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
Ammonia variations in Owerri metropolis and ecological impact
(Conscientia Beam, 2020-04-15) Nnadozie, C. F.; Nkwoada, A. U.; Akagha, C. I.
Ammonia emissions inventory is rarely reported in Nigeria and when at high levels is toxic to animals including humans. It is instructive to evaluate the levels of ammonia in metropolitan area as a priority to promote a clearer understanding of its distribution and interaction. The study investigated the levels of ammonia in different parts of Owerri Metropolis and its ecological impact. Ambient atmospheric NH3 concentrations have been measured for Owerri metropolis, away from point sources, for a period of three consecutive months in 2018 calendar year. Measured lowest mean NH3 concentrations have been in August at 0.04633 mg/L, which exceeded the critical loads and occupation exposure limits. There has been no significant change in the spatial variation in NH3 concentrations between the months albeit different locations varied significantly. The ecosystems where lichens and bryophytes are key species within the studied area may be under threat from loss of biodiversity while levels of human exposure to NH3 are completely unacceptable and require reducing and controlling measures. Hence, excess ammonia will induce elevated nitrification and denitrification driving higher greenhouse gas emissions
Open Access
An experimental investigation of pristine barite adsorption on sodium oleate and sodium palmitate
(Science Publishing Group, 2018) Nwoko, Christopher Ikpe Amadi; Nkwoada, Amarachi Udoka; Okoji, Josephine,; Opah, Solomon
Characterization of the pristine barite mineral was established using a scanning electron microscope (SEM) and Fourier Transform Infra-Red (FTIR). Barite was applied for sodium oleate and sodium palmitate adsorption in aqueous solutions. Equilibrium adsorption data were fitted into two adsorption isotherms, three kinetic models and thermodynamic study. The concentration of the ion and pH in the solution proved to be a controlling factor in the adsorption process. Sodium oleate and sodium palmitate soaps adsorbed strongly onto the barite mineral at pH 9 and a temperature of 293k. They result was affected by the high bulk density and chemical resistance nature of barite indicated by successive increase in dosage amount. The effect of concentration and time typically gave a C-type adsorption isotherm. Adsorptive isotherm showed that sodium palmitate adsorption over natural barite was better described by the Langmuir adsorption isotherm while oleate desorption gave a good fitting with Freundlich isotherm. The adsorptive kinetics of sodium palmitate fitted well into pseudo 1st order and 2nd order kinetics. Intra particle diffusion was not the rate-determining step. Thermodynamic study showed a physiosorption that was exothermic. Hence the findings showed that pristine barite absorbs at optimum pH and temperature of 9 and 293k.
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.
Open Access
Characterization of selected honey in SouthEast Nigeria: Theoretical translation
(U. P., 2017) Nwoko, C. I. A.; Nkwoada, A. U.; Ubeh, E. O.; Njoku, A.
With the vast honey bee species producing honey for international export and consumption in Nigeria, there is need for theoretical translation of quality assessment and characterization of honey for human consumption. The physicochemical and mineral contents of some selected honey in the five South east geopolitical states of Nigeria was performed for above mentioned application. The results were evaluated with 3D plot to identify the statistical significance of the parameters analyzed. The levels of glucose and fructose were accepted by codex alimentation standard and rejected samples B, C, and G. A correlation of similar botanical origin was demonstrated in sample B, C and G and similarly observed in their moisture content been > 21%. The pH and electrical conductivity showed no significant variation. The codex hydroxyl methyl furfural standard identified samples B, E and L to be “aged honey” or falsified honey in circulation. The 3D plot showed the significant variation of hydroxyl methyl furfural content of samples. A hypothesis was observed when the samples and previously analyzed Nigerian samples were compared; metal concentration levels of Group 1 elements > Group 2 > transition metals in Nigerian honey and formed an identification trend.
Open Access
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
Chemo-remediation of crude oil polluted soils obtained from recent polluted site in oil producing environs in Rivers State Nigeria
(eSciPub, 2019) Iwu, Irenus Chinonye; Onu, Uchenna Lynda; Nkwoada, Amarachi; Onwumere, Fidelis
The chemo- remediation of crude oil polluted soils from recent pollution sites in oil producing environs in River state was carried out by both in vivo and in vitro methods using macro-soil nutrients ( Nitrate, Phosphate and Potassium) as index for remediation. The soil samples were labeled A, B, C, D1 to D6, sample A was obtained from pollution free site used as a control.Sample C was crude oil polluted soil not treated with surfactant, sample B was crude oil polluted soil leached with surfactant and not mineralized. Samples D1-D6 were polluted soil samples, leached with surfactant and mineralized with fertilizer. The samples were leached with linear alkyl benzene sulphonate (LABS) and later mineralized with Nitrate, Phosphate and Potassium (N.P.K) fertilizer and returned to the site of excavation to fallow for four months. The samples were later re-excavated and taken to the laboratory for analysis. Nitrate and phosphate contents were obtained with the aid of spectrum lab 725 UV visible spectrophotometer and potassium content was determined by use of a flame photometer. Results showed that sample A had nitrate concentration of 330ppm, sample B had concentration of 21ppm, sample C had a concentration of 54ppm while samples D-D6 had concentrations ranging from300ppm to 420ppm.Similarly, The phosphate concentrations were 68.50ppm, 17.00ppn, 28.00ppm and 48.80-136.40ppm for sample A, B, C.D1-D6 respectively. The potassium concentrations were not different as concentrations of 46ppm, 12ppm, 28ppm and 38ppm-64ppm was recorded for samples A, B, C, and D1-D6 respectively. These results revealed that crude oils not only renders soils unusable but also destroys the nutrient availability in soils. The soils can therefore quickly be reclaimed by leaching them with surfactants and mineralizing them with adequate inorganic fertilizer.
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