Chemistry

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    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.
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    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.
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    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.
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    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.
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    PHYTOCHEMICAL AND PHARMACOLOGICAL EXAMINATION OF ENTANDROPHRAGMA ANGOLENSE AND CRYPTOLEPIS SANGUINOLENTA
    (1994-03) KOLAWOLE, A. J.
    Dried, pulverized stem bark and the root bark of Entandrophragma anqolense were separately extracted with methanol. The crude methanolic extract of the stem and root bark of E. anqolense were subjected to column fractionation and purification. This exercise afforded the Isolation of methyl angolensate, 2.26% yield from the stem bark and 0.27% yield from the root bark. The effect of the crude methanolic stem bark extract was investigated on indomethacin-induced gastric ulcer in rats. Its effect was dose-dependent, doses ranging from 0.4 to 1.6 gkg-1 body weight (BW) produced significant effect (P < 0.05). At the highest dose used (1.6gkg-1 BW), complete inhibition of ulceration occurred. Toxicity study showed that the extract was not toxic when doses ranging from 20-200gkg-1 BW was administered to experimental rats. It was established that methyl angolensate is the major anti- ulcer principle present in the methanolic extract of the stem bark of E. angolensate. Methyl angolensate produced a dose-related inhibition of gastric ulceration induced by indomethacin, 40mgkg BW being more effective than 40mgkg-1 BW of propanolol. 80mgkg-1 BW of methyl angolensate completely inhibited gastric ulceration. Methyl angolensate also significantly reduced gastric acid secretion induced by histamine and carbachol (1.0mgkg-1 BW). Thus we confirmed that methyl angolensate produces its anti-ulcer activity through inhibition of gastric acid secretion. The roots of Cryptolepis sanquinolenta were extracted with methanol. Column fractionation of the methanolic extract afforded the Isolation of a new benzocarboline alkaloid labelled (CS-1) melting point 272-274°C. Spectroscopic analysis of CS-1 including the infra-red (IR), 13 ultra-violet (UV), mass spectrum (MS), proton and C-nuclear magnetic spectroscopy were reported. This new alkaloid exhibited anti-microbial activity on five pathogenic organisms. The in-vivo anti-malarial study of the aqueous extract of the roots of sanguinolenta was done on Plasmodium yoeli nigeriensis in mice. Anti-malarial activity of the extract was determined by examining the blood schizontocidal action in established infection using chloroquine as Standard drug for comparison. The extract showed a dose-dependent effect against the malarial parasite.
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    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.
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    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.
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    DEVELOPMENT OF RESIN-BOUND REAGENTS FOR ANALYSIS OF CARBOXYLIC ACIDS AND AMINES
    (1993-12) ADEWUYI, G. O.
    Resin-bound-reagents made up of ionically-bound 2- naphthalene-methanol and covalently bound and sodium-benzoxazole- 2-sulfonate have been synthesized and utilized as analytical reagents for the pre-chromatographic derivatization of fatty acids (i.e. acetic, lauric, capric, hexanoic, octanoic, nonanoic, palmitic, docosanoic linoleic), 1° and 2° aliphatic amines and amino acids respectively. The reagents have been designed to contain fluorescent moieties attached to the anionic and cationic resin backbones through sulfonated ester linkages. These moieties imparted UV and FL detector properties to the final derivatives. The derivatization reactions were performed before the thin- layer Chromatographie separations. Standards we,-e prepared and were used in monitoring the extent of reactions on the resin support. The derivatives were chromatographed and fluorescent spots were observed under UV light. These solid phase derivatizations have led to preliminary investigation of these two functionalities before embarking on instrumentation analysis such as high performance liquid chromatography with UV or fluorescence detection and HPLC-MS Identification.
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    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.