Perfume is an expensive ingredient for most laundry detergents. To target its delivery to the fabric fibres at the right moment after the wash, improve its performance and reduce costs, using perfume microcapsules is one of the technologies that have been developed. Old technology based on melamine-formaldehyde resins presents some safety and environmental issues and current microcapsules made by interfacial polymerisation techniques do not provide the desired performance. In this work it has been done a deep study of the interfacial polymerisation process focusing on the effect that the formulation and process conditions have on the final properties of the microcapsules produced. The microcapsule walls have been characterized by SEM, TEM and FTIR. The encapsulation efficiency, release profile of the perfume from the microcapsules and their mechanical properties have also been measured. Microcapsules prepared at low temperature with a mix of trimesoyl and terephthaloyl chloride as organic monomers and diethylenetriamine, hexamethylenediamine and ethylenediamine as aqueous monomers showed good mechanical strength and low permeability which make them of industrial interest. Microencapsulation of glycerol for its potential use in lipsticks and other cosmetic products has also been achieved. The use of a salt (magnesium sulphate) greatly stabilized the emulsion and permitted to form small and uniform microcapsules. The process conditions selected may also be applied to encapsulate other oil-based or water soluble active ingredients for various industrial applications.

Calcium phosphate (CaP) based material, especially hydroxyapatite (HAp) nanoparticles have a wide range of applications in a number of fields, such as drug delivery, gene therapy, bone cements, dental applications, chromatography and waste water remediation. Depending on the application, there is often a need for the nanoparticles to be in a particular size range. One of the potential applications of HAp is for drug delivery; as a transfection vector in specific. The main aim of this study was to evaluate the potential of various produced CaP nanoparticles for this matter. The HAp and CaP nanoparticles in this study were systematically investigated and produced by several methods, firstly by the wet chemistry method of sol-gel, where the process conditions of varying its stirring rates and temperatures were taken into consideration; secondly by the supercritical fluid techniques of Gas Anti-Solvent (GAS) and Solution Enhanced Dispersion of Supercritical Fluids (SEDS), where the process conditions of varying the processing temperature, pressure and supply of antisolvent flowrate were investigated. Lastly, several phases of CaPs were produced by a systematic investigation of CaP precipitation processes (via direct precipitation method and SEDS processing technique) by varying the Ca/P ratios. The processing conditions such as the stirring rate, temperature, pressure and antisolvent flowrate played a significant role on the nanoparticle size and morphology.

Electrostatic phenomena are pervasive in powder handling processes. In this study, contact electrification and electrostatic interactions during powder handling processes are explored using the discrete element method coupled with computational fluid dynamics (DEM-CFD), in which contact electrification and electrostatic interaction models are developed and implemented. The effects of particle shape on contact electrification are also investigated, for which multi-sphere methods are adapted and implemented into the DEM-CFD. The electrostatic and dynamic behaviours in various powder handling processes are analyzed, which include contact electrification of spherical particles during fluidization; electrostatic interactions during deposition of mono-charged and bi-charged particles; contact electrification and electrostatic interactions of spherical particles during fluidization; contact electrification of elongated particles in a vibrating container and particles of arbitrary shapes in a rotating drum. It is found that charge accumulation and distribution of particles are caused by contact electrification and dispersion of mono-charged particles and agglomeration of bi-charged particles are induced by electrostatic interactions. The combined effects of contact electrification and electrostatic interactions can alter the dynamic behaviours of particles and the performance of powder handling processes. Non-uniform charge distributions can be induced on particles of irregular shapes and the charge accumulation is also affected by particle shapes.

The production of ceramic catalyst supports is commonly performed by the extrusion of a paste. The rheological properties of the paste as it passes through the extruder have a strong influence on the extrudate properties such as porosity and strength, which in turn affect the catalytic performance of the final product. An assessment of the effect of acid type and strength and powder type on the rheological properties of concentrated boehmite slurries has been made. In particular, evidence of gel formation is looked for, and the surface chemistry is examined using zeta potential measurements. Further understanding of the observed rheological changes is obtained by performing nuclear magnetic resonance studies and cryogenic microscopy. The effect of powder properties and acid type and strength on the saturation states of a formulation has been examined using mixer torque rheometry. The prediction of saturation states from bulk density measurements is discussed. The predictive capability of the mixer torque rheometer with regards extrusion formulations is investigated. The effect of acid type and strength on successful extrusion formulations and extrudate properties is discussed.

Clear scientific links between major diseases and diet are the main reasons for a change in food processing technology and products. Duplex emulsions offer the possibility of reduction of the fat content, and also encapsulation of bio-components and their targeted delivery within the human body. In this work the formulation and production/processing of food grade W\(_1\)/O/W\(_2\) duplex emulsions were investigated in relation to emulsion’s stability. It was shown that when the osmotic pressures between the two water compartments in duplex W\(_1\)/O/W\(_2\) emulsions were balanced, there was still a release of salt in storage. The extent and rate of release was proportional to glucose concentration in the W\(_2\). Duplex emulsions are shear-sensitive and shear-intensive processing could lead to their considerable damage. By using three secondary emulsification techniques: Shirasu Porous Glass (SPG) cross-flow membranes, SPG rotating membrane and high-shear mixer, it was shown that the amount of salt released during storage depends on the emulsification technique. The SPG rotating membrane technique was used to investigate its emulsifying potential. Droplet sizes of simple O/W emulsions were independent of the dispersed phase volume, increasing with the viscosity of the continuous phase and size of the membrane pores. It was also shown that droplet size could be controlled by the concentration and properties of an emulsifier.

Developing a catalyst that accepts a wide range of fuels for hydrogen production is an important design aspect for the successful multi-fuel reformer. This thesis aims to synthesize and evaluate Ni-Cu/Al\(_2\)O\(_3\) catalysts for methanol and methane steam reforming. Detailed characterizations of catalysts, as well as the role of the bimetallic nature of Ni-Cu metals on the catalytic reaction are presented and discussed. A series of Ni\(_x\)-Cu\(_y\)/Al\(_2\)O\(_3\) catalysts with various metals loadings (x= 10, 7, 5, 3 and 0% weight and y= 0, 3, 5, 7 and 10%, respectively) were prepared. The temperature programed reduction revealed that bimetallic catalysts displayed a new hydrogen uptake peak compared with monometallic metal catalyst and this was attributed to NiCuO reduction. The X-ray diffraction patterns indicated Ni\(_x\)Cu\(_1\)\(_-\)\(_x\)O phase formation. The methanol steam reforming was evaluated over the prepared catalysts over the range of temperatures 225-325°C in a fixed bed reactor. It was found that bimetallic Ni-Cu had a strong influence on the amount of CO\(_2\) and CO by controlling the water gas shift reaction and decomposition reaction. The highest amount of hydrogen produced among the other prepared catalysts was 2.2 mol/mol-CH3OH for 5%Cu-5%Ni at 325°C. Low temperature methane steam reforming at 500-700°C was investigated. The synergetic effect between Cu and Ni metals was also investigated, showing that Cu provides a stabilizing effect by forming Ni-Cu alloy and controlling the catalyst structure. The 7%Ni-3%Cu revealed the highest conversion of 71.1% methane and produced the maximum amount of hydrogen at 2.4 mol/mol-CH4 among the other prepared catalysts at 600°C and S/C of 3. The bimetallic reacted Ni-Cu catalysts revealed less carbon selectivity (0.9% for 5%Ni-5%Cu) compared to 10%Ni (4.6%) catalyst at 600°C.

Developing solid oxide fuel cell (SOFC) systems that operate in lower temperature regimes improves system stability, widens materials selection and lowers performance degradation issues previously observed with higher temperature cells. In this work, the development of an intermediate temperature SOFC (IT-SOFC) based on a Ce-doped Scandia-stabilised Zirconia (ScSZ) structure manufactured via screen-printing is outlined. In this thesis we report on the successful manufacture of anode supported 8YSZ baseline cells and cells containing Ni-10Sc1CeSZ anodes supporting 10Sc1CeSZ electrolytes both prepared via die pressing, screen-printing and co-sintering. Commercial 8YSZ and 10Sc1CeSZ reference cells were also tested. This research aims to demonstrate the viability of 10Sc1CeSZ within an IT-SOFC cell structure and examine the effectiveness of 10Sc1CeSZ on lowering the cell operating temperature. Results for the tested cells on H\(_2\) at 800\(^o\)C show the lab grade and commercial grade YSZ cells obtained OCV values of 1.06V and 1.04V and maximum power density values of 392 mW cm\(^-\)\(^2\) and 466 mW cm\(^-\)\(^2\) respectively. The commercial 10Sc1CeSZ cells exhibited the highest OCVs > 1.10V of all tested cells with the lowest area specific resistance of 0.496 Ω cm\(^2\) obtained for the lab grade 10Sc1CeSZ cells. Peak power densities of 68.24 mW cm\(^-\)\(^2\) and 9.12 mW cm\(^-\)\(^2\) at 800\(^o\)C were achieved for the biogas fuelled lab grade YSZ and 10Sc1CeSZ cells respectively.

This thesis illustrates two novel routes for fabricating hierarchical micro-to-nano structures with interesting optical and wetting properties. The co-presence of asperities spanning the two length scales enables the fabrication of miniaturised, tuneable surfaces exhibiting a high potential for applications in for instance, waterproof coatings and nanophotonic devices, while exploiting the intrinsic properties of the structuring materials. Firstly, scalable, superhydrophobic surfaces were produced via carbon nanotubes (CNT)-based electrohydrodynamic lithography, fabricating multiscale polymeric cones and nanohair-like architectures with various periodicities. CNT forests were used for manufacturing essential components for the electrohydrodynamic setup and producing controlled micro-to-nano features on a millimetre scale. The achieved high contact angles introduced switchable Rose-to-Lotus wetting regimes. Secondly, a cost-effective method was introduced as a route towards plasmonic bandgap metamaterials via electrochemical replication of three-dimensional (3D) DNA nanostructures as sacrificial templates. A range of sub-30nm 3D DNA polyhedrons, immobilised onto conductive and insulating surfaces, were replicated with gold via electrochemical deposition and sputtering. Microscopic characterisation revealed detailed gold replicas preserving both edges and cavities of the DNA nanostructures. Accurate tuning of both polyhedrons’ dimensions and gold plating conditions finally enabled sub-100nm structures which show promising optical properties such as, birefringence for potential applications in photonics, metamaterials and sensing.

This thesis is concerned with the manufacture of granular laundry detergents in counter-current spray dryers making use of turbulent swirling flows. It contributes to a comprehensive description of this process by providing a) an experimental study of the swirling fluid dynamics in various scales and designs, introducing the use of sonic anemometry to this context, b) the description of a complex fouling dynamics at the walls, quantified by rates of deposition and re-entrainment of material, and c) the analysis of the sources of particle-droplet agglomeration in different sections of the dryer, under the operation of one or multiple sprays. This thesis demonstrates that the interaction with the walls is a central part of the process. In the one hand, friction affects the structure of the flow: it reduces its angular momentum and destabilizes the swirl, which causes recirculation in the dryer and the production of turbulence. In the other, particles deposit at the walls forming a multi-layer that continuously builds and breaks up. A tracer experiment has revealed that this equilibrium in part governs the product residence time, and ultimately how particles dry and aggregate. The data provided here constitute the first evidence of such a behavior in spray dryers.

Graphene is a relatively new carbon material increasingly finding technological applications due to its unique physical and engineering properties. Here, its application as catalyst for the oxygen reduction reaction (ORR) in alkaline media is investigated. First, the role of graphene-related materials (including multi-walled carbon nanotubes) as catalyst supports is compared to the widely used carbon black, finding that the ORR follows a mixed behaviour between the direct 4-electron pathway and the indirect 2-step mechanism on graphene-supported platinum catalysts. Further, different combinations of boron, nitrogen, phosphorus and sulphur metal-free doped-graphene catalysts have been systematically synthesised and evaluated, finding that dual-doped graphene catalysts yield the best ORR performance. Specifically, phosphorus and nitrogen dual-doped graphene (PN-Gr) demonstrates the highest catalytic activity, with 3.5 electrons transferred during the ORR. Doped-graphene/perovskite oxide hybrid catalysts have been also tested, yielding PN-Gr/La0.8Sr0.2MnO3 the best ORR activity in terms of measured current density, achieving a value that is 85% of that reported for a commercial Pt/C catalyst. Moreover, SN-Gr/La0.8Sr0.2MnO3 produces the lowest amount of peroxide formation with only 10%. These results confirm the graphene-derived catalysts as promising alternatives to the current platinum-based catalysts, and could enable the important issues related to its practical application to be overcome.