomum melegueta (AM) was investigated as corrosion inhibitor for mild steel in aerated 1M HCl and 0.5M H2SO4 solutions using gravimetric and electrochemical techniques. AM extract was found to inhibit both the cathodic and anodic partial reactions of the corrosion process, via adsorption of the organic matter on the metal/solution interface, as described by the Langmuir as well as Flory-Huggins adsorption isotherms. Corrosion rates in all systems studied increased with rise in temperature. Increasing the temperature of the system enhanced inhibition efficiency of AM extract in 1M HCl, but decreased efficiency in 0.5M H2SO4. Molecular dynamics simulations were performed to theoretically illustrate the electronic structure and adsorption behaviour of the active constituents of the seeds of Aframomum melegueta; paradol (1-(4-Hydroxy-3-methoxyphenyl)decan-3-one) and shogaol ((E)-1-(4-Hydroxy-3- methoxyphenyl)dec-4-en-3-one) in order to theoretically evaluate their contributions to the corrosion inhibiting action of the extract.Item Open Access Determination of the binding characteristics of dicoumarol to bovine serum abumin by UV/visible spectroscopic method(U. P., 2020) Okoro, O. A.; Onwumere, F. C.; Enebeaku, C. K.; Akalezi, C. O.8-Anilinonaphthalene-1-Sulfonic acid (ANS) was used as a probe to study the binding characteristics of Dicoumarol to Bovine Serum Albumin (BSA). The absorbance of ANS-BSA complex was decreased by the binding of Dicoumarol. This suggests that there is competition between Dicoumarol and ANS for the binding sites in the BSA. It means that ANS and Dicoumarol shared some of the binding sites on BSA. From the scatchard plot for the binding of Dicoumarol to BSA it is seen that Dicoumarol has three high affinity binding sites with association constants Kl=14.5245 x 106,10.6281x106,11.6811x106 respectively, and three secondary binding sites with association constants Kl =14.0084 x 10615.8816 x 106 and 19.2058x106 respectively and numerous low affinity binding sites.Item Open Access Effect of adenine, guanine and hypoxanthine on the corrosion of mild steel in H3PO4(U. P., 2015) Chahul, H. F.; Akalezi, C. O.; Ayuba, A. M.The corrosion inhibition potentials of adenine (AD), guanine (GU) and hypoxanthine (HYP) on the corrosion of mild steel in 0.1 M H3PO4 was investigated at 303 and 333 K using weight loss and potentiodynamic polarization techniques. The results obtained, indicated that AD, GU and HYP inhibited the corrosion of mild steel in phosphoric acid. Results obtained from potentiodynamic polarization studies showed that AD, GU and HYP acted as mixed corrosion inhibitors by retarding both the anodic and cathodic half reactions of the corrosion process. Iodide ions, I- increased inhibition efficiencies of the purines. Adsorption of AD, GU and HYP on the mild steel surface was spontaneous and aligned with Langmuir isotherm model.Item Open Access 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 inhibitionItem Open Access GC-MS analysis of phytochemicals from the extract of Hibiscus sabdariffa grown in Northen Nigeria(U. P., 2021) Okere, G. J.; Oguzie, E. E.; Ogukwe, C. E.; Akalezi, C. O.Hibiscus sabdariffa, also known as Roselle belongs to Malvacae family. It is popularly known in Nigeria as Zobo. It has been used traditionally to cure certain ailments like cold, due to its rich pharmacological potential. Hence this study aimed at validating the pharmacological potential of Hibiscus sabdariffa by identification of the compounds present in its leaves using GC-MS technique. The extract was obtained by heating the leaves in ethanol under reflux. The ethanol extract was then subjected to GC-MS analysis. The constituents were identified by comparing their mass fragmentation (MS) pattern with those gathered in the library of NIST-MS and with those reported in literature. The graph obtained from the study revealed the presence of nine (9) organic compounds in Hibiscus sabdariffa leaf extract (HSLE) namely cyclohexane carboxylic acid ester, cyclopropane carboxylic acid methyl ester, hexanoic acid-4-octyl ester, hexadeca-2-11-dienoic acid, n hexadecanoic acid, oleic acid, octadecanoic acid, E-13-docosenoic acid and E-11-hexadecanal. Oleic acid has the highest peak value with the retention time of 20.711 which makes it the most abundant fraction and the active ingredient in the HSLE. The presence of some of these bioactive compounds has proved the scientific evidences for the antihypertensive and anti-inflammatory properties of the plantItem Open Access Mild steel protection in acidic media using Mucuna pruriens seed extract(U. P., 2016-04-07) Akalezi, C. O.; Ogukwe, C. E.; Ejele, E. A.; Oguzie, E. E.The inhibition of corrosion of mild steel in 1 molar hydrochloric acid solution (1 M HCl) by Mucuna pruriens seed extract (MPSE) was investigated by weight-loss and electrochemical techniques. A significant decrease in the corrosion rate of mild steel was observed in the presence of the investigated additive and the inhibition efficiency was found to depend on the concentration of the MPSE. The potentiodynamic polarization data indicated that this additive was of mixed type, but the anodic effect was more pronounced. Nyquist plots showed that on increasing the MPSE concentration, the charge transfer resistance increased and double layer capacitance decreased. The thermodynamic parameters of adsorption revealed a strong interaction between the MPSE constituents and the corroding metal surface. MPSE lowered the corrosion reaction by blocking the mild steel surface through chemical adsorption. The mechanism of inhibition was discussed in the light of the chemical structure of the four major components of MPSEItem Open Access New amine/phenylglycedyl ether adducts for mild steel protection in 1 M HCl: Experimental and computational study(Wiley-VCH GmbH, 2020) Akalezi, C. O.; Onwumere, F. C.; Alisa, C. O.; Nnanyereugo, M. N.; Oguzie, E. E.The key objective of this study is to ascertain the effect of structure and increased molecular size on the corrosion inhibition potential of two synthesized amines, when compared to their precursor compounds. The product amines were N-(2-hydroxy-3-phenoxy) ethanol amine (NHPE), N,N potentials were assessed using experimental and quantum theoretical modeling and calculations. Some key electronic properties such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies, gap energy, dipole moment and sur face area, were calculated and discussed. The various approaches adopted in this study were in reasonable agreement and the following average inhibition efficiency trend was obtained: NNHPE (75.7%)>NHPE (68.3%)> PGE (64.2) >MEA (61.0).