Extraction, Isolation and Biological studies of Pentanisia prunelloides and Hippobromus pauciflorus
- Authors: Ngcetane , Lazola Luyolo
- Date: 2020
- Subjects: Medicinal plants Antioxidants
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: http://hdl.handle.net/10353/18766 , vital:42731
- Description: Enormous amounts of drugs or drug components have been found with the use and help of ethnobotanical knowledge of plants by the indigenous civilisation of that region. The primary reason that plants are chosen as a potential source of new medicines is that they are readily available to researcher and the public either free of charge or at a low and affordable cost in the rural majority community in the developing world. The aim of this study was to evaluate the chemical content of two commonly used medicinal plants of the Eastern Cape Province of South Africa and to explore their antioxidant potential. Crude extracts of Hippobromus pauciflorus and Pentanisia prunelloides were obtained by means of sequential solvent extraction followed by evaluation of the phenolic and flavonoid content of extracts and the anti-oxidant ability of the both plant samples and also their ability to hinder lipid peroxidation. For the H.pauciflorus sample, different masses of crude extracts were obtained with Dichloromethane (0.817 g) yielding the smallest mass and the 70% Ethanol (120.196 g) extract yielding the largest mass. The total phenolic content of the plant sample extracts were measured using the Folin-Ciocalteau reagent. The Methanol extract (133.019 ± 0.003 μgGAE/mL) exhibited the largest content while the EtOH extract (13.981 ± 0.001 μgGAE/mL) exhibited the least content. The MeOH extract exhibited the highest flavonoid content (46.005 ± 0.001 μgQE/mg extract) while the Hexane extract (19.000 ± 0.008 μgQE/mg extract) exhibited the least. 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper Frap assay was performed with the Ethyl Acetate extract displaying the least anti-oxidant ability (10.284 ± 0.014 AAE/mL) while the Hex extract (204.705 ± 0.119 AAE/mL) displayed the highest anti-oxidant ability. 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay was performed with the hexane, methanol and ethanol extracts exhibiting an anti-oxidant property with IC50 values of 3.594x10-3 ± 0.133 mg/mL, 0.185 ± 0.019 mg/mL and 0.011 ± 0.002 mg/mL respectively. Inhibition of lipid peroxidation at 150 μg/mL was performed where the Dichloromethane extract showed the highest inhibition percentage (-75.000 ± 0.119%) while the Hex extract (-41.667 ± 0.021005%) showed the lowest inhibition percentage at 300 μg/mL; only the DCM extract (-3.051 ± 0.018%) displayed inhibition ability. For the P.prunelloides sample, different masses of crude extracts were obtained with EA extract (0.348 g) yielding the smallest mass and the MeOH (47.941 g) extract yielding the largest mass. Phenolic content was evaluated with the DCM extract (122.827 ± 0.010 μgGAE/mL) exhibited the largest content while the MeOH extract (48.788 ± 0.001 μgGAE/mL) exhibited the least content. Flavonoid content was evaluated with the DCM extract (88.543 ± 0.005 μgQE/mg extract) exhibited the largest content while the EtOH extract (19.254 ± 0.001 μgQE/mg extract) exhibited the least content. FRAP assay was performed with the DCM extract (13.021 ± 0.008 AAE/mL) displaying the least anti-oxidant ability while the MeOH extract (217.758 ± 0.025 AAE/mL) displaying the highest anti-oxidant ability. DPPH assay was conducted with EA and methanol extracts exhibiting antianti-oxidant ability and having IC50 values of 0.579 ± 0.021 mg/mL and 0.006± 0.001 mg/mL respectively. Inhibition of lipid peroxidation at 150 μg/mL was performed with the n-Hex extract (-36.395 ± 0.015%) showing the highest inhibition percentage while the DCM extract (-17.647 ± 0.005%) the lowest and at 300μg/mL the EA (- 12.881 ± 0.018%) and DCM (-0.847 ± 0.009%) extracts displayed inhibition. An attempt was made to isolate and elucidate the compounds in the extracts but unsuccessful, although the TLC results indicated several compounds that can be elucidated in future study
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Fabrication of a photocatalytic PAN supported C-TiO2-CFA nanocomposite for use in water treatment
- Authors: Mpelane, Amkelwa
- Date: 2020
- Subjects: Photocatalysis
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: http://hdl.handle.net/10353/18744 , vital:42729
- Description: The goal of this study was to fabricate a visible light responsive composite of C-TiO2-CFA. The prepared nanocomposite (C-TiO2-CFA) was immobilized on poly(acrylonitrile) membrane to address the drawback of recovering the nanosized photocatalyst from water after photodegradation experiments. The C-TiO2-CFA nanocomposites were fabricated using a modified sol-gel method, while the C-TiO2-CFA/PAN membranes were prepared via the phase inversion technique. The nanocomposites were fully characterized using FTIR, XRD, SEM-EDX, TEM, DRS, and BET surface area analysis. The prepared C-TiO2-CFA/PAN membranes were evaluated in the photodegradation of methyl orange and the golden yellow dyes, as well as the photoreduction of lead and cadmium heavy metals in synthetic wastewater. UV-Visible spectroscopy was used to follow the changes in the concentration of organic dyes, while inductively coupled plasma optical emission spectroscopy was used to follow changes in the concentration of the heavy metals. FTIR analysis confirmed the presence of functional groups expected on the prepared C-TiO2- CFA/PAN membranes and EDX analysis accounted for the elements expected. The prepared membranes all exhibited an asymmetric structure as depicted by cross-sectional view study via SEM analysis. TEM and SEM analyses revealed that the prepared C-TiO2-CFA nanocomposite was roughly spherical in shape with an estimate particle size of 10.94 nm according to TEM and 11.62 nm according to XRD using Scherrer equation. The incorporation of carbon into the lattice structure of titanium dioxide resulted in a reduction in bandgap from 3.19 eV to 2.78 eV through introduction of mid-band states, allowing visible light utilization. The best nanocomposite was obtained by doping TiO2 with 4% carbon and having a C-TiO2 to CFA ratio of 4:1 respectively. The C-TiO2-CFA nanocomposite exhibits a crystalline structure with a mixture of rutile and anatase phases. The parameters investigated in the evaluation of photocatalytic performance of C-TiO2- CFA/PAN were effect of photocatalyst load on PAN membrane, initial dye concentration, pH and light source in the activation of photocatalyst. For both dyes (methyl arrange and golden yellow), it was observed that photodegradation efficiencies increased with an increase in catalyst load. In the photodegradation of MO and GY using the membrane with 1% C-TiO2- CFA, removal efficiencies of 73.3% and 59.99% were attained respectively, while the membrane with 2% C-TiO2-CFA achieved MO and GY photodegradation efficiencies of 99.8% and 99.2% respectively. Photodegradation efficiencies of MO and GY were observed to decrease with an increase in dye concentration. Low pH (3) was observed to favour the photodegradation of MO and GY azo dyes. Photodegradation efficiencies of 99.8% and 99.2% were attained where obtained at lower MO and GY initial concentration. The modified photocatalyst (C-TiO2-CFA/PAN) exhibited better photoactivity under sunlight irradiation compared to strict UV light irradiation. Evidently, the C-TiO2-CFA/PAN membranes can be 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper utilized as a sustainable and stable photocatalyst to efficiently eliminate methyl orange and golden yellow dyes. A PAN membrane with 2 wt% C-TiO2-CFA revealed enhanced cadmium and lead removal efficiencies in comparison to PAN membranes with 1 wt% and 1.5% C-TiO2-CFA. A Cd2+ removal efficiency of 95% was obtained using 2 wt% C-TiO2-CFA/PAN nanocomposite membranes. Cadmium removal efficiencies of 92.5% and 91% were obtained using the 1.5 wt% and 1 wt% C-TiO2-CFA/PAN nanocomposite membranes. A lead removal efficiency of 97% was obtained using PAN membrane with 2 wt% C-TiO2-CFA. Pb2+ removal efficiencies of 90.9% and 94.6% were obtained using the 1.5 wt% and 1 wt% C-TiO2-CFA/PAN nanocomposite membranes. The photoreduction activity was observed to decrease with an increase in cadmium and lead initial concentrations. A cadmium and lead removal efficiencies of 95% and 97% were observed at lower Cd2+ and Pb2+ initial concentrations (20 ppm), respectively. The removal efficiencies varied marginally with changes in pH values. The fouling activity of the C-TiO2 modified PAN asymmetric membranes and pure PAN was investigated by carrying out pure water filtration tests as well as bovine serum albumin (BSA) filtration tests. A bovine serum albumin rejection of 98% was obtained utilizing the 2 wt% CTiO2-CFA/PAN membrane.
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Preparation and characterization of sodium alginate-based dissolvable bandages as potential wound dressings
- Authors: Ndlovu, Sindi Prescila
- Date: 2020
- Subjects: Nanostructured materials
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: http://hdl.handle.net/10353/18800 , vital:42734
- Description: Burn wounds are among the leading causes of mortality and morbidity globally. Burn wounds are painful, cause social isolation and causes post-traumatic stress disorder (PTSD) due to prolonged hospital treatment. The challenges encountered in the treatment of burn wounds are infections resulting from the use of wound dressings that do not protect the wounds from microbial invasion. Sodium alginate-based dissolvable bandages were prepared and encapsulated with various antibiotics (ampicillin and ciprofloxacin) and nanoparticles (i.e. zinc oxide and silver). The dissolvable bandages were characterized by FTIR, SEM/EDX, TEM, XRD and TGA. Furthermore, the porosity, water uptake, biodegradation, antibacterial studies, and water vapour transmittance properties of the bandages were also studied. The prepared sodium alginate-based dissolvable bandage incorporated with varied amount of drugs (such as ampicillin, ciprofloxacin, zinc oxide and silver nanoparticle) exhibited good porosity, high water uptake, excellent WVTR with sustained drug release profiles. The loading of ZnO Nps, CLP/ZnO Nps and Ag Nps/CLP into the bandages improved the antibacterial activity of the bandages against both gram-negative and gram-positive strains of bacteria. XRD confirmed the amorphous nature of the dissolvable bandage and the absence of free drugs. FTIR revealed the successful encapsulation of the antibiotics and nanoparticle into the dissolvable bandages. The dissolvable bandages exhibited high water uptake ranging from 870-4468% with good porosity suggesting that they can absorb large amount of wound exudates. The drug release for all the bandages obeyed the Korsemeyer Peppas drug release model with n values in the range 0.1-1.0. The results obtained indicate that the bandages are potential wound dressings for burns and for patients with sensitive skins.
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Synthesis and application of coal fly ash supported C doped TiO2/SnO2 photocatalyst in water treatment
- Authors: Sambakanya, Siyasanga
- Date: 2020
- Subjects: Photocatalysis
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: http://hdl.handle.net/10353/18838 , vital:42869
- Description: Coal fly ash supported carbon doped titanium dioxide/tin oxide (C doped TiO2-SnO2/CFA) nanoparticles were successfully synthesised using a sol gel method and calcined at 550 °C. The crystal structure, optical properties, morphology and other properties were analysed using XRD, UV-Vis, FTIR, TEM, SEM, DRS and EDX. SEM analysis showed that the nanoparticles (NPs) of C doped TiO2-SnO2/CFA were quasi spherical. XRD showed that C doped TiO2-SnO2/CFA nanoparticles were polycrystalline and consisted of both rutile and anatase phases. TEM analysis also displayed small NPs of C-TiO2-SnO2/CFA (12.62 nm) than TiO2 (16.19 nm) and SnO2 (19.98 nm). DRS revealed reduced band gap of C-TiO2 (2.78 eV) than TiO2 (3.19 eV) after doping. The photocatalytic efficiency of the prepared C-TiO2-SnO2/CFA nanoparticles was determined using methyl orange (MO) and methylene blue dye (MB) as standard dyes in the photodegradation as well as lead and mercury in the photoreduction of lead and mercury ions in water. The degradation experiments were carried under natural solar irradiation and UV light. The photodegradation experiments carried under visible light showed excellent photodegradation of MO & MB in water. This is a good indication that doping was successful as it imparted visible light activity in the C-TiO2-SnO2/CFA NPs. The photocatalyst efficiency was further tested while varying parameters including photocatalyst load, pH, and initial pollutant concentration in the photodegradation of MO & MB as well as in photoreduction of Pb2+ and Hg2+ in water to establish optimum operating conditions. The degradation rate of MO & MB increased when photocatalyst loading increased. When the pH was increased, the photocatalytic efficiency of the prepared photocatalyst towards methyl orange was reduced; however methylene blue degradation increased with increase in pH. The reduction of Pb2+ also increased with increasing pH whereas that of Hg2+ increased with decreasing pH. It was found that photodegradation was directly proportional to and photoreduction was inversely proportional to initial pollutant concentration.
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