Synthesis of folate-conjugated palladium nanoparticles
- Authors: Xolo, Luthando
- Date: 2018
- Subjects: Nanotechnology , Nanostructured materials Complex compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/36442 , vital:33943
- Description: In this study, the synthesis of two new folate-conjugated palladium (Pd) nanoparticles was carried out. This was done via two steps; firstly, the synthesis of palladium nanoparticles (PdNPs) capped with 4-aminothiophenol (4-Atp) and secondly, they were conjugated to the folate to form Folate-4Atp-PdNPs. All the above were characterized by using Fourier Transform Infrared spectroscopy (FTIR) which confirmed the formation of the targeted product (PdNPs-4-Atp-folate) as well as the 2-Aet linked with folate product (2-Aet-folate). The optical properties of the products formed were characterized further by using UV-Vis spectroscopy and Photoluminescence (PL). The size and shape of the nanoparticles were obtained by Transmission Electron Microscopy (TEM). The FTIR confirmed the formation of desired nanoparticles (Fa-4Atp-PdNPs), with peak of C=O stretching vibration at 1659 cm-1. The UV-Vis showed absorption peaks at 236 nm and 285 nm which was due to n-π* and π-π* transitions. The nanoparticles also showed excitation and emission peaks at 360 nm and 455 nm from the PL when excitation wavelength was set at 270 nm. The methanol soluble nanoparticles had an average size of 36 nm while the water-soluble nanoparticles were 4 nm in size. The HRTEM also showed the methanol nanoparticles were amorphous while the water-soluble nanoparticles were crystalline. The work reports on comparison of the methanol-soluble and water-soluble nanoparticles size distribution and the effect of capping agent used on the nanoparticles.
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- Date Issued: 2018
The synthesis of functionalized carbon nanomaterial from waste tyre sourced carbon for chemosensing during purification processes
- Authors: Du Plessis, Jacolien
- Date: 2018
- Subjects: Nanostructured materials , Nanotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/29925 , vital:30794
- Description: The short lifetime of tyres causes great environmental harm due to their non-biodegradable nature resulting in land and water pollution. Exploration of novel uses for recycled tyres is therefore imperative. The use of recycled waste tyres as carbon source for the synthesis of fluorescent chemosensing carbon nanomaterial for the detection of harmful chemicals in water is proposed in this work. Three key problems are addressed in this study: i) re-using of waste tyre products, ii) synthesis of low-cost carbon nanomaterial, iii) detection of harmful compounds within environment systems. The fluorescent triazolyl-coumarin compound, 7-(diethylamino)-3-(4-(1-hydroxyethyl)-1H-1,2,3-triazol-1-yl)-2H-chromen-2-one, was synthesized in multiple steps from 4-diethylamino salicylaldehyde. The last step included the use of Cu(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition (“click-reaction”) to form a triazole ring. Carbon spheres were synthesized through catalytic chemical vapour deposition (CVD) from waste tyre pyrolysis oil (WTPO), as the carbon source, in the presence of a catalytic amount of ferrocene. The quality and quantity of the carbon spheres had an overall improvement as the synthesis temperatures increased from 800 oC to 950 oC. The diameter of the carbon spheres reduced from 1017 nm to 577 nm as seen in TEM and SEM imaging. TGA and XRD analysis indicated a direct relationship between an increase in synthesis temperatures with an increase in the crystallinity of the carbon spheres. Commercially available naphthenic oil was used as a reference to compare the impact of the starting carbon precursor on the morphology of the carbon nanomaterial under the same reaction conditions. Multi-walled carbon nanotubes were synthesized at the lower temperatures of 800-850 oC. Carbon fibres and carbon spheres were observed at the synthesis temperatures of 900-950 oC. The carbon source played a role in the morphology of the carbon nanomaterial as it could be seen between the complex natured WTPO and the pure naphthenic oil. The purified carbon spheres synthesized at 950 oC from WTPO were functionalized with the triazolyl-coumarin units on the surface through Steglich esterification using DCC/DMAP to yield fluorescent carbon spheres. Complexation studies of the functionalized carbon spheres were done using UV/Vis spectroscopy and fluorescence with a wide range of ions; Ag+, Al3+, Co2+, Cr3+, Cu2+, Fe3+, ii Hg2+, Li+, Ni2+, Pb2+ and Zn2+. The triazolyl-coumarin carbon spheres showed reasonable sensitivity and selectivity towards Fe3+ in water with a quenching effect in fluorescence. Titration studies with Fe3+ indicating an exponential decay of quenching in the fluorescence up to 68% with detection limit at 2.73 x 10-5 M.
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- Date Issued: 2018