Theses and Dissertations

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Integration of routine core data and petrographic analysis to determine the sandstone reservoir flow units in the Bredasdorp Basin, Offshore South Africa
(University of Fort Hare, 2024-11) Tyhutyhani, Nobathembu; Magoba, M.; Gwavava, O.
The integration of routine core data and petrography to determine the sandstone reservoir flow units was extensively performed in four selected wells: F-A10, F-A13, FO1, and F-O2 in the Bredasdorp Basin, offshore South Africa. Determining the quality of reservoirs and identifying minerals present is crucial for defining the best reservoir interval for hydrocarbon flow and storage and avoiding exploration errors by using suitable drilling and hydraulic fluids. Moreover, it also helps select the best Enhanced Oil Recovery (EOR) methods. The analysed wells were randomly chosen throughout the upper shallow marine interval to examine the impact of diagenetic minerals on reservoir flow units using geophysical wireline logs, routine core analysis, and core samples. The routine core analysis data consisted of nine hundred core plugs, which were used to establish reservoir flow units from four independent methods, namely: Pore Throat Radius, Flow Zone Indicator, Stratigraphic Modified Lorenz Plot, and Improved Stratigraphic Modified Lorenz Plot. The analysis of seventeen thin sections and fifteen scanning electron microscopy samples were employed to determine the impact of diagenetic minerals on petrophysical properties. The gamma-ray log and core samples identified one reservoir from each well. The permeability and porosity of the four identified sandstone reservoirs ranged from 0–22% and 0–2250 mD, respectively. The Stratigraphic Modified Lorenz Plot results showed five flow units classified as high, moderate, low, very low, and tight reservoir rock. In contrast, the Improved Stratigraphic Modified Lorenz Plot showed six flow units: fractured, super-conductive, conductor, semi-conductor, baffle, and semi-barrier. The Improved Stratigraphic Modified Lorenz Plot method proved more effective than the Stratigraphic Modified Lorenz Plot method in identifying flow units. The pore throat radius revealed that the pores ranged from nano-porous (≤ 1 𝜇𝑚) to megaporous (≥ 10 𝜇𝑚). The best reservoir intervals had megaporous radii and were classified as high or super-conductive flow units. In contrast, the poorer or impervious reservoir intervals had nanoporous radii and were classified as tight or baffle flow units. Four hydraulic flow units were identified and ranked as impervious, poor, fair, and good. Core logging of selected reservoirs revealed that FA10 and F-A13 were composed of glauconitic, medium-grained sandstone, fine-grained sandstone, and claystone. F-O1 was composed of fine-to-coarse grained sandstone that was moderately to well-sorted. F-O2 comprised of fine-grained, argillaceous sandstones that were poorly to moderately sorted. The Scanning Electron Microscopy analysis revealed that the clay minerals in the selected wells were smectite, illite, and chlorite. The effect of diagenetic minerals on petrophysical properties was apparent in the pore-filling minerals (glauconite, siderite, smectite, illite, chlorite, quartz and feldspar overgrowth, calcite, and calcareous sponge), which affected intergranular pore spaces and pore connectivity. Various diagenetic processes, such as cementation, compaction, and pore-filling minerals, significantly impacted the reservoir petrophysical characteristics of the studied reservoirs, particularly the F-O2 reservoir. These results can serve as input parameters for the Bredasdorp Basin's static and dynamic reservoir models.
Synthesis and characterization of hybrid compounds containing ferrocene scaffold as potential anticancer drugs
(University of Fort Hare, 2024-11) Ndlovu, Sijongesonke; Aderibigbe, B.A.
Cancer is one of the diseases, and its treatment suffers from several limitations. For instance, there are several commercially available drugs to treat this lethal disease. However, they still display shortcomings such as drug toxicity and resistance, poor water solubility, poor bioavailability, and severe side effects. Thus, their efficacy is compromised by these limitations. The emerging drug repurposing strategy is gaining momentum from medicinal researchers. This comes after several compounds have been reported to possess various biological activities. Thus, the hybridization approach via drug reprofiling has been an interesting field of research. Hence, this study reports the synthesis of hybrid compounds as potential anticancer drugs. Two ferrocene scaffolds (ferrocene and ferrocene carboxaldehyde) were modified to keto-ferrocene butanoic acid (16) and methyl-ferrocenol (18) and hybridized with several selected pharmacophores via esterification and amidation reactions using suitable functional groups, resulting in a class of eleven esterlinked (19-29) and five amide-linked (30 34) hybrids. The characterization techniques including Fourier Transform Infrared (FTIR) spectroscopy, Nuclear magnetic resonance (NMR) spectroscopy, and Liquid chromatography mass spectrometry (LC-MS) confirmed the successful development of these hybrids by displaying the expected signals at the expected regions of the spectra. Most importantly, the molecular weights calculated corresponded with those obtained by the LCMS on the samples. In vitro, two hybrid compounds, 20 ( thymol-keto-ferrocene butanoate) and 27 (ursolic-ferrocenoate), were the most promising anticancer compounds, displaying a 50% cytotoxic effect against cervical cancer (HeLa) and Chinese hamster ovary (CHO) cell lines and less than 20% on normal cells (VERO). Noteworthy, the cytotoxicity was concentrationdependent. Furthermore, hybrid 20 was the most effective compound with a selective index greater than one from the series. Thus, the findings from the molecular docking of these two most promising hybrids further confirmed the in vitro findings, which revealed high negative docking scores, signifying binding interactions and good binding affinity of the compounds towards the biological targets. The in silico predictions of the two also showed they are non-toxic, have a good bioavailability score (0.55<), are P-gp substrates, and do not inhibit most of the CPY enzymes. Hence, this study reveals the efficacy of synthesizing hybrid compounds containing ferrocene scaffolds and plant-based pharmacophores, such as thymol and ursolic acid. Developing hybrid molecules is a promising synthetic approach for potent anticancer agents.
Design and characterization of sodium alginate-based scaffolds for the treatment of burn wounds
(University of Fort Hare, 2024) Ndlovu, Sindi Prescila; Aderibigbe, B.A.; Motaung, S.
Burn injuries have a considerable impact on mortality and morbidity rates due to the systemic immune changes and increased infection risks that they cause. These factors hinder the healing process and allow microbial invasion, leading to prolonged hospital stays and increased mortality rates. In this study, sodium alginate-based membranes, topical gel, and nanofibers were prepared and evaluated as potential wound dressings that are affordable and effective for treating burn wounds, suggesting that they can also be accessible to low income individuals. The topical gels were prepared from sodium alginate (SA), Carbopol, Carboxymethyl cellulose (CMC), and polyethylene glycol (PEG). The gels were loaded with Capparis sepiaria extract to enhance their antibacterial efficacy. Membranes were designed from SA/Gum acacia/PVA/PF127 and loaded with Capparis sepiaria, and nanofibers were developed from SA/PVA/PLGA and loaded with Capparis sepiaria. The topical gels, membranes, and nanofibers were evaluated using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), and X-ray diffraction (XRD), which confirmed the successful preparation of these three classes of wound dressings. The Water Vapor Transmission Rate (WVTR) values of the membranes and nanofibers were in a range of 1654.73 ± 0.74 and 319.24 ± 9.82 g/m2.24h, respectively, which is suitable for application on burn wounds, preventing moisture accumulation and reducing the risk of infection. The viscosity of the topical gels was in the range of 12 ± 0-7720 ± 152.83 and 20 ± 9.78-5256 ± 61.10 cP at 50 and 100 rPM, respectively, revealing a thixotropic/pseudoplastic behaviour, indicating that they can be easily applied on the wound bed. The membranes were biodegradable, with good swelling behaviour, showing their capability to absorb excess wound exudate. The membrane’s mechanical properties were studied, and their tensile strength was suitable for dermal application without causing discomfort upon removal from the wound bed. The topical gels, membranes, and nanofibers scaffolds displayed superior antibacterial efficacy against some gram-positive and gram-negative bacteria strains compared to the employed commercial wound dressing in this study that are responsible for the chronicity of burn wounds, such as Pseudomonas aeruginosa, Enterococcus faecalis, Mycobacterium smegmatis, Escherichia coli, Enterobacter cloacae, Proteus vulgaris, and Staphylococcus aureus. These three wound dressings showed a non-toxic effect on the immortalized human keratinocyte cells (HaCaT) cells, with a % cell viability of more than 85%. Furthermore, the wound dressings' capability to promote blood clotting was significant. The non-toxic nature of the wound dressings supported significant cell adhesion, migration, and proliferation than the commercial wound dressing used in the study. The three classes of SA-based wound dressings (i.e., topical gels, membranes, and nanofibers) displayed superior biological properties than commercial wound dressing, revealing their potential application as wound dressings on burn wounds.
Flow unit determination of the upper shallow marine sandstone resevoirs in the Bredasdorp Basin, offshore South Africa
(University of Fort Hare, 2024) Mudau, Ndamulelo; Magoba, M.; Opuwari, M.
This study comprehensively analyses reservoir flow units and distribution in four wells (E-E1, E-S3, E-S5, and E-W1) of the lower Cretaceous upper shallow marine sandstone reservoirs in the Bredasdorp Basin, offshore South Africa. The study integrated multiple techniques, including the Stratigraphic Modified Lorenz Plot, Improved Stratigraphic Modified Lorenz Plot, Winland pore throat radius, Stratigraphic Flow Profile, and Flow Zone Indicator, to establish the spatial flow unit distribution of the upper shallow marine reservoirs. Analyses of 400 core plugs, 14 thin section slides, and 15 Scanning Electron Microscopy samples and core logging provided detailed insights into petrophysical properties and diagenetic minerals affecting the flow units within the reservoir. A comprehensive examination of gamma-ray logs and core samples identified a prominent glauconitic sandstone reservoir in the upper shallow marine formations. The conventional core analysis revealed substantial variability in porosity (0.3 % - 18 %, average 6.4 %) and permeability (0.008 - 170 mD, average 24.5 mD). Stratigraphic Modified Lorenz Plot Identified three flow units: barrier, baffle, and normal flow units, with storage capacity and flow capacity, ranging from 1.6 – 12.9 and 0.08 – 32.6, respectively. Improved Stratigraphic Lorenz Plot (ISMLP) results identified six flow unit types: barrier, semi-barrier, semi-conductor, conductor, superconductor, and fractured. Flow unit ranking indicated reservoir quality ranges from barrier/seal (0°- 15°) to fractured (75° - 85°). Pore throat radius (R35) results revealed diverse rock-type distributions from nanoporous to macroporous, ranging from 0.3 µm to 6.6 µm. These rock types indicated fair reservoir quality. Flow Zone Indicator (FZI) identified five distinct Hydraulic Flow Units (HFUs): HFU 1, HFU 2, HFU 3, HFU 4, and HFU 5, with values ranging from 0.19 µm to 28.7 µm, with an average value of 2.9 µm. Flow zone correlation revealed widespread low-flow zones and localized moderate-flow zones. Core logging analysis revealed distinct lithological characteristics among the reservoirs. Wells E-E1 and E-S3 comprise medium- to coarse-grained sandstones with rip-up clasts of claystone and siltstone, predominantly pyritic and glauconitic. In contrast, well E-S5 exhibits cross-bedded sandstones, fining upward with claystone clasts, pebble shaped lithic grains, and conglomerates formed from rounded gravel. E-W1 consists of fine- to medium-grained sandstones and conglomerates with scattered pebbles. Multiple facies were identified in each well's cored intervals, with well E-E1 containing five facies (A-E), wells E-S3 and E-S5 having four facies (A-D), and well E-W1 having three facies (A-C). Diagenetic minerals such as glauconite, pore-filling illite, smectite, and cementations (quartz overgrowth and calcite) significantly affected the baffle and barrier flow units. The results from this study will improve the understanding of flow unit distribution and reservoir heterogeneity in Bredasdorp Basin. It can also be used as input parameters for the 3D dynamic flow unit modeling of the upper shallow marine sandstones in this Basin.
Assessing drought impacts on riparian vegetation and local community adaptation: A case of Buffalo River Catchment, Eastern Cape province, South Africa
(University of Fort Hare, 2023) Mpanyaro, Zolisanani; Kalumba, A.M.; Zhou, L.
River catchments are vulnerable to drought events that significantly affect the ecosystem and the livelihoods of local communities, especially in water-scarce countries like South Africa. The significance of the Buffalo River catchment lies in its ecological value and the vital role it plays in supporting local communities. Despite the catchment's importance, there is a notable lack of documented evidence on drought effects in the area, underscoring the need for this research. Accordingly, the study assessed the impacts of drought on riparian vegetation and local communities’ adaptation strategies (1990 to 2020). To this end, the study utilised Landsat imagery, various indices (NDVI, TDVI, MNDWI), and the Standardized Precipitation Index (SPI), along with semi-structured questionnaires. The findings indicated that drought events resulted in precipitation variability (SPI 6 and 12 months), and a decline in river discharge (R² = 0.0235) with a moderately positive correlation (r = 0.77) between precipitation and water drainage. These results indicate adverse effects on riparian vegetation, leading to substantial challenges for local communities that rely on these resources. Local communities relying on riparian resources have faced significant disruptions, such as reduced agricultural productivity, limited water access, and various socio-economic challenges due to drought. As a result, the local community in the Buffalo River catchment has devised various adaptation strategies to drought impacts. The communities have experienced reduced agricultural productivity, limited water access, and other socio-economic difficulties due to drought. In response, they adopted several adaptation strategies, such as rainwater harvesting (65%), water reuse (36%), livelihood diversification (20%) conservation (12%), and alternative water sources (6%). The significance of this research lies in its potential to guide policymakers in developing community-based adaptation strategies, which could enhance the resilience and sustainability of river ecosystems in drought-prone areas.
Synthesis, characterisation and photovoltaic evaluation of twodimensional organometallic halide perovskite for perovskite solar cells application
(University of Fort Hare, 2024-12) Maqolo, Manduleli; Oyedeji, O.O.; Adjogri, S.J.; Meyer, L.
In recent years, traditional three-dimensional (3D) hybrid organic-inorganic perovskites have emerged as a new category of high-performance semiconductors, attracting extensive research owing to their appealing optoelectronic characteristics. Perovskite materials exhibit characteristics such as excellent charge mobility, adjustable band gap, and straightforward synthesis methods, resulting in a high-power conversion efficiency of 25.7% when employed as photo-absorbers in solar cells. The significant disadvantage of conventional perovskite materials is they are not stable, and poisons associated with lead, creating a necessity to address these issues. Moving to low dimensions of perovskite can increase stability, and environmentally safe metals that are non-toxic can be used, like Sn and Ge. This study aims to synthesize, characterize, and study the optical, morphological, and photovoltaic properties of lead-free two-dimensional organometallic bromide perovskites as potential light harvesters for perovskites solar cell applications. Using aniline and o-phenylenediamine, two ligands (C₆H₅NH₃Br and C₆H₄(NH₃Br)₂) and perovskite complexes were further prepared by reacting the ligands with CuBr₂, FeBr₂, CoBr₂, MnBr₂, ZnBr₂, and NiBr₂ to form twelve (12) perovskite complexes, and all the complexes were prepared at room temperature. The conductivity of the perovskites was studied using a conductor meter. The values range between 7.32 to 29.1 μS/cm, indicating that these materials are non-electrolytes and can be used as photo-absorbers. The as-prepared materials techniques like FTIR, ¹H and ¹³C NMR, UV-vis, PL, SEM, EDX, TGA, HRTEM, and XRD were used for analysis. In FTIR, the presence of functional groups such as NH₃, CH, CN, and MBr vibration peaks was observed around ~3350, ~2970, ~1025, and ~500 cm⁻¹, which suggests that the ligand successfully bonded with metal bromide. The elemental analysis was performed using EDX to assess the presence and distribution of elements, including C, N, Br, Cu, Fe, Co, Mn, Zn, and Ni in the materials. NMR analysis was conducted to elucidate the chemical structure, wherein an N-bonded proton was around 5 ppm. The aromatic-based protons were observed to be between 6 ppm and 8 ppm. In ¹³C NMR shows a resonance peak between 123.12 and 141.89 ppm, confirming the successful synthesis of perovskite materials. The topographic morphology of the materials was conducted using SEM images, and granules were obtained for flat grains. The crystal structure was monoclinic, orthorhombic, and triclinic (anorthic), with lattice d spacing ranging from 0.177 to 1.208 nm. These materials are highly stable at room temperature; in TGA, they show stability from 40 to 135°C. PL spectra of the synthesized perovskites exhibit emission peaks within the 605-610 nm range. The broad and high-intensity MLCT absorption bands make these aniline-based perovskites extremely useful for harvesting and transforming less energetic photons, thus showing their importance in photosensitization processes and solar energy conversion applications. Electrochemical measurements of the cyclic voltammetry system showed oxidation peaks in C1 to C12 curves, corresponding to the electron-donating group associated with the oxidation of Br⁻ ions. The reduction peaks correspond to the reduction of M²⁺ ions, where M represents the metal used (Cu, Fe, Co, Mn, Zn, and Ni) and is associated with electron-withdrawing groups. The electrochemical impedance measurements revealed charge-transfer and electrical properties relevant to optoelectronic performance. Hence, the overall findings indicate that the synthesized perovskite materials can be used as potential photo-absorbers.
Development and in vitro biological evaluation of hybrid wound dressings as potential therapeutics for the treatment of infected wounds
(University of Fort Hare, 2024) Kula, Hlalisa; Aderibigbe, B.A.; Motaung, S.
Infected wounds are challenging to treat and are identified as the leading causes of global mortality and morbidity. Improper management can result in amputations if not properly treated with appropriate wound dressings. The mental health of wound patients is great and some of them suffer from post-traumatic stress disorder (PTSD) due to prolonged hospitalisation. The problem associated with the treatment of infected wounds is that most commercially available wound dressings fail to cater for the wounds by not protecting the wounds from microbial invasion, non-compatibility, and inability to accelerate the wound healing process. Biopolymers such as polyvinyl alcohol (PVA), Hydroxypropylmethylcellulose (HPMC), Carboxymethylcellulose (CMC), and Sodium alginate (SA) were explored for preparation of hydrocolloids (single and double-layer) and cryogels loaded with Capparis sepiaria extract (cs-PE). The wound dressings were characterized by FTIR, SEM, and XRD. The mechanical properties such as tensile strength, thickness, and folding endurance were also evaluated. The tensile strength of the hydrocolloids ranged between 0.346 ± 0.13 to 5.590 ± 0.52 MPa and cryogels were between 0.094 ± 0.03 – 12.261 ± 0.56 Mpa. The surface pH of the dressings was in the range of 4.0-6.8 and the Water Vapour Transmission Rate (WVTR) ranged from 1032 ±2.79 to 9480 ±0.002 g/m2 .day-1 . The prepared biopolymer-based wound dressings incorporated with Capparis sepiaria exhibited good antimicrobial activity. XRD showed the amorphous nature of the wound dressings and the absence of free drugs, revealing their inability to trigger skin irritation. The antibacterial activity, cytotoxicity and wound scratch healing assay results showed that the prepared hydrocolloids and cryogels are effective against selected species of bacteria that are common in infected wounds, non-toxic, induce haemostatic effect, and have excellent capability to promote skin cell migration and proliferation. These features make them potential wound dressings for treating infected wounds.
Long term trends in extreme daily temperature and precipitation on sub-Antarctic Marion Island from 1950 to 2020
(University of Fort Hare, 2024) Kabase, Zenande; Hedding, D.W.
Sub-Antarctic Marion Island (46° 54’ S, 37° 53’ E) has experienced notable changes due to global climate change in recent decades. Records indicate a gradual increase in mean annual air temperature, with a rise of 2.4°C per century. Both maximum and minimum temperatures have increased by over 1°C, while annual rainfall has decreased to less than 2000 mm over the past seventy-one years. The onset of extreme events in the Antarctic Peninsula and subAntarctic region was observed in the early 2000s, and forecasts suggest these events will become more frequent, intense, and prolonged in the future. The objective of this study was to analyse the trends and patterns of daily extreme climatic parameters, specifically air temperature and precipitation, on Marion Island from 1950 to 2020. This analysis aimed to contextualize these changes within the observed alterations in the island's synoptic weather, providing insight into the underlying drivers. Daily temperature and precipitation data were obtained from the South African Weather Service (SAWS) and analysed. Linear regression statistics were employed to evaluate trends and patterns in the daily extremes, utilizing 25 extreme indices developed by the Expert Team on Climate Change Detection Indices (ETCCDI). The results spanning 71 years revealed a consistent climate shift on Marion Island. Mean annual air temperatures and daily maximum temperatures increased by 1.2°C (p < 0.01), while daily minimum temperatures rose by 0.9°C (p < 0.01). There was a significant rise in warm spells (p < 0.05) and warm nights (p < 0.01), accompanied by a notable decrease in cold spells (p < 0.01), cold nights, and annual frost days. The annual precipitation trend indicated a decline, with a significant reduction of 1042.3 mm (p < 0.01) in mean annual rainfall, along with a decrease in heavy precipitation events over the study period. Additionally, the occurrence of consecutive dry days increased by an average of 5 to 7 days between 1950 and 2020. Anthropogenic forcing, particularly the positive phase of the Southern Antarctic Mode, is identified as the primary cause of ocean and atmospheric warming in the sub-Antarctic region. The positive shift of the Southern Antarctic Mode due to anthropogenic forcing is a significant impact of how climate change is affecting the region and surrounding areas, and how frequent the phase could be due to an intensification of climate change conditions in the region. This phenomenon leads to the intensification and poleward migration of the Southern Hemisphere westerly winds. Changes in wind patterns, such as prolonged exposure to warm north-westerly winds and reduced exposure to post-cold front sectors associated with passing cyclones, likely contribute to the observed trends in temperature extremes and precipitation on Marion Island. Continued elevation of daily air temperature extremes and reduction in daily precipitation extremes may result in abnormal warming, further deglaciation, further retreat of the permanent snowline, disruption of soil frost and needle ice processes, and prolonged drying of the mires on this periglacial sub-Antarctic island.
Water scarcity and small-scale maize farming at the rural household level: A case study of Matatiele Local Municipality, Eastern Cape, South Africa
(University of Fort Hare, 2024) Jikwana, Kholekile; Mazinyo, S.P.; Ngavara, S.
The impact of water scarcity on maize production and other agricultural products at the rural household level can affect food security as many small-scale farmers depend mostly on their farm produce for sustenance. Unpredictable changes in rainfall are known to impact the water supply for irrigation purposes. Moreover, Matatiele, the area under investigation is prone to periods of droughts and floods. The researcher investigated the effects of water scarcity on small-scale maize farming at the rural household level in the Matatiele area. The research objectives were to: 1) Describe and discuss the average monthly rainfall in the Matatiele area between 1993 and 2022. 2) To determine the rural household’s food security status. 3) To determine the effect of water scarcity on rural small-scale crop farming and, 4) to identify coping mechanisms on how to deal with water scarcity and food insecurity. A quantitative descriptive survey was employed to elicit information from participants. The rainfall pattern information was obtained from South African Weather Services, interpreted and described. A non-probable sampling technique was used to interview 140 household heads, using a structured questionnaire. The results demonstrated that the rainfall patterns in the Matatiele area vary from year-to-year. The lowest rainfall precipitation between 1993 and 2022 was 470.7 mm in 2015, and the highest was 1135 millimetres in 2022. The small-scale farmers experience moderate food security, as 67.9% of the participants stated that they never had to skip a meal, 70% never had to ration the size of meals, and 77.1% never went without food for a whole day. Most (82.9%) of the participants in this study reported that water access and water scarcity are their most considerable constraints when it comes to farming maize and other agricultural produce. They do not have access to municipal water, so most use private water sources such as boreholes. Only 18.6% use communal water sources, and only 5.7% use government-provided water sources. The variability impacts small-scale farmers, as they need long-term coping strategies to cope with the year-on-year variability yearly in rainfall patterns. They rely on shortterm strategies such as borrowing food from neighbours during hard times. Water scarcity is a reality and impacts small-scale farming at the rural household level negatively, which leads to food insecurity. A needs assessment is recommended to determine how the local government can assist small-scale farmers in dealing with the erratic rainfall pattern, which displays periods of droughts and floods. Long-term strategies are recommended, such as implementing water tanks and building dams and irrigation systems, to support small-scale farmers during periods of food insecurity.
Petrographic and Petrophysical Characterization of Sandstone Reservoir Rocks for CO₂ Geological Storage in the Bredasdorp Basin, offshore South Africa
(University of Fort Hare, 2024-11-26) Hoza, Siyamtanda; Magoba, M.
This study aimed to integrate the petrophysical and petrographic analyses to characterize the Lower Cretaceous sandstone reservoirs for CO2 geological storage in the Bredasdorp Basin offshore South Africa. These reservoirs are excellent for studying the potential CO2 storage, since they are depleted oil and gas reservoirs with vast exploration data available. Four wells intersecting the Lower Cretaceous sandstone reservoirs were selected for this study, namely E-AQ1, E-G2, F-A10, and F-A13. Dataset use for the study included wireline logs, geological well completion reports, 1393 conventional core analysis, 13 core samples, 16 thin section slides, and micromorphology images for 8 core samples. Interactive Petrophysics software was utilized to evaluate the petrophysical parameters. Gamma ray logs were used to identify and delineate the sandstone reservoirs above 800 m depth to determine the reservoirs' porosity, clay volume, water saturation, and permeability. Data from core samples and well logs were used to estimate the pore throat size and to compute storage and flow capacity. The thin-section petrography combined with the Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) was employed to assess the influence of clay minerals on reservoir characteristics. The average calculated values for volume of clay, effective porosity, water saturation, and permeability varied between 12.66 - 30.73 %, 9.37 - 13.6 %, 6.17 - 68.88 %, and 6.68 – 502 mD, respectively. E-AQ1 and E-G2 exhibited low porosity of less than 10 %, whereas F-A10 and F-A13 showed good porosity of more than 10 %. F A13 showed the highest permeability of 502.47 mD, while E-G2 showed the lowest value of 6.68 mD. E-G2 showed the highest clay volume at 30.73 %, while F-A13 showed the lowest value at 12.66 %. Furthermore, F-A10 showed the highest water saturation of 68.88 %, whereas well F-A13 showed the smallest value of 6.17 %. The pore throat radius revealed that F-A10 and F-A13 have a higher heterogeneity in the pore throat size distribution, and E-AQ1 and E-G2 showed the lowest heterogeneity, indicating that EAQ1 and E-G2 will have a consistent fluid flow when CO2 is injected. The storage and flow capacities ranged from 5.45 – 666.65 m and 12.43 – 9949.23 mD*m, respectively. Comparing the storage and flow capacities of E-G2, F-A10, and F-A13, E-G2 has the lowest storage capacity, and F-A10 has the highest. F-A13 has the lowest flow capacity, and F-A10 has the highest. The core description results for E-AQ1 showed a fine to medium-grained sandstone with glauconite, which is very calcareous. It has a calcite cement characterized by fracturing and tight cementation. E-G2 showed light grey, fine-grained sandstones, highly glauconitic, and visible bitumens. F-A10 showed medium to fine-grained, glauconitic, calcareous sandstones with better-preserved cross-bedding and heavily burrowed zones, indicating a high-energy depositional environment. F-A13 showed medium grey sandstones with varying grain sizes, visible pore spaces, and bioturbation, transitioning from fine-grained to medium-grained with depth. Thin section and SEM-EDS results show that the porosity for E-AQ1 was affected by quartz overgrowth and calcite cementation. E-G2 had carbonaceous material filling the pore spaces and compaction, thus affecting porosity. Feldspar overgrowth was observed from the intervals chosen for F-A10 and F-A13. Coarse grains were identified in F-A10, and they improved the overall porosity by creating larger spaces between particles. Glauconite was identified in all the wells. The most influential diagenetic processes impacting porosity, permeability, and water saturation included cementation (calcite and hematite), quartz and feldspar overgrowth, compaction, clay mineral authigenesis, and feldspar alteration. E-AQ1 showed poor reservoir quality due to quartz overgrowth reducing porosity and calcite cementation reducing permeability. On the other hand, F-A13 displayed a very porous sandstone reservoir containing smectite with a swelling nature, a needle-like illite, and an angular quartz grain, with calcite cementation and minimal compaction. The presence of clay minerals in the reservoir sands had a great impact on permeability and porosity. Based on the results and the criteria used, F-A10 and F-A13 are the most favourable reservoirs for CO2 storage due to their high porosity, permeability, storage and flow capacities, low volume of clay and water saturation and favourable mineralogical characteristics that enhance reservoir quality. The results from this study can help guide future CO₂ storage projects by offering a clear understanding of the reservoir quality and how well these sandstone reservoirs can hold and transport CO₂. By knowing more about factors like porosity, permeability, clay volume, and water saturation changes over time, this study can help choose the best areas for CO₂ injection and predict how CO₂ will move through the rocks. This information can also help evaluate other similar reservoirs for CO₂ storage, supporting efforts to safely store carbon in South Africa and contribute to the global climate change mitigation and the transition to a low-carbon future.
Assessing the extent and impacts of illegal sand mining along the Wild Coast Zone of the Amathole District in the Eastern Cape province, South Africa
(University of Fort Hare, 2024) Dandala, Mzikayise Colemand; Nel, W.; Kalumba, A.M.
Sand mining is widespread, and its practice is increasing in developing and developed nations. However, the increased demand for sand has led some communities to mine sand illegally. Illegal sand mining brings irreversible environmental damage, and the physical and environmental effects of sand mining have developed into crises that often result in changes in land use dynamics. The Wild Coast zone of South Africa is recognised as an international biodiversity hotspot. Therefore, assessing the extent and impacts of illegal sand mining in this biodiversity hotspot is crucial for guiding environmental planning. However, traditional methods for monitoring illegal sand mining are time-consuming and costly. This study employed a monitoring and modelling spatiotemporal approach, which is non-destructive, costeffective, covers larger areas, and is a time-saving alternative to conventional methods. The research objectives were: (i) to evaluate the spatial and temporal trends of illegal sand mining (i.e., pit size) along the coastal zone from Kei River mouth to Lubanzi River mouth over the last 22 years (2000 – 2022) and (ii) to assess the impact of illegal sand mining activities on the landscape dynamics (i.e., land use change and vegetation cover change) in the study area. Aerial images and field surveys were used to assess the extent of illegal sand mining over the last few years. Additionally, 30-meter resolution images of Landsat from 2000 to 2022 were used to assess land cover and vegetation changes. The comprehensive analysis of illegal sand mining activities along the Eastern Cape coast from 2000 to 2022 has provided valuable insights into the escalating challenges of unauthorised extraction. The study identified a minimum of 24 illegal sand mining sites, with evidence indicating a significant growth in illegal sand mining activities over the observed period. The spatial extent of sand pits has expanded, reflecting the increasing demand for construction materials driven by rapid population growth. The physical damage caused by illegal sand mining was observed across most areas, with noticeable aftereffects such as the creation of sand pits and dumping. These findings underscore the urgency of addressing the drivers behind the growth of illegal sand mining, particularly the need for stronger legislation and law enforcement to curb unauthorised extraction. The assessment of the impact of illegal sand mining on landscape dynamics revealed significant changes in land use patterns, particularly in the conversion of vegetated lands to bare soil. The transition from other vegetation to bare soil highlights the early stages of environmental degradation resulting from sand mining activities. Additionally, the decline in forest and water areas underscores the loss of critical ecosystems along the coastal zone. This study highlights the pressing need for comprehensive regulatory measures and stakeholder collaboration to address the growing threat of illegal sand mining. By understanding sand mining activities' spatial and temporal trends and their impact on landscape dynamics, policymakers can develop targeted interventions to safeguard coastal ecosystems and promote sustainable development in the Eastern Cape region and beyond.
Isolation, characterization of pectin from citrus lemon waste and their biological potential
(University of Fort Hare, 2024) Dambuza, Anathi; Oyedeji, O.
This research offers an in-depth examination of pectin derived from lemon peels. The lemon peels were sourced from two distinct geographical areas (Peddie and Fort Beaufort) over two successive years (2023 and 2024), referred to as PP 2023, PP 2024, FBP 2023, and FBP 2024. Authentication and verification of the plant were done, and the voucher specimen was obtained. The voucher specimen numbers for both Fort Beaufort and Peddie lemon samples were UFH-2023-06-01 and UFH-2023-06-02 respectively. The extraction process involved drying the lemon peels, grinding them into powder, sifting to obtain 500 µm particles, and subjecting them to a conventional extraction method using 2M HCl. The yields of the pectin samples were found to be statistically significant (p<0.05), with PP 2023 at 13.1 ± 0.03%, PP 2024 reaching 13.0 ± 0.02%, FBP 2023 at 12.2 ± 0.03%, and FBP 2024 achieving a maximum yield of 12.2 ± 0.02%. The slight differences in yield may be attributed to variations in growing conditions, including factors such as climate and soil, which could have influenced the pectin content in the lemons. Physicochemical characterizations showed that all samples had anhydrouronic acid content greater than 65%, making them suitable for pharmaceutical and food industry applications, as suggested by the FAO. SEM analysis revealed rough, jagged morphologies for the extracted pectin, contrasting with the smoother surface and consistent size of commercial pectin. The EDX analysis showed that Commercial pectin had 36.54 % carbon and 56·02 % oxygen levels typical of pectin makeup, in contrast, FBP 2023 and FBP 2024 had oxygen levels at 62.11 % and 63·92 % respectively signifying differences in their structural composition. PP 2023 had a carbon level (41.45%), with some chlorine originating from HCl used during the extraction process, whereas PP 2024 had similar high oxygen content but a lower percentage of carbon indicating a form of pectin that is relatively pure. FTIR confirmed the presence of characteristic functional groups such as Hydroxyl Groups (–OH), Carboxyl Groups (C=O) and β-Glycosidic Linkages (C–O), and the Thermogravimetric analysis was utilized to examine the thermal properties of all four samples of the extracted pectin in relation to commercial pectin. The results indicated that the extracted pectin underwent three stages of degradation, whereas the commercial pectin exhibited four stages of degradation. Additionally, differential scanning calorimetry (DSC) was employed to assess the thermal stability of the pectin samples. The DSC analysis showed that Commercial P possesses the highest heat resistance, among the samples tested by having a melting enthalpy of 400 J/g and a melting temperature of 94°C, on the other hand, FBP samples exhibited moderate stability. Chromameter analysis of colour, in pectin showed that Commercial P had a shade (brightness L*= 69.96) which suggests a preference for colours in food products, on the other hand, PP 2024 had a darker shade (brightness L*=61.03) possibly influenced by polyphenols content. Moreover, FBP 2023 exhibited a yellow hue (chromaticity C*=24.50) likely due, to carotenoids presence, in contrast, PP 2023 had lower chromaticity leading to a less attractive look. In ¹³C NMR spectra, peak at 32,38 ppm which was only on commercial pectin revealed aliphatic carbons, then at 52–70 ppm, 110–112 ppm, and around 170 ppm were attributed to methoxyl groups that are attached to the galacturonan, arabinose anomeric resonances, and C-6 of the carboxyl group of the galacturonic acid in esterified form, respectively. Consistency in these peaks suggests similar functionality. The 2,2-Dipheynl-1-picraylhydrazyl assay and reducing power assay were used to investigate the antioxidant activities of pectin samples, the DPPH assay demonstrated that pectin has antioxidants, as the IC50 of PP 2024 was 1062.5 ± 20.0 mg/L, PP 2023 was 1201.3 ± 22.0 mg/L, FBP 2023 was 1304.6 ± 19.0 mg/L, FBP 2024 was 1382.6 ± 29.9 mg/L and lastly, Commercial P had 1019.4 ± 17.1 mg/L. The reducing power of all pectin was later assessed, and they revealed their potential antioxidant properties. Ascorbic acid which was used as a standard antioxidant exhibited the highest reducing capacity as its absorbance at at 2500 mg/l was 1.75, followed by PP 2023 and PP 2024, while FBP 2023 showed the lowest capacity among the pectin samples, these results indicate that pectin possesses antioxidant properties, attributed to the presence of reductones that disrupt free radical chains and prevent peroxide formation. These findings provide valuable insights into the compositional, thermal, and functional properties of pectin, highlighting its potential as a natural polymer for use in food, pharmaceutical, and medical applications.
Synthesis, characterisation and evaluation of functionalized Lignocelluloses-clay nanocomposites for organic pollutant removal from water
(University of Fort Hare, 2015) Mafukidze, Donovan M; Tichagwa, L; Lutz, M; Katwire, D M
PMPSgLig-NaMMT nanocomposites were prepared from methacryloxypropyltrimethoxysilane (MPS), lignocellulose and montmorillonite clay. The potential enhancement of organic pollutant adsorption capabilities of PMPSgLig-NaMMT nanocomposite from water through functionalization was investigated. PMPSgLig-NaMMT was functionalized by esterification and etherification using different methods so as to increase the surface hydrophobicity of the material and hence improve its compatibility with the target pollutants. Specific chemical routes specially tailored for PMPSgLig-NaMMT were established for functionalization mostly based on the common esterification (Fischer esterification) and etherification (Williamson‟s etherification) reactions. In the functionalization methods, factors such as pH environment, nanocomposite composition, nature of functionalization moiety, and use of or absence of solvents and their variations were studied. FT-IR, XRD, SEM and TGA were used to characterize the synthesized and functionalized nanoadsorbents. The techniques showed successful functionalization via esterification and etherification methods albeit to different extents, with clear retention of the material‟s original structure though there were signs of degradation with some methods. Characterization was supported by adsorption studies to validate implications and draw conclusions. The use of 1,10-phenathroline as a model organic pollutant in water in the adsorption studies showed that adsorbents conformed to monolayer adsorption following pseudo-second order kinetics for adsorption of organic pollutants accurately represented. Most importantly the studies revealed the significant impact of the nanocomposite composition on the overall absorbent performance. Adsorption studies also showed that functionalization via esterification methods gave rise to better adsorbents.
Isolation, characterisation of terpenoids and biosynthesis of silver nanoparticles of acacia mearnsii de wild and acacia Karroo Hayne and their Bioassays
(University of Fort Hare, 2015) Avoseh, Opeyemi Nudewhenu; Oyedeji, O O; Oyedeji, O A
Great wealth of traditional knowledge about the use of plants had been transferred from generation to generations leading to the present day drug discovery and invention of new scientific methods of isolation, purification and identification. With the discovery of new diseases and drug-resistant organisms, there is no other source or deposit of lead compounds or drugs than the plant kingdom. As a result of this, about 25% of the current drug administered owe their origin to plant sources with the view to reduce the carcinogenic effect of synthetic drugs. Volatile terpenoids among other broad spectrum of natural product had been implicated to show high therapeutic properly. In the present study, selected locally-used medicinal plants were exploited for the presence of potent bioactive compounds and ability to form nanoparticles with distinctive property for use as chemoprotective agent against inflammation, tumors, cancer and other chronic diseases. Acacia mearnsii De Wild and Acacia karroo Hayne studied in this report are known to be invasive species with no proper regulation to conserve and preserve them. However, ethnopharmacology report of these plant species in the Southern Africa region reveals that they are good antiseptic, anti-diarrhea, anti-inflammation and a forage for livestock. These plants were subjected to volatile extraction protocol of some parts of the plants (stem and leaves) followed by examination of the anti-inflammation capacity of the extracts using an animal model. In addition, the bye-product (hydrosol) from the stem bark of each species possess a high reducing and stabilizing property leading to synthesis of silver nanoparticles, followed by investigation of the anti-inflammation potential of the synthesized silver nanoparticles using animal model. The volatile oils of the leaves and stem bark of Acacia mearnsii De Wild obtained by hydro-distillation were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). Twenty, Thirty-Eight, Twenty-nine and Thirty-Eight components accounting for 93.8%, 92.1%, 78.5% and 90.9% of the total oils of the fresh, dry leaves and fresh, dry stem bark respectively. The major components of the oil were octadecyl alcohol (25.5%) and phytol (10.5%); cis-verbenol (29.5%); phytol (10.1%) and phytol (23.4%) for the fresh leaves, dried leaves, and fresh stem, dry stem bark respectively. Oral administration of essential oils at the dose of 2% showed significant (p<0.05) anti-inflammatory properties in the albumin induced test model in rats. Oils from the fresh leaves and dry stems inhibited inflammation beyond 4 h post treatment. Furthermore, the chemical composition of the essential oils obtained by hydro-distillation from the leaves and stem bark (dry and fresh) of Acacia karroo Hayne, analysed by GC-MS, shows that hexanal (10.67%) and ß-ionone (9.74%) were dominant in the dried leaves, β-pinene (14.30%), and (Z)-2-Hexen-1-ol (10.21%) in the fresh leaves while Octacosane (10.59%) and phytol (23.38%) were dominant in the dry and fresh stem respectively. The anti-inflammation ability of these oils after an albumin-induced inflammation on wistar rats, shows a significant effect at the 1st h of treatment with a significance of P< 0.01 for all part plants, while the fresh leaves shows further inhibitory activities at the 2nd h of analysis. Silver nanoparticles (AgNPs) were successfully synthesized from AgNO3 through a green route using the aqueous extract (hydrosols) of Acacia mearnsii De Wild and Acacia karroo Hayne as reducing agent and as well as capping agent. The Acacia-mediated AgNPs were characterized with the use of UV-vis absorption spectroscopy, Fourier Transform Spectroscopy (FT-IR), Transmission electron microscope (TEM), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDX), and X-ray Diffractometry (XRD). A spherical, 10-40 nm diameter silver nanoparticles were synthesized with very low level of stability for the AMDS and the AKDS-AgNPs. In addition, nociceptive activity with a mice rat reveals higher inhibition at the neurogenic phase for the AKDS-AgNPs, while AMDS-AgNPs exhibited a high inhibition at the inflammatory phase. The potent anti-inflammatory activity of essential oils of A. mearnsii De Wild and A. karroo Hayne hereby confirmed its traditional use in treating various inflammatory diseases, while the inflammatory studies on the synthesized AgNPs reveals a very active compound which can be used as a potent opioid or non-steroidal anti-inflammatory drug (NSAID).
Chemical constituents and biological studies of Tagetes minuta L. and Rauvolfia caffra Sond
(University of Fort Hare, 2015) Mlala, Sithenkosi; Oyedeji, O O; Nkeh-Chungag, B N
Consequently, specific parts or the whole plant can be used for various treatments. The aim of this study was to extract, isolate and characterize the biologically active volatile and non-volatile compounds from Tagetes minuta and Rauvolfia caffra respectively. Tagetes minuta plant was considered for extraction of essential oils using hydrodistillation method. Cis-β-ocimene (38.03%), caryophyllene oxide (18.04%), alloocimene (25.35 %), isopropyl tetradecanoate (17.02 %), cis-ocimene (38.14%) and trans-β-ocimene (37.03%) were the major components of essential oil analyzed from fresh stem, dried stem, fresh leaf, dried leaf, fresh flower and dried flower respectively. The volatile compounds were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography (GC). Essential oil of dried stem leaf and flower parts of T. minuta exhibit antioxidant activity as demonstrated by the DPPH and FRAP bioassays. Crude extracts were extracted from R. caffra stem bark using sequence of solvents namely n-hexane, dichloromethane, ethyl acetate, methanol and ethanol. A white powder, a β-sitosterol (non-volatile compound) was isolated by column chromatography from ethyl acetate fractions of R. caffra stem bark and identified on various spectroscopic techniques such as FTIR and (1D and 2D) NMR. Melting point was also determined to be a sharp 129-130 ºC. DCM, EA, MetOH and EtOH fractions as well as β-Sitosterol (compound SM/01), showed antioxidant activity when tested on DPPH, FRAP, total phenolic and flavonoid bioassays. This antioxidant activity might be due to the presence of hydroxyl groups in the compound and crude fractions. On the other hand, T. minuta’s essential oil showed high antioxidant activity when evaluated on the DPPH and FRAP bioassays, which can be attributed to the presence of oxygenated monoterpenes and sesquiterpenes known to act as free radical scavenging and reducing agents. The use of R. caffra stem bark extracts against hypertension and other diseases by traditional healers could be attributed to the presence of phytochemicals (polyphenols and flavonoids) with known health benefits. Thus, it is recommended that the plant should be exploited further using modern techniques involving separation and purification of compounds that can be used for drug formulation. This study supports the use of T. minuta and R. caffra as the potential natural antioxidant source to manage various diseases including hypertension.
Synthesis and structural studies of NiS and PdS nanoparticles/nanocomposites from dithiocarbamates single source precursors
(University of Fort Hare, 2016) Nqombolo, Azile; Ajibade, P A
The main aim of this research is to synthesize Ni(II) and Pd(II) dithiocarbamate complexes and use them as single source precursors for the synthesis of NiS and PdS nanoparticles and metal sulphides potato starch nanocomposites. Four dithiocarbamate ligands were synthesized and characterized using elemental analysis and spectroscopic techniques. The ligands were used to prepared homoleptic Ni(II) and Pd(II) complexes of the dithiocarbamate ligands. The metal complexes were characterized with elemental analysis, UV-Vis, FTIR and 1H-NMR spectroscopic techniques. Conductivity measurements indicate that all the complexes are non-electrolytes in solution and results from the electronic spectra studies confirmed the proposed 4-coordinate square planar geometry around the metal ions. The nickel complexes showed d-d transitions around 477 nm while in the palladium complexes, no d-d transitions were observed but the compounds showed strong metal to ligand charge transfer transitions. From the FTIR spectra studies, it can be confirmed that the complexes were successfully synthesised because all peaks of interest were observed at expected regions from the literature. The νC-N was observed around 1469-1495 cm-1, νC=S around 1101-1188 cm-1 and νC-S around 738-1060 cm-1 for both Ni(II) and Pd(II) complexes. νNi-S was observed around 375-543 cm-1 and νPd-S around 529-545 cm-1. The FTIR also confirmed that the dithiocarbamate ligands act as bidentate chelating ligands through the sulfur atoms. The complexes were used as single source precursors and thermolysed in hexadecylamine (HDA) at 220 °C to prepare four HDA-capped nickel sulfide nanoparticles and four palladium sulfide nanoparticles. The as-prepared nanoparticles were studied with optical absorption spectra, photoluminescence, powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The optical studies results showed that NiS have large band gaps that are greater than that of the bulk, therefore they are found to be blue shifted relative to the bulk, which shows that they have small particle size and thus confirming their quantum confinement effect. PL spectra reveal that the emission peaks are red shifted compared to the absorption band edges of the nanoparticles. The XRD patterns confirmed the formation of cubic and rhombohedral phase for NiS nanoparticles and cubic phase for PdS nanoparticles. SEM images of both NiS and PdS show uniform surface morphology at low and high magnification with different shapes. EDS analyses confirmed the presence of Ni, S, and Pd in each of the spectrum indicating that the nanoparticles were successfully synthesized. TEM images showed that the synthesised nanoparticles have uniform and narrow size distribution with no agglomeration. The sizes of the NiS nanoparticles were found to be in the range of 12-38 nm for NiS1, 8-11 nm for NiS2, 9-16 nm for NiS3 and 4-9 nm for NiS4. The TEM images for the as-prepared PdS nanoparticles showed that the average crystallite sizes are 6.94-9.62 nm for PdS1, 8-11 nm for PdS2, 9-16 nm for PdS3 and 4-9 nm for PdS4 respectively. The nanoparticles were used to prepare potato starch nanocomposites and SEM images indicate that the surface morphology of starch polymer nanocomposites compose of potato starch and few particles in between the pores of the matrix, this is due to the small ratio of nanoparticles used.
Remediation of metal ions in aqueous solution using activated carbon from Zea may stem
(University of Fort Hare, 2016) Matandabuzo, Mzukisi; Ajibade, P A
Zea mays stem and its activated carbon were prepared through chemical activation method using four different activating reagents (NaOH, H₃PO₄, H₂SO₄, KOH) and were used as adsorbents for the removal of Pb(II), Cu(II), Hg(II) and Cr(III) from aqueous solution. The results shows that activated carbon has high surface area and pore volume compared to the powdered raw Zea mays stem. Prepared activated carbon was characterized using physico-chemical properties such as carbon yield, iodine number, moisture content, percentage adsorption, and analytical instruments such as Fourier transform Infrared spectroscopy (FTIR), atomic absorption spectrometer (AAS), scanning electron microscopy (SEM), Energy Dispersive X-ray analysis (EDS), powder X-ray Diffraction (pXRD). The adsorption of Pb(II), Cu(II), and Cr(III) ions were pH, contact time, and concentration dependent. Based on the results obtained from the batch experiments, activated carbon prepared from Zea mays stem is not good enough for the removal of Hg(II) from aqueous solution. Adsorption ability was calculated and found to be 66.67% for activated carbon obtained from H₂SO₄, 21.21% for activated carbon obtained from KOH, and 20% for activated carbons obtained from NaOH and H₃PO₄. The pH 5-6 was chosen for all experiments, contact time was 2 hours, and adsorbent dosage was 2 g, initial concentration range from 200, 400, 600, 800, and 1000 ppm at room temperature. The metal ion removal trend was found in the order Pb(II)>Cu(II)>Cr(III)>>Hg(II). The Langmuir model fitted well in most of the cases with > 0.99. Consequently, the adsorption of Pb(II) and Cu(II) followed Langmuir isotherm model while that of Cr(III) best fitted the Freundlich isotherm model. The results indicated that the adsorption process followed two possible mechanisms. (I) Metal ion – adsorbent complex model and (II) Metal ion – ion-exchange adsorbent complex model.
Investigation into the characteristics and possible applications of biomass gasification by-products from a downdraft gasifier system
(University of Fort Hare, 2015) Melapi, Aviwe; Mamphweli, D; Katwire, D M
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 byproducts which can be used for various application 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 byproducts 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 lignocellulosegasification. 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.
Ni(II) and Pb(II) dithiocarbamate complexes as precursors for the synthesis of HDA-capped NiS and PbS nanoparticles
(University of Fort Hare, 2015) Chintso, Thobani; Ajibade, P A
Ni(II) and Pb(II) dithiocarbamate complexes were synthesized and characterized by elemental analysis, UV-Vis, FTIR and TGA and some of the Ni(II) complexes and one Pb(II) were further analyzed by 1H-NMR and 13C-NMR spectroscopy. Generally all the dithiocarbamate ligands are soluble in water while the complexes were soluble mostly in solvents such as chloroform, toluene, DMSO and DCM. Based on the elemental analysis, the dithiocarbamate complexes are formulated as four coordinate (tetrahedral or square planar) compounds. However, the FTIR showed that each of the dithiocarbamate ligands acted as bidentate ligand through two sulfur atoms. The TGA of the most complexes showed one major decomposition step to give respective metal sulfide above 200 oC. In this research project, dithiocarbamate complexes were used as single source precursor for the synthesis of metal sulfide nanoparticles. We studied the optical and structural properties of metal sulfide nanoparticles using UV-Vis, photoluminescence (PL), powder X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The absorption spectra of the metal sulfide nanoparticles are blue shifted in respect to bulk material and they also showed broad emission. The XRD of the NiS nanoparticles were indexed to the cubic and rhombohedral phase, with crystallite sizes of 15 - 18 nm. The XRD of PbS nanoparticles were indexed to the face centered cubic and cubic rock salts, with the crystallite sizes 12 - 18 nm. The TEM images of the metal sulfide nanoparticles showed particles with spherical and rectangular shapes with crystallite sizes 4 - 35 nm.
Biological evaluation and semi-synthesis of Isolated compounds from (Syzygium aromaticum (L.) Merr. & Perry) Buds
(University of Fort Hare, 2014) Sibusiso, Rali; 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

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