Department of Chemical and Earth Sciences

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http://hdl.handle.net/20.500.11837/159

The Department of Chemical and Earth Sciences collection provides access to the academic and research outputs of staff and students. This collection includes research publications, conference papers, and examination question papers. The Department encompasses a broad range of disciplines, including Geography and Environmental Studies, Applied Remote Sensing & Geographic Information Systems (GIS), Geology, and Pure and Applied Chemistry. By integrating theoretical knowledge with practical laboratory and field-based research, the Department equips students with analytical, technical, and problem-solving skills to address scientific, environmental, and societal challenges. Through the preservation and dissemination of these resources, the collection supports teaching, learning, and research, while fostering innovation, environmental stewardship, and sustainable development within the University and the wider community.

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Studies on the Metabolism of Lactose, Melibiose, Sucrose and Raffinose by Erwin/a Chrysanthemi
(University of Fort Hare, 1995) Mabinya, Leonard Vuyani
One of the challenging problems for a bacterial cell is to detect chemical changes that constantly occur in its environment, and to regulate and integrate its metabolism in response to such changes. The primary function of many cellular activities in these organisms is directed towards this task. These activities may include transport processes‚ cellular locomotion and chemotaxis, and the secretion of digestive enzymes (Saier, 1977; Dills et al.‚ 1980; Postma and Lengeler, 1985; Mitchell, 1985).
Separation of Bi, Ca, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sn, Ti, V and Zn in soil samples using thenoyltri:fluoroacetone as the most selective single ligand by the appropriate use of solvent extraction under the optim~m pH conditions
(University of Fort Hare, 2003-01) Mamela, Mojalefa Daniel
In this investigation, three soil samples collected from non-arid land were qualitatively analysed using both the electron microscopy and AAS methods and elements such as Bi, Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sn Ti, V and Zn were positively identified in each of them. However, the electron microscopy method also revealed the presence of Na, K and Mg in these samples. Due to the logistical problems our scope of analysis was restricted to the first sixteen elements only.
Variation in the essential oil composition of calendula officinalis L
(University of Fort Hare, 2008) Okoh, Omobola
Variations in the yield and composition of the essential oils from Calendula officinalis L. cultivated in Alice (Eastern Cape) are reported. Essential oils were obtained by hydrodistillation using the Clevenger apparatus and analysis was performed by GC-MS. The yield in essential oil revealed a maximum at the full-flowering stage (0.97%) and a minimum during the pre-flowering stage (0.13%). The composition showed different patterns at different phases of the vegetative cycle. Sesquiterpenes (α-cadinene, α-cadinol, T-muurolol, and epi-bicyclosesquiphellandrene) and monoterpenes (limonene, 1,8- cineole, and trans-β-ocimene) showed highest correlations with the age of the plant. An interesting stage is the post-flowering period, the essential oil being rich in α-cadinene, α- cadinol, T-muurolol, limonene, 1,8-cineole, with p-cymene presenting lower levels. The oils were extracted by hydrodistillation from fresh leaves, dry leaves, and fresh flowers yielding 0.06 %, 0.03 %, and 0.09 %, respectively. The analysis of oils by GCMS revealed a total of 30, 21, and 24 compounds from the fresh leaves, dry leaves, and the flowers, respectively, representing 91.7, 89.8, and 87.5% of the total oil composition. Sesquiterpenoids dominated in the fresh leaves (59.5 %) and flowers (26 %), while the monoterpenes dominated in the dry leaves (70.3 %). T-Muurolol (40.9 %) predominated in the fresh leaf oil, α-thujene (19.2 %) and δ-cadinene (11.8 %) were present in high quantities. In contrast, 1,8-cineole (29.4%), γ-terpenene (11.6 %), δ-cadinene (9.0 %), β- pinene (6.9 %), and α-thujene (6.3 %) were the major components in the dry leaf oil, while in the fresh flower oil, α-thujene (15.9 %), δ-cadinene (13.1 %) and γ-cadinene (10.9 %) were the major components. The significance of the effect of drying and age on essential oil composition is discussed.
Variation in the essential oil composition of Calendula Officinalis L
(University of Fort Hare, 2008) Okoh, Omobola Oluranti; Sadimenko, A P; Afolayan, A J
Variations in the yield, chemical composition, antibacterial, and antioxidant properties of the essential oils of Rosmarinus officinalis L. cultivated in Alice, Eastern Cape of South Africa over a period of 12 months using the solvent-free microwave extraction and traditional hydrodistillation methods were evaluated. The GC-MS analyses of the essential oils revealed the presence of 33 compounds with 1,8-cineole, a-pinene, camphor, verbenone, bornyl acetate and camphene constituting about 80 percent of the oils throughout the period of investigation, with the solvent-free microwave extraction method generally yielding more of the major components than the hydrodistillation method. Each of the major components of the oils varied in quantity and quality of yield at different periods of the year. The method of extraction and time of harvest are of importance to the quantity and quality of essential oil of Rosmarinus officinalis. Higher amounts of oxygenated monoterpenes such as borneol, camphor, terpene- 4-ol, linalool, a-terpeneol were present in the oil of SFME in comparison with HD. However, HD oil contained more monoterpene hydrocarbons such as a-pinene, camphene, β-pinene, myrcene, a-phellanderene, 1,8-cineole, trans- β-ocimene, γ-teprinene, and cis-sabinene hydrate than SFME extracted oil. Accumulation of monoterpene alcohols and ketones was observed during maturation process of Rosmarinus leaves. Quantitative evaluation of antibacterial activity, minimum inhibitory concentration values were determined using a serial microplate dilution method. The essential oils obtained using both methods of extraction were active against all the bacteria tested at a concentration of 10 mg mL-1. The minimum inhibitory concentrations for the SFME extracted oils ranged between 0.23 and 1.88 mg mL-1, while those of the HD extracted oils varied between 0.94 and 7.5 mg mL-1, thus suggesting that the oil obtained by solvent free microwave extraction was more active against bacteria than the oil obtained through hydrodistillation. The antioxidant and free radical scavenging activity of the obtained oils were tested by means of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH+) assay and β- carotene bleaching test. In the DPPH+ assay, while the free radical scavenging activity of the oil obtained by SFME method showed percentage inhibitions of between 48.8 percent and 67 percent, the HD derived oil showed inhibitions of between 52.2 percent and 65.30 percent at concentrations of 0.33, 0.50 and 1.0 mg mL-1, respectively. In the β-carotene bleaching assay, the percentage inhibition increased with increasing concentration of both oils with a higher antioxidant activity of the oil obtained through the SFME than the HD method. Thin layer chromatography (TLC) was used to analyze the chemical composition of the extracts using three eluent solvent systems of varying polarities i. e. CEF, BEA and EMW and sprayed with vanillin-sulfuric acid. The chemical composition of the different extracts was similar with the exception of methanol and water extracts which had only one or two visible compounds after treating with vanillin-spray reagent. To evaluate the number of antibacterial compounds present in the fractions, bioautography was used against two most important nosocomial microorganisms. S. aureus (Gram positive) and E. coli (Gram negative). Nearly all the crude serial extraction fractions contained compounds that inhibited the growth of E. coli. The hexane extract had the most lines of inhibition followed by ethyl acetate. Bioassay-guided fractionation against E. coli was used to isolate antibacterial compounds. The largest number of antibacterial compounds occurred in the hexane fraction. Furthermore we tried to complete the characterization by extracting and studying other biologically important plant metabolites such as phenolic compounds to evaluate the antioxidant capacity of Rosmarinus extracts
Chemical transformations and phytochemical studies of bioactive components from extracts of rosmarinus officinalis L.
(University of Fort Hare, 2010) Okoh, Omobola Oluranti
Variations in the yield, chemical composition, antibacterial, and antioxidant properties of the essential oils of Rosmarinus officinalis L. cultivated in Alice, Eastern Cape of South Africa over a period of 12 months using the solvent-free microwave extraction and traditional hydrodistillation methods were evaluated. The GC-MS analyses of the essential oils revealed the presence of 33 compounds with 1,8-cineole, a-pinene, camphor, verbenone, bornyl acetate and camphene constituting about 80% of the oils throughout the period of investigation, with the solvent-free microwave extraction method generally yielding more of the major components than the hydrodistillation method. Each of the major components of the oils varied in quantity and quality of yield at different periods of the year. The method of extraction and time of harvest are of importance to the quantity and quality of essential oil of Rosmarinus officinalis. Higher amounts of oxygenated monoterpenes such as borneol, camphor, terpene- 4-ol, linalool, a-terpeneol were present in the oil of SFME in comparison with HD. However, HD oil contained more monoterpene hydrocarbons such as a-pinene, camphene, β-pinene, myrcene, a-phellanderene, 1,8-cineole, trans- β-ocimene, γ-teprinene, and cis-sabinene hydrate than SFME extracted oil. Accumulation of monoterpene alcohols and ketones was observed during maturation process of Rosmarinus leaves. Quantitative evaluation of antibacterial activity, minimum inhibitory concentration values were determined using a serial microplate dilution method. The essential oils obtained using both methods of extraction were active against all the bacteria tested at a concentration of 10 mg mL-1. The minimum inhibitory concentrations for the SFME extracted oils ranged between 0.23 and 1.88 mg mL-1, while those of the HD extracted oils varied between 0.94 and 7.5 mg mL-1, thus suggesting that the oil obtained by solvent free microwave extraction was more active against bacteria than the oil obtained through hydrodistillation. The antioxidant and free radical scavenging activity of the obtained oils were tested by means of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH+) assay and β- carotene bleaching test. In the DPPH+ assay, while the free radical scavenging activity of the oil obtained by SFME method showed percentage inhibitions of between 48.8 % and 67 %, the HD derived oil showed inhibitions of between 52.2 % and 65.30 % at concentrations of 0.33, 0.50 and 1.0 mg mL-1, respectively. In the β-carotene bleaching assay, the percentage inhibition increased with increasing concentration of both oils with a higher antioxidant activity of the oil obtained through the SFME than the HD method. Thin layer chromatography (TLC) was used to analyze the chemical composition of the extracts using three eluent solvent systems of varying polarities i. e. CEF, BEA and EMW and sprayed with vanillin-sulfuric acid. The chemical composition of the different extracts was similar with the exception of methanol and water extracts which had only one or two visible compounds after treating with vanillin-spray reagent. To evaluate the number of antibacterial compounds present in the fractions, bioautography was used against two most important nos ocomial microorganisms. S. aureus (Gram positive) and E. coli (Gram negative). Nearly all the crude serial extraction fractions contained compounds that inhibited the growth of E. coli. The hexane extract had the most lines of inhibition followed by ethyl acetate. Bioassay-guided fractionation against E. coli was used to isolate antibacterial compounds. The largest number of antibacterial compounds occurred in the hexane fraction. Furthermore we tried to complete the characterization by extracting and studying other biologically important plant metabolites such as phenolic compounds to evaluate the antioxidant capacity of Rosmarinus extracts.
Chemical transformations and phytochemical studies of bioactive components from extracts of Rosmarinus officinalis L
(University of Fort Hare, 2010) Okoh, Omobola Oluranti; Sadimenko, A P; Afolayan, A J
Variations in the yield, chemical composition, antibacterial, and antioxidant properties of the essential oils of Rosmarinus officinalis L. cultivated in Alice, Eastern Cape of South Africa over a period of 12 months using the solvent-free microwave extraction and traditional hydrodistillation methods were evaluated. The GC-MS analyses of the essential oils revealed the presence of 33 compounds with 1,8-cineole, a-pinene, camphor, verbenone, bornyl acetate and camphene constituting about 80 percent of the oils throughout the period of investigation, with the solvent-free microwave extraction method generally yielding more of the major components than the hydrodistillation method. Each of the major components of the oils varied in quantity and quality of yield at different periods of the year. The method of extraction and time of harvest are of importance to the quantity and quality of essential oil of Rosmarinus officinalis. Higher amounts of oxygenated monoterpenes such as borneol, camphor, terpene- 4-ol, linalool, a-terpeneol were present in the oil of SFME in comparison with HD. However, HD oil contained more monoterpene hydrocarbons such as a-pinene, camphene, β-pinene, myrcene, a-phellanderene, 1,8-cineole, trans- β-ocimene, γ-teprinene, and cis-sabinene hydrate than SFME extracted oil. Accumulation of monoterpene alcohols and ketones was observed during maturation process of Rosmarinus leaves. Quantitative evaluation of antibacterial activity, minimum inhibitory concentration values were determined using a serial microplate dilution method. The essential oils obtained using both methods of extraction were active against all the bacteria tested at a concentration of 10 mg mL-1. The minimum inhibitory concentrations for the SFME extracted oils ranged between 0.23 and 1.88 mg mL-1, while those of the HD extracted oils varied between 0.94 and 7.5 mg mL-1, thus suggesting that the oil obtained by solvent free microwave extraction was more active against bacteria than the oil obtained through hydrodistillation. The antioxidant and free radical scavenging activity of the obtained oils were tested by means of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH+) assay and β- carotene bleaching test. In the DPPH+ assay, while the free radical scavenging activity of the oil obtained by SFME method showed percentage inhibitions of between 48.8 percent and 67 percent, the HD derived oil showed inhibitions of between 52.2 percent and 65.30 percent at concentrations of 0.33, 0.50 and 1.0 mg mL-1, respectively. In the β-carotene bleaching assay, the percentage inhibition increased with increasing concentration of both oils with a higher antioxidant activity of the oil obtained through the SFME than the HD method. Thin layer chromatography (TLC) was used to analyze the chemical composition of the extracts using three eluent solvent systems of varying polarities i. e. CEF, BEA and EMW and sprayed with vanillin-sulfuric acid. The chemical composition of the different extracts was similar with the exception of methanol and water extracts which had only one or two visible compounds after treating with vanillin-spray reagent. To evaluate the number of antibacterial compounds present in the fractions, bioautography was used against two most important nosocomial microorganisms. S. aureus (Gram positive) and E. coli (Gram negative). Nearly all the crude serial extraction fractions contained compounds that inhibited the growth of E. coli. The hexane extract had the most lines of inhibition followed by ethyl acetate. Bioassay-guided fractionation against E. coli was used to isolate antibacterial compounds. The largest number of antibacterial compounds occurred in the hexane fraction. Furthermore we tried to complete the characterization by extracting and studying other biologically important plant metabolites such as phenolic compounds to evaluate the antioxidant capacity of Rosmarinus extracts.
Preparation of photocatalytic TiO₂ nanoparticles immobilized on carbon nanofibres for water purification
(University of Fort Hare, 2011) Nyamukamba, Pardon; Tichagwa, L; Greyling, C
Titanium dioxide nanoparticles were prepared using the sol-gel process. The effect of temperature and precursor concentration on particle size was investigated. The optimum conditions were then used to prepare carbon and nitrogen doped titanium dioxide (TiO2) nanoparticles. Doping was done to reduce band gap of the nanoparticles in order to utilize visible light in the photocatalytic degradation of organic compounds. A significant shift of the absorption edge to a longer wavelength (lower energy) from 420 nm to 456 nm and 420 nm to 428 nm was observed for the carbon doped and nitrogen doped TiO2 respectively. In this study, the prepared TiO2 photocatalyst was immobilized on carbon nanofibres to allow isolation and reuse of catalyst. The photocatalytic activity of the catalyst was tested using methyl orange as a model pollutant and was based on the decolourization of the dye as it was degraded. The doped TiO2 exhibited higher photocatalytic activity than the undoped TiO2. The materials prepared were characterized by XRD, TEM, SEM, FT-IR, DSC and TGA while the doped TiO2 was characterized by XPS, ESR and Raman Spectroscopy.
Preparation and evaluation of Lignocellulose-Montmorillonite nanocomposites for the adsorption of some heavy metals and organic dyes from aqueous solution
(University of Fort Hare, 2011) Bunhu, Tavengwa; Tichagwa, L
The need to reduce the cost of adsorption technology has led scientists to explore the use of many low cost adsorbents especially those from renewable resources. Lignocellulose and montmorillonite clay have been identified as potentially low cost and efficient adsorbent materials for the removal of toxic heavy metals and organic substances from contaminated water. Montmorillonite clay has good adsorption properties and the potential for ion exchange. Lignocellulose possesses many hydroxyl, carbonyl and phenyl groups and therefore, both montmorillonite and lignocellulose are good candidates for the development of effective and low cost adsorbents in water treatment and purification. The aim of this study was to prepare composite materials based on lignocellulose and montmorillonite clay and subsequently evaluate their efficacy as adsorbents for heavy metal species and organic pollutants in aqueous solution. It was also important to assess the adsorption properties of the modified individual (uncombined) lignocellulose and montmorillonite. Lignocellulose and sodium-exchanged montmorillonite (NaMMT) clay were each separately modified with methyl methacrylate (MMA), methacrylic acid (MAA) and methacryloxypropyl trimethoxysilane (MPS) and used as adsorbents for the removal of heavy metals and dyes from aqueous solution. The lignocellulose and NaMMT were modified with MMA, MAA and MPS through free radical graft polymerisation and/or condensation reactions. NaMMT was also modified through Al-pillaring to give AlpMMT. The materials were characterised by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS) and characterisation results showed that the modification of the montmorillonite with MAA, MMA and MPS was successful. The modified lignocellulose and montmorillonite materials were evaluated for the adsorption of heavy metal ions (Cd2+ and Pb2+) from aqueous solution by the batch method. The adsorption isotherms and kinetics of both Cd2+ and Pb2+ onto the NaMMT clay, AlpMMT and lignocellulose materials are presented. The Langmuir isotherm was found to be the best fit for the adsorption of both heavy metals onto all the adsorbents. AlpMMT showed very poor uptake for heavy metals (both Cd2+ and Pb2+). PMMAgMMT, PMAAgMMT, PMAAgLig and PMPSgLig showed improved adsorption for both heavy metals. The mechanism of heavy metal adsorption onto the adsorbents was best represented by the pseudo second-order kinetic model. PMPSgLig, NaMMT and AlpMMT showed relatively high adsorption capacities for methyl orange, while the adsorption of neutral red was comparable for almost all the adsorbents. Neither the Langmuir model nor the Freundlich model was found to v adequately describe the adsorption process of dyes onto all the adsorbents. The pseudo second-order model was found to be the best fit to describe the adsorption mechanism of both dyes onto all the adsorbents. The modification of lignocellulose and montmorillonite with suitable organic groups can potentially produce highly effective and efficient adsorbents for the removal of both heavy metals and dyes from contaminated water. Novel adsorbent composite materials based on lignocellulose and montmorillonite clay (NaMMT) were also prepared and evaluated for the removal of pollutants (dyes and heavy metals) from aqueous solution. The lignocellulose-montmorillonite composites were prepared by in situ intercalative polymerisation, using methyl methacrylate, methacrylic acid and methacryloxypropyl trimethoxysilane (MPS) as coupling agents. The composite materials were characterised by FTIR, TGA, TEM and SAXS. SAXS diffractograms showed intercalated nanocomposites of PMMAgLig-NaMMT and PMAAgLig-NaMMT, whereas PMPSgLig-NaMMT showed a phase-separated composite and the same results were confirmed by TEM. The lignocellulose-montmorillonite composites were assessed for their adsorption properties for heavy metal ions (Cd2+ and Pb2+) and dyes (methyl orange and neutral red) from aqueous solution. Among these composite materials, only PMAAgLig-NaMMT showed a marked increase in the uptake of both Cd2+ and Pb2+ relative to lignocellulose and montmorillonite when used independently. The adsorption data were fitted to the Langmuir and Freundlich isotherms, as well as to the pseudo first-order and pseudo second-order kinetic models. The data were best described by the Langmuir isotherm and the pseudo second-order kinetic model. On the adsorption of dyes, only PMPSgLig-NaMMT showed enhanced adsorption of methyl orange (MetO) compared with lignocellulose and montmorillonite separately. The enhanced adsorption was attributed to the synergistic adsorption due to the presence of MPS, lignocellulose and NaMMT. Competitive adsorption studies were carried out from binary mixtures of MetO and Cd2+ or Pb2+ in aqueous solution. The adsorption process of MetO onto the composite material was found to follow the Freundlich adsorption model, while the mechanism of adsorption followed both the pseudo first-order and pseudo second-order models. This particular composite can be used for the simultaneous adsorption of both heavy metals and organic dyes from contaminated water. The adsorption of neutral red to the composite materials was comparable and the pseudo second-order kinetic model best described the adsorption mechanism.
Photocatalytic activity and antibacterial properties of Ag/N-doped TiO2 nanoparticles on PVAE-CS nanofibre support
(University of Fort Hare, 2012) Ocwelwang, Atsile Rosy; Tichagwa, L
Lack of potable water is one of the major challenges that the world faces currently and the effects of this are mainly experienced by people in developing countries. This has therefore propelled research in advanced oxidation technologies AOTs to improve the current water treatment methods using cost effective, non toxic and efficient treatment methods. Hence, in this study the sol-gel synthesis method was used to prepare TiO2 nanoparticles that were photocatalytically active under UV and visible solar light as well as possessing antibacterial properties. Silver and nitrogen doping was carried out to extend the optical absorption of TiO2. For easy removal and reuse of the photocatalyst the nanoparticles were immobilized on chitosan and poly (vinyl-alcohol-co-ethylene) using the electrospining technique. The synthesized nanomaterials were characterized by FTIR, XRD, SEM/EDS, TEM, DRS, and TGA. FTIR and EDS analysis confirmed the formation and composition of TiO2 nanopowders for the doped and undoped nanoparticles. XRD analysis showed that the anatase phase was the dominant crystalline phase of the synthesized nanopowders. SEM and TEM respectively illustrated the distribution and size of the electrospun nanofibers and the nanoparticles of TiO2. DRS results showed that there was a significant shift in the absorption band edge and wavelength of Ag-TiO2 to 397 nm, followed by N-TiO2 at 396 nm compared to the commercial titania which was at 359 nm. The photocatalytic activities and antibacterial properties of these materials were tested on methylene blue dye and E.coli microorganism respectively. Ag-TiO2 immobilized on nanofibers of chitosan and PVAE had the highest photocatalytic activity compared to N-TiO2. Similar results were observed when the biocide properties of these materials were tested on E. coli.
Development of a visible light active, photo-catalytic and antimicrobial nanocomposite of titanium dioxide and silicon dioxide for water treatment
(University of Fort Hare, 2012) Mungondori, Henry Heroe; Tichagwa, L
The aim of this study was to prepare composite materials based on titanium dioxide (TiO2) and silicon dioxide (SiO2), and to evaluate their photo-catalytic and antimicrobial properties. Carbon and nitrogen doped TiO2nano-particles were prepared via a sol gel synthesis, which is a simple hydrolysis and condensation technique. In situ doping was carried out using glucose and urea as carbon and nitrogen sources respectively. Doping increased the spectral response of titanium dioxide photo-catalyst, allowing it to utilise the visible region which is much wider than the UV region (about 40 % of the solar spectrum), thus making it a more efficient photo-catalyst. The carbon and nitrogen doped TiO2-SiO2nano-particles were immobilized on glass support material to allow for easy separation of the spent photo-catalyst after the photo-degradation process. Tetraethyl orthosilicate (TEOS) was employed as both a binder and precursor for silicon dioxide. A mixture of TiO2 and TEOS in a 1:1 ratio was allowed to polymerize on a glass support which had been treated with hydrofluoric acid to introduce OH groups. The prepared photo-catalytic material was characterized by FT-IR, XRD, DRS, TEM, EDX, and BET analyses. Carbon was found to be more effective as a dopant than nitrogen. It brought about a band gap reduction of 0.30 eV and a BET surface area of 95.4 m2g-1 on the photo-catalyst as compared to a gap reduction of 0.2 eV and surface area of 52.2 m2g-1 for nitrogen doped TiO2. On the other hand, introduction of SiO2 allowed utilization of visible light by the TiO2-SiO2 nano-composite leading to an improved rate of photo-degradation of both methyl orange and phenol red. However, the immobilization of TiO2 on support material made it less effective towards inactivation of E. coli ATCC 25922 bacterial cells when compared to powdered TiO2 which was able to inactivate about 98 % of the bacterial cells within an hour of treatment.
Interaction of terpenes and oxygenated terpenes with some drugs
(University of Fort Hare, 2012) Ajayi, Emmanuel Olusegun; Sadimenko, A P; Afolayan, A J
SFME and HD for the extraction of essential oil in Lavandula officinalis in Alice have been reported. A total of 59 compounds were identified with the major compound being 1,8-cineole, an oxygenated monoterpene, with 46.89% and 44.84% yield obtained for HD and SFME respectively. Charge transfer (CT) complexes formed between α-pinene, 1,8-cineole and camphor as electron donors with iodine as the electron acceptor have been studied spectrophotometrically in methylene chloride solution. The Benesi- Hildebrand equation has been applied to estimate the formation constant (Kf) and molecular extinction coefficient (εCT). The value of Kf is the highest in camphor-I2 complex compared to the other two complexes. Antibacterial assessment was carried out on the various reagents, determining the MIC of individual reagents and in combination. The results show an improvement, on combination of the various reagents than when tested alone.
Development of a bench scale single batch biomass to liquid fuel facility
(2013) Zhang, Yusheng
The research described in this dissertation was motivated by the global demand for energy that is not dependent on coal, oil, natural gas and other non-renewable fossil fuels. The technology used in this project is related to the use of biomass to produce a viable alternative to conventional sources of fuel. A bench scale biomass to liquid (BTL) facility was built and tested. This produced results confirming the feasibility of the BTL process. The findings of the pilot study outlined in this dissertation justified the conclusion that the next step will be to expand the capacity and productivity of the BTL pilot plant to an industrial scale. Biomass comes from a variety of renewable sources that are readily available. In this case, the material used in the fixed bed biomass gasification facility to generate wood gas was agricultural and forestry waste, such as straw and woodchips. The gasifier had the capacity to produce up to 10 cubic metres/hr of gas with a carbon monoxide and hydrogen content of between 20–40% by volume, when it was operated at ambient pressure and with air as the oxidizer. The gas, produced at a temperature above700ºC, was cooled in a quench/water scrubber in order to remove most of the mechanical impurities (tars and water-soluble inorganic particles), condensed and dried with corn cobs before being compressed in cylinders at over 100 bar(g)for use in the Fischer-Tropsch Synthesis (FTS). The syngas was subjected further to a series of refining processes which included removal of sulphur and oxygen. The sulphur removal technology chose entailed applying modified activated carbon to adsorb H2S with the help of hydrolysis in order to convert organic sulphur impurities into H2Swhich reduced the sulphur content of the gas to less than 5ppbv. Supported cobalt catalyst (100 grams), were loaded into single-tube fixed bed FT reactor with an inner diameter of 50 mm. The reactor was fitted with a heating jacket through which, heated oil ran to cool the reactor during a normal reaction occurring at <250 ºC, while nitrogen was used in the heating jacket during reduction, which occurred at temperatures up ~350 ºC. The FTS reaction was carried out at different pressures and temperatures. Liquid and wax products were produced from the facility. The properties of the liquid and solid hydrocarbons produced were found to be the same as FT products from other feed stocks, such as natural gas and coal.
Gasification characteristics of sugarcane bagasse
(University of Fort Hare, 2013) Anukam, Anthony Ike; Meyer, E L; Mamphweli, S; Okoh, O
Sugarcane is a major crop in many countries. It is the most abundant lignocellulosic material in tropical countries such as South Africa. It is one of the plants with the highest bioconversion efficiency. The sugarcane crop is able to efficiently fix solar energy, yielding some 55 tons of dry matter per hectare of land annually. After harvest, the crop produces sugar juice and bagasse. Sugarcane bagasse is a residue that results from the crushing of sugarcane in the sugar industry. It is a renewable feedstock that can be used for power generation and manufacturing cellulosic ethanol. As biomass, sugarcane bagasse holds promise as a fuel source since it can produce more than enough electricity and heat energy to supply the needs of a common sugar factory. However, in the sugarcane industry the bagasse is currently burnt inefficiently in boilers that provide the heating for the industry. This project seeks to investigate the possibility of gasifying sugarcane bagasse as an efficient conversion technology. The investigation is necessary because fuel properties govern the gasifier design and ultimately, the gasification efficiency. Proximate and ultimate analysis of sugarcane bagasse was conducted after which the results were used to conduct a computer simulation of the mass and energy balance during gasification. The kinetic investigation undertaken through the TGA and DTG analyses revealed the activation energy and pre – exponential factor which were obtained by the model – free Kissinger method of kinetic analysis and were found to be 181.51 kJ/mol and 3.1 × 103/min respectively. The heating value of sugarcane bagasse was also measured and found to be 17.8 MJ/kg, which was used in the calculation of the conversion efficiency of the gasification process. Fuel properties, including moisture content and gasifier operating parameters were varied in order to determine optimum gasifier operating conditions that results in maximum conversion efficiency. The highest conversion efficiency was achieved at low moisture content after computer simulation of the gasification process. Moisture content also affected the volume of CO and H2 as the former decreases with increasing moisture content while the latter increases with increasing moisture content, accelerating the water – gas reaction. Scanning electron microscope fitted to an Energy dispersive X – ray spectroscopy was also used in order to view the shape and size distribution as well as determine the elemental composition of sugarcane bagasse. The results obtained established that the fuel properties and gasification conditions affect the conversion efficiency. During computer simulation, it was established that smaller particle size resulted in higher conversion efficiency. The smaller throat diameter also resulted in higher conversion efficiency. The throat angle of 25° also resulted in higher conversion efficiency. The temperature of input air was also found to be one of the major determining factors in terms of conversion efficiency. The dissertation presents the proximate and ultimate analysis results as well as the kinetic analysis results. The SEM/EDX analysis as well as the computer simulation results of the gasification process is also presented. The major contribution of this project was on the investigation of the gasification characteristics of sugarcane bagasse and the utilization of these in the design of a laboratory scale sugarcane bagasse gasifier with enhanced conversion efficiency through computer simulation.
Phytochemical analyses and Brine shrimp (Artemia Salina) lethality studies on Syzygium cordatum
(University of Fort Hare, 2013) Chiguvare, Herbert; Oyedeji, O
Syzygium cordatum Hoscht ex. C Krauss, also known as water berry, is normally used by the people of South Africa for respiratory ailments including tuberculosis, stomach complaints, treatment of wounds and as emetics. An extract of the leaves can be used as a purgative for diarrhoea treatment. The leaves of Syzygium cordatum Myrtaceae were obtained from the Eastern Cape Province of South Africa, air dried and sequential solvent extraction was done to obtain various non volatile crude extracts. The volatile extract, that is the essential oil was extracted from the leaves using hydrodistillation and analysis of compounds was done by GC/MS for composition. 32 compounds were obtained from the fresh leaves and 18 compounds were obtained from the dry leaves. The fresh oil contains caryophyllene (11.8 percent) and caryophyllene oxide (11.1 percent) as the main sesquiterpene component. α-Pinene(5.0 percent) was the only monoterpene compound identified in the fresh oil in substantial amount. The dry leaves oil had copanene (17.0 percent), β-Caryophellene (26.0 percent), cubenol (6.5 percent) and caryophellene oxide (14.2 percent) as the dominant constituent of the oil. Summary of the classes of compounds in the oil revealed that the chemical profile of both oils were dominated by sesquiterpenoid compounds. This is the first time that terpenoids compounds are being identified in both the fresh and dry leaf oil of S. cordatum. Hexane leaf extract was selected due to the interest in the terpenoid compounds. Column chromatography of the hexane crude gave five (5) of which two are fully reported. The isolates were fully elucidated using spectroscopic methods to be β-Sitosterol (HC3) and Friedela-3-one (HC1A/HC1D). Cytotoxicity analysis was carried out on the crude using the Brine shrimps assay. Isolates 1C and1D showed significant lethality using the brine shrimps assay with lethality values (LC50) of 4.105mg/ml for HC1C and 4.11mg/ml for 1D/1A respectively.
Synthesis and characterization of metal sulfide nanoparticles/polymer nanocomposites
(University of Fort Hare, 2013) Mbese, Johannes Zanoxolo; Ajibade, P A
The focus of this project was to synthesize and characterize metal sulfide nanoparticles /polymer nanocomposites. The work involved the synthesis of dithiocarbamato ligands and complexes derived from aniline. Zn(II), Cd(II) and Hg(II) dithiocarbamato complexes were used as single-molecule precursors for the synthesis of the ZnS, CdS and HgS nanoparticles and their optical and structural properties studied. The other focus of this work was to synthesize a combined functionality metal sulfide nanoparticles/polymer nanocomposites by dispersing as-synthesized ZnS, CdS and HgS nanoparticles in polymethyl methacrylate (PMMA) matrix. The characterization of the ligands, complexes, nanoparticles and nanocomposites were investigated using relevant instrumental tools like UV-Vis, photoluminescence (PL), Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy dispersion X-ray (EDX), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
The characterization and electrochemistry of dye-sensitized solar cells
(University of Fort Hare, 2013) Caga, Noloyiso; Meter, E L; Mamphweli, S N; Ajibade, P A
In this study a presentation of the technology behind dye-sensitized solar cells, their design as well as the role of the different parts of the cell. The characterization of the cell is divided into four sections namely: the characterization of the paste required to make the TiO2 film and its optical properties using SEM-EDX and XRD analytical techniques; Analysis of the various absorptions of three Ru-based dyes using UV-Vis spectroscopy, Photoluminescence and Fourier Transform Infra-Red spectroscopy; the characterization and the analyses of the entire cell using Electrochemical Impedance Spectroscopy. The nine cells were prepared by examining RuL2(CN)2 , RuL2(NCS)2 or N3 dye and RuL2(NCS)2 TBA+ or N719 dye. [L = 2,2'-bipyridyl-4,4'-dicarboxylic acid ;TBA = tetra-butyl ammonium] were combined with three electrolytes namely: Z–150 , AN–50 and PN–50. The Iodolyte PN–50 is an iodide based low viscosity electrolyte with 50 mM of tri-iodide dissolved in a solvent called propionitrile (PN). The Iodolyte AN–50 is an iodide based low viscosity electrolyte with 50 mM of tri-iodide dissolved in a solvent called acetonitrile (AN). The Iodolyte Z–150 is an iodide based low viscosity electrolyte with 150 mM of tri-iodide dissolved in a solvent called 3-methoxypropionitrile (MPN) and with additives such an ionic liquid, malkylbenziimidazole and guanidine thiocyanate. A solar simulator was utilized with which the standard solar irradiation can be created in laboratory conditions. The fill factors as well as overall performance efficiencies of the these cells are quite low < 1.0%,.
Computational studies, synthesis and characterization of Ruthenium(ii) anticancer complexes.
(University of Fort Hare, 2014) Adeniyi, Adebayo Azeez
As demand for water grows in South Africa, alternative sources are actively being sought to augment conventional water supply. While domestic rainwater harvesting has been put forward as one such an alternative water supply, little information is available on whether harvested rainwater is safe for human use or even how local communities feel about using the water from such an alternative source. The SU team tested the chemical and microbial quality of rainwater collected from the rainwater tanks of 29 houses over six months. In addition, 68 households were interviewed to investigate the acceptance and perception on the use of the domestic rainwater harvesting tanks. The results obtained for the chemical analysis indicated that the rainwater quality was within potable, chemical standards. Metals, cations and anions that were analysed for in the harvested rainwater samples were all below the recommended drinking water guidelines. However, the microbial analysis showed that the presence of the following group of indicator organisms exceeded the recommended drinking water guidelines: total coliforms, Eneterocci, faecal coliforms, and heterotrophic bacteria. The presence of several opportunistic pathogens, including E.coli, Cryptosporidium and Salmonella, were also detected. In short, the water from the rainwater harvesting tanks in Kleinmond is not fit for human consumption, and prior treatment is required before the water source can be used for drinking purposes. The main causes of contamination are dirt and faeces (from birds and small animals) on the roof surface, which fall into the tank. Other sources of rainwater contamination include leaf debris and organic material washed into the tank, animals or birds that fall into uncovered tanks as well as breeding mosquitoes. It was found that many of the households placed their garbage bags on top of the tanks to protect them from being ripped open by stray dogs. These garbage bags could easily contaminate the rainwater, especially if the tanks are leaking or broken and/or the lid is absent. This general lack of awareness of contamination hazards highlights the importance of training users in the proper use and maintenance of the technology. It has been recommended that some form of pre-treatment be installed to make the rainwater safe for drinking. As a follow up to this part of the project, the SU team is now investigating the use of solar water pasteurisation and filtration systems for the treatment of harvested rainwater. Interestingly, the SU user survey indicated that the majority of community members of the Kleinmond Housing Scheme instinctively steered clear of using the water from their rainwater harvesting tanks for drinking purposes. About two-thirds of the respondents do not use the water in the tank for drinking, while by far the majority of those who use it for drinking do so only sometimes (24%). The majority of respondents who do drink the water pre-treat it first. One mother reported that her baby developed a rash after rainwater was used to bath him, while others said that drinking the water was ‘bad for your stomach’. The majority of respondents indicated that they use the harvested rainwater for household chores instead, such as laundry, cleaning, and gardening. One respondent was even applying his rainwater to help run his small car wash business. This thesis is centred on the application of Ru-based complexes as a promising alternative to cis-platin in cancer chemotherapy. Cis-platin is known to be the most prescribed chemotherapy which has more than 70% application in cancer cases especially the testicular cancer. An insight is provided in Chapter One and Two into the literatures reports on the application of Ru(II)-based complexes in cancer chemotherapy. In order to address some of the pressing challenges in rational design of Ru-based anticancer complexes, section 3.3 and 3.4 deal with efforts to elucidate the complication of their chemistry and instability while in section 3.5 efforts are made to find solution to the lack of proper knowledge of their targets using different theoretical approaches as presented in Chapter Three. In addition to the theoretical study, this thesis also comprises of the synthesis of the bis-pyrazole derivatives type of ligands and the derivatives of their Ru(II)-based complexes as provided in Chapter Four and Five respectively. Also the computational methods were used to elucidate the structural and spectroscopic properties of the synthesised ligands and their Ru(II)-based complexes. The geometrical and electronic properties are studied in relation to the stability and the reported anticancer activities of Ru(II)-based complexes in section 3.3. In subsection 3.3.1, several quantum properties including the natural energy decomposition analysis (NEDA) and quantum theory of atoms in a molecule (QTAIM) are computed on three models of RAPTA-C complexes using DFT with hybrid functional and basis set with ECP and without ECP. The higher stability of Carbo-RAPTA-C and Oxalo-RAPTA-C over RAPTA-C comes from the lower exchange repulsion and higher polarization contributions to their stability which gives insight into experimental observation. A similar study was carried out in subsection 3.3.2 on half-sandwich Ru(II)-based anticancer complexes with 6-toluene and 6-trifluorotoluene. The trifluorotoluene and the hydrated models are characterised with higher charge transfer, polarizability, synergistic effect of ligand fragments, stronger and higher HB interactions that support their reported experimental anticancer activities and the mechanism of their activation by hydrolysis. Also in the subsection 3.3.3, the factors that determine the stability and the effects of non-covalent interaction on the two models of these half-sandwich 6-arene ruthenium anticancer complexes and their respective hydrated forms were investigated using DFT method. Lastly in section 3.3, the subsection 3.3.4 deals with the intramolecular properties of five sets of ruthenium based anticancer complexes using DFT method. The spectroscopic and the non-linear optical properties of selected Ru(II) anticancer complexes are shown in Section 3.4. In subsection 3.2.1, DFT method was applied to study the thermodynamic and spectroscopic properties of three Ru-based complexes in order to give possible reasons for the reported experimental stability of complexes 1 and 2 with bidentate chelating ligands than complex 3. A further study was carried out in Subsection 3.4.2 where computational method was used to gain insight into the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Lastly in this section, subsection 3.2.3 deals with application of different density functional methods (DFT) to optimize and study the chemistry of five potential anticancer complexes in terms of their electronic, conductive and spectroscopic properties. The carboxylic and pyrazole units are found to significantly enhance the polarizabilities and hyperpolarizabilities of the complexes while the chloride only improves the polarity of the complexes. The possible targets of Ru(II)-based anticancer complexes are predicted using docking methods as presented in section 3.5 of this thesis. In subsection 3.5.1, the interactions of selected Ru(II)-based complexes with different cancer receptors are carried out using computational docking. The study focuses more on finding alternative protein targets other DNA for some Ru(II)-based complexes using computational docking. A further study on addressing the problem of the improper knowledge of of the targets of Ru-based anticancer complexes was carried out in subsection 3.5.2. Some promising anticancer complexes of Ru(II) such as RAPTA based complexes formulated as [Ru(η6-p-cymene)L2(pta)] and those with unusual ligands are docked against receptors using Autodock, Glide and Gold. Lastly in section 3.5, docking packages Molegro and Autodock were applied in subsection 3.5.3 to predict the anticancer activities of selected Ru(II) complexes against twelve anticancer targets. Introducing the quantum calculated atomic charges of the optimized geometries is found to significantly improve the docking predictions of these anticancer metallocompounds. In section 4.3-4.6, the spectroscopic and the geometric properties of ligands with pyrazole, methylpyrazole, bipyridine and phenanthroline derivatives were studied at both experimental and computational levels. The computational results are perfectly in agreement with the experimental results especially in terms of the spectroscopic properties. The spectroscopic analyses as well as the computed properties were used to establish the successful synthesis of the ligands. Many of the functional groups in these ligands are found to be Raman active which also help in their spectroscopic elucidation. Lastly in chapter five, the method used for the synthesis of forty Ru(II)-based complexes were presented with their experimental spectroscopic features being elucidated using theoretical methods. A very high correlation was observed between experimental and theoretical characterisation of the complexes which is an indication of successful synthesis of the complexes.
Ethanol production from lignocellulosic sugarcane leaves and tops
(2014) Dodo, Charlie
Various methods for the production of bioethanol using different feedstocks have been researched on. In most work on bioethanol synthesis from sugar cane, tops and leaves have been regarded as waste and generally removed and thrown away. In this work, lignocellulosic sugarcane leaves and tops were not discarded but instead used as biomass to evaluate their hydrolyzate content. The leaves and tops were hydrolysed using different methods, namely concentrated acid, dilute acid pre-treatment with subsequent enzyme hydrolysis and compared with a combination of oxidative alkali pretreatment and enzyme hydrolysis. Subsequent fermentation of the hydrolyzates into bioethanol was done using the yeast saccharomyces cerevisae. Acid hydrolysis has the problem of producing inhibitors, which have to be removed and this was done using overliming with calcium hydroxide and compared to sodium hydroxide neutralization. Oxidative alkali pre-treatment with enzyme hydrolysis gave the highest yields of fermentable sugars of 38% (g/g) using 7% (v/v) peroxide pre-treated biomass than 36% (g/g) for 5% (v/v) with the least inhibitors. Concentrated and dilute acid hydrolysis each gave yields of25% (g/g) and 22% (g/g) yields respectively although for acid a neutralization step was necessary and resulted in dilution. Alkaline neutralization of acid hydrolyzates using sodium hydroxide resulted in less dilution and loss of fermentable sugars as compared to overliming. Higher yields of bioethanol, 13.7 (g/l) were obtained from enzyme hydrolyzates than 6.9 (g/l) bioethanol from dilute acid hydrolyzates. There was more bioethanol yield 13.7 (g/l) after 72h of fermentation with the yeast than 7.0 (g/l) bioethanol after 24h. However, the longer fermentation period diminishes the value of the increase in yield by lowering the efficiency of the process.
Biological Evaluation and Semi-synthesis of Isolated Compounds from (Syzygium aromaticum (L.) Merr. & Perry) Buds.
(University of Fort Hare, 2014) Rali, Sibusiso; Oyedeji, O.O.; Nkeh-Chungag, B.N.
Natural products play a fundamental role in modern drug discovery as they continue providing diverse bioactive lead compounds for new drug formulation. However, isolation of these valued compounds is problematic. On the other hand, the morbidity and mortality rates caused by non-communicable diseases are increasing with improved longevity. Thus, the study herein focused on the isolation of plant-derived compounds from Syzygium aromaticum and evaluated their biological properties. Syzygium aromaticum is a well-known plant which belongs to family Myrtaceae. Dried flower buds of S. aromaticum were subjected to sequential solvent extraction. The ethyl acetate extract (15.535 g) was subjected to column chromatography using a silica gel (0.063-0.200 mm) for isolation. This has led to the isolation of three distinct compounds that were identified as eugenol, maslinic acid (MA) and oleanolic acid (OA). The structural elucidation of these valued compounds was done using NMR, GC-MS, LC-MS, FT-IR and Mp. Further semi-synthesis of the oleanolic acid afforded acetate and ester OA-derived compounds with better solubility properties. All these compounds were evaluated for analgesic and anti-inflammatory properties. All tested compounds were administered at a dose of 40 mg/kg to both Wistar rats and Swiss mice. Significant (p<0.01) analgesic and anti-inflammatory properties are obtained for all compounds. The effects of eugenol in all experiment were better except in the thermal-induced pain or tail flick test. In the case of modified compounds, the formalin induced pain test disclosed that oleanane derived compounds confessed analgesic and anti-inflammatory effects better than OA, whereas, in tale flick test oleanolic acid proved superior analgesic effects compared to all its derivatives with the exception of the acetyl- derivative. Acute anti-inflammatory test showed that acetyl-derivatives were more active than other compounds. In conclusion, chromatographic techniques and semi-synthesise of oleanolic acid have resulted to several plant-derived compounds with analgesic and anti-inflammatory properties. The semi-synthesized compounds may serve as alternative drug candidates for new analgesic and anti-inflammatory drug formulation derivative. Acute anti-inflammatory test showed that acetyl-derivatives were more active than other compounds. In conclusion, chromatographic techniques and semi-synthesise of oleanolic acid have resulted to several plant-derived compounds with analgesic and anti-inflammatory properties. The semi-synthesized compounds may serve as alternative drug candidates for new analgesic and anti-inflammatory drug formulation.
Investigation into the characteristics and possible applications of biomass gasification by-products from a downdraft gasifier system.
(University of Fort Hare, 2014) Melapi, Aviwe;
Biomass gasification has attracted the interest of researchers because it produces zero carbon to the atmosphere. This technology does not only produce syngas but also the by-products which can be used for various applications depending on quality. The study conducted at Melani village in Alice in the Eastern Cape of South Africa was aimed at investigating the possible applications of the gasification by-products instead of being thrown away. Pine wood was employed as the parent feedstock material for the gasifier. Biomass gasification by-products were then collected for further analysis. The studied by-products included tar (condensate), char, soot and resin. These materials were also blended to produce strong materials. The essence of the blending was to generate ideal material that is strong but light at the same time. The elemental analysis of the samples performed by CHNS analyser revealed that carbon element is in large quantities in all samples. The FTIR spectra showed almost similar results for all the studied samples, since the samples are end products of lignocellulose gasification. The major functional groups observed in all the samples under FTIR included C=C, O-H, C-H, C-O, C-C. Samples under XRD showed amorphous structure as they mostly absorbed within the range of 10°-35°. SEM gave the sticky images of resin as well as porous char structures. Char showed a higher heating value of 35.37MJ/Kg when compared to other by-products samples.

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