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- ItemOpen AccessKinetics and Mechanism of Aquation of Tris (3, 4, 7, 8 - Tetramethyl - 1, 10 - Phenanthroline) Iron (II) Suphate in Aqueous Sodium Lauryl Sulphate.(Obafemi Awolowo University, 1984) Soriyan, Oladega Omopariola; Ige, JideIn this thesis we report the kinetics and mechanism of the aquation of tris(3, 4, 7, 8-tetramethyl1,10 phenanthroline) Iron(II) sulphate in aqueous micellar solution of Sodium Lauryl sulphate(NaLS). The aquation is inhibited by NaLS in the presence of H+, OH- , SO42- , NH4+ and tetraethylammonium ion (Et4N*). The inhibition is attributed to the stable association or binding between the complex and the micelle and the decrease in the activity of water in the micellar phase. The partitioning of the substrate between the bulk water solution and the micellar phase is in favour of the latter. The kψ-[surfactant] profiles are structured due to micellar evolution. A mechanism which fits kinetic data at low surfactant concentration is proposed. From the rate law obtained and kinetic data observed, the micelle-complex binding constant K1 and micelle-acid binding constant K3 are calculated to be 2.81 x 105 and 13.80 mol -1dm3 respectively in acid medium. Using Scat chard method, K1 in neutral medium is 3.95 x 105 mol-ldm3. The decrease in K1 in acid medium is due to competition for the binding sites on the micelle by the acid proton H+ and the complex ion. The rate of reaction is a function of equilibrium distribution of all the substrates between the micellar phase and bulk water phase. The evolution of the micelle with respect to the c.m.c. is also a function of the nature of the substrate present in solution. Calculated activation parameters suggest strong steric stabilisation of the transition state with respect to enthropy. The magnitudes of activation parameters ΔH# and ΔS# are functions of the surfactant concentration. ΔH# (KJ mol-1) and ΔS# (JK-1 mol-1) for the aquation in 0.00, 1.0 x 10-4 and 2.0 x 10-4 mol dm-3 NaLS are respectively: 100.40 ± 2.04, 22.58 ± 0.16; 111.48 ± 1.15, 48.94 ± 0.09; 119.19 ± 1.15, 67.16 ± 0.09 in 1.00M H2SO4.
- ItemOpen AccessChemical Examination of the Leaves of AZADIRACHTA INDICA A. JUSS. (NEEM) for Insect Anti-Feedants.(Obafemi Awolowo University, 1985) Adesanya, Adepeju Olubamwo; Ogunkoya, L.The chemistry of the extractives from the leaves of Azadirachta indica and its closely related species, Melia azedarach is reviewed. Cold methylated spirit was resolved into four fractions on the basis of their solubilities in the non-polar solvent hexane and in aqueous alkali. Each of these fractions was tested for repellent activity on the bean seed weevil; Callosobruchus maculatus. three of the fractions inhibited the emergence of the bean seed weevils and were therefore considered to possess the expected insect repellent activity. From one of these fractions, thick oil was isolated after purification using idolumn and thin layer chromatographic methods. Spectroscopic studies of this thick oil revealed the presence of one major compound whose molecule contained an ester group and a C=C in conjugation with another Pi electron system.
- ItemOpen AccessChemical Studies on Human Breast Milk.(Obafemi Awolowo University, 1985) Jeje, Temitayo Enitan; Oke, O. L.The variation in some chemical constituents of human breast milk from the first month to the fifteenth month of' breast-feeding was studied. Deductions were then made as to the effect this variation had on the nutritional status of the children whose mothers' breast milk was collected. This study was done on milk samples collected from nursing mothers of children who were healthy and of those who were malnourished. The results obtained showed a decrease in the protein and immunoglobulin contents for both groups studied. An increase in the lactose content was observed for the healthy group while no definite trend could be discerned in the malnourished group. The average values obtained for proximate compositions were: Protein: 1.30+0.18g/100ml; 1.27+0.30g/100ml; Fat: 1.85+1.06%; 1.39+37%; Lactose: 5.77+2,5g/100ml; 7.19+1.73g/100ml; pH: 7.03+0.22; 6.54+0.30: For the healthy and malnourished groups respectively. Values obtained for immunoglobulin were: IgA 117.00g/100ml to 100.00g/100ml and 25.00g/100ml to 6.00g/100ml; IgG 27.00g/ 100m1 to 16.00g/100ml and 12.00g/100ml to 8.00g/100ml, for the healthy and malnourished groups respectively. The thiocynate content of the analysed milk varied from a minimum of 0.35, u mole/1 to a maximum of 0.90, u mole/1, for the healthy group and for the malnourished group from a minimum of 0.10, u mole/1 to a maximum, 0.75 p mole/1. Amino acid values for the malnourished group were slightly higher than those for the Healthy group with the exception of lysine. The limiting amino acid in both groups was methionine. The children in this study were observed to grow well during the first four months of life until retardation in growth started reaching a maximum at the sixth month. This period was observed to correspond with the weaning period, when maize gruel (ogi) or Baby Custard diet had been introduced. The extent and duration of these food supplements presumably tend to influence to a large extent the eventual nutritional status of the infant.
- ItemOpen AccessComparative Analytical Methods for the Monitoring of Polyaromatic Hydrocarbons in Nigerian Crude Oil.(Obafemi Awolowo University, 1985) Fakankun, Olusola Akanbi; Adeyemi, S. A.This study involves the use of comparative analytical techniques for the monitoring, determination and characterization of poly-aromatic hydrocarbon compounds found in Nigerian crude oils collected from Bonny, Brass, Escravos, Forcados, Pennington and Qua-Iboe Terminals. The analytical approach adopted involved the use of conventional fluorimetry, synchronous excitation, nuclear magnetic resonance, high performance liquid chromatography coupled to ultraviolet and fluorescence detectors, and gas chromatograph - mass spectrometry techniques. Certain physicochemical measurements of the crude oils such as viscosity, elemental analysis, specific gravity and refractive index were also measured. All the crude oil samples from the seven terminals were found to contain about the same number of isomeric polynuclear hydrocarbons, for instance, the major isomeric compounds found in most of the crude oils analysed were carbazole, benzofluorene, naphthalenes, phenanthrenes, anthracenes, benzo(a, b, c)pyrenes, C1- C3 akylbencenes, and C1 - C4 alkylnaphthalenes. From the results obtained an average of forty polynuclear aromatic hydrocarbons could be classified as priority pollutants in the Nigerian crude oil. Among the techniques used, HPLC-UV happens to be the most suitable technique in that many more compounds were identified relative to other techniques such as GC - MS, fluorescence, However, the GC - MS result obtained from Ebubu flow station sample was used as a confirmatory guide to the comparative analytical techniques employed in this study.
- ItemOpen AccessPeriodate Oxidation of Tris-(4,4'- Dimethyl-2.2' Bipyridine) iron (ii)(Obafemi Awolowo University, 1986) Ayodele, Ezekiel TemitayoThis work covers the periodate oxidation of tris-(4,4'-dimethyl-2,2'-bipyridine) iron (II) complex. The reactive periodate species postulated from the ionic strength dependence in acid medium are IO3+ H6IO6 or I(OH)6+. In both acid and neutral med the ionic strength dependence of observed rate constant was found to fit into Bronsted Bjerrum Christiansen formulation while in alkaline medium significant deviation was observed. In acid medium, a reaction order of 0.2 obtained with respect to the periodate ion species shows that the reaction proceeds via a complex mechanism. The reaction was found to be acid dependent, and protonation of the periodate or complex occurs prior to electron transfer and the reaction proceeds by outer-sphere mechanism. In alkaline medium, the formation of mesoperiodate and other polymeric species for which the accompanying equilibria are not precisely known makes the reaction more complex and the postulation of a reasonable mechanism impossible. In neutral medium as in acid medium, reaction proceeds through the formation of an outer-sphere complex. At low periodate ion concentration, a stoichiometry of 1:1 with respect to the complex and periodate was obtained while at high periodate ion concentration the stoichiometry is 3:1.
- ItemOpen AccessPreparation and Conductivity Measurements of some Metal 9, 10- Dihydroxyoctadecanoates(Obafemi Awolowo University, 1986) Mbaneme, Prince Chukwulozie; Akanni, M.S.The preparation of 9,10-dihydroxyoctadecanoic acid is carried out using oleic and elaidic acids as reported by Swern and Co-workers. Characterization of the acids is done by taking the melting points and the infrared spectra. The 9,10-dihydroxyoctadecanoic acid obtained from Oleic acid is used in preparing lead(II), Zinc(II), Mercury(II) and Cadmium(II) 9,10-dihydroxyoctadecanoates. The identity of lead(II) and Zinc(II) 9,10-dihydroxyoctadecanoates is established by the results of the melting points, elemental analysis, IR and NMR spectra. The electrical conductances of the pure soap and some binary mixtures with the corresponding metal Octadecanoates are measured. It is found that while the plots of logarithm of conductivity against inverse temperature of the lead(II) 9,10-•dihydroxyoctadecanoate (Pb(OH)2A2) show a maximum, that of Zinc(II)9,10-dihydroxyoctadecanoate(Zn(OH)2A2 and its binary mixtures Zinc(II)octadecanoate/Zinc(II)9,10-dihydroxyoctadecanoate (ZnA2/Zn(OH)2A2) are linear. However, for the binary mixtures of lead(II)octadecanoate/lead(II)9,10-dihydroxyoctadecanoate (pbA2/Pb(OH)2A2) at low mole fractions (XPb(OH)2A2 <0.02) non-linear graph characteristics of the behaviour of lead(II) carboxylate systems are observed while for high mole fractions (XPb(OH)2A2 > 0.03) the shape of the curves resemble that of pure Pb(OH)2A2,the observance of a maximum in the system is interpreted in terms of the interaction of lead ions with the hydroxyl groups. Plots of molar volume against temperature for PbA2 /Pb(OH)2A2 show curvature in support of such interactions, suggesting deviations from ideal behaviour of the liquid systems. The activation energies for conduction and dissociation (ΔHKµ +ΔH/3) for the pure lead(II) and Zinc(II)9,10-dihydroxyoctadecanoates and their mixtures are obtained. For lead(II) octadecanoate/ lead(II)9,10-dihydroxyoctadecanoate at low mole fraction the enthalpy decreases steadily up to a point with increase in mole fraction and then increases. However, for the zinc soaps and its mixtures the enthalpy terms are found to be fairly constant with increasing mole fraction even when the actual conductivity falls.
- ItemOpen AccessPeriodate Oxidation of Tris-(4,4'- Dimethyl-2.2' Bipyridine) iron (ii).(Obafemi Awolowo University, 1986) Ayodele, Ezekiel Temitayo; Ige, W. J.This work covers the periodate oxidation of tris-(4,4'-dimethyl-2,2'-bipyridine) iron (II) complex. The reactive periodate species postulated from the ionic strength dependence in acid medium are IO3+ H6IO6 or I(OH)6+. In both acid and neutral med the ionic strength dependence of observed rate constant was found to fit into Bronsted Bjerrum Christiansen formulation while in alkaline medium significant deviation was observed. In acid medium, a reaction order of 0.2 obtained with respect to the periodate ion species shows that the reaction proceeds via a complex mechanism. The reaction was found to be acid dependent, and protonation of the periodate or complex occurs prior to electron transfer and the reaction proceeds by outer-sphere mechanism. In alkaline medium, the formation of mesoperiodate and other polymeric species for which the accompanying equilibria are not precisely known makes the reaction more complex and the postulation of a reasonable mechanism impossible. In neutral medium as in acid medium, reaction proceeds through the formation of an outer-sphere complex. At low periodate ion concentration, a stoichiometry of 1:1 with respect to the complex and periodate was obtained while at high periodate ion concentration the stoichiometry is 3:1.
- ItemOpen AccessElectrical Conductivity and Viscosity of Nigerian Traditional Soaps in Non-aqueous Solvents.(Obafemi Awolowo University, 1986) Adebajo, Moses Olorunfemi; Akanni, M. S.The electrical conductance and viscosities of different concentrations of alcoholic solutions of Nigerian traditional soap are measured as a function of temperature. Sodium, potassium and potassium/sodium (50:1) soaps are prepared from palm kernel oils using laboratory reagent alkalis. Their conductances are also measured. While the conductance values vary with the state of purity of the soaps and the polarity of the solvents, no significant change is observed in viscosity in relation to their purity. The conductances of the prepared potassium soaps are found to be higher than those of the prepared sodium soaps, suggesting the metal ions to be the main charge carriers. The plots of logarithm-of conductivity against inverse temperature for all the soaps arc linear in Methanol and ethanol while such plots are non-linear in 1-propanol, a solvent in which the soaps are least soluble with low conductance values. However, the plots of logarithm of viscosity against inverse temperature are linear for the soaps in all the alcohols within the range of the concentration studied. Data are presented for both the activation energy for viscous flow and conductance. In each case, the energy values appear to increase with the molecular weight of the solvents. The viscosity data arc fitted to the Jones-Dole equation and the A and B-coefficients are evaluated. The trend of the values of the 3-coefficients with temperature and polarity of the solvents is discussed. The removal of excess acid/base/water appears to enhance the foaming capability of the soaps. Some other undetermined minor or trace impurities seem to have little or no effect on the foaming efficiency of the traditional soaps.
- ItemOpen AccessClass Structure and Character Tables of Permutation Groups for Weakly Bound Polymer Molecules and Some Applications.(Obafemi Awolowo University, 1987) Adekola, Folahan Amoo; Odutola, J. AdePermutation and permutation-inversion groups for polymer molecules have been systematically studied. This encompasses review of the permutation and permutation-inversion groups for dimer molecules, followed by extension to trimers, tetramers and higher polymer molecules. Some formulae for determining the conjugacy classes of both the symmetric and non-symmetric polymers are presented. It has been shown that the character tables for the polymer molecules are easy to construct once the feasible operations of the appropriate monomer groups are determined. The Frobenius formula for characters of induced representations and Clifford’s theorem has been used to compute the characters of the irreducible representations of the various polymer groups. The permutation groups for (NH3)3, (C6H6)3 and (NH3)4 have been found to consist of 1296, 10368 and 31104 elements while their various permutation-inversion groups have 2592, 20736 and 62208 elements respectively. The character tables of non-symmetric polymer molecules are relatively much easier to construct. A method for determining the nuclear spin functions and hence the statistical weights is presented using (H20)3 and (NH3)2 as examples. The general theory of the nuclear hyperfine structure has been simplified and this has been used in predicting the possible number of spectral transitions for some molecules.
- ItemOpen AccessPreparation and Characterisation of Pyrolytically-Deposited Thin Oxide Films from Metal-Organic Compounds(Obafemi Awolowo University, 1987) Lambi, John Ngolui; Ajayi, O.B.; Akanni, M.S.A simple and versatile pyrolytic method of preparing thin metal oxide films that is based on the Metal Organic Chemical Vapour Deposition (MOCVD) technique and that is operative at relatively low temperatures (420°C) has been utilised to prepare the thin metal oxide films of indium, zinc, aluminium and copper from the appropriate metal acetylacetonate or carboxylate. To fully understand the pyrolytic route leading to film formation, the thermal decomposition of some of the starting materials was investigated in detail at 420°C in air and N,, using separately, a Muffle furnace and a flow system. The identities of the products as determined by a combination of techniques are Cu, CO2, a carboxylic acid and an odd chain-length alkene, in the case of the copper(II) soaps; ZnO, CO2 and a ketone for the zinc soaps; and a mixture of Cu, Cu20 and CuO in the case of the copper(II) acetylacetonate. While mechanisms have been proposed to account for the degradative routes of the soaps, which of the metal acetylacetonates is still inconclusive. A combination of Ion Beam, X-ray and optical absorption studies have shown that the oxide films of indium, zinc and aluminium are, of the expected stoichiometry, while that of copper is of mixed composition (CuO/Cu2O/Cu). It is not immediately clear why carbon and alkali metal contamination was observed for the Al2O3 and CuO/Cu2O/Cu films but not for the In2O 3 film. Scanning Electron Microscopy (SEM) has shown the films to be polycrystalline. The observed optical characteristics (high transmittances, T = 75-90%; moderate reflectances, R < 21%; low absorbances, A < 8%; high refractive indices, nf > 1.5 and low extinction coefficients, k < 0.4) are as expected for these thin films. Potential uses of these thin layers based on their observed properties are also discussed.
- ItemOpen AccessExtraction and Identification of Some Antioxidant and Antimicrobial Compounds from Urena Lobata (Linn) Leaves(2015-03-23) Adeloye, Adewale OlufunshoThis study examined the extract of Urena lobata L. leaves for its antioxidant, antibacterial and antifungal activities with a view to isolating and characterizing the biologically active components that might be present and thus provide justification for the ethnomedicinal uses of the plant in the treatment of various diseases for which it was used. Urena lobata L. leaves were collected, identified and air-dried for 3 weeks after which they were ground into coarse powder and extracted at room temperature with 50% aqueous ethanol for 72 hours with occasional agitation. The filtrate was concentrated to dryness in vacuo on a rotary evaporator to obtain the crude extracts. The crude extract was dissolved in distilled water and then partitioned successively with four different organic solvents which included n-hexane, dichloromethane, ethyl acetate and n-butanol. The solvent fractions obtained were concentrated in vacuo and then evaluated for antibacterial, antifungal activities tests. In another bench-top bioassay antioxidant screening method, all the solvent fractions were screened for antioxidant activity using the rapid thin layer chromatographic method with l,1-diphenyl-2-picrylhydrazyl (DPPH) solution in methanol as detecting reagent. A detailed bioactivity guided fractionation was carried out on the ethyl acetate extract by gradient column chromatography using combination of Accelerated Gradient Chromatographic (AGC) method and Sephadex LH-20 adsorbent. Preliminary evaluation of the crude extract for antibacterial and antifungal activity using Agar-well diffusion method with streptomycin as standard antibiotic showed that the extract had a broad spectrum of activity against both Gram positive and Gram negative bacteria isolates. The ethyl acetate and n-butanol fractions had a fast antioxidant reaction with DPPH solution, while the n-hexane and dichloromethane fractions gave no reaction with the test reagent. Three flavonoid compounds were isolated from the ethyl acetate fraction namely: 1 kaempferol, 2 quercetin, and 3 tiliroside (3-O-β-D-(6"-O-transp-coumaroyl)-α-L-glucopyranosyl-kaempferol). The structures of the flavonoid compounds were determined from spectra obtained on them using infra-red, IH and 13C NMR. The study concluded that the isolated flavonoid compounds were part of the compounds responsible for the biological activity of Urena lobata leaf extract.
- ItemOpen AccessDetailed Subsurface Structural and Stratigraphic Interpretation of Kunbi Marginal Oil Fleld, Niger Delta, Using Three Dimensional (3-D) Seismic Reflection Data(2015-04-29) Obaoye, Michael OlajideThe primary objective of this study was to determine the proven, probable and possible oil reserves in the supposedly marginal Kunbi Field as a means of establishing if the oil accumulation in the field is in commercial quantity. The methodology involved the integration of seismic 3-D structural and stratigraphic time interpretation; seismic attributes like reflection intensity, root means square amplitude and complex trace attributes like instantaneous amplitude, instantaneous frequency and phase to maximize information derivation from the field. Depth mapping was integrated with detailed petrophysical analysis to build a static model with constant petrophysical parameters which were used to calculate the reserves. Post well completion nuclear logging using Haliburton's Reservoir Monitoring Tool was conducted to re-establish oil contacts by measuring carbon-oxygen ratio and other elemental yields. Stratamplitude and complex trace attributes were extracted from the interpreted seismic to infer the field's depositional environments and facies. The gamma ray log characteristic shapes were also used in conjunction with reflection geometry and high resolution biostratigraphic studies to completely detail the sequence stratigraphic setting and depositional environment of the field; classify the reservoirs according to sedimentation stacking processes. The interpreted 3-D seismic time maps were then converted to depth maps using the average velocity method while a detailed petrophysical analysis was then integrated with the depth maps to build a static model which was used to calculate the original oil in place and ultimate recoverable reserves. The result of the analysis of stratamp in Excel showed that even though the reservoirs were optimally located structurally at all the eight oil bearing levels, some of them were not optimally located stratigraphic wise and require some lateral shifts from 35 meters up to 247 meters. Integration of seismic reflection geometry, logs' shapes interpretation and Stratamplitude study confirmed that the reservoirs in this depocenter were of shallow marine, deltaic, river mouth siliciclastic sand bars, fluviatile derived, transported and deposited under moderate to high energy regime and wave dominated. The result of the static modelling and the resulting reserves calculation revealed that Kunbi Field proven, probable and possible reserves were in excess of 99.5, 162.4 and 272.2 MMBL STOIIP prior to nuclear logging with Haliburton's Nuclear Reservoir Monitoring Tool compared with the previous estimation of proven reserves of 56.9 MMBL STOIIP using the 2-D seismic data. However, post completion nuclear logging suggested that the probable (P1+P2) reserves can be as high as 256 MMBOL as compared with 162 MMBOL STOIP above. It was concluded that in addition to the proved, probable and possible oil reserves in this field, there were other drillable updip and upside oil potentials within the farmout polygon.