In this dissertation, the aim was to develop a platinum specific resin to be utilized for the early removal of platinum from the industrial feed solution. Efforts were therefore directed towards the syntheses of silica based resins, with active centra, designed for platinum. The large chlorometallate ions present in the feed stream, were characterized in terms of physical parameters relevant to phase distribution, namely distortability (RD), charge density, softness (σ) etc. Matching cations for each of the types were investigated. In order to attempt the design of platinum specific resins, different structural amines were used to aminate the silicone precursor and to subsequently fix these onto the silica framework. Two different solvents namely alcohol and dmf were used in this process, resulting in two sets of resins, with different properties. The design was based on previous experience with these ions, with reference to their behaviour towards different types of cations. The platinum species, PtCl6 2- and PtCl4 2-, as well as the most important contaminants in the feed stream, were typified, bearing in mind size, charge, charge density and distortability. Different types of cationic centra, having differences in charge density, stereochemical crowding and extent of hydrophobicity, were synthesized and tested-both as solvent extractants (where possible) and silica based resins. The results indicated that, partly screened secondary ammonium cationic resin species, which could be regarded as “intermediate”, proved to be satisfactory both in their high percentage extraction for PtCl4 2- and rejection of contaminants like chlororhodates, chloroiridates(III) and FeCl4 -. It was however necessary, to work at a redox potential, where iridium(IV) in the form of IrCl6 2-, was absent. Various 2-aminoalkane resins were prepared, with variation in the length of alkane group and synthesised by the two different solvents. The latter resulted in two sets of resins with not only differing compactness, but also having significantly different properties with reference to platinum specificity, HCl effect and stripping potential. The 2-aminobutane and 2-aminoheptane resins in particular, proved to be very satisfactory platinum specific resins, both with respect to selectivity, platinum capacity and stripping potential. The various physical parameters could be applied to identify the chemical behaviour of anions and assist in the development of anion specificity for the relevant species.

In this thesis, the aim was to develop resins which are platinum and gold specific to be utilized for the early removal of these metals from the industrial feed. Efforts were therefore directed towards the synthesis of silica based resins with active centra which were designed for platinum and gold specificity respectively. The large chlorometallate ions in the feed stream were characterized in terms of physical parameters relevant to phase distribution namely distortability (RD), charge density, softness (σ) etc. Matching cations for each of the types were investigated. In order to attempt the design of platinum specific resins different structural amines were used to aminate the silicone precursor and subsequently to fix these onto the silica framework. Two different solvents i.e. alcohol and dmf were used for this process, resulting in two sets of resins with different properties. For gold specific resins, various polyethers were attached to a different type of silicone precursor, which was attached to the silica framework. The design was based on previous experience with these ions with reference to their behaviour towards different types of cations. The platinum species PtCl6 2- and PtCl4 2-, the gold species AuCl4 -, as well as the most important contaminants in the feed stream were typified bearing in mind size, charge, charge density and distortability. Different types of cationic centra having differences in charge density, stereochemical crowding and extent of hydrophobicity were synthesized and tested both as solvent extractants (where possible) and silica based resins. The results indicated that partly screened secondary ammonium cationic resin species, which could be regarded as “intermediate”, proved to be satisfactory both in their high percentage extraction for PtCl4 2- and rejection of contaminants like chlororhodates, chloroiridates(III) and FeCl4 -. It was, however, necessary to work at a redox potential where iridium(IV) in the form of IrCl6 2- is absent. Various 2-aminoalkane resins were prepared with variation in the length of alkane group and synthesized in the two different solvents. The latter resulted in two sets of resins with different compactness also having significantly different properties with reference to platinum specificity, HCl effect and stripping potential. The 2- aminobutane and 2-aminoheptane resins both proved to be very satisfactory platinum specific resins with respect to selectivity, platinum capacity and stripping potential. The various physical parameters could be utilized to accommodate the chemical behaviour. To obtain gold specific resins, experiments were performed with resins having oxygen-donor atoms which can readily be protonated to form onium type cations for example amides and ether oxygen atoms. In the case of the latter, various polyethers with a different number of ether groups (polyether groups linked by ethylene and propylene groups) and variations of hydrophobicity (by substitution) have also been studied. Linked to the polyether groups were alkane and aryl groups. Those having 8 to 10 ether groups and aromatic tail ends proved to be moderately successful in terms of gold capacity and sharp breakthrough curves of their columns, however, platinum could not be very effectively rejected.

In this study a method was developed to identify and quantify platinum(II) complexes of the type [PtCl4-n(OH)n]2- and [PtCl4-n(H2O)n]2-n. Separation of the various species was achieved with the aid of a hyphenated reversed phase HPLC-ICP-MS technique coupled with an ion-pairing reagent, HMHDCl2. The adsorption of HMHD2+ onto a C-18 column was investigated by generating a series of breakthrough curves. It was found that the selectivity for high charge density anions originates from its low surface coverage relative to TBA+, which on the other hand could not separate Pt(II) complexes. The peaks in the chromatographic traces were assigned by following the stepwise ligand substitution of [PtCl4]2- in hydroxide medium with UV/Vis spectrophotometry and HPLC-ICP-MS simultaneously. A computer program was written by the author to analyse chromatographic data by deconvoluting the chromatogram into its individual components and calculating the mole fraction of each component. The validity of the consecutive pseudo-first order model was validated by constructing 3D Mauser diagrams with the raw spectrophotometric data (A1 vs A2 vs A3). Additional software was used to simulate the raw spectrophotometric data and processed chromatographic data. The pseudo-first order rate constants obtained in both cases were in agreement with each other. Hence, peaks were assigned to [PtCl4]2-, [PtCl3(OH)]2-, [PtCl2(OH)2]2-, [PtCl3(H2O)]-. The molar extinction coefficient spectra of [PtCl3(OH)]2- and [PtCl2(OH)2]2- were obtained by simulating the spectrophotometric data at wavelengths from 280 to 450 nm. The reaction of [PtCl4]2- with sodium hydroxide was investigated with UV/Vis spectrophotometry at 25 °C. A rate constant consisting of a first and second order term was obtained. The first order term agreed with what has been reported in the literature for aquation of [PtCl4]2- at 25 degrees C. The influence of temperature was established by conducting the experiment at different temperatures. It was found that the reaction proceeds essentially via aquation at elevated temperatures.