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This project was a joint venture between Loughborough University, the academic investigator, and ICI, the industrial sponsor. The aim was to develop and validate filter cycle scale-up methodologies, based on laboratory experiments at Loughborough and full-scale plant work at several ICI sites. Two ICI products, which experience processing problems during filtration, were chosen for assessment. They were a catalyst material (predominately iron oxide), processed by Synetix using rotary vacuum filters (RVFs), and titanium dioxide (TiO2) processed by Tioxide using a diaphragm filter press. A number of objectives were originally highlighted: (1) to develop and validate scale-up methodologies for a pressure filter and vacuum filter; (2) to develop models required to provide accurate predictions of filter performance; (3) to produce PC simulations of RVF and diaphragm filter press; (4) to produce reliable filter cycle data for process feeds of interest to ICI.

Forest soil phosphorus (P) chemical behavior was evaluated in some mid-rotation fertilized loblolly pine (Pinus taeda L.) plantations in East Texas, that differed in their site drainage characteristics. Forest floor mass and carbon content in the forest floor were determined. Total P (PT) in the forest floor, and total and Mehlich-1 P and citratedithionite (CD) and acid ammonium-oxalate (AAO) extractable P, Al, Fe, and Mn within the mineral soil upper 100 cm were determined. Colorimetric determination of AAOand CD-extractable P by the molybdenum blue ascorbic acid method, without the use of pre-digestion, was assessed by an automated continuous flow injection system. Phosphorus distribution between different operationally defined solid phases and its relationships with CD and AAO extractable Mn, Al, Fe among depth, site, drainage class and treatment were evaluated. Soil P forms were highly correlated with iron oxides across sites, drainage classes, treatments, and depth intervals with significant differences in P content and distribution in the soil profile and solid phases among drainage classes. Soil P distribution patterns differed among drainage classes, yet it followed the distribution of the iron oxides. Iron oxide’s role as a sink for soil P was higher in the well-drained compared to the poorly drained sites. Amorphous phases of iron oxides were higher in the poorly drained sites and dominated the role of iron oxides as a sink for P under the poor drainage conditions. Fertilization resulted in significantly higher forest floor mass, P content in the forest floor, and total P (PT) and CD-extractable P (Pd) in the soils’ upper 10 cm. The treatment effect on P in the forest floor, and on PT and Pd in the upper 10 cm of the mineral soil was equivalent to 6, 19, and 11% of the applied P, respectively. AAO-extractable P was highly correlated with Mehlich-1 P in the fertilized plots. Treatment and site drainage class effects on P accumulation in the different solid phases in the mineral soil and in the forest floor and the potential contribution of these pools to P availability in subsequent rotations, following clearcutting, are discussed.

Transmission [57]Fe Mossbauer Spectroscopy has been used to investigate two standard iron oxides and two environmental corrosion products in the temperature range 10-300 Kelvin. This was achieved using a specially developed Air Products cryogenic refrigeration system using gaseous helium as the refrigerant - thereby removing the requirement of an expensive liquid helium facility normally required for low temperature work. Characteristic spectra and transitions were observed for both the standard oxides. The environmental corrosion products demonstrated the differences in observed spectra between a sample which exhibits only bulk properties and one in which the particle size distribution within the sample is such that relaxation phenomena become important. The interpretations-made from the variable temperature Mossbauer data were confirmed by the complementary technique of X-ray diffraction. Conversion electron Mossbauer spectroscopy (C.E.M.S.) and conversion X-ray Mossbauer spectroscopy (C.X.M.S.) backscatter techniques have also been developed and are now routinely available in our laboratory. The greater escape depth of the conversion X-ray allows the C.X.M.S. method to be used to record spectra from samples to which a protective layer such as a paint, varnish, grease or oil layer has been applied. To ensure a surface sensitive signal, the substrate surfaces had to be enriched in the Mossbauer isotope 57Fe. This was achieved by vacuum evaporation of 57Fe onto the substrate surface and subsequent diffusion of the 57Fe into the near surface region - this diffusion had to be accomplished without oxidising the surface. Samples thus prepared were subsequently exposed to aggressive atmospheres and their CXM spectra recorded. The limitation of the method is that only room temperature spectra can be recorded at present and difficulties are encountered in the assignment of spectra that contain only quadrupole doublets.

The objective of this research was to study the catalytic graphitization of cellulose fibers coated with iron oxide nanoparticles. Bleached cellulose fibers and iron oxide nanoparticles coated cellulose fibers were pyrolyzed at five elevated temperatures. The crystallographic structures of carbon-encapsulated iron oxide nanoparticles were then investigated by the following techniques: Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Raman Spectroscopy, Transmission Electron Microscopy (TEM), and Selected-Area Electron Diffraction (SAED). The graphitization of cellulosic fibers was enhanced by the presence of iron oxide nanoparticles. Moreover, iron oxide nanoparticles deposited on cellulosic fiber samples pyrolyzed above 800°C produced graphitic structures. TEM and XRD were performed to identify and characterize the phase transitions of carbon-encapsulated iron oxide nanoparticles after pyrolysis treatment at four temperatures: 500°C, 800°C, 1000°C, and 1600°C. TEM of samples pyrolyzed at or above 800°C showed resulting units were core-shell structures consisting of dark grains and a light matrix with graphitic structure.

The research described in this Dissertation is concerned generally with the exploration of the potential use of lanthanide elements in nanostructured materials for the purpose of modification of the magnetic and optical properties. This is explored through a focus on the development of lanthanide-containing iron oxide nanosystems. Our objectives of producing lanthanide containing nanostructured materials with potentially useful optical and magnetic applications has been achieved through the development of lanthanide-doped Fe3O4 and -Fe2O3 nanoparticles, as well as a unique core-shell magnetic-upconverting nanoparticle system.Necessary background information on nanomaterials, rationale for the study of lanthanide-containing iron oxide nanosystems and context for discussion of the results obtained in each project is provided in the Introduction Chapter. The syntheses of Fe3O4 nanoparticles doped with Eu(III) and Sm(III) are discussed, along with structural characterization and magnetic property investigation of products In Chapter 2. The following Chapter expands the study of lanthanide doping to -Fe2O3, a closely related yet distinct magnetic nanoparticle system. A completely different synthesis is attempted, and comparisons between the two systems are made.The development of novel synthetic methodologies used to create such products has yielded high-quality lanthanide-containing materials and are evidenced by TEM images displaying nearly monodisperse particles in each of our efforts. The modifications to the magnetic properties resulting from lanthanide doping include theobservation of ferromagnetism in the Fe3O4 system and increased magnetic saturation of -Fe2O3 nanoparticles, and are characterized by VSM and the visual observation of magnetic alignment of products. Our efforts towards developing a novel methodology capable of producing high quality Fe3O4 nanoparticles, and subsequent characterization of products, were published in the Journal of the American Chemical Society.Optically active, magnetic, core-shell nanoparticles are investigated in Chapter 4 for the potential uses in diagnosis and treatment of cancer. This multifunctional system uses Fe3O4 as a magnetic core, shelled by upconverting lanthanide-containing nanomaterials, and is rendered biocompatible through encapsulation of the core-shell structure by a silica shell. Added functionality is achieved through amine functionalization of the silica surface, with the goal of coupling the inorganic nanoparticle with drug targeting groups. TEM results indicate successful formation of the core-shell nanoparticles, and expected magnetic and optical properties are shown by visual observation and luminescence spectroscopy, respectively.

The work in this thesis is concerned with the Green Rusts, which are bluegreen metastable Fe(II) - Fe(III) hydroxy compounds incorporating anions such as SO42-, Cl- or CO3-. These Green Rust compounds (or Fe-GR compounds to distinguish them from the aluminium Green Rusts (Al-GRs) which are isostructural Fe(II) - Al(III) hydroxy compounds) can be produced in a consistent fashion from Fe(II) solutions by the method of induced hydrolysis using Fe(III) gel at pH 7 and under anoxic conditions. A series of sulphate and chloride Fe-GR samples were synthesised, and characterised primarily by the analytical techniques of M8ssbauer spectroscopy, X-Ray diffractometry, infra-red spectroscopy, and vacuum microbalance to measure surface area using the BET N2 adsorption method. For comparison, a few samples of the analogous Al-GR compounds were also synthesised and characterised by the analytical techniques mentioned above. The results in this thesis showed that the systems producing the Fe-GR compounds were of a highly complex nature, and that the amount of precipitate formed depended crucially on the starting conditions. For the 0.1 M FeSO4 system, the GR formed was almost always accompanied by a goethite phase while, for the 0.1 M FeC12 system, pure GR material was only formed at initial Fe(II) - Fe(III) ratios (IFFRs) greater than 6. Any-differences between__the, sulphate and chloride Fe-GRs can. be attributed to the difference in anion-type. X-Ray diffraction in conjunction with electron microscopy and surface area measurements confirm-that the Fe-GRs have a pyroaurite crystal structure, with brucite-like layers formed by a matrix of Fe2+ and Fe 3+ cations and each layer bridged to the other by anions. As far as Messbauer spectroscopy is concerned, the most important diagnostic parameter is the quadrupole splitting (QS) of the Fe(II) doublet measured at 77K for the wet, fresh precipitate (i. e. frozen material). For sul phate Fe-GRs derived from 0.1 M FeSO4 the mean QS is 2.93 ± 0.05 mms-', while for the chloride Fe-GRs derived from 0.1 M FeC12 the mean QS is 2.80 ± 0.05 mms-1. Surface areas for the sulphate Fe-GRs are in the range 40-65 m2. g-1. The products of oxidation and ageing for the Fe-GRs indicate several transformation pathways, especially for the chloride Fe-GRs. Sulphate Fe-GRs converted to goethite on oxidation under both wet and dry conditions, while the chloride Fe-GRs converted to akaganeite on dry oxidation, and to lepidocrocite on wet oxidation. Under both wet and dry anoxic conditions, the chloride Fe-GRs converted to magnetite. In the case of the sulphate Fe-GRs, there was a suggestion that, under the right wet anoxic conditions, the material probably transformed into magnetite. These facts clearly demonstrate that the Fe-GRs are intermediaries in the thermodynamic transformation of Fe in the II oxidation state to Fe in the III oxidation state.

Silica is one of the most abundant elements on the planet, has flexible bonding properties and generally excellent stability. Because of these properties, silica has been a vital component in technologies ranging from ancient glassware to modern supercomputers. Silica is able to form a wide range of materials both alone and as a component of larger material frameworks. Porous silica based nanomaterials are rapidly growing in importance because of their many applications in a wide variety of fields. This thesis focuses on the synthesis of silica based porous nanomaterials: nanocrystalline zeolites, mesoporous silica nanoparticles, and iron oxide core/shell nanocomposites. The synthetic conditions of these materials were varied in order to maximize efficiency, minimize environmental impact, and produce high quality material with far reaching potential applications. The materials were characterized by physicochemical techniques including Transmission Electron Microscopy, Dynamic Light Scattering, Powder X-Ray Diffraction, Solid State NMR, and Nitrogen Adsorption Isotherms. The materials were evaluated and conditions were controlled to produce high yields of quality nanomaterials and hypothesize methods for further synthetic control. The products will be used in studies involving nanoparticle toxicity, environmental remediation, and drug delivery.

This study examines the use of unmodified magnetite nanoparticles (Fe3O4 NPs) for selective extraction and enrichment of the catecholamines dopamine (DA), noradrenaline (NE), and adrenaline (E), prior to analysis using capillary electrophoresis with UV detection. Coordination between Fe3+ on-the-surface Fe3O4 NPs and the catechol moiety of catecholamines enables Fe3O4 NPs to capture catecholamines from an aqueous solution. We obtained maximum loading of catecholamines on the NP surface by adjusting the pH of the solution to 7.0. In addition, catecholamine loading on the Fe3O4 NPs increased in conjunction with NP concentrations. Ligand exchange found H3PO4 to be efficient in the removal of adsorbed catecholamines on the NP surface. Adding 1.2% poly(diallyldimethylammonium chloride) to the background electrolyte caused efficient separation of the liberated catecholamines with baseline resolution within 20 min. Under optimal extraction and separation conditions, the limit of detections at a signal-to-noise ratio of 3 for E, NE, and DA were 9 nM, 8 nM, and 10 nM, respectively. Significantly, we successfully used the combination of a phenylboronate-containing spin column and the proposed method to determine the concentrations of NE and DA in urine and the content of NE in Portulaca oleracea L. leaves.

This study is to probe into the surface characteristics, crystalline identification and inner structural changes of the synthetic iron oxides which are synthesized from pure Fe(¢»), citrate/Fe(¢») and silicate/Fe(¢») solutions at different MRs respectively. This study is also to compare the adsorption capabilities of these synthetic iron oxides serving as the adsorptive materials in containing arsenic wastewater through adsorption experiments. By means of the XRD identification analysis, the synthetic iron oxides of pure Fe(¢») and silicate/Fe(¢») are non-crystal ferrihydrite, but the synthetic iron oxide of citrate/Fe(¢») is crystal magnetite with magnetism. By means of IR spectrum analysis and comparison with the IR spectrum of iron mineral, the FTIR spectrum of pure Fe(¢») and silicate/Fe(¢») synthetic iron oxide are similar to that of ferrihydrite; The FTIR spectrum of citrate/Fe(¢») synthetic iron oxide is similar to that of magnetite. The degree of pore volume and surface area for synthetic iron oxides are as follows: silicate/Fe(¢») > Fe(¢») > citrate/Fe(¢»). With the citrate/Fe(¢») MRs increasing, the pore volume and surface area of synthetic iron oxide will decrease. However, with the silicate/Fe(¢») MRs increasing, the pore volume and surface area of synthetic iron oxide do not make great difference. Results of kinetic adsorption experiments show that the synthetic iron oxides of citrate/Fe(¢») or silicate/Fe(¢») at different MRs will adsorb arsenic better at low pH. With the pseudo-first order and the second order kinetic adsorption model to simulate the adsorption experiment data, the results show that the simulation results are consistent with the pseudo-second order kinetic adsorption model. The equilibrium adsorption experiments show that the adsorption capacity of arsenic for synthetic iron oxides is as follows: citrate/Fe(¢») > Fe(¢») > silicate/Fe(¢»), and that the adsorption capacity will decrease with the pH increasing.