Browsing by Author "Ogukwe, C. E."
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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 Corrosion inhibition and adsorption of Anthocleista djalonesis leaf extract on the acid corrosion of mild steel(U. P., 2012) Ogukwe, C. E.; Akalezi, C. O.; Chidiebere, M. A.; Oguzie, K. L.; Iheabunike, Z. O.; Oguzie, E. E.Aqueous extracts of the leaves of Anthocleista djalonesis (AD) have been investigated as non toxic corrosion inhibitors for mild steel in acidic environments (1 M HCl and 0.5 M H2SO4, respectively). Corrosion rates were evaluated at 30 oC using the weight loss, electrochemical impedance spectroscopy and potentiodynamic polarization techniques. AD extract was found to inhibit mild steel corrosion in both acidic media via adsorption of the extract organic matter on the metal/solution interface. Polarization data indicate that the extract functioned via a mixed inhibition mechanism, affecting both the cathodic and anodic partial reactions of the corrosion process. Molecular dynamics (MD) simulations were performed to illustrate the adsorption process of some specific components of the extract.Item 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.Item 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 Phytochemistry and antimicrobial properties of gmelina arborea (Verberaceae) ethanolic leaf extract and its secondary metabolites(MEDWIN Publisher, 2020-12-04) Ijezie, M. K. L.; Ezirim, S.; Azih, I.; Ogukwe, C. E.; Akalezi, C. O.The aim of this study was to determine the antimicrobial potential of Gmelina arborea ethanolic leaf extract which is used in traditional medicine for treating different ailments such as hallucinations, piles, abdominal pains, burning sensation, diabetes and fever. It is also intended to study its acidic, basic and neutral metabolites with a view to identify the phytochemical compounds responsible for the observed antimicrobial properties. Phytochemical screening was carried out on the airdried ethanolic leaf extract and its secondary metabolites in the Research Laboratory of Phytochemistry/ Chromatography, N4 Alaenyi Street, Owerri, Imo State, Nigeria. The antimicrobial study was carried out using the Agar disc diffusion method and determination of Minimal Inhibitory Concentration (MIC) in the department of Microbiology, Federal Medical Centre, Owerri, Imo State, Nigeria. The ethanol leaf extract and its secondary metabolites (acidic, basic and neutral) were prepared and assayed for antimicrobial activities. The test microorganisms used were Streptococcus spp, Staphylococcus aureus, Salmonella spp, Escherichia coli and Coliform bacilli. Inhibition zone diameter was used as a measure of the antimicrobial activity. The results of the antimicrobial screening of the crude extract and metabolites showed that the crude extract, acidic and neutral metabolites possessed antimicrobial activity to various extents against the microorganisms tested whereas the basic metabolite showed no activity at all. The results showed that the crude extract exhibited its greatest activity against Streptococcus spp, Staphylococcus aureus and Escherichia coli with inhibition diameter of 20 mm at 1.0 mg/ml and MIC of 0.5 mg/ml. The least activity was against Salmonella spp with inhibition zone diameter of 15 mm and MIC of 0.5 mg/ml. The acidic metabolite exhibited its greatest activity against Escherichia coli with inhibition zone diameter of 35 mm at 1.0 mg/ ml and MIC of 0.25 mg/ml. The least activity was against Staphylococcus aureus and Salmonella spp with inhibition zone diameter of 25 mm at 1.0 mg/ml and MIC of 0.5 mg/ml respectively. The neutral metabolite exhibited its greatest activity against Salmonella spp and Coliform bacilli with inhibition zone diameter of 30 mm at 1.0 mg/ml and MIC of 0.5 mg/ml. The least activity was against Staphylococcus aureus with inhibition zone diameter of 22 mm at 1.0 mg/ml and MIC of 0.5 mg/ml. The phytochemical screening results showed the presence of alkaloids, flavonoids, tannins, saponins, cyanogenic glycosides, steroids, carbonyl compounds and carbohydrates. Saponins, carbonyl compounds and carbohydrates were shown to be much higher in concentration than other phytochemicals. The results obtained in this study confirm the antimicrobial properties of Gmelina arborea leaf extract and suggest that this property resides in the acidic and neutral metabolites since the basic metabolite showed no activity at all. The study supports the use of this plant in folk medicine for treatment of ailments such as stomach disorders, healing of wounds, burning sensation and fever.