Scholarly works
Permanent URI for this collectionhttps://repository.ui.edu.ng/handle/123456789/406
Browse
13 results
Search Results
Item Effects of phosphate chemicals treatments on auto battery waste contaminated soil in Nigeria(2009) Ogundiran, M.B; Osibanjo, O.Auto battery waste contaminated site poses potential threats to the environment and biological life through lead toxicity, thus making remediation imperative. The possibility of using phosphate chemicals to reclaim a grossly lead-contaminated site was explored. The study site was an abandoned lead-acid battery waste dumpsite in Nigeria. Phosphate chemicals were applied at 5 and 10% phosphorus levels to the contaminated soil collected from the site in incubation experiments. The air-dried sub-samples of the incubated soils were analyzed for pH, P, bioavailable Pb and TCLP- extractable Pb. Results showed that 99.5% of the applied phosphorus was removed by the end of the first week of incubation. Incubation time showed less effect on Pb immobilization. A 10% phosphorus application resulted in reductions of water soluble Pb between 77.8% and 86.4% thus eliminating to a reasonable extent, the hazard to living things and the environment. TCLP extractable Pb was reduced from 50.2 mg/L in untreated soil to below the acceptable value of 5.0 mg/L. An application of 10% CHP produced overall effectiveness in the reduction of bioavailable Pb, TCLP-extractable soil Pb. This treatment also had little effect on soil acidification and resulted in the least residual P. Results therefore indicated that phosphorus can be used as potential chemical remediation for cleanup of battery waste contaminated soils.Item Mobility and speciation of heavy metals in soils impacted by hazardous waste(2009) Ogundiran, M.B; Osibanjo, O.This study describes the mobility and chemical fractionation of heavy metals (HMs) from a site impacted by auto battery slag that was generated from secondary lead smelting operations. Samples were collected from the waste pile and from the immediate surrounding soil at four depths to assess the migration and potential bioavailability of Pb, Cd, Cr, Ni and Zn. Total levels of the HMs and their fractionation were determined. The results indicate that highest levels of HMs are present in the uppermost layer with significant migration down the depth, thereby posing a threat to groundwater quality. In the fractions, the concentrations of the metals follow this sequence: Pb4Zn4Cd4Cr4Ni. The chemical fractions of Pb, Cd, Cr, Ni and Zn in the samples, expressed as mean concentrations of the sum of the individual chemical fractions, demonstrate that the HMs exist mainly in the non-residual fractions. For instance, the percentage of non-residual fractions of lead in the waste pile and the surrounding soil ranged from 48.9 to 95.6% and 69.4 to 98.3% respectively. The mobility factors of the heavy metals are significantly high indicating high potential mobility and bioavailable forms [IS1]of these HMs. The high concentrations of the HMs particularly Pb in the non-residual fractions, as observed in this study, shows the impact of anthropogenic activities on enrichment of natural soil with bioavailable HMs. Consequently, there is a need to be cautious in the way waste that is generated from heavy metals projects is added to natural soil.Item Heavy metal concentrations in soils and accumulation in plants growing in a deserted slag dumpsite in Nigeria(2008) Ogundiran, M.B; Osibanjo, O.Early detection and remediation of heavy metals in soil and vegetation will ameliorate serious threats posed to human existence. An auto battery manufacturing company dumped slag containing proportion of heavy metals in an hectare of land at Lalupon, Ibadan, Nigeria. The extent of contamination of soil by heavy metals and their accumulation in plants around the abandoned slag was studied. Plants and the surrounding soils were sampled from different directions at increasing distance from the vicinity of the waste pile and their concentrations of heavy metals were determined. The levels of Pb, Zn and Ni in mg/kg ranged from 34.8 – 41500, 16.3 – 849 and ND – 48.2; 9.2 – 9700, 16.0 – 271 and 2.83 – 36.9; 4.5- 5670, 8.00 – 174 and ND – 322 in soil, plant root and plant shoot, respectively. The plant samples from the immediate environment of the waste were highly contaminated with Pb. Six plant species, particularly Sporobolus pyramidalis, met some of the conditions to be classified as hyperaccumulators for Pb, Ni and Zn, and three other plants fulfilled the criteria for heavy metal excluders. We conclude that the potential hyperaccumulators and excluders, under controlled conditions, can be used for phytoremediation of the site.Item PHYSICOCHEMICAL STUDIES OF SOME TRIVALENT METAL β-DIKETONATES(1976-06) ADIMADO, A. A.Forty trivalent metal chelates of 2-thenoylacetone,2 thenoyltrifluoroacetone, 2-furoylacetone, 2-furoyltrifluoroacetone. benzoylacetone, benzoyltrifluoroacetone and nicotinoyltrifluoro— acetone (where metal(Hl) = Al, Crf Mn, Fe and Co) as well as some mixed ligand p-diketonate complexes of iron(IH), have been prepared and their spectroscopic and magnetic properties have been examined. Among the series of compounds studied, Al(fbd) Mn(fbd)3, AKtftbd), Co(tftbd)3, Cr(tffbd)3, Mn(tffbd)3, Co(tffbd)3, M(tbd)3, M(tfpybd)3 (where M = Al, Cr, Mn, Fe and Co ), Fe(bzac)2 (tftbd), Fe(tftbd)2(bzac), Fe(fbd)2(tbd)and Fe(tbd)2(fbd) have been investigated for the first time. The effects of 3-pyridyl, 2-thienyl, 2-furyl, phenyl and trifluoromethyl substituents have been discussed in relation to the lowest spin-allowed transition, п3- п4 and M-O,VC--O and VC--C-—C stretching vibrations. Substitution of a methyl group in 2,4-pentanedione - by a furyl ring, and a methyl group in 1-(2-furyl )-l,3-butanedione by a trifluoromethyl are found to strengthen the C---O and C —C—C and weaken the M—0 bonds of the chelate rings; while the 2-thienyl group shifts the M—O and C -- 0 to lower, and C---C to higher frequencies. The phenyl substituent, as expected, strengthens the M-O and C---C bonds and weakens the C--O bonds. The most sensitive M-0 stretching modes follow the order Co(lII) >A1(III) > Cr(III)> Mn (III) > Fe (III). However, the lowest spin-1llowed п3- п4 translation of the β-ketoenolate anion, although found to be metal sensitive, does not follow the same trend. Trifluoromethyl group substitution resulted in the bathochromic shift of the п3- п4 transitions. The ligand field energy parameters Dq,f (ligand)), B35 and β35 have been calculated and the following order of nephelauxetic effect in the ligands has been derived: Htffbd > Htbd > Hfbd > Hacac > Hbztfac > Htftbd > Hbzac > Htfpybd. While the spectrochemical series of the ligands depicted by the magnitude of f(ligand) parameter also follow:'.the orders tfpybd < bztfac < fbd < tffbd < tbd < acac ~ bzac < tftbd. The reflectance spectra and magnetic properties of these compounds revealed that they are very similar to the corresponding tris—(2,4—pentanedionato) metal(III) octahedral complexes.Item SECONDARY METABOLITES FROM A LOCAL MEDICINAL PLANT - GARDENIA ERUBESCENS. STAPF. AND HUTCH(1995-03) ADELAKUN, E. A.A detailed Chemical analysis of the stem of Gardenia erubescens Stapf. & Hutch. was carried out. The crushed stem was sequentially extracted with petroleum ether, ethyl acetate and methanol. Subsequently the Petroleum ether, ethyl acetate and methanol extracts when subjected to phytochemical tests revealed the presence of steroids, flavonoids and saponins, while anthraquinones and alkaloids were not detected. The petroleum ether extract and the n-butanol soluble fraction of the methanol extract were further subjected to chromatographic analyses using a combination of column, TLC and preparative TLC. The TLC analysis of petroleum ether extract showed the presence of steroids and flavonoids as the major components. TLC analysis of the n-butanol soluble fraction of methanol extract however revealed only the presence of saponins. Purification of the petroleum ether extract on column of silica gel afforded, after further purification by preparative TLC, five known compounds, one fraction containing isomerie mixture of two compounds and one new bisnortriterpenoid compound. From the saponin fraction of the n- butanol soluble fraction of methanol extract, five compounds were isolated and identified. Four of these compounds were known while one was a new_ oleanene-type compound. A total of fourteen compounds were isolated and identified from both the petroleum ether extract and n-butanol soluble fraction of the methanol extract of the stems of Gardenia ernbescens. Characterization of the known compounds was achieved through spectral correlation with authentic samples and/or derivatisation and comparison of melting points with the known compounds. Full characterization of the new compounds was accomplished by use of 2D nmr experiments - COSY and 1H-13C nmr correlation spectra, assisted by NOE difference spectroscopy. The known compounds isolated and identified from Gardenia ernbescens in this work were: •D-Mannitol •Stigmasterol •Stigmasterol-3β-D-glucopyranoside •5-Hydroxy-7,4'-dimethoxyflavanone •5-Hydroxy-7,4'-dimethoxyflavone •5-Hydroxy-7,3',4'-trimethoxyflavanone •3β-Acetoxyolean-12en-30-oic acid •Isomerie mixture of oleanolic and ursolic acids •3β,23-Dihydroxyolean-12-en-28-oic acid •2β,3β -Dihydroxyolean-12-en-28-oic acid •2β,3β,23-Trihydroxyolean-12-en-2 8-oic acid and the two novel compounds were: •Erubescenone and •3β,23,24-Trihydroxyolean-12-en-28-oic acid.Item A SEMI-EMPIRICAL SELF-CONSISTENT FIELD MOLECULAR ORBITAL (SCF-MO) STUDY OF THE GROUND STATE PROPERTIES OF SUBSTITUTED NAPHTHALENE COMPOUNDS(1990-03) ADEKUNLE, A. O.The ground and excited state properties of naphthalene and some of its derivatives have been studied. The molecular orbitals were evaluated using the modified Huckel Molecular Orbital (HMO) theory and the calculated molecular properties such as dipole moments, electronic transition frequencies, have been compared with experimental values. The electronic absorption spectra of some of the compounds were further studied in detail as to their band systems and characteristics, solvent polarity effects and hydrogen bonding effects. The dipole moment changes from ground to excited states were generally determined to be high. A linear regression analysis obtained for plots of the 'L(b) band maxima (υ(obs) versus solvent physical properties and solvent empirical parameters has shown that there is no meaningful correlation between solvent dielectric constant (ɛ) and solvent induced shifts. The oscillator strengths have been found to be generally low for the examined compounds in all the solvents. However, the electronic relaxation times calculated for each of the compounds give strong indication as to the likelihood of the band systems arising from mixed states. The relationship between relaxation times, t, and solvent viscosities,ᶯ, allows the prediction of large changes in spherical symmetries of the two band systems ('La and ’Lb) in both 1-naphthylamine and 4-nitro-l-naphthylamine. A possible existence of free internal rotation in the excited states of these molecules, has thus been suggested. The infrared spectra have been studied in the solid state and in solution and the vibrational frequencies assigned by making correlations with spectra of substituted benzene compounds and other related compounds. The substituent modes for each of the compounds have been discussed in detail.Item SYNTHETIC STUDIES ON STEROIDAL ALKALOIDS(1966) ADEGOKE, E. A.In the first part of this thesis, a brief survey of the chemistry of veratramine viz. its occurrence, isolation and structural diagnosis is given. This part also includes a review of recent work on the stereochemistry and the synthetic work of other workers on the alkaloid. The main section describes three approaches to the synthesis of the C-Nor-D-homo ring system of the veratrum alkaloids. Howell and Taylor’s acetate diester 6(β-acetoxy-1 β:2αdi (methoxy carbonyl methyl)-9β-methyl-trans decalin prepared from 2:3:4:9:10:12- hexahydro-6-methoxy-12-methyl-2-oxophenanthrene was successfully cyclised to the potential intermediate 6(β -acetoxy-1 β:2α-( cyclopen- tan-3-one)-9-methyl-trans decalin. The pentanone was ring extended to give a solid substance which certainly contained the steroidal ring system of veratramine but which could not be obtained in the pure form. Attempts aimed at an easier preparation of the pentanone acetate by alkylating 1-oxo-6-ethoxy-8a-methyl-1,2,3,7,8, 8a hexahydro naphthalene with different alkylating agents were unsuccessful, the starting material being recovered in each case. In a second approach, 1-(2-cyanoethyl)-2-hydroxy naphthalene was converted to 2:3:4:9:10:12-hexahydro-6-methoxy-7-(3-bromo- propyl)-12-methyl-2-oxophenanthrene and 8-oxo-10a-methyl-1,2,3,4,5,6,8,9,10,10a-decahydro-1-oxa chrysene. The benzene nucleus of either intermediate was resistant to reduction and so they could not be used for further work. In the last attempt, 2-benzoyloxy-1,2,3,4,5,6,7,9,10,11,12,13 dodecahydro-12-methyl-7-oxophenanthrene was prepared starting with 2-naphthol and the tricyclic enone was successfully condensed with 2,2-ethylenedioxy-5-bromo pentan-2-one in the presence of potassium t-butoxide in t-butanol. The adduct was successively reduced, reacted with methyl magnesium bromide, deketalized y acetylated, ozonised and cyclised to give an oily substance which contained the veratramine steroidal nucleus as revealed by its U.V. spectrum. The oil did not crystallize. An oil which should probably crystallize more readily could be obtained if complete reduction of the original ansaturated adduct could be accomplished in the attempts some new compounds were prepared. These were mainly naphthalene, phenanthrene and hydrochrysene compounds. I.R U.V, or N.M.R. spectroscopic data were recorded for all the new compounds and for most of the known ones. Some structural formulae are repeated in the script, so as to aid the reader’s comprehension.Item PETROLEUM HYDROCARBONS POLLUTION OF NIGERIAN WATERS AND SEDIMENTS AROUND LAGOS AND NIGER DELTA AREA OF NIGERIA(1989-03) ADEKANMBI, O. E.There is a paucity of scientific data on the levels and pattern of distribution of petroleum hydrocarbons in the Nigerian aquatic environment. The levels of total hydrocarbons in 241 water and 222 sediment samples in’ the major river systems draining into Nigerian coastal environment around Lagos and the Niger Delta area have been used to monitor the pattern of distribution of hydrocarbons within these areas over different weather regimes during 1984-85. The Utorogu pipeline oil spillage incident in Bendel State of Nigeria in 1984 was used as a case study for assessment of environmental impact of oil spillage in aquatic ecosystem in Nigeria. Samples were also collected and analyzed for total hydrocarbons from Kaduna (Northern Nigeria) and Ibadan (Western Nigeria) for comparative information and controls respectively. Water samples were analyzed for petroleum hydrocarbon by infrared (IR) and gas chromatographic (GC) techniques whereas sediment samples were analyzed by gravimetry and gas chromatography (GC). The infrared (IR) results for 1984 (wet season) showed that Lagos and Lekki lagoons had hydrocarbon level (presented as range followed by mean value in bracket), 1.64-11.40 (5.60) mg/1; Niger Delta, ND (net detectable)-70.70 (6.18)mg/1; Utorogu 0.17-10.50 (2.22)mg/1; Kaduna 4.30-9.90 (6.98)mg/1, while Ibadan water samples (serving as control area) showed no detectable levels of hydrocarbon. In 1985 (dry season) there was a decrease in the hydrocarbon levels found in the water samples. Lagos and Lekki lagoons recorded 0.10-0.41 (0.25)mg/1; Niger Delta 0.10-1.80(0.52)mg/1 and Utorogu 0.17-4.67 (2.14)mg/1. The gas chromatographic values for hydrocarbon concentration in water were much lower than the infrared values. All the samples except Upomani discharge point (3.36 mg/1) had values below 1 mg/1 by GC. Nonetheless, the IR values correlated well with the GC values. The corresponding hydrocarbon levels (on dry weight basis) in sediment samples in 1984 were: Lagos and Lekki lagoons ND-95.54 (30.33) µg/g; Niger Delta ND-74.05 (9.09) µg/g; Utorogu 14.04- 267.48 (98.88) µg/g and Kaduna 0.62-21.52 (12.36) µg/g. In 1985 the values of hydrocarbon levels recorded in the sediment samples were as follows: Lagos and Lekki lagoons 0.20-10.30 (4.20) µg/g; Niger Delta 0.05-44.06 (6.64) µg/g; Utorogu (Jan-Feb.) ND-9.41 (2.98) µg/g; Utorogu (June-July) 0.03- 68.06 (21.66) µg/g; Kaduna 2.91-5.00 (3.96) µg/g and Ibadan 8.09-27.79 (17.94) µg/g. The Lagos lagoon sediment samples monitored from January to December 1985 gave ND-2766.27 (11.13) µg/g. The results of this work showed that Lagos lagoon was more polluted than the Niger Delta in terms of petroleum hydrocarbons. Highest values of petroleum hydrocarbons were recorded close to oil activity points such as Ogharife field effluent canal, Chanomi creek at Egwa field, Orughene creek, in the Niger Delta area; or near human settlements such as Obotebe and Bakana or in an industrial area like Lever Brother's discharge point and Berger/National Oil/Ijora in Lagos. The results of Utorogu oil spillage gave a picture of the impact of oil in the aquatic environment. During the first sampling trip which took place within four months after the oil incident, aquatic lives (plants and animals) were seriously affected in the Utorogu swamp, but before the end of the study period (June 1985) the swamp had recovered and was bubbling with life again. Oil pollution indicator parameters such as the Carbon Preference Index (CPI), Pristane: Phytane ratio (Pr/Ph); Presence of Phytane, and Unresolved Complex Mixture (UCM) and the Marine Oil Pollution Index (MOPI) indicated that some of the stations were polluted by oil while most of the points studied in both Lagos and the Niger Delta were contaminated with petroleum hydrocarbons which may be from crude oil, refined oil or both. Moreover, all the contaminated and polluted samples showed petroleum hydrocarbon at different stages of weathering as reflected in their carbon range, the Pristane: n-C(17); Phytane:n-C(18) and UCM: n-alkane ratios.Item KINETICS AND THERMODYNAMIC STUDIES OF NADP BINDING REACTIONS OF GENETIC VARIANTS OF HUMAN ERYTHROCYTE GLUCOSE 6-PHOSPHATE DEHYDROGENASE(1978-12) ADEDIRAN, S. A.Inherited Glucose-6-Phosphate dehydrogenase (G6PD) deficiency in humans results in hemolytic anaemia. The enzyme G6PD provides a crucial link in a series of biochemical reactions which occur in the red blood cell that leads to the steady state accumulation of NADPH, reduced glutathione by glutathione reductase, and the removal of potentially dangerous organic peroxides which, if not scanvenged, may result in the formation of radical species of oxygen which damage the energy generation system, which in turn may result in swelling, lysis and hemolytic anaemia. The objective of this thesis was to investigate the human variants of the enzyme G6PD in order to provide a better understanding of the molecular basis of the enzyme activity and factors affecting the onset of the human disease. Human Erythrocyte Glucose-6- Phosphate dehydrogenase has been known to occur in many genetic variants and the catalytic active enzyme of each variant are tetramers and dimers in acidic and alkaline solution respectively. The question then is whether there would be differences in the reactivities of these variants and whether there are differences in the reactivities of the two active forms of the enzyme from the same variant. A comparative analysis of the kinetic and thermodynamic studies of NADP+ binding reactions of these variants under controlled and well-defined experimental conditions of pH and ionic strength was therefore undertaken. The binding reaction of NADP+ to G6PD B+ was also studied as a function of ionic strength of the buffers in order to evaluate the effect of these variations in the buffer system on the co-operative interactions of the NADP+ binding sites on the enzyme. The findings show that there are two binding sites on each of the enzyme variants and these were identified as imidazolium groups of histidine and sulfhydryl groups. The logKm versus pH curves show a broad plateau between pH 6.7 and 8.2 interrupted by a sharp minimum at pH 7.1 for all the enzyme variants. An explanation of this behaviour in terms of co-operative ionization of groups on the enzyme and enzyme-substrate complex which may be linked to the association - dissociation behaviour of the enzyme is proposed. In agreement with G6P binding data, the plot of the enthalpy of the dissociation of enzyme - NADP+ complex against pH shows the shape of a two U—shaped curves consistent with the existence of a tetrameric form of enzyme at acidic pH and dimeric form at alkaline pH. A similar plot of the activation energy of the reaction for each variant shows a consistent decrease of the activation energy with increase in pH, the activation energy at the pH 5.8 being almost halved at the alkaline pH of 9.0, This behaviour is explained to arise from the dimer enzyme being more reactive than the tetramer. There are two schools of thought about the existence and nature of cooperativity among the NADP+ binding sites on G6PD subunits. The study reported in this thesis has unequivocally solved the controversy between the two schools. It is now established that the tetrameric form of the enzyme shows no Cooperativity while the dimeric form is cooperative. The disagreement between the two schools of thought has been explained in the variable experimental conditions used by the workers in the two schools. We have shown that an experimental condition that favours tetramer formation therefore favours non-cooperativity while a condition that favours dimer formation favours cooperativity. The inhibition study by primaquine phosphate shows a complex interaction of this effector with G6PD. There is activation of the G6PD activity at low effector concentration and inhibition at high concentration. This interaction may be due to oxidation of NADPH at low primaquine concentration resulting in generation of more NADP+ which increases the activity of the enzyme. Such a situation might account for the increased hemolysis in variant subjects with low Artracellular NADPH concentration which will result in low level of reduced glutathione. Reduced glutathione is necessary for the maintenance of the integrity of the red cells.Item NEW CHROMONE ALKALOIDS FROM THE ROOT -BARK OF SCHUMANNIOPHYTON MAGNIFICUM (HARMS)(1981-09) ADEBOYE, J. O.The chemical investigations of some representative alkaloids of Rubiaceae are reviewed. The total syntheses of emetine and quinine are also reviewed while the biogenesis of anthraquinones and biosyntheses of chromones, nicotinic acid 'and nicotine are outlined. The bronchiodilator activities of Khellin and some chromone derivatives are compared and a brief review of the pharmacological activities of a few of the Rubiaceous alkaloids is given. From the methanol extract of the root-bark of Schumanniophyton magnificum, a well known chromone, 5, 7-dihydroxy-2-methylchromone (noreugenin) 97 was isolated in addition to five alkaloids designated SRB2, SRB3, SRB(3)’, SRB(3)" and SRB(4). The constitutional formulae of two of these alkaloids, schumannificine (SRB ) 4 -138 and N-methylschumannificine (SEB(3) 147, have been shown to be new linear tetracyclic compounds with ring D being piperidine in nature on the basis of the chemical evidence and spectral analyses. SRB(2) has been shown to be identical in physical and spectral properties with the product of dehydrogenation of schumannificine (SRB(4) which was named dehydroschumannificine 142. The synthesis of dehydroschumannificine 142 was attempted , This was done in order to correlate the structure that was assigned to it with the natural alkaloids, schumannficine 138and N-methylschumannificine 147, but only the first intermediate, 2,4,6-trihydroxynicotinophenone no 146 was obtained. It was characterised by its spectral properties. The spectral properties of SEB(2)' and SEB(3)" are discussed briefly arid since no conclusive work has been done on then they are tentatively assigned structures 148 & 149 respectively on the basis of their spectral, data.