Theses

Permanent URI for this collectionhttps://repository.ui.edu.ng/handle/123456789/407

Browse

Filters

Settings

End date: 1988

Search Results

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    DESULPHURIZATION OF NIGERIAN LAFIA COAL FOR METALLURGICAL COKE PREPARATION
    (1988-01) ADERONPE, W. I. A.
    The Government-owned integrated iron and steel plant under construction in Ajaokuta has been designed to operate through the blast-furnace process. The blast-furnace requires metallurgical coal. It therefore became necessary and relevant to the national economy to scientifically work on Nigerian coals with a view to using same as metallurgical coal. Lafia coal is the only Nigerian coal that produces coke lump after dry distillation (carbonization). The property of coke- ability therefore attracted attention towards Lafia coal. The main interest was to so prepare the coal that as much as possible of it will be usable for metallurgical coke preparation for use in Ajaokuta blast-furnace. Lafia coal was subjected to chemical characterization and petrological studies. It became clear that it was high in ash and sulphur. Silicates, pyrites and carbonates of various elements constituted the inorganic mineral inclusions. Analytical data gave the sulphur varieties in Lafia coal to be organic (0.1 - 0.7%), pyritic (1.4 - 4.4%) and sulphate (0.01 - 0.07%). Pyritic sulphur which predominates in Lafia coal can be removed by physical means. Chemical desulphurization which is reducto-oxidative type of chemical reaction impares coal cokeability. A plunge was thus made for physical desulphurization techniques to bring down the total sulphur in Lafia coal to the level that will make it acceptable as a metallurgical coal with regards to its sulphur content. Trace elements in Nigerian coal ash determined using the Atomic Absorption Spectrophotometer (AAS) and confirmed with the Inductively Coupled Plasma Emission Spectrophotometer (ICPES) showed that the relative abundance of the elements in the coals depended on the biogeo-chemistry of the area of the deposit as follows: Lafia coal; F>Zn>Mn»V Cr>Ni>Cu>B>Pb>Ca>Be>Mo>Cd>Hg Enugu coal; B>Mn>V F>Cr>Zn>Cu>Pb Ni>Co>Be>Mo>Hg Okaba coal; Mn»B»V>Cr>Cu>Pb>F=Ni>Zn Co>Be>Mo>Hg Trace element content of coal was considered in connection with the impact of coal utilization on the environment. From the study it was concluded that either the wet concentrating table or the froth flotation method could be used to substantially desulphurize Lafia coal to meet the requirement of metallurgical coal.
  • Thumbnail Image
    Item
    AN INVESTIGATION OF SOME HORMONAL BASES FOR ABSCISSION IN COWPEA (VIGNA UNGUICULATA L. WALP.)
    (1977-05) ADESOMOJU, A. A.
    The Investigations carried out on the abscission problem in cowpea are reviewed. The Isolation 5 characterization 9 physiological roles, chemistry, biosynthesis and metabolism of the various groups of plant hormones are also reviewed. Using biological assays and combined gas-liquid chromatography- mass spectrometry (GC-MS, some of the hormones in the extensively purified acidic ethyl acetate extracts obtained from 2-day old and 6-day old cowpea fruits were examined. Biological assays indicated the presence of only Inhibitors in the 2-day old fruits but inhibitors as well as gibberellins and auxins were indicated to be present in the 6-day old fruits, GC-MS analysis of the extract from 2-day old fruits afforded the identification of the known inhibitors, abscisic acid and phaseic acid. 6’-hydroxymethyl abscisic acid was also identified in the extract and this is the first reported evidence that 6’-hydroxymethyl abscisic acid occurs naturally. Several plant hormones were identified (GC-MS analysis) in the extract from 6-day old fruits. These were abscisic acid, phaseic acid, dihydrophaseic acid,’1iso1dihydrophaseic acid, 6’-hydroxyinethy abscisic acid; gibberellins A4, A6, A8, ‘iso’ A8,and A20. Gibberellins A1,A5,and A29 were also believed to be probably present. Two components, believed to be two new gibberellins were also identified in the extract and were tentatively called gibberellins X and Y. Tentative structures were assigned to these two new gibberellins. Purified acidic ethyl acetate extract obtained from fruits that were over six days old was also analysed on the GC-MS. The result was essentially similar to that obtained for the extract from the 6-day old fruits. The crude acidic ethyl acetate extracts from 6-day old seeds and the fruit walls of the 6-day old fruits were also examined on the GC-MS. Several gibberellins were tentatively identified in the extract from the seeds but only one gibberellin could be identified in the extract from the fruit walls. The methyl esters of 16α-hydroxy, 17-hydroxy, and 16α, 17-dihydroxy derivatives of gibberellin A34 and the 16-epimers of the last two compounds were synthesized from gibberellin A4. This was done in order to correlate the structures that were tentatively assigned to the two new gibberellins with the natural compounds. The disparity in the hormonal contents of the 6-day old and 2-day old fruits is discussed in relation to the abscission problem in cowpea.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    EXTRACTIVES FROM KHAYA SPECIES
    (1968-03) ADESOGAN, E. K.
    The chemistry of ß-furan-containing extractives obtained from trees of the family Meliaceae (and one tree from the family Rutaceae) is briefly reviewed and their biogenesis is discussed. In continuation of our study of the extractives from the family Meliaceae in this department, five species of the genus Khaya have been examined. The seed, timber, bark, root, and root-bark of three species, K. senegalensis, K. ivorensis, and K. grandifoliola, and the seeds of the two others, K. anthotheca, and K. nyasica were examined. The extracts are mainly the tetranortriterpenes with a ß-substituted furan, and about thirty of these were isolated and structures were assigned to nearly all of them. The known ones include khivorin, 7-deacetoxy-7-oxo-khivorin, 7-cleacetoxy-7-oxogedunin, methyl angolensate, mexicanolide, and deacetylgedunin. Those characterised and reported for the first time include khayasin, 6-deoxy-3ß-tigloyloxyswietenolide, 6-deoxy-3ß-benzoyloxyswietenolide, khayanthone, 3-deacetylkhivorin, 3-deacetyl-7-deacetoxy-7-oxokhivorin, methyl 6-hydroxyangolensate, grandifoliolin, 3-destigloyl-6-deoxyswietenine, 3-destigloyl-6- deoxy-3ß-acetoxyswietenine, 3ß-dihydrocarapin, and 3-destigloyl-6- deoxy-3ß, 12ß-diacetoxyswietenine. Others prepared before, but isolated as natural products for the first time include deoxy- andirobin, and 6-deoxyswietenolide. In addition two substances, A and B from K. ivorensis root-bark have structures proposed for them which are still to be confirmed, while not much is known of the structures of a few others especially methyl senegalensate. Most of these extracts contain glycosides and steroids, ß-sitosterol in particular. Of these only the steroid hormone 20ß-acetoxy-3-oxopregn-4-ene, a new compound, was sufficiently studied to be assigned a structure which was confirmed. The structural elucidation of these compounds have depended almost entirely on their spectral properties including those of their Chemical transformation products. Obviously physical properties played a great part especially in confirming a known compound by comparison of data. The co-occurence of some of these compounds have strengthened the argument for the biogenesis proposed. The chemotaxonomic implication was also discussed. A number of interesting reactions including some rearrangements are discussed and mechanism for some of them have been suggested.
  • Thumbnail Image
    Item
    STUDIES ON THE CHARACTERISTIC pH OF HAEMOGLOBINS
    (1972-01) ADEOSUN, O. S.
    The thermodynamics of the azide binding reactions of the hybrids of human and canine haemoglobins (i.e. α2Aβ2Ca and α2Caβ2A) as well as the isolated α and ß polypeptide chains of human and canine haemoglobins have been studied at various pH's and temperatures. Plots of -ΔH° against pH, for all the species, show a distinct maximum. The pH at which the maximum value of - ΔH° occurs is termed the 'characteristic pH' (pH ch). From the results it is concluded that the value of pH ch for the haemoglobin tetramer is an average of the pH ch's of the separate α and ß polypeptide chains although: the form of the curve of -ΔH° against pH is a function of the tetramer and cannot be obtained by averaging -ΔH° values for the individual chains. The Bohr effect of the two hybrids has also been measured and compared with that of the parent haemoglobins. A study of the equilibrium reaction between oxyhaemoglobin and carbonmonoxide was carried out and the accompanying thermodynamic data assessed in terms of the mechanisms postulated for explaining ligand binding reactions of methaemoglobin.
  • Thumbnail Image
    Item
    THE REACTIONS OF SOME ACTIVATED AROMATIC HALIDES WITH PIPERIDINS, AND N-BUTYLANINE IN DIPOLAR APROTIC AND DIPOLAR PROTIC SOLVENTS
    (1975) ADENLE, M. A.
    The reactions of 2-chloro-5-nitro pyridine with piperidine have been studied in acetone and in nethanol. In acetone, the rate constants are measured as a function of the anine concentration. In methanol, the Arrhenius parameters are obtained. In methanol, except for a very slight (almost negligible) downward trend of rate constants at very high concentration which is explained in terms of Charge - transfer complexes, there is no base catalysis and the observed rate constants are the rates of formation of the intermediate complex. The rates of reaction of 1-X-2, 4-dinitrobenzene (X=F, Cl) with piperidine and n-butylamine in methanol, acetone, and chloroform (stabilised and destabilised) have been measured as a function of the amine concentration. In acetone, the reactions of both substrates with piperidine show true base catalysis with K3/K2 > 50 in both cases. In Chloroform with n-butylamine, there is very little rate increase with increasing amine concentration. For both Substrates, K3/K2=3. This is explained in terms of hydrogen-bonding in the intermediate state. In methanol, the reaction of the chloro Substrate with piperidine gives a small linear increase of rate constants with increasing amine concentration; while for the fluoro substrate, the graph of rate constants against amine concentration gives a doubly sloped curve. This is due to some special unknown medium effects. In acetone, the reactions with n-butylamine give rather peculiar results. The chloro substrate appears to be more sensitive to catalysis by amine than the fluoro substrate - a Situation hitherto unknown. In general, for the reactions in methanol and Chloroform, there is not much base influence; while those in acetone are dependent on the base strength.