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Presence of heavy metals in the environment is a worldwide known contamination problem. Depending on their chemistries and level of contamination, these heavy metals can have severe effects on the ecosystem, aquatic life and eventually humans. Researchers have been particularly interested in finding methods for the removal of these pollutants from the environment. Several methods have been proposed and some have been used with some degree of success. Methods used for trace metal removal include, chemical precipitation, chemical reduction, solvent extraction, micellar ultrafiltration, organic and inorganic ion exchange, adsorption processes, etc. However, the matrix in which these heavy metals are present in is sometimes very complex and some of these heavy metals are present in the environment at very low concentrations, say ppb levels. However, they can have adverse effects even at such low-level concentrations. The above-mentioned methods usually suffer from the effects of the matrix and by-products produced after treatment such as sludge in the case of precipitation. Hence, in this study molecularly imprinted polymers (MIPs) were used. MIPs are highly cross-linked polymers prepared with the presence of template molecule. Once the template has been removed it leaves behind a cavity that can only fit the template, hence MIPs are very selective for the template molecule. Metals of interest in this study were uranium (VI) and chromium (VI). Therefore, two separate imprinted polymers were prepared using chromium and uranium as template molecules for selective extraction of these oxy-ions from aqueous samples. Beside removal of heavy metals, the study also focussed on developing MIPs for selective recovery of high value compounds from plant materials (onion and Moringa oleifera). Three separate imprinted polymers using chromium, uranium or quercetin templates were prepared by bulk polymerization method. Functional monomers used were 4-vinylpyridine; 1-(prop-2-en-1-yl)-4-(pyridin-2-ylmethyl)piperazine (PPMP) and methacrylic acid; and 4-vinylpyridine for chromium, uranium and quercetin imprinted polymers, respectively. For all imprinted polymers, ethylene glycol dimethacrylate (EDMA) and 1,1‘-azobis(cyclohexanecarbonitrile) (ACCN) were used as the cross-linking monomer and initiator, respectively. Control polymers (CP) or non-imprinted polymers (NIP) for each imprinted polymer were prepared and treated exactly the same as imprinted polymers but with omission of respective templates. Following removal of respective templates with appropriate solutions, various parameters that affect selective adsorption such as solution pH, initial concentration, aqueous phase volume, sorbent dosage, contact time, breakthrough volumes etc., were optimized to get optimal adsorption of the imprinted polymers. Optimal parameters for Cr (VI) adsorption were as follows: solution pH, 3; contact time, 120 min; eluent, 20 mL of 0.1 M NaOH; and sorbent amount, 125 mg. Maximum retention capacity of IIP and CP was 37.58 and 25.44 mg g-1, respectively. The observed selectivity order was as follows, Cr (VI) > SO4 2- > F- > PO4 3- > NO2 - > NO3 - > Cl-. However, in the presence of high concentrations of sulphate ions, the selectivity on the CP completely collapsed. For uranium VI removal, the optimal pH was 4.0-8.0, sorbent amount was 20 mg, contact time was 20 min and the retention capacity was 120 mg of uranyl ion per g of IIP. The selectivity order observed was as follows, UO2 2+ > Fe3+ >> Cu2+ > Co2+ > Mn2+ > Zn2+ ~ Ni2+. The binding capacity of quercetin MIPs was investigated at 25 and 84°C, respectively, in batch mode. The slopes for the effect of extraction time revealed that the mass transfer of the analytes was higher at 84°C than at 25°C. Also, the binding capacity for the most promising MIP and its corresponding NIP increased at 84°C but the MIP had higher binding capacity. The increase in binding capacity for the MIP was from ~30 μmol g-1 at 25°C to ~120 μmol g-1 at 84°C. For the corresponding NIP, the binding capacity values were ~15 and ~90 μmol g-1, at 25 and 84°C, respectively. A demonstration of MIP selectivity at higher temperature using standard solutions of selected flavonols showed that the MIP still retained its selectivity for quercetin. Similar selectivity was observed when preliminary application studies on aqueous yellow onion extracts were investigated. The study clearly demonstrated the suitability of the developed imprinted polymers (for chromium, uranium and quercetin) for selective adsorption of Cr (VI), UO2 2+ and quercetin from their respective complex matrices. Breakthrough volume of molecular imprinted polymer solid-phase extraction (MISPE) was investigated using a mixture of myricetin, quercetin and kaempferol. The breakthrough volumes for quercetin, kaempferol and myricetin were 22, 27 and 8 mL, respectively. The number of theoretical plates (N) for the MISPE column corresponding to these volumes were 18, 47 and 4 for quercetin, kaempferol and myricetin, respectively. Using these results, selectivity of MIP and its retention capacity was evaluated. The extractions of Moringa leaves and flowers were carried out using a MISPE cartridge and various solvents were investigated for the selective elution of quercetin from the MIP sorbents. For identification and quantification of quercetin and other flavonols, a high performance liquid chromatography (HPLC) was used. Recoveries of quercetin from different Moringa extracts ranged from 87 – 92% and this demonstrated that the MISPE method can be used for the recovery of quercetin and kaempferol from the Moringa extracts. Amount of quercetin found in Moringa leaves was 1555 mg kg-1. All the imprinted and non-imprinted polymers prepared in the study were characterized with Fourier Transform Infrared (FTIR) spectroscopy. Scanning electron microscopy (SEM) was used for recording surface morphology of all the polymers. Surface area and pore size analysis were recorded on Micromeritic Tristar BET. For quercetin MIP, thermogravimetric analysis (TGA) was also used in addition to the mentioned techniques. In additional studies, the concentrations of metals in the soil and, in the leaves and flowers of Moringa plant grown in South Africa were examined. The investigation included heavy metals, major and trace nutrient elements. The analysis of metals was achieved after total digestion of soils or leaves using a microwave, and the concentrations of metals were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES). These results were compared to those obtained from some selected vegetables like spinach, cabbage, cauliflower, broccoli, and peas. No toxic heavy metals were detected in the leaves and flowers of Moringa. On average Moringa contained higher concentration of Ca (18500 mg kg-1) and Mg (5500 mg kg-1) than other vegetables compared with in the study. Other major nutrients contained in Moringa were much similar to other vegetables. Besides metals, the concentrations of flavonols (myricetin, quercetin, kaempferol) determined from Moringa leaves and flowers were also compared to selected vegetables. Plant and vegetable materials were extracted under reflux using acidified methanol (1% HCl) solution. Following which, the flavonols were identified and quantified using reverse phased-high performance liquid chromatography method equipped with UV detection. Moringa leaves exhibited highest concentrations of myricetin (1296.6 mg kg-1), quercetin (1362.6 mg kg-1), kaempferol (1933.7 mg kg-1) than vegetables (spinach: myricetin 620.0 mg kg-1, quercetin 17.9 mg kg-1, kaempferol 215.3 mg kg-1). Lastly, the antioxidant activity of Moringa flowers and leaves were compared to that of the aforementioned selected vegetables. The antioxidant activity was studies by analyzing the total phenolic content (TPC), total flavonoid content (TFC), reducing power, radical scavenging activity, and the 2,2-diphenyl-1- picrylhydrazyl free radical (DPPH) method. Moring contained almost twice the TPC and thrice the TFC than the vegetables. Also, Moringa demonstrated higher reducing power and lower percentage of free radicals remaining (DPPH method). Hence, Moringa showed to be a good antioxidant source than the selected vegetables compared with.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Physics, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Daryush Ila. / M.S.

Lau Wai Cheung = 以低能氫離子形成具多官能團的交聯聚合物薄膜 / 劉慧璋. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Lau Wai Cheung = Yi di neng qing li zi xing cheng ju duo guan neng tuan de jiao lian ju he wu bo mo / Liu Huizhang. / Abstract --- p.ii / Abstract (Chinese) --- p.iii / Acknowledgements --- p.iv / Table of Contents --- p.v / List of Figures --- p.xi / List of Tables --- p.xv / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.1.1 --- Polymer properties --- p.1 / Chapter 1.1.2 --- Polymer films --- p.2 / Chapter 1.2 --- Basic Idea of the study --- p.3 / Chapter 1.2.1 --- Previous works --- p.3 / Chapter 1.2.2 --- Related works --- p.4 / Chapter 1.2.3 --- Computational analysis --- p.5 / Chapter 1.2.4 --- Present studies --- p.7 / Chapter 1.3 --- Polymer surface modification techniques --- p.7 / Chapter 1.4 --- Preparation of cross-linked films --- p.9 / Chapter 1.4.1 --- Preparation of films --- p.9 / Chapter 1.4.2 --- Treatment of films --- p.10 / Chapter 1.4.3 --- Formation of the polymer network on films --- p.10 / Chapter 1.5 --- Analysis methods of films --- p.12 / Chapter 1.5.1 --- Film analysis by XPS --- p.12 / Chapter 1.5.2 --- Film analysis by AFM --- p.14 / Chapter 1.6 --- Polymer films with desired functionalities --- p.15 / Chapter 1.6.1 --- Film properties with desired functionalities --- p.15 / Chapter 1.6.2 --- Films with hydroxyl and carboxyl functionalities --- p.16 / Chapter 1.6.3 --- Films with mixed functionalities --- p.17 / Chapter 1.7 --- Goal of the present study --- p.17 / Chapter 1.7.1 --- Objective of this thesis --- p.17 / Chapter 1.7.2 --- Possible applications --- p.18 / Chapter 1.8 --- References for Chapter1 --- p.19 / Chapter CHAPTER 2 --- EXPERIMENTATION --- p.24 / Chapter 2.1 --- Introduction --- p.24 / Chapter 2.2 --- Sample preparation --- p.24 / Chapter 2.2.1 --- Preparation of polymer solutions --- p.24 / Chapter 2.2.2 --- Preparation of cleaned surfaces --- p.25 / Chapter 2.2.3 --- Spin coating --- p.26 / Chapter 2.2.4 --- Confirmation of Polymer network --- p.26 / Chapter 2.3 --- Low Energy Ion Beam (LEIB) system --- p.27 / Chapter 2.3.1 --- Principle --- p.27 / Chapter 2.3.2 --- Function of each component --- p.31 / Chapter 2.3.2.1 --- Ion source --- p.31 / Chapter 2.3.2.2 --- Einzel focusing lenses --- p.31 / Chapter 2.3.2.3 --- Deflectors --- p.32 / Chapter 2.3.2.4 --- Wien Filter --- p.32 / Chapter 2.3.2.5 --- Decelerator --- p.35 / Chapter 2.3.2.6 --- Target chamber and dose estimation --- p.35 / Chapter 2.4 --- X-ray Photoelectron Spectrometer (XPS) --- p.36 / Chapter 2.4.1 --- Principle --- p.36 / Chapter 2.4.2 --- Qualitative analysis --- p.37 / Chapter 2.4.2.1 --- Survey spectrum --- p.37 / Chapter 2.4.2.2 --- Core level spectrum --- p.38 / Chapter 2.4.2.3 --- Valence band spectrum --- p.38 / Chapter 2.4.2.4 --- Line shifts --- p.39 / Chapter 2.4.2.5 --- Lineshapes --- p.39 / Chapter 2.4.3 --- Quantitative Analysis --- p.40 / Chapter 2.4.3.1 --- Atomic concentration --- p.40 / Chapter 2.4.3.2 --- Layer thickness --- p.40 / Chapter 2.4.3.3 --- Curve fitting --- p.41 / Chapter 2.5 --- Ultrahigh Vacuum (UHV) System --- p.42 / Chapter 2.6 --- Other instruments --- p.42 / Chapter 2.7 --- References for Chapter2 --- p.43 / Chapter CHAPTER 3 --- POLY (ACRYLIC ACID) BOMBARDMENT BY LOW ENERGY H+ IONS --- p.45 / Chapter 3.1 --- Basic modeling and analysis method --- p.45 / Chapter 3.1.1 --- Peak fitting before bombardment --- p.45 / Chapter 3.1.2 --- Analysis of PVA surface after bombardment --- p.47 / Chapter 3.1.2.1 --- Peak fitting after bombardment --- p.47 / Chapter 3.1.2.2 --- Mechanism of PAA during bombardment --- p.48 / Chapter 3.1.2.3 --- Identification of the new component after bombardment --- p.50 / Chapter 3.2 --- Surface reaction with impact energy of 10 eV --- p.52 / Chapter 3.2.1 --- Cross-linking with different doses --- p.52 / Chapter 3.2.2 --- Effect of surface functionality with different ion doses --- p.57 / Chapter 3.3 --- Surface reaction with different impact energies --- p.59 / Chapter 3.3.1 --- Cross-linking with different impact energies --- p.59 / Chapter 3.3.2 --- Effect on surface functionality with different impact energies --- p.64 / Chapter 3.4 --- Surface reaction with impact energy of 1 eV --- p.66 / Chapter 3.4.1 --- Formation of a cross-linked polymer network using PAA --- p.66 / Chapter 3.4.2 --- Effect of surface functionality with different ion doses --- p.68 / Chapter 3.5 --- Chapter summary --- p.70 / Chapter 3.6 --- References for Chapter3 --- p.71 / Chapter CHAPTER 4 --- THE MECHANISM OF POLY (ACRYLIC ACID) BOMBARDMENT --- p.72 / Chapter 4.1 --- Surface reaction of PAA after bombardment --- p.72 / Chapter 4.1.1 --- Introduction --- p.72 / Chapter 4.1.2 --- Formation of ester group --- p.73 / Chapter 4.1.3 --- Loss of carbon dioxide --- p.73 / Chapter 4.1.4 --- Regeneration of carboxylic acid --- p.74 / Chapter 4.2 --- Analysis of the surface after bombardment --- p.74 / Chapter 4.2.1 --- Loss of oxygen --- p.74 / Chapter 4.2.2 --- Remaining un-reacted carboxyl acid --- p.75 / Chapter 4.3 --- Chapter summary --- p.80 / Chapter 4.4 --- References for Chapter4 --- p.81 / Chapter CHAPTER 5 --- POLY (VINYL ALCOHOL) BOMBARDMENT AND MECHANISM BY LOW ENERGY H+ IONS --- p.82 / Chapter 5.1 --- Basic modeling and analysis method --- p.82 / Chapter 5.1.1 --- Peak fitting before bombardment --- p.82 / Chapter 5.1.2 --- Analysis of PVA surface after bombardment --- p.84 / Chapter 5.1.2.1 --- Peak fitting after bombardment --- p.84 / Chapter 5.1.2.2 --- Mechanism of PVA during bombardment --- p.85 / Chapter 5.1.2.3 --- Identification of the new component after bombardment --- p.86 / Chapter 5.2 --- Surface reaction of PVA after bombardment --- p.88 / Chapter 5.2.1 --- Formation of a cross-linked polymer network using PVA --- p.88 / Chapter 5.2.2 --- Effect of dosage on the surface functionality of PVA at 10eV bombardment --- p.89 / Chapter 5.2.3 --- Remaining un-reacted hydroxyl group --- p.92 / Chapter 5.3 --- Chapter summary --- p.96 / Chapter 5.4 --- References for Chapter5 --- p.97 / Chapter CHAPTER 6 --- CONTROLLED FABRICATION OF POLYMER THIN FILMS WITH MULTIPLE FUNCTIONAL GROUPS --- p.98 / Chapter 6.1 --- Introduction --- p.98 / Chapter 6.2 --- Hydrogen bonding effect --- p.99 / Chapter 6.3 --- Analysis of mixed PVA and PAA before bombardment --- p.101 / Chapter 6.2.1 --- Peak fitting before bombardment --- p.101 / Chapter 6.2.2 --- Quantitative analysis before bombardment --- p.103 / Chapter 6.4 --- Analysis of mixed PVA and PAA after bombardment --- p.104 / Chapter 6.4.1 --- Peak fitting after bombardment --- p.104 / Quantitative analysis after bombardment --- p.107 / Chapter 6.4 --- Chapter summary --- p.110 / Chapter CHAPTER 7 --- CONCLUSION --- p.111 / Chapter 7.1 --- Summary --- p.111 / Chapter 7.2 --- Future works --- p.112

Orientador: Deyse E. O. S. Carpenter. / Dissertação (mestrado) - Universidade Regional de Blumenau, Centro de Ciências Tecnológicas, Programa de Pós-Graduação em Engenharia Ambiental.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2014. / Boron nitride (BN) in its cubic form (cubic boron nitride (c-BN)) is one of the known superhard materials with superior mechanical, chemical and electronic properties. These properties have made it an excellent material in many modern industrial and electronic applications and as such, extensive research grounds have been developed for over half a decade now with the aim of finding alternative ways to synthesize it. The work presented in this thesis was inspired by the fact that defects introduced into the hexagonal form of boron nitride (h-BN) under certain conditions can lead to a change in its local structure and hence the formation of the cubic BN symmetry. The work focused on the introduction of different ions which included helium, lithium, boron, nitrogen and argon into h-BN, by the ion implantation process, in order to promote a defect-induced phase change to the cubic symmetry and possibly to other BN polymorphs. We introduced these ions at different fluences (number of ions per unit area) and energies so as to investigate the best conditions that will influence the lowest activation energy that will in turn favour the c-BN formation. The resulting thin hard layer could be an excellent sub-surface treatment. All the samples used were high quality polycrystalline and single crystal h-BN, obtained from various manufacturers. The fluence range used was from 1×1013 ions/cm2 to 5×1016 ions/cm2, with energy ranging from 40 keV to 150 keV. This energy and fluence choice was inspired by previous research that had been done at higher energies (MeV range) and recommended that low energy (keV range) and fluence could induce similar change. To investigate these effects, various analysis techniques were employed. The major techniques involved optical vibrational methods using Raman Spectroscopy ii iii (RS) and Fourier Transform Infrared Spectroscopy (FTIR) carried out on the samples before and after implantation. Other techniques used included Glancing Incidence X-ray Diffraction (GIXRD), Transmission Electron Microscopy (TEM), and Energy Dispersive X-ray Spectroscopy (EDS). Raman and FTIR measurements showed the introduction of new phonon and vibrational modes in the samples after implantation. The position, size and broadening suggested that they originated from a symmetry attributed to nano-structured cubic BN (nc-BN). The nature and extent of the nc-BN features was very dependent on the implantation parameters with different atomic mass ions each having an optimum fluence with regards to the intensities of the Raman and FTIR signal associated with them. Glancing incidence X-ray diffraction showed new diffraction patterns whose angles corresponded to the cubic and rhombohedral BN symmetries. The linewidths of these peaks were used to estimate the crystal size, which were in the nanoscale range, hence complementing the results obtained by optical spectroscopy. The High-Angle Annular Dark-field Scanning Transmission Electron microscopy (HAADF-STEM) analyses showed regions with low contrast within the implanted region, suggesting that there were regions within the implanted layer that contained dense structures which were attributed to the cubic BN symmetry. Computer simulations using the Stopping and Range of Ions in Matter (SRIM) programme were performed to understand the events that take place during the interaction of the ions with h-BN. Phonon confinement model calculations were also performed to understand the nature of peaks forming after implantation with an aim of support Raman measurements and to estimate the size of the nc-BN domains. With these complementary analyses, it was concluded that indeed implantation is an effective method of creating nanocrystalline c-BN under less extreme conditions of pressure and temperature.