The development of platinum and palladium-selective polymeric materials
- Authors: Fayemi, Omolola Esther
- Date: 2013 , 2013-05-03
- Subjects: Polymers , Platinum , Palladium , Adsorption , Sorbents , Nanofibers , Amines , Nanoparticles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4287 , http://hdl.handle.net/10962/d1002964 , Polymers , Platinum , Palladium , Adsorption , Sorbents , Nanofibers , Amines , Nanoparticles
- Description: The adsorption and separation of platinum(IV) and palladium(II) chlorido species (PtCl₆²⁻ and PdCl₄²⁻) on polystyrene-based beads and nanofibers as well as silica microparticles functionalized with polyamine centres derived from ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) is described. The functionalized sorbent materials were characterized by using microanalysis, SEM, XPS, BET and FTIR. The nanofiber sorbent material functionalized with ethylenediamine (F-EDA) had the highest loading capacity which was attributed to its high nitrogen content (10.83%) and larger surface area (241.3m²/g). The adsorption and loading capacities of the sorption materials were investigated using both the batch and column studies in 1 M HCI. The adsorption studies for both PtCl₆²⁻ and PdCl₄²⁻ on the polystyrene-based sorbent materials fit the Langmuir isotherm while the silica-based sorbents fitted the Freundlich isotherm with R² values > 0.99. In the column experiment the highest loading capacity of Pt and Pd were 7.4 mg/g and 4.3 mg/g respectively on the nanofiber sorbent material based on ethylenediamine (EDA). The polystyrene and silica-based resins with triethylenetetramine (TETA) functionality (M-TETA and S-TETA) showed selectivity for platinum and palladium, respectively. Metal chlorido complexes loaded on the sorbent materials were recovered by using 3% m/v thiourea solution as teh eluting agent with quantitative desorption efficiency under the selected experimental conditions. The separation of platinum from palladium was partially achieved by selective stripping of PtCl₆²⁻ with 0.5 M of NaClO₄ in 1.0 M HCI with PdCl₄²⁻ was eluted with 0.5 M thiourea in 1.0 M HCI. The selectivity of the M-TETA and S-TETA sorbent materials was proved by column separation of platinum(IV) and palladium(II), respectively, from synthetic solutions containing iridium(IV) and rhodium(III). The loading capacity for platinum on M-TETA was 0.09 mg/g while it was 0.27 mg/g for palladium on S-TETA. , Acrobat PDFMaker 10.1 for Word , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
a pH-metric speciation and anti-diabetic study of oxovanadium (IV) amino acid derivatives
- Authors: Gundhla, Isaac Zvikomborero
- Date: 2011 , 2011-03-15
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4399 , http://hdl.handle.net/10962/d1006691
- Description: Novel oxovanadium(IV) complexes of glycine, ʟ-alanine, 1-methylimidazole-2-carboxylic acid, imidazole-2-caboxylic acid and imidazole-4-carboxylic acid were synthesized and isolated in the solid state. The ligands and complexes were characterized by elemental analysis, melting point, NMR, IR and UV-vis spectroscopy. The IR studies showed that glycine and ʟ-alanine coordinate monodentately through the amine nitrogen whilst the imidazole-carboxylic acid derivatives assume a bidentate chelation. The electronic spectroscopic studies indicate distorted octahedral geometry for the oxovanadium complexes of amino acids and a square pyramidal geometry for oxovanadium(IV) complexes of imidazole carboxylic acid derivatives. The reaction of vanadyl (VO2+) with glycine, ʟ-alanine, imidazole-2-cabrboxylic acid, imidazole-4-carboxylic acid and 1-methylimidazole-2-carboxylic acid was studied in aqueous solution by pH-potentiometry under oxygen and carbon dioxide-free conditions. The data obtained from these titrations were used to calculate the protonation and stability constants. The results showed that all ligands are suitable for bidentate coordination in the formation of monomeric species although the solid state studies of the oxovanadium(IV) complexes of amino acids showed a monodentate coordination. The overall stability constants for the (VIVO)-ʟ-alanine system (log β120 = 18.27(6)), (VIVO)-glycine system (β120 = 17.22(6)), (VIVO)-imidazole-4-carboxyic acid (β120 = 11.38(8)), (VIVO)-imidazole-2-carboxylic acid (β120 = 11.62(6)) and (VIVO)-1-methylimidazole-2-carboxylic acid (β120 = 15.49(9)) were obtained. The calculations for the species distribution in the experimental pH range showed that the neutral bis-coordinated complexes are dominant over the biological pH range. The glucose uptake effect of oxovanadium(IV) complex of ʟ-alanine, imidazole-4-carboxylic acid, imidazole-2-carboxylic acid and 1-methylimidazole-2-carboxylic acid was investigated using 3T3-L1 adipocytes, Chang liver and C2C12 muscle cells at various concentrations. The compounds had significant glucose uptake on Chang liver cells only at a concentration of 0.1-10 μM whilst in the C2C12 muscle and 3T3-L1 cells the compounds showed little to no activity probably due to the lower concentrations employed as a result of the cytotoxicity of these compounds on these two cell lines.
- Full Text:
- Date Issued: 2011