School of Physical Sciences

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Open Access
Natural products for materials protection: Corrosion and microbial growth inhibition using capsicum frutescens biomass extracts
(American Chemical Society, 2012-12-17) Oguzie, Emeka E.; Oguzie, Kanayo L.; Akalezi, Chris O.; Udeze, Irene O.; Ogbulie, Jude N.; Njoku, Victor O.
Extracts of the fruit of Capsicum frutescens (CF) were assessed for anticorrosion and antimicrobial activity. The anticorrosion effect of the ethanol extract on low carbon steel in acidic media was studied experimentally using gravimetric, impedance, and polarization techniques, while the antimicrobial efficacy of ethanol, methanol, water, and petroleum spirit extracts respectively against the corrosion-associated sulfate reducing bacteria (SRB), Desulfotomaculum species, was assessed using the agar disc diffusion method. CF extract effectively inhibited both corrosion and SRB growth due to the action of the phytochemical constituents present therein, including alkaloids (8.8%), tannins (0.4%), and saponins (39.2%). The corrosion process was inhibited by adsorption of the extract organic matter on the steel surface, whereas the antimicrobial effect results from disruption of the growth and essential metabolic functions of the SRB. Molecular dynamics (MD) simulations were performed to theoretically illustrate the electronic structure and adsorption behavior of the active alkaloidal constituents of CF extract, capsaicin and dihydrocapsaicin, and afforded molecular level insights on their individual contributions to the corrosion inhibiting action of the extract
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
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
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
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
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 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
Gas chromatography-spectrophotometric (GC- MS) studies on therapeutic potentials of costus afer ker gawl leaves
(U. P., 2018) Ogukwe, Cynthia E.; Akalezi, Chris O.; Anukam, Basil N.; Idika, Idika D.; Awosu, Emmanuel A.
The ethanol leaf extract of Costus afer was subjected to qualitative phytochemical screening, column chromatography and GC-MS analysis to ascertain the compounds that exhibit anti-inflammatory and anti-oxidant properties as claimed by herbalists and traditionalists. The presence of Flavonoids, Saponins, Steroids, Terpenoids and Anthraquinones were indicated in the phytochemical screening. Eluent fractions from the moderately polar solvent of the column chromatography generated Gas Chromatogram that had 6 prominent peaks indicated that the prevailing compounds were oxirane hexadecyl (4.09%), n-Hexadecanoic acid(3.68%), 9-octadecenoic acid (z)- methyl ester(3.08%), 6-octadecenoic acid (z)- (13.49%) and two pentacyclic compounds identified as Cycloursan-3-ol, acetate (36.17%) and lupenone (39.50%). The two pentacyclic compounds confirmed the presence of steroids and validates the use of C.afer leaf for anti inflammatory therapy and as an antidote for acute toxi.
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
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 plant
Open Access
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.
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
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).
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 MPSE
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
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
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
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.
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
Ground water quality assessment of newly created Local Governments in Nigeria – A case of Nkwerre, Local Government, Imo State
(U. P., 2013) Onunkwo, A. A.; Uzoije, A. P.; Onyekuru, S. O.; Agumanu, A. E.; Chinaemelu, E. S.
The creation of new Local governments in Nigeria brought about new socio-economic order such as over population, pressure on the available facilities and new land use elements with their generated wastes. There is the need to examine the present status of the underground water resource of these regions for effective development of the newly created local governments. For this reason it becomes necessary to carry out the ground water quality assessment of newly created local governments in Nigeria as a source of data base for development using Nkwerre Local Government Area of Imo State as a case study. The study was carried out by acquiring geologic and topographic maps of the area for easy identification of sample population areas and to identify geological boundaries, Spring out crops, landuse element especially waste dump sites. Agricultural and industrial projects were visited and examined. A total of 6 water samples from bore holes within six communities were collected and analyzed. Analysis was carried out using atomic absorption spectroscopy for major cations. Heavy metal analysis was undertaken using spectrophometer, potassium was determined using flame photometer method, concentration of total iron (Fe2+) was determined calorimetrically using spekker absorption meter while total dissolved solids (TDS) was determined using glass fiber filter. Turbidity. Physical parameters like ph and dissolved oxygen were measured insitu in the field with appropriate standard maters. The result of geochemical analysis shows that the water has high turbidity, high iron, slightly acidic, soft portable and suitable for industrial, agricultural and domestic purposes, but requires treatment to reduce iron and turbidity. The water type belongs to a no dominant cation and anion type and can be grouped as Mg2+-Ca2+ - So42+ - HCo3 water. North western segment in infested with ecoli bacteria. The general pollution index of 0.777 shows that the water in the area is ideal for various purposes, however, remediation of iron, turbidity and bacteria presence is proposed.