Thesis (PhD)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: Please refer to fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming.

Thesis (PhD)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The photo-mineralization of organic compounds (in the combined presence of a Ti02 based semiconductor catalyst, UV radiation and molecular oxygen) represents an advanced oxidation technology with significant potential for environmental pollution abatement. This oxidation process (generally known as photocatalytic oxidation - PCO) is currently the subject of extensive global research, with the main objective being the oxidative removal of organic and inorganic pollutants from water, air and soil. Presently, many barriers still block the way to commercial implementation of this technology, hence a unique (and effective) configuration of catalyst, light source and reactor design needs to identified. In terms of the water treatment scenario (which is the emphasis of this work) the need exists to develop a practical and affordable PCO reactor for water treatment on a large scale. The two laboratory-scale PCO reactors investigated in this work were based on a "falling film" flow reactor design and were constructed with commercially available materials and components. Degussa P-25 Ti02 was used as semiconductor catalyst and two types of low-pressure mercury lamps as the UV light source. Three modes of operation were investigated in order to determine the practical feasibility of the reactors. These included the recirculation, single pass and sequential single pass modes. The reactors were operated either as a Ti02 slurry-phase reactor (Reactor 1), or with Ti02 immobilized on stationary fiber glass and fibrous activated carbon sheet modules (Reactors 2A and 28 respectively). Extensive parametric evaluations were done using conventional one-factor variation and statistical methods according to optimal experimental design principles. The PCO treatment of two model organic pollutants (para-Chlorophenol and cyanobacterial microcystin YA, YR, LR and RR) were investigated. These pollutants were spiked into various water matrices to the desired concentration level. The combined photocatalyticcarbon adsorption treatment of these two pollutants was also investigated in Reactor 28. The experimental results obtained through this work showed that both model pollutants were successfully degraded in several water matrices by means of treatment in the respective PCO reactors. Moreover, this research was the first ever demonstration of the Ti02 photocatalytic degradation of microcystin toxins in the aqueous phase. The large number of parametric and optimization studies yielded the relative contributions of the various process parameters (in terms of the defined photocatalytic efficiency parameters as responses) very effectively. Furthermore, statistical evaluation of the experimental data provided valuable insight into the scientific phenomena associated with Ti02 mediated PCO processes. / AFRIKAANSE OPSOMMING: Die foto-mineralisasie van organiese verbindings (in die gekombineerde teenwoordigheid van 'n Ti02 gebaseerde halfgeleier katalisator, UV straling en molekulêre suurstof) verteenwoordig 'n gevorderde oksidasie-tegnologie met beduidende potensiaal vir bekamping van omgewingsbesoedeling. Hierdie oksidasie-proses (algemeen bekend as fotokatalitiese oksidasie - FKO) is tans wêreldwyd die onderwerp van ekstensiewe navorsing, met hoofdoel die oksidatiewe verwydering van organiese en anorganiese besoedelingstowwe uit water, lug en grond. Huidiglik bestaan daar nog vele struikelblokke wat die weg na kommersiële implementering van hierdie tegnologie blokkeer, gevolglik moet 'n unieke (en effektiewe) konfigurasie van katalisator, ligbron en reaktor-ontwerp nog identifiseer word. In terme van die waterbehandeling situasie (wat die klem van hierdie werk is) bestaan die nodigheid om 'n praktiese en bekostigbare FKO reaktor te ontwikkel vir watersuiwering op 'n groot skaal. Die twee laboratorium-skaal FKO reaktore in hierdie studie was gebaseer op 'n "vallende film" vloeireaktor ontwerp en is gekonstrueer met kommersieël beskikbare materiale en komponente. Degussa P-25 Ti02 is aangewend as halfgeleier katalisator en twee tipes lae-druk kwik lampe as die UV ligbron. Drie bedryfsmodes is ondersoek met die doel om die praktiese haalbaarheid van die reaktore te bepaal. Hierdie het ingesluit die resirkulasie, enkeldeurvloei en enkeldeurvloei-sekwensie modes. Die reaktore is bedryf as óf 'n Ti02 flodder-fase reaktor (Reaktor 1) óf met Ti02 ge-immobiliseer op 'n stasionêre veselglas en veselagtige ge-aktiveerde koolstof blad-modules (Reaktor 2A en 28 onderskeidelik). Omvattende parametriese evaluasies is gedoen deur gebruik te maak van konvensionele een-faktor variasie en statistiese metodes na aanleiding van optimale eksperimentele ontwerp beginsels. Die FKO behandeling van twee modelorganiese besoedelingstowwe (para-Chlorofenol en siano-bakteriese mikrosistien YA, YR, LR en RR) is ondersoek. Hierdie besoedelingstowwe is ge-ent in verskeie watermatrikse tot die verlangde konsentrasievlak. Die gekombineerde fotokatalitiese - aktiveerde koolstof behandeling van die twee besoedelingstowwe is ook ondersoek in Reaktor 28. Die eksperimentele resultate verkry deur hierdie werk het getoon dat beide die modelbesoedelingstowwe suksesvol gedegradeer is in verskeie watermatrikse deur behandeling in die onderskeie FKO reaktore. Trouens, hierdie navorsing was die eerste demonstrasie ooit van die Ti02 fotokatalitiese degradasie van mikrosistien toksiene in die waterige fase. Die groot aantal parametriese en optimiseringstudies het die bydraes van die verskeie proses-parameters (in terme van die gedefinieerde fotokatalitiese effektiwiteitsparameters as response) baie effektief verskaf. Verder, statistiese evaluasie van die eksperimentele data het waardevolle insig verskaf tot die wetenskaplike verskynsels te assosieer met Ti02 gemedieërde FKO prosesse.

Digitized from microfiche to pdf. / Please refer to full text.

Digitized from microfiche to pdf format. / Thesis (PhD (Chemistry))--University of Stellenbosch, 1977. / Please refer to full text.

Thesis (PhD)--University of Stellenbosch, 2011. / In this thesis we describe the application of novel salicylaldimine and iminopyridyl nickel metallodendrimer complexes as catalysts in the transformation of á-olefins as well as in the polymerization of norbornene. New cyclic dendrimers based on cyclam as a core (L1-L8) were synthesized and characterized via FTIR and NMR spectroscopy, mass spectrometry and microanalysis. Subsequently the generation 1 cyclam-based dendrimers as well as the commercial generation 1 to generation 3 DAB-PPI dendrimers were functionalized with salicylaldimine and iminopyridyl moieties on the periphery to produce new ligands, DL1-DL10. These modified dendritic ligands were subsequently complexed to Ni salts to obtain the metallodendrimer complexes, C1-C8. The metallodendrimers were characterized by FTIR spectroscopy, mass spectrometry, microanalysis, magnetic susceptibility measurements, UV-Vis spectroscopy and thermal gravimetrical analysis (TGA). The DAB G1-G3 salicylaldimine ligands (DL1-DL3) were subjected to computational studies and the optimized structures were obtained by density functional theory (DFT) calculations. The effect of the increase in dendrimer generation on the structural arrangement of the dendrimer was also investigated. The following aspects were probed using molecular modeling: a) the possible coordination site for the Ni to the first generation dendrimer ligand, DL1, and b) the optimized structure of the first generation salicylaldimine nickel complex, C1. We subsequently evaluated catalysts, C1-C7, in the vinyl polymerization of norbornene, using methylaluminoxane (MAO) as a co-catalyst. All the catalysts were found to be active for norbornene polymerization with the weight of the polymers obtained ranging from 5.12 x 105 - 11.17 x 106 g/mol. The DAB-based iminopyridyl catalysts (C4-C6) exhibited higher activities than its analogous salicylaldimine catalysts (C1-C3) under the same reaction conditions. Also, the cyclam-based salicylaldimine nickel catalyst (C7) exhibited higher activities than the DAB-based salicylaldimine nickel catalyst, C1. A negative dendritic effect was observed for the G1-G3 DAB salicylaldimine catalysts since the optimum activity for the G3 catalyst, C3, was lower than that for the G2 catalyst, C2. These nickel complexes were also evaluated as ethylene oligomerization catalysts and were found to produce a range of ethylene oligomers (C4-C18) as well as some longer chained oligomers, when employing EtAlCl2 as a co-catalyst. We observed however that the free EtAlCl2 mediates the Friedel-Crafts alkylation of the solvent, toluene, in the presence of the obtained ethylene oligomers to give uneven carbon number products, which are mixtures of alkylated benzenes. Our metallodendrimer catalysts also isomerized and in some cases dimerized 1-pentene. In both ethylene oligomerization and 1-pentene isomerization processes, the salicylaldimine catalysts exhibited higher activity towards olefin transformation than the iminopyridyl catalysts. The cyclam-cored dendrimer catalyst again showed the highest activity. From the results obtained thus far it can be concluded that these nickel metallodendrimers exhibit great potential as catalysts in the transformation of unsaturated hydrocarbons.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The wine industry is an important sector of agriculture and wine analysis forms the basis of assessing compliance of its commodities with regulatory standards and research in this field. Liquid chromatography (LC) is extensively used for the determination of a wide range of nonvolatile wine components, but conventional detectors impose performance limitations on the technique that prevents its application to sophisticated analytical problems. In particular, conventional detectors for LC often lack the sensitivity and specificity for the determination of many wine compounds, especially trace level analytes, and furthermore, do not possess spectral capabilities for compound identification or structure elucidation. The hyphenation of mass spectrometry (MS) to LC has led to the introduction of a range of detectors that confers high levels of sensitivity and selectivity to the technique. In addition, a wide variety of MS architectures are available that are inherently suited for targeted analysis or structure elucidation studies. In this dissertation, the potential benefits of liquid chromatography – tandem quadrupole mass spectrometry (LC-MS/MS) to solve analytical problems relevant to the wine industry are explored. LC-MS/MS is a particularly versatile analytical technique because both mass analysers can be operated in full-spectrum mode or selected-ion monitoring, which, together with optional fragmentation, gives rise to four modes of operation that may be used for highly specific and sensitive targeted analysis or spectral investigations. In multiple reaction monitoring (MRM) mode, both analysers are set at single ion frequencies specific for the compound under investigation and one or more of its product fragments, respectively. MRM mode is ideally suited for trace level analysis in complex mixtures, even in cases where the target components are not resolved from interferences. In this study, MRM detection was used to solve challenges relevant to the wine industry for the selective quantitation of target analytes that could not be analysed by conventional LC methods. The application of this approach for the analysis of natamycin, ethyl carbamate (EC) and 3-alkyl-2- methoxypyrazines (MPs) in wine is demonstrated. Natamycin is an antimicrobial preservative that is not permitted in wine in the European Union. A rapid and sensitive method for the determination of natamycin was developed, and has been used since 2009 to regulate this vitally important sector of the South African wine export industry. EC is a natural carcinogen that occurs at trace level amounts in alcoholic products. It also has the potential to accumulate in wines and can occur in very high concentrations in some fruit brandies. The determination of EC is complicated by its physicochemical properties, and available analytical methods suffer from drawbacks such as the requirement for elaborate extraction procedures and high solvent consumption. A novel method for the determination of EC in wines, fortified wines and spirits is described and it was applied to perform an audit of the South African industry as well as to investigate factors responsible for its accumulation in alcoholic beverages. This work forms an integral part of the food safety mandate of the State and it ensures that export products comply with international norms for trade. MPs are ultra-trace-level aroma compounds that contribute to the varietal character of Sauvignon blanc wines. Their analytical determination is challenging due to their low levels of occurrence. The loading capacity of LC combined with the sensitivity and resolving power of MS was exploited to analyse concentrated extracts, in order to achieve very low limits of detection. The performance of the LC-MS/MS method enabled the quantitation of these compounds at their natural levels of occurrence, including the first quantitation and spectral confirmation of 3- ethyl-2-methoxypyrazine in wine. Extensive data pertaining to South African Sauvignon blanc wines are reported and statistical analysis is performed, reporting the correlation of variables such as vintage and origin as well as wine parameters such as malic acid with wine MPs. Furthermore, the application of LC-MS/MS for structural elucidation and screening of target classes of analytes was demonstrated for the analysis of red wine anthocyanins. The anthocyanidin-glycosides are responsible for the colour of red grapes and wine, contribute to the sensory properties of wine, and are also of interest due to their beneficial biological properties. Their determination is complicated by their large numbers and structural diversity, further exacerbated by diverse reactions during wine ageing as well as the lack of reference standards for most members of this class of compounds. Tandem MS in scan mode was used for the highly selective detection of glycosylated anthocyanins and derivatives, exploiting the predictable elimination of the sugar moiety in neutral loss mode. Concurrent survey scan experiments were used to unambiguously identify neutral loss detected compounds. The method therefore follows a simplified and structured approach for unambiguous peak identification based on elution order and mass spectral information to impart a high level of certainty in compound identification. In summary, the work presented in this dissertation demonstrates that LC-MS/MS is a versatile and powerful analytical approach for the analysis of diverse compounds of relevance to the wine industry. The sensitivity and specificity of MRM mode, and the selectivity and spectral capabilities of neutral loss and survey scan modes of MS/MS detection, is amply demonstrated by the applications presented in the dissertation. / AFRIKAANSE OPSOMMING: Die wynbedryf is ‘n belangrike komponent van landbou en wyn-analise vorm ‘n integrale deel van gehalteversekering ten opsigte van toepaslike wetlike standaarde. Wyn-analise is ook belangrik in navorsing oor die samestelling van wyn. Vloeistofchromatografie word dikwels aangewend vir die bepaling van ‘n wye verskeidenheid nie-vlugtige wynkomponente, maar konvensionele detektors plaas beperkinge op die aanwending van die tegniek tot gesofistikeerde analitiese toepassings. Meer spesifiek, konvensionele detektors vir vloeistofchromatografie beskik nie oor die sensitiwiteit en selektiwiteit vir die bepaling van baie wynkomponente nie, veral in die geval van spoorvlakanalise, en beskik boonop ook nie oor spektrale vermoëns vir identifikasie van komponente en struktuurbepaling nie. Die koppeling van vloeistofchromatografie met massaspektrometrie het ‘n reeks detektors tot die tegniek toegevoeg wat hoë vlakke van sensitiwiteit en selektiwiteit bied. Verder bied die verskeidenheid van massaspektrometrie-konfigurasies ook instrumente wat inherent geskik is vir geteikende analise of struktuurbepaling, afhangende van die doel van die ondersoek. In hierdie dissertasie word die voordele ondersoek wat verbonde is aan die aanwending van vloeistofchromatografie – tandem kwadrupool massaspektrometrie om relevante analitiese vraagstukke in die wynbedryf op te los. Hiedie tegniek is besonder toepaslik aangesien beide massa-analiseerders in geselekteerde-ioon modus of in volle skandering gebruik kan word. Tesame met opsionele fragmentasie, gee hierdie uitleg aanleiding tot vier funksionaliteite wat vir hoogs sensitiewe geteikende analise of spektrale onledings gebruik kan word. Eerstens word beide massa analiseerders vir enkel-ioon frekwensies opgestel, spesifiek tot die teikenkomponent en een of meer van sy produkfragmente, wat verkry word deur komponentspesifieke fragmentasie. Hierdie modus is by uitstek geskik vir spoorvlakontleding van komplekse monsters, selfs wanneer die teikenkomponente nie chromatografies van die matriks geskei is nie. In hierdie studie is die tegniek aangewend vir die hoogs sensitiewe bepaling van spoorvlak komponente wat nie met konvensionele detektors gemeet kon word nie. Die aanwending van hierdie tegniek word gedemonstreer vir die spoorvlakbepaling van natamycin, etielkarbamaat en 3-alkiel-2-metoksiepierasiene in wyn. Natamycin is ‘n antimikrobiese preserveermiddel wat ontoelaatbaar is in wyn in die Europese Unie. ‘n Vinnige en sensitiewe metode vir die bepaling van natamycin is ontwikkel, en word reeds sedert 2009 aangewend om hierdie uiters belangrike sektor van die Suid-Afrikaanse wyn uitvoerbedryf te reguleer. Etielkarbamaat is ‘n karsinogeen wat natuurlik voorkom in spoorhoeveelhede in alkoholiese produkte. Dit kan ook onder sekere omstandighede akkumuleer in wyn en in hoë konsentrasies voorkom in vrugtebrandewyne. Die bepaling van etielkarbamaat word bemoeilik deur sy chemiese eienskappe, en gevolglik word analitiese metodes gekenmerk deur uitgebreide, arbeidsintensiewe monstervoorbereiding en die gebruik van groot hoeveelhede, meestal giftige, oplosmiddels. ‘n Nuwe metode vir die bepaling van etielkarbamaat in wyn, gefortifiseerde wyn en spiritualië word beskryf en word aangewend om die faktore vir vorming daarvan te ondersoek. Die metode word aangewend om die Suid-Afrikaanse bedryf te ouditeer in terme van die voedselveiligheid mandaat van die Staat, en om te verseker dat uitvoere voldoen aan standaarde vir internasionale handel. Metoksiepierasiene is vlugtige, ultraspoorvlak wynaromakomponente wat verantwoordelik is vir die kenmerkede kultivarkarakter van Sauvignon blanc wyne. Hul analitiese bepaling word bemoeilik deur hulle lae konsentrasies in wyn. Die ladingskapasiteit van vloeistofchromatografie tesame met die sensitiwiteit en selektiwiteit van massaspektrometrie was benut om hoogs gekonsentreerde ekstrakte te ontleed. Baie hoë vlakke van sensitiwiteit word sodoende verkry. Die verrigting van die metode was voldoende om hierdie komponente teen hulle natuurlike konsentrasies te kwantifiseer, insluitende die eerste kwantifisering en spektrale bevestiging van 3-etiel-2-metoksiepierasien. Omvattende data van die vlakke van hierdie komponente in Suid- Afrikaanse Sauvignon blanc wyne word getoon en statistiese ontleding is gedoen om korrelasies tussen veranderlikes soos oorsprong en oesjaar sowel as basiese wyn veranderlikes soos byvoorbeeld appelsuur, met metoksiepierasienvlakke te ondersoek. Verder was die toepassing van vloeistofchromatografie – tandem massaspektrometrie tot struktuurbepaling en skandering vir groepe van komponente gedemonstreer vir die ontleding van rooiwyn antosianiene. Die antosianien-glukosiede is verantwoordelik vir die kleur van rooi druiwe en wyn, dra by tot die sensoriese eienskappe daarvan, en is ook relevant as gevolg van die voordelige biologiese eienskappe daarvan. Die bepaling van hierdie komponente word gekompliseer deur hulle groot getalle en strukturele diversiteit, verder bemoeilik deur die wye verskeidenheid van reaksies wat hulle ondergaan tydens veroudering. Daar is ook ‘n gebrek aan beskikbaarheid van standaarde vir die meeste van die lede van hierdie klas van komponente. Tandem massaspektrometrie was in skanderingsmodus gebruik vir hoogs selektiewe deteksie van die antosianien-glukosiede deur die voorspelbare eliminasie van die suiker komponent in neutrale verliesskandering te benut. Gelyktydige skanderings van die komponente wat met neutraleverliesskandering waargeneem word, is gebruik vir ondubbelsinnige komponent identifikasie. Die metode volg daarom ‘n eenvoudige en gestruktureerde benadering vir piek identifikasie wat gebaseer is op chromatografiese orde, sowel as massaspektrale inligting, om ‘n hoë vlak van sekerheid aan die identifikasie van komponente te verleen. Samevattend, word daar getoon deur die werk wat in hierdie dissertasie uiteengesit is dat vloeistofchromatografie – tandem massaspektrometrie ‘n veelsydige en kragtige tegniek bied vir chemiese analise relevant tot die wynbedryf. Die sensitiwiteit, selektiwiteit en spektrale vermoëns van die tegniek word duidelik deur toepassings in die dissertasie getoon.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In this study an economical, environmentally friendly, selective and efficient process for the extraction and recovery of [AuCl4]- from aqueous acidic chloride-rich solutions, particularly those aqueous solutions having low concentrations of the precious metal complexes has been investigated. Functionalized poly(styrene-co-maleimide) (PSMI) nanoparticles were synthesized by thermal imidization of the poly(styrene-co-maleic anhydride) (PSMA) copolymer with 3-N,N-dimethylaminopropylamine. Stable water-based dispersions were obtained containing spherical, monodisperse PSMI nanoparticles with a narrow size-distribution and average diameters of 50 ± 5 nm. The specific surface area of the bulk PSMI nanoparticles is 88.1 ± 2.2 m2/g with an average pore diameter of 82.3 Å. 13C NMR, FTIR and elemental analyses confirmed the successful and complete conversion of PSMA into the PSMI derivative. The functionalized PSMI nanoparticles synthesized were investigated as a novel anion-exchange material for the extraction of [AuCl4]- ions from aqueous acidic solutions. Batch sorption studies were carried out as a function of various parameters, such as initial gold concentration, PSMI mass, contact time and agitation rate. The [AuCl4]- extraction occurred with extremely fast sorption kinetics and is dependent on the rate of agitation during the batch sorption process. The functionalized PSMI nanoparticles show a maximum gold loading capacity of 1.76 mmol/g (347.7 mg/g). Langmuir and Freundlich isotherm models were applied to analyze the experimental sorption data. The best model describing the sorption process is given by the Langmuir model. Desorption efficiencies of about 80 % and 93 % were obtained using acidified thiourea (0.25 M thiourea/2 M HCl) and a mixture of 10 M HNO3/0.5 HCl as elutant solutions, respectively. X-ray photoelectron spectroscopy (XPS) analysis unambiguously confirms that the immobilized gold species exists in several oxidation states of 0, +I and +III on the PSMI nanoparticles. This proves that the [AuCl4]- ions initially present in the gold feed solutions unfortunately are subject to a reduction phenomenon on the surface of the functionalized PSMI nanoparticles. The existence of the various gold species contributed significantly to poor desorption efficiencies. In addition to PSMI nanoparticles, micro- to millimeter size PSMI resin beads was prepared by an electrospray methodology. This allows for a wide range of PSMI spherical and quasi-spherical bead diameters of shape to be prepared by manipulation of the experimental conditions employed during the electrospray process, such as the concentration of the PSMI in solution, the capillary tip-to-collector distance, flow rate and the applied voltage. 13C NMR and FTIR spectroscopy analyses show that the electrospray methodology allows PSMI resin beads preparation without any change in chemical composition of the PSMI material. Surface area and porosity analysis shows that 450 μm and 1620 μm PSMI beads selected for use in the gold extraction experiments are microporous and have BET specific surface areas of 2.8 ± 0.4 m2/g and 2.0 ± 0.1 m2/g, respectively. Micro- to millimeter size PSMI resin beads of 450 μm and 1620 μm diameter were tested as potential anion-exchange resins for the extraction of [AuCl4]- from aqueous acidic solutions. The time-dependent studies reveal that the extent of gold uptake increases with an increase in contact time and is dependent on the gold concentration in the [AuCl4]- feed solutions. A maximum loading capacity of 120.7 mg/g and 98.16 mg/g was attained for the 450 μm and 1620 μm resin beads, respectively. The experimental sorption data followed a linear trend consistent with a Freundlich sorption model. This sorption trend for [AuCl4]- suggests that a multi-layer sorption process predominates. Desorption of immobilized gold species from the loaded PSMI resin beads was investigated using various elutants such as HCl, HNO3, thiourea, NaCN and NaOH solutions. The best results were obtained using a mixture of 10 M HNO3/0.5 M HCl as elutant with a desorption efficiency of about 97%. Finally, superparamagnetic magnetite (Fe3O4) nanoparticles with a high degree of crystallinity and phase purity were synthesized by a chemical co-precipitation of Fe2+ and Fe3+ salts. The average diameters of the obtained Fe3O4 nanoparticles were about 7 – 8 nm. The Fe3O4 nanoparticles were coated with oleic acid surfactant molecules and used as seed particles for the preparation of 50 nm diameter magnetic PSMI nanoparticles via an in situ imidization reaction. TEM analysis confirmed that the magnetically responsive PSMI nanoparticles consist of magnetite core-polymer shell structure, although more work is required to perfect such materials. / AFRIKAANSE OPSOMMING: In hierdie studie is ‘n ekonomiese, omgewings vriendelike, seleketiewe en effektiewe proses vir die ekstraksie en herwinning van [AuCl4]- uit suur chloried-ryke oplossings, spesifiek oplossings van lae konsentrasies van edel metal komplekse was bestudeer. Gefunksionaliseerde poli(stireen-ko-maleïmied) (PSMI) nanopartikels was gesintetiseer deur middel van termiese imidisasie van die poli(stireen-ko-maleïk anhidried) kopolimeer met 3-N,N-dimetielaminopropielamien. Stabiele dispersies in water was gevind wat soos sweriese mono-disperse PSMI nanopartikels met ‘n noue partikel-grootte verspreiding met ‘n gemiddelde deursnee van 50 ± 5 nm. Die spesifieke oppervlak area van die massa PSMI nanopartikels is 88.1 ± 2.2 m2/g met ‘n gemiddelde porie-grootte van 82.3 Å. 13C NMR, FTIR en elementêre analiese bevestig die suksesvolle en volledige omskakeling van PSMA na PSMI. Die gefunksionaliseerde PSMI nanopartikels was bestudeer as ‘n nuwe anion-uitruil material vir die ekstraksie van [AuCl4]- ione uit suur oplossings. Stel sorpsie studies was uitgevoer as ‘n funksie van verskeie parameters soos onder andere die goud konentrasie in oplossing, PSMI massa, kontak tyd en ‘n mengings tempo. Die [AuCl4]- ekstraksie gebeur met ‘n geweldige sorpsie kinetika en is afhanklik van die mengings tempo gedurende die stel sorpsie proses. Die gefunksionaliseerde PSMI nanopartikels het ‘n maksimum goud sorpsie kapsiteit van 1.76 mmol/g (347.7 mg/g). Langmuir en Freundlich isoterm modelle was gepas en geanaliseer op die experimentele sorpsie data waarvan die Langmuir isoterm model die data die beste gepas het. De-sorpsie effektiwiteit van ongeveer 80 % en 93% was vekry vir die aangesuurde thiourea (0.25 M thiourea/2 M HCl) en ‘n mengsel van 10 M HNO3/0.5 M HCl as elueer oplossings, onderskeidelik. X-straal foto-elektron spektroskopie (XPS) analiese bevestig ongetwydeld die geimmobileerde goud spesies in oksidasietoestande van 0, +I, en +III op die PSMI nanopartikels. Hierdie is bewyse dat die [AuCl4]- oorspronklik teenwoordig in die goud oplossings is onderhewe auto-reduksie fenomeen op die oppervlak van die gefunksionalieerde PSMI nanopartikels. Die bestaan van verskeie goud spesies dra by tot die power de-sorpsie effektiwiteit van ge-immobiliseerde goud. Bykomend tot die nanopartikels is mikro- tot millimeter grootte PSMI partikels voorberei met ‘n elektro-sproei proses. Hierdie metode stel ons instaat om ‘n wye reeks sferiese en quasi-sferiese PSMI partikel se deersnee voorteberei. Deur die manupulasie van die eksperimentele kondisies gedurende die elektro-sproei proses, soos die konsentrasie van die PSMI in oplossing, die kapilêre punt-tot-ontvanger afstant, vloeispoed en die toegepasde potensiaal. 13C KMR en FTIR spectroskopiese analiese wys dat die elektro-sproei proses die PSMI partikel bereiding toelaat sonder enige veranderinge in die chemiese samestelling van die PSMI materiaal. Oppervlak area en porie-grootte analise wys dat 450lksdfhld en dskl jmm partikels gebruik in die goud ekstraksie eksperimente is mikro-porieës en het spesifieke oppervlak-areas van 2.8 ± 0.4 m2/g en 2.0 ± 0.1 m2/g onderskeidelik. Mikro- tot millimeter grootte poli(stireen-ko-maleimied) (PSMI) partikels van 450 μm en 1620 μm deursnee was getoets as potensieele anion-uitruilings-hars vir die ekstraksie van [AuCl4]- vanuit suur oplossings. Die tyd afhanklike studies gee aanduiding dat die mate van goud opname toeneem met ‘n toename in kontak-tyd en is afhanklik van die goud konsentrasie in die [AuCl4]- oplossings. ‘n Maksimum opname-kapasiteit van 120.7 mg/g en 98.2 mg/g was verkry vir die 450 μm en 1620 μm hars partikels onderskeidelik. Die eksperimentele sorpsie-data volg ‘n lineêre neiging in ooreenstemming met die Freundlich model. Die sorpsie neiging van [AuCl4]- dui aan dat ‘n meervuldige laag sorpsie proses domineer. De-sorpsie van die geimobiliseerde goud spesies vanaf die PSMI hars partikels was bestudeer deur gebruik te maak van verskeie elueermiddels soos HCl, HNO3, thiourea, NaCN en NaOH oplossings. Die beste resultate is verkry deur ‘n mengsel te gebruik van 10M HNO3/0.5M HCl as elueermiddel met n de-sorpsie effektiviteit van ongeveer 97%. Superparamagnetiese magnetiet (Fe3O4) nanopartikels met ‘n hoë graad van kristaliniteit en fase-reinheid was voorberei deur ‘n chemiese ko-neerslagvorming van Fe2+ en Fe3+ soute. Die gemiddelde deursnee van die Fe3O4 nanopartikels was ongeveer 7 – 8 nm. Die Fe3O4 nanopartikels was omhul met oleic suur benatter molekules wat gebruik word as saadjies vir voorbereiding van 50 nm deursnee-magnetiese PSMI nanopartikels deur middel van ‘n imidisasie reaksie. TEM analiese bevestig dat die magnetiese PSMI partikels nanopartikels bestaan uit ‘n magnetiet-kern polimeer-skil struktuur.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: see full text for abstract. / AFRIKAANSE OPSOMMING: Sien volteks vir die opsomming.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The aim of the work presented in this thesis was to design ionic organic framework materials based on carboxylate salts with the intention of engineering interesting properties, such as porosity, into these framework materials. The first section focuses on the characterisation and porosity studies of an ionic framework material, 3,4-lutidinium pamoate hemihydrate, with THF-filled channels in the solid state. It was shown that this framework is able to exchange the THF in the channels for a wide variety of compounds, with many of these exchanges occurring in a single-crystal to single-crystal fashion. Competition experiments conducted with the framework, both by immersing crystals of the framework in solvent mixtures, as well as by exposing crystals of the framework to mixtures of solvent vapours, indicated that it is able to selectively exchange for one guest over another. The kinetics of exchange of this framework were studied, and it was possible to identify a kinetic model describing this process. A second novel framework-type material, 4-phenylpyridinium pamoate, was identified during the course of this study, as well as five isostructural frameworks containing different guest molecules. In this case the framework consists of discrete units that close-pack in such a way that guest molecules are included in constricted cavities in the solid state. Although this framework-type material is not porous, it is thermally quite stable and also highly selective. It is able to selectively encapsulate 1,4-dioxane when crystallised from various solvent combinations including 1,4-dioxane. In addition, eight novel structures with pamoic acid in combination with various pyridyl derivatives were obtained. A third novel framework material was obtained with N,N'-bis(glycinyl)pyromellitic diimide in which, due to the extended hydrogen-bonded network formed between the constituents of the framework, DMF molecules are aligned in channels. It was found that this framework material can also be formed by mechanochemical synthesis, and investigation of the thermal behaviour of this framework showed that it has the potential to be porous, since the framework appears to remain intact after desolvation. Furthermore, six novel structures with N,N'- bis(glycinyl)pyromellitic diimide in combination with various N-heterocycles were obtained. All structures obtained in this study were also further analysed to determine whether there are particular structural features that are required for framework formation. Insights gained from these investigations, in terms of degree of ionisation of the anion, packing arrangements and hydrogen bonding patterns as well as the molecular shape of the components are discussed. / AFRIKAANSE OPSOMMING: Die doel van die werk wat in hierdie tesis voorgelê word is om ioniese organiese raamwerkmateriale gebaseer op karboksilaatione te ontwerp, met die voorneme om interessante eienskappe in hierdie materiale te bewerkstellig. Die eerste afdeling fokus op die karakterisering en porositeit van ‘n ioniese organiese raamwerkmateriaal, 3,4-lutidiniumpamoaathemihidraat, wat kanale gevul met tetrahidrofuraan (THF) besit. Dit is aangetoon dat dit moontlik is vir hierdie raamwerkmateriaal om die THF in die kanale te verruil vir ‘n wye verskeidenheid stowwe, waarvan baie van hierdie uitruilings geskied as ‘n enkelkristal tot enkelkristal transformasie. Kompetisie-eksperimente is met hierdie raamwerkmateriaal uitgevoer deur die kristalle in mengsels van oplosmiddels te onderdompel, sowel as deur die kristalle aan mengsels van die oplosmiddeldampe bloot te stel. Die resultate het aangedui dat dit moontlik is vir hierdie raamwerkmateriaal om een gasstof selektief teenoor ‘n ander te verruil vir die THF in die kanale. Die kinetika van die uitruilingsproses van hierdie materiaal is ook bestudeer en dit was moontlik om ‘n kinetiese model te identifiseer wat die uitruilingsproses beskryf. ‘n Tweede nuwe raamwerk-tipe materiaal, 4-fenielpiridiniumpamoaat, is deur die loop van hierdie studie geïdentifiseer, sowel as vyf isostrukturele raamwerkmateriale waarvan net die gasstof verskil. In hierdie geval bestaan die raamwerk uit diskrete eenhede wat op so ‘n wyse saampak dat die gasstowwe in vernoude porieë ingesluit word. Alhoewel hierdie raamwerk-tipe materiaal nie poreus is nie, is dit termies stabiel en ook hoogs selektief. Die raamwerkmateriaal kan selektief 1,4-dioksaan enkapsuleer wanneer dit gekristalliseer word vanuit ‘n verskeidenheid oplosmiddel kombinasies met 1,4-dioksaan. Verder is agt nuwe strukture verkry met die pamoaat ioon in kombinasie met ‘n verskeidenheid piridien-derivate. ‘n Derde nuwe raamwerkmateriaal is verkry met N,N'-bis(glisiniel)piromellitiese diïmied waarin, danksy die uitgebreide waterstofgebinde netwerk tussen die komponente van die raamwerk, die DMF molekules in kanale aangetref word. Hierdie raamwerkmateriaal kan deur meganochemiese sintese berei word en verdere ondersoek na die termiese gedrag van hierdie raamwerkmateriaal dui aan dat dit die potensiaal het om porositeit te toon, aangesien die raamwerk behoue bly nadat die DMF molekules verwyder is. Ses nuwe strukture is ook met N,N'-bis(glisiniel)piromellitiese diïmied in kombinasie met ‘n wye verskeidenheid stikstof-bevattende heterosikliese verbindings verkry. Alle strukture wat tydens hierdie studie verkry is, is verder ondersoek om te bepaal of daar spesifieke strukturele kenmerke is wat benodig word vir die vorming van raamwerkmateriale. Insigte wat verkry is vanuit hierdie ondersoeke, in terme van die graad van ionisasie van die anioon, die rangskikking van molekules in die struktuur en waterstofbindingspatrone, sowel as die molekulêre vorm van die komponente, word bespreek.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: In this study, two novel ligands were synthesized and separately two crown ether derivatives were all immobilized onto four different silica substrates. These immobilized ligand systems were used to extract six different metal and metalloid ions in water. The extraction capacity of the different immobilized ligands was compared with each other to determine whether the substrates had any influence on the extraction capabilities of these ligands. After the extraction experiments, recovery of the immobilized ligands was attempted by re-protonating the ligands so as to displace the metal ions. Two free parent ligands, 1,4,7-tris-[(S)-2-hydroxypropyl]-1,4,7-tri-azacyclodecane (THTD) and 1,4,8-tris-[(S)-2-hydroxypropyl]-1,4,8-tri-azacycloundecane (THTUD), were synthesized. Previous formation constant data indicated that THTD and THTUD form very stable complexes with Cd2+ which should make these ligands ideal for the extraction of Cd2+. These two ligands are less symmetric due to the carbon bridges between the nitrogen atoms, which differ in length. This gives the ligands the special feature that they can form five - and six membered rings during complexation with the metal ions. The ligands were fully characterized by NMR, mass spectrometry and elemental analysis. Characterization of the silica substrates was done using BET, low angle X-ray diffraction and FTIR. MCM-41 has the highest surface area, followed by SBA-15, Si gel (60 Å) and HMS. Although MCM-41 has the largest surface area, it was not the best support to use. HMS and Si gel (60 Å) have the smallest and almost identical surface areas. Yet, Si gel (60 Å) was a far better support to use than HMS, and even better than MCM-41. The worst supports were SBA-15 and HMS. A spacer, 3-Glycidyloxypropyl-trimethoxysilane (glymo), was introduced to immobilize the ligands to the silica substrates. Solid state NMR and FTIR analysis confirmed that the spacer could indeed be successfully immobilized on the various silica supports. The immobilized ligands were fully characterized with the use of solid state NMR and FTIR. The thermal stability of the immobilized ligands was determined by means of TGA. The immobilized ligands are stable up to 200ºC where after they started to disintegrate. According to literature, 15-crown-5 and 18-crown-6 are suitable ligands for the extraction of Sr2+ and UO22+. Since these ligands were to be immobilized, (2-aminomethyl)-15-crown-5 and (2-aminomethyl)-18-crown-6 were used because of the amino group that can be used as an anchor for immobilization. To immobilize these ligands onto the activated silica substrates, two methods were used: 1) directly onto the substrate by using the amino groups at the end of the carbon arm and 2) by means of the glymo spacer which connects the (2-aminomethyl)-15-crown-5 and (2-aminomethyl)-18-crown-6 to the silica substrates. The immobilization was confirmed and the ligand-substrate moiety fully characterized by solid state NMR and FTIR. The thermal stability of the immobilized crown ethers was determined by means of TGA as stable up to 200ºC where after they disintegrated. Extraction experiments were conducted at 25ºC and atmospheric pressure. The extractions were done at pH values of 4.5 and 5.9. The extraction capacity of the immobilized ligands was determined by ICP analysis. As expected, the extraction done at pH 5.9 was significantly better than at pH 4.5. Cr6+ was the best-extracted metal ion. The best extraction results were obtained with Si gel (60 Å) as support. It was also noticeable that the extraction capacity increased with a spacer added to the support, except for the extraction of UO22+. Better extraction for the uranyl was obtained using the 15-crown-5 and 18-crown-6 immobilized directly onto the supports, rather than with a spacer added. Recovery of the metal ions and the immobilized ligands was attempted, but without success. This aspect will be examined again in future work. In conclusion, ligands were successfully synthesized and immobilized. These immobilized ligands produced moderate extraction results with a number of metal ions from aqueous solution. / AFRIKAANSE OPSOMMING: Hierdie studie behels die sintetisering van 2 nuwe ligande en die immobilisering daarvan, te same met 2 kroon eters, op vier verskillende silika substrate. Die geïmobiliseerde ligande is gebruik vir die ekstraksie van verskillende metaal - en metaloied ione uit water. Die ekstraksie kapasiteit van die onderskeie geïmobiliseerde ligande is vergelyk om te bepaal of die substrate ‘n uitwerking op die ekstraksie vermoeë van die ligande het. Herwinnings eksperimente is uitgevoer deur die verplasing van die geadsordeerde metaal ione deur middel van reprotonasie van die ligande. Twee nuwe azamakrosikliese basis ligande, 1,4,7-tris-[(S)-2-hidroksipropiel]-1,4,7-tri-azasiklodekaan (THTD) en 1,4,8-tris-[(S)-2-hidroksipropiel]-1,4,8-tri-azasikloundekaan (THTUD), is gesintetiseer. Vormings konstante data dui daarop dat THTD en THTUD uiters stabiele komplekse met Cd2+ vorm wat hierdie ligande dus geskik behoort te maak vir die ekstraksie van Cd2+. Die twee ligande toon ook ‘n mindere mate van simmetrie as gevolg van die verskillende lengtes van die koolstof brûe tussen die stikstof atome. Hierdie eienskap verskaf aan die ligande die moontlikheid om beide vyf- en sesledige ringe vorm tydens kompleksering met die metaal ione. Die ligande is ten volle gekarakteriseer deur middel van KMR-metings, massa-spekstroskopie en element analise. Karakterisering van die silika substrate [Si gel (60 Å), MCM-41, SBA-15, and HMS] sluit in BET, lae hoek X-straaldiffraksie en FTIR. MCM-41 het die grootste oppervlakte, gevolg deur SBA-15, Si gel (60 Å) en HMS. Ten spyte van die feit dat MCM-41 die grootste oppervlakte het, was dit egter nie die beste subtraat om te gebruik nie. Die interne areas van die uiters groot porie-oppervlaktes van MCM-41 is nie toeganklik vir immobilisering nie a.g.v. die uiter klein porie-openinge. Si gel (60 Å) en HMS het die kleinste oppervlak areas. Si gel (60 Å) is ‘n baie beter substraat om te gebruik as HMS, en selfs ook beter as MCM-41 aangesien die totale oppervlakte van die Si gel (60 Å) gebruik kan word. Die mees ongeskikte substrate was SBA-15 en HMS. Die alreeds klein oppervlak areas word verder “verklein” a.g.v. die klein porie openinge wat die interne oppervlekte van die porieë ontoegangklik maak. ‘n Verbinder, 3-Glysidieloksipropiel-trimetoksisilaan (glymo) is gebruik om die ligande op die silika substrate te immobiliseer. Vaste toestand KMR en FTIR analise het bevestig dat die verbinder suksesvol geïmmobiliseer is op die onderskeie silika substrate. Die geïmmobiliseerde aza makrosikliese ligande is ten volle gekarakteriseer deur vaste toestand KMR en FTIR. Die termiese stabiliteit is bepaal d.m.v GTA en die geïmmobiliseerde ligande is stabiel tot 250ºC. Die basis ligande 15-kroon-5 an 18-kroon-6 is uiters geskik vir die ekstraksie van Sr2+ en UO22+. Om hierdie kroon eters te immobiliseer, is (2-aninometiel)-15-kroon-5 en (2-aninometiel)-18-kroon-6 gebruik. Die amino groep dien as anker vir die immobilisering. Twee metodes van immobilisering op silika is gebruik: 1) direkte immobilisering op die substraat en 2) immobilisering d.m.v. die glymo verbinder. Die immobilisering is bevestig en die ligand-substraat funksionel groep is gekarakteriseer d.m.v. vaste toestand KMR en FTIR. Die termiese stabiliteit van die geïmmobiliseerde kroon eters is bepaal d.m.v. GTA en is stabiel tot 200ºC. Ekstraksie eksperimente is uitgevoer by 25ºC en atmosferiese druk. Die ekstraksies is uitgevoer by pH waardes van 4.5 en 5.9. Die adsorpsie kapasiteit van die geïmmobiliseerde ligande is bepaal d.m.v. IGP analise. Soos verwag is die ekstraksie by pH 5.9 beter as by pH 4.5. Cr6+ ekstrksie was die hoogste met al die die ligande geïmmobiliseerd op die onderskeie substrate. Si gel (60 Å) was die beste substraat om te gebruik. Die ekstraksie kapasiteit van al die metaal ione het verbeter met die toevoeging van ‘n verbinder, behalwe vir UO22+. Beter ekstraksie van die UO22+ is verkry met die gebruik van die kroon eters wat direk op die substrate geïmmobiliseer is, eerder as met ‘n verbinder toegevoeg. Herwinning van die metaal ione en die ligande is probeer deur standard filtrasie. Na die filtrasie is die geïmmobiliseerde ligande en substrate met water gewas. Die filtreerpapier en ligande is met HNO3 behandel, maar van die metaal ione het egter op die filtreer papier agter gebly en die IGP resultate het ‘n hoër herwinning getoon as wat tydens die ekstraksie verkry is. Hierdie aspek sal weer in die toekoms ondersoek moet word. Die ligande is suksesvol gesintetiseer en geïmmobiliseer. Hierdie geïmmobiliseerde ligande toon gemiddelde ekstraksie resultate met ‘n aantal metaal ione uit waterige medium by ‘n pH van 5.9.