School of Physical Sciences

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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 extract
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.
Open Access
Adsorptive removal of methylene blue from aqueous solution using agricultural waste: Equilibrium, kinetic and thermodynamic studies
(U. P., 2015) Enenebeaku, K. Conrad; Okorocha, J. Nnaemeka; Akalezi, O. Chris
The potential of raw corn cobs (RCC) powder, for the removal of methylene blue (MB) dye from aqueous solution was investigated. The adsorbent was characterized by FTIR and SEM analysis. Batch adsorption studies were conducted and various parameters such as contact time, adsorbent dosage, initial dye concentration, pH and temperature were studied to observe their effects in the dye adsorption process. The optimum conditions for the adsorption of MB onto the adsorbent (RCC) was found to be: contact time (30mins), pH (10.0) and temperature (343K) for an initial MB dye concentration of 100mg/l and adsorbent dose 1.0g. The experimental equilibrium adsorption data fitted best and well to the Freundlich and Halsey isotherm models. The maximum adsorption capacity was found to be 18.28mg/g. The kinetic data conformed to the pseudo-second-order kinetic model, suggesting that the rate limiting step may be chemisorptions. Adsorption mechanism was investigated with intra-particle diffusion model and it indicated that intra-particle diffusion was not the rate determining step. Thermodynamic quantities such as Gibbs free energy (∆G0), enthalpy (∆H0) andentropy (∆S0) were evaluated. The negative values of ∆G0 and the positive value of ∆H0 obtained indicated the spontaneous and endothermic nature of the adsorption process while the positive ∆S0 value obtained indicated increased randomness during the adsorption process.
Open Access
Antibacterial activity and identification of metabolites from the semi-purified fraction of chrysophyllum albidum leaf (African Star Apple)
(U. P., 2020) Azih, Ifeanyi; Ijezie, Magnus; Ugariogu, Sylvester N.; Akalezi, Christogonus O.
The medicinal uses of natural products especially medicinal plants have increased tremendously due to the multidrug resistance of some microorganisms and due to the availability and affordability of these plants. This study was aimed at the identification of metabolites from the fractions of Chrysophyllum albidium and their antibacterial activity. The phytochemical analysis and antibacterial analysis were done using standard methods; Harborne and Agar-disc diffusion methods, respectively. The metabolite identification was done using infra-red (IR) and gas chromatography – mass spectrometry (GC-MS). The preliminary result of the antibacterbial screening showed that the neutral metabolite possessed the highest antibacterial activity and was then chosen for the IR and GC-MS study and purified using preparative thin layer chromatography. Various fractions were obtained from the chromatographic purification and in particular N3 fraction demonstrated the highest antibacterial activity against the test microbes with the zones of inhibition indicated against the test organism as follows: Streptococcus spp (18 mm), Staphylococcus aureus (20 mm), Salmonella typhi (25 mm), Escherichia coli (20 mm) and no inhibition zone against Enterobacter cloacae. The results confirm that the plant has some antibacterial activity.
Open Access
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.
Open Access
Application of geographic information system (GIS) in composite land capability index mapping of a developing country (A case study of Enugu area, South -Eastern, Nigeria,
(U. P., 2011) Onunkwo, A. A.; Ibeneme, S. I.; Onyekuru, S. O.; Uzoije, A. P.
Enugu, the area under study is experiencing a high rate of population growth. Problems of housing, on employment, waste disposals and the general lowering of standard of living are always associated with over population. It has therefore become necessary to map out areas of residential, industrial and waste disposal land use for future utilization. Land capability index mapping using geographic information system(GIS) is one of the appropriate tools for solving these impending problems. Land capability index mapping of Enugu environs in composite form has been undertaken using Arc view 3.2 academic, excel statistical software and GIS Authcard software. A total of 12 land use determinants have been selected as the thematic data layers and the basic factors influencing the choice of waste, residential and industrial land use. These themes which are in map form are slope, water table, surface and subsurface water conditions, elevation, geology, soil, drainage and geo-structural stability(fault, erosion, landslide and flooding). These maps have been scanned, geo-referenced , digitized and polygonized using authcard drawing capacities to convert them to vector formats and later exported to arc view software environment for analysis. The thematic layers were weighted using the criteria obtained from fieldwork, laboratory and literature surveys. The thematic layers were further subjected to overlays using the arcview software overlay model builder. The operation yields layers showing areas of preferred waste disposal, residential and industrial landuse options in a map form. Three different maps of land use options(waste, industrial and residence) were produced. Areas of varying suitability were isolated, 3 each for waste, residence and industry, indicating suitable, low suitability and unsuitable areas respectively. The three land use maps were superimposed to obtain a single one appropriate for purposes of urban environmental planning.
Open Access
Bioassay-guided isolation, purification and charaterization of antimicrobial compound from acidic metabolite of piper umbellatum seed extract
(Canadian Center of Science and Education, 2014) Ejele, A. E.; Akalezi, C. I.; Iwu, I. C.; Ukiwe, L. N.; Enenebaku, C. K.; Ngwu, S. U.
The antimicrobial potential of ethanol extract of Piper umbellatum seeds and its acidic, basic and neutral metabolites were evaluated using the disc diffusion method. The results showed that the acidic and neutral metabolites exhibited greater antibiotic activities against the tested microorganisms; Coliform bacilli, Salmonella typhi and Staphylococcus aureus and gave inhibition zone diameters greater than 28 mm against both C. bacilli and S. aureus. These results were interpreted in terms of differences in phytochemical composition of these metabolites and indicated that an effective anti-Staphylococcal drug could be developed from P. umbellatum extract for chemotherapy of diseases caused by S. aureus, which is known all over the world to develop resistance to most potent antibiotic drugs. Chromatographic purification of the acidic metabolite gave five fractions whose antimicrobial potential against some pathogens was evaluated and compared with Amoxil (a positive standard antimicrobial drug). The results showed that all the chromatographic fractions possessed inhibitory activities against the tested microbes. Spectroscopic analysis of IR, 1H– and 13C–NMR data suggested that the active principle in acidic metabolite of P. umbellatum could be Naringin, a naturally occurring polyphenol and antibiotic drug.
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Chemical interactions of synthetic and natural remediating agents with crude oil on agricultural soil
(Pelaga Research Library, 2014) Ogukwe, Cynthia E.; Oze, Gabriel O.; Enenebeaku, Conrad E.; Akalezi, Chris O.
Altered chemical system of an Agricultural Soil resulting from crude oil spillage was subjected to NPK fertilizer and compost manure for remediation. The effect of the remediating agents was observed in-situ by examining the soil parameters before, during and after the interactions. An Ultraviolet(UV) Spectrophotometer V180 was used for the evaluation of the Total Hydrocarbon content of the soil. Remediated state of 92.5% TPH reduction, pH, moisture balance and soil restoration was achieved with a combination of 150g NPK fertilizer and 150g compost manure per meter square (300g remediating agent /m2) plot of land, after seven weeks of application.
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.
Open Access
Corrosion inhibition and adsorption behavior of methionine on mild steel in sulfuric acid and synergistic effect of iodide ion
(Elsevier Inc., 2007) Oguzie, E. E.; Li, Y.; Wang, F. H.
The corrosion inhibition of mild steel in sulfuric acid by methionine (MTI) was investigated using electrochemical techniques. The effect of KI additives on corrosion inhibition efficiency was also studied. The results reveal that MTI inhibited the corrosion reaction by adsorption onto the metal/solution interface. Inhibition efficiency increased with MTI concentration and synergistically increased in the presence of KI, with an opti mum[KI]/[MTI] ratio of 5/5, due to stabilization of adsorbed MTI cations as revealed by AFM surface morphological images. Potentiodynamic polarization data suggest that the compound functioned via a mixed-inhibition mechanism. This observation was further corroborated by the fit of the experimental adsorption data to the Temkin and Langmuir isotherms. The inhibition mechanism has been discussed vis-à-vis the presence of both nitrogen and sulfur atoms in the MTI molecule
Open Access
Corrosion inhibition of aluminium in acidic and alkaline media by Sansevieria trifasciata extract
(Elsevier Ltd, 2007) Oguzie, E. E.
The inhibitive action of leaf extracts of Sansevieria trifasciata on aluminium corrosion in 2 M HCl and 2 M KOH solutions was studied using the gasometric technique. The results indicate that the extract functioned as a good inhibitor in both environments and inhibition efficiency increased with concentration. Synergistic effects increased the inhibition efficiency in the presence of halide additives. Temperature studies revealed a decrease in efficiency with rise in temperature and corrosion activation energies increased in the presence of the extract. A mechanism of physical adsorption is proposed for the inhibition behaviour. The adsorption characteristics of the inhibitor were approxi mated by Freundlich isotherm
Open Access
Corrosion inhibition of aluminium pigments in aqueous alkaline medium using plant extracts
(Canadian Center of Science and Education, 2012) Akalezi, Chris O.; Ogukwe, Cynthia E.; Enenebaku, Conrad K.; Oguzie, Emeka E.
This work examines the efficacy and efficiency of Bucolzia coriacea (BC) and Cninodoscolus chayansa (CC) plants extracts as corrosion inhibitors for aluminum pigments using gas volumetric technique. The results obtained from this study indicate that all the extracts inhibited the corrosion process by extending the latency periods of the aluminum pigment-extract mix far beyond that of the bare aluminum pigment. Inhibition efficiency obtained was not only concentration dependent but also plant dependent and followed the order: BC>CC. A linear correlation was obtained between inhibition efficiency and duration of latency for each extract. Molecular modeling was used to evaluate the structure, electronic reactive parameters of the plant extracts in relation to their effectiveness as corrosion inhibitors.
Open Access
Corrosion inhibition properties of Gongronema latifollium extract in acidic media
(U. P., 2016-06-04) Akalezi, C. O.; Ogukwe, C. E.; Ejele, E. A.; Oguzie, E. E.
Corrosion inhibition of mild steel in 1 M HCl acid solution by Gongronemena latifolium (GL) extract 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 GL extract. 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 extract concentration, the charge transfer resistance increased and double layer capacitance decreased. Adsorption of inhibitor GL extract on the mild steel surface is found to obey the Langmuir adsorption isotherm. Increase in activation energy of corrosion process in presence of GL extract indicates physical adsorption.
Open Access
Corrosion inhibitive effect and adsorption behaviour of hibiscus sabdariffa extract on mild steel in acidic media
(UP, 2008) Oguzie, E. E.
The inhibiting action of the calyx extract of Hibiscus sabdariffa on mild steel corrosion in 2 M HCl and 1 M H2SO4 solutions was assessed using a gasometric technique. The results demonstrate that Hibiscus sabdariffa extract suppressed the corrosion reaction in both acid media and inhibition efficiency increased with extract concentration with slightly higher values obtained in 1 M H2SO4. Synergistic effects increased the efficiency of the extract in the presence of halide additives. Adsorption characteristics of the extract were approximated by the Langmuir isotherm. The inhibition mechanisms, estimated from the temperature dependence of inhibition efficiency as well from kinetic and activation parameters show that the extract functioned via mixed inhibition mechanism. It is suggested that molecular as well as protonated organic species in the extract contribute to the observed inhibiting action
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.
Open Access
Effect of 2-amino-3-mercaptopropanoic acid (cysteine) on the corrosion behaviour of low carbon steel in sulphuric acid
(Elsevier Ltd., 2007) Oguzie, E. E.; Lia, Y.; Wang, F. H.
The effect of cysteine (cys) on the corrosion of low carbon steel (LCS) in sulphuric acid solution was investigated using electrochemical and scanning electron microscopy (SEM) techniques. Electrochemical impedance spectroscopy (EIS) results reveal that the presence of cys at low concentrations (0.1–0.5mmolL 1) promoted the LCS corrosion process, whereas an inhibiting effect was observed at higher concentrations (1.0–5.0 mmolL 1), which was enhanced on deaeration of the test solution. Polarization results revealed that cys actually inhibited the cathodic process at all concentration but exerted a stimulating effect on the anodic metal dissolution reaction. Despite the cathodic inhibiting effect, the polarization resistances at low cys concentrations were less than that in the blank acid. This suggests that the anodic reaction was the predominant influence determining the corrosion rates in the presence of cys. This has been discussed vis-` a-vis the catalytic effect of the Fe–cys complex, which turns the Fe surface more electrochemically active
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.
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 inhibition
Open Access
Engineering properties and uses of soil derive from maastritchian Ajali formation in a part of Se Nigeria
(European Centre for Research Training and Development UK (www.eajournals.org), 2014-12) Onunkwo, A. A.; Uzoije, A. P.; Onyekuru, S. O.
The study is necessitated by the recent move by Imo State government of Nigeria to raise Okigwe town to urban status. Ajali Formation being the prominent geological terrain in Okigwe area, most structures would be erected on the soil derived from it. The parameter measured include grain size, atterberg limits, and compaction, shear strength, permeability and porosity as well as bulk density. The result shows that the soil underlain by Ajali Formation within Okigwe area is sandy silt with low clay content and has plasticity index, bulk density, porosity and permeability values of 9.65%, 2.06%,kg/m3, 0.45 and 0.35cm/s respectively. The value for the optimum moisture content (OMC) maximum dry density(MDD) shear strength, angle of internal friction are 13.5%, 2.06kg/m3, 106.86KN/M2 and 28.4o. These values indicate that the soil derived from Maastrichtian Ajali Formation within Okigwe area of south eastern Nigeria is of high strength, porous and permeable and can be used as a recharge site for regional aquifer, but cannot be used as a waste disposal area or for road construction. The soil due to its low plasticity index with no swelling characteristics and high shear strength is a good site for building foundations, but cannot be used in dam construction. It is ideal for projects requiring good drainage and embankments. However, for the soil to be used in any engineering construction works, it has to be compacted to its maximum dry density value of 2.06kg/m3 within the range of optimum moisture content of 13.5% as to achieve maximum strength.
Open Access
Equilibrium, thermodynamic and kinetic studies on adsorption of zinc (II) from solutions using different low-cost adsorbents
(Open Science, 2015-11-05) Njoku, Pascal C.; Atu, A. Ayuk; Atulegwu, P. Uzoije; Justus I. Okolie
Many industrial wastewaters contain numerous toxic metals such as zinc, which must be removed before reuse of the water or discharge into the environment. In this present study, unripe plantain peel activated carbon (UPPAC), pineapple peel activated carbon (PPAC) and commercial activated carbon (CAC) were utilized as low cost adsorbents for the removal of Zn (II) from aqueous solutions. Batch adsorption methodology was used to evaluate the effect of solution pH, initial metal ion concentration, adsorbent dose, contact time and temperature on adsorption. Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectrophotometer (FTIR) were used to characterize the adsorbents. The equilibrium isotherm data were analyzed using the Langmuir, Freundlich and Temkin isotherm model. The kinetic data were analyzed using the pseudo-first order, pseudo-second order equations, Elovich equation and intraparticle rate equation. Maximum adsorption of Zn (II) on UPPAC, PPAC and CAC (82.45%, 89.95% and 93.45%) was observed at pH 6 and pH 7. The adsorbed amount of Zn (II) increased with increase in contact time and reached equilibrium within 180 minutes. The maximum adsorption was found to be 200 mg/L in the studied range (200 – 1000 mg/L). The adsorption capacity and percent removal of Zn (II) were found to increase with increase in temperature. The Freundlich isotherm models provided the best fit to the experimental data for Zn (II) as indicated by the regression coefficient values (R2> 0.97). The pseudo-second order equation gave the best fit to the experimental data for the metal ion (R2 > 0.99). Thermodynamic analysis showed a spontaneous adsorption process as negative values of ∆Go (-1.269 to -5.530) were obtained at all temperatures. The positive enthalpy change ∆Ho, 18.00, 20.46 and 23.45 kJ mol-1 for UPPAC, PPAC and CAC indicated an endothermic process. A highly disordered process was indicated by the positive entropy change ∆So .