Industrial alkaline electrolysers were electrochemically characterised and analysed on an internal combustion engine. These electrolysers exhibited low efficiencies, low gas flowrates and subsequently zero change in engine emissions due to the poor design and build. An improved alkaline electrolyser was designed, built and tested exhibiting improved efficiency/gas output compared to the industrial electrolysers and an improved reduction in emissions. The increased power consumption of the electrolyser results in a rise in electrode degradation which is responsible for the decrease in electrode lifetime. A method for prolonging the electrode lifetime is proposed through a metallic “oxygen-getter”. Implementation of this has shown to prevent cathodic corrosion of the electrode material and thus reduces oxide layer formation. Electrode lifetime in an alkaline electrolyser increased, but the commercial trend is shifting towards the more attract PEM technology for electrolysis due to higher current densities, ability to handle variable input loads and non-caustic liquid requirement. A commercial on-demand PEM electrolyser was tested and system designed for integration with an existing hydrogen refuelling station at the University of Birmingham. This mimicked the case for a distributed hydrogen system where the hydrogen is produced onsite for fuel cell vehicles resulting in a carbon neutral fuel.

This work had as main objective to recover bioactive compounds, more specifically phenolics, from cider lees using subcritical water, an environmentally benign fluid. Maximum solubilisation was obtained at 150ºC for 30 minutes, and a decrease is observed at higher temperatures, indicating the occurrence of precipitation. Maximum total phenolic content (FCR) was obtained at 220ºC for 10 minutes. Chlorogenic acid was identified as the major phenolic in cider lees, however at 220ºC for 10 minutes, only trace levels were found, therefore the high total phenolic content should be the result of interactions between phenolics and macromolecules present in solution. Sequential subcritical water was employed to reduce complexity of extracts produced. Maximum antioxidant capacity (FCR, ORAC) was obtained at 120ºC and 220ºC, where at 120ºC is due to cider phenolics while at 220ºC, after the removal of most of the compounds, it is only left cell wall carbohydrates and chitin, which should be responsible for the formation of derivatives with high antioxidant capacity. Cyclodextrin was used to improve oxidative stability of the cider lees extracts, however while it improved the oxidative stability for cider lees extracts obtained at low temperatures, to cider lees extracts obtained at higher temperatures, no improvement was registered.

Microfluidic systems attract attention because the benefit they offer such as very high surface area to volume ratio and the precise control of the flow features or droplets formation. However, the study of displacement flows has not been systematically explored. This thesis presents a study of the behaviour of liquid-liquid two-phase flows in microchannel during the displacement of one liquid by another. Liquid displacement using immiscible and miscible fluid pairs were carried out. The kinematic viscosities of the fluids used range from 1 to 100 cSt. Three types of straight channel and a T-junction channel were tested. The flow activities at the fluids interface, with the addition of surfactants, were mainly investigated. Flow regimes were identified and their occurrence was illustrated via flow pattern maps. CFD simulations are applied largely in the study of fluid mechanics aiming to confidently predict flow behaviour from computational methods. The experimental results were used to validate CFD simulations carried out using the Fluent package incorporating the VoF model. Good agreement between simulation and experiment results was achieved.

Fouling and cleaning processes impact industrial production, in terms of economics, product quality, product safety, and plant efficiency. Therefore, optimisation of fouling and cleaning processes is a significant issue, and needs a good understanding of fouling and cleaning kinetics. Ideal monitors should determine the right time when a process run should stop and when a plant will be clean in order to improve the process efficiency. This thesis investigated the fouling and cleaning behaviour of dairy fluids in a plate heat exchanger (PHE) and bench scale fouling rig, using whey protein concentrate (WPC) and WPC-/m (with added minerals) as fluid models. Fouling and cleaning monitoring methods were also investigated as new ways to operate and control the processes. Experiments displayed that fouling increased with increasing protein concentration up to a limit of approx. β-Lg 0.3 wt. %. Increasing the flow rate from 100 to 150 l/h decreased the Δ(ΔP) fouling rate for β-Lg concentrations of 0.1, 0.3 and 0.5wt.% by 34, 70 and 72.7%, respectively, due to the increasing of shear stresses at the heat transfer surface. Adding minerals to WPC has lowered the temperature at which β-Lg begins to denature. The differences in fouling behaviour of WPC and WPCm had an effect on cleaning behaviour. Increasing the mineral content in WPC deposits leads to cleaning behaviour which differs completely from that of proteinaceous deposit as no pressure peak is observed.

Chromatography remains the most commonly employed method for achieving high resolution separation of large-sized biomolecules, such as plasmid DNA, typically around 150-250 nm in diameter. Currently, fractionation of such entities is performed using stationary phases designed for protein purification, typically employing pore sizes of about 40 nm. This results into a severe underexploitation of the porous structure of the adsorbent as adsorption of plasmid DNA occurs almost exclusively on the outer surface of the adsorbent. In this study, the effect of two processing parameters, the ionic strength of agarose solution and quenching temperature, on the structure of the resulting particles was investigated. Three characterization methods, Atomic Force and cryo-Scanning Electron microscopy, as well as mechanical testing of single particles where used to quantify the effect of these parameters on the pore size/size distribution and mechanical properties of the adsorbent. In the presence of salt, it was found that agarose fibres tend to aggregate, leading to a gel with large pore size and wide pore size distribution. In fact, for the narrow range of ionic strength used (0-0.1m), a five-fold increase in pore size of the gel was observed. The same type of enlarged agarose structures was observed when slow cooling was applied during the gelation of agarose. The increase in pore size of the gel was also accompanied by an increase in the compression strength and the elastic modulus of the particles, i.e. particles with 200 nm pore size were found to have higher compression strength (1.5-fold difference) than those with 40 nm pore size.

Microencapsulation is an efficient technology to deliver perfume oils from consumer products onto the surface of fabrics. Microcapsules having uniform size/mechanical strength, may provide better release performance. Membrane emulsification in a dispersion cell followed by in-situ polymerization was used to prepare narrow size distribution melamine-formaldehyde (MF) microcapsules containing several types of oil-based fragrances or ingredients. Investigated in this study are the parameters impacting to the size and size distribution of the droplets and final MF microcapsules. A pilot plant-scale cross-flow membrane system was also used to produce MF microcapsules, demonstrating that the membrane emulsification process has potential to be scaled up for industrial applications. In this study, health and environmental friendly poly (methyl methacrylate) (PMMA) microcapsules with narrow size distribution were also prepared for the first time using the dispersion cell membrane emulsification system. Characterization methods previously used for thin-shell microcapsules were expanded to analyse microcapsules with thick shells. The intrinsic mechanical properties of thick shells were determined using a micromanipulation technique and finite element analysis (FEM). The microcapsules structure was also considered in the determination of the permeability and diffusivity of the perfume oils in good solvents.

Build-up is a fouling process in which a small fraction of a powder becomes a film adhered to a surface. Specifically buildup in auger fillers which is the focus of this thesis is a significant problem for industry leading to equipment downtime for cleaning, drives tripping due to high torque and reduced powder quality. The work presented in this thesis shows that for a unblended powder with a particle size similar to that of the auger fillers auger/tube clearance, build-up will be formed when powders have b-1 Kawakita parameter of less than 0.5 MPa and tablet strengths below 0.6 MPa post compression to 58 MPa. It is proposed based upon results the work of Crutchley and Bridgewater [29] and Calvert et al. [30] that powders which form build-up due so due to the stresses they experience as they pass through the auger/tube clearance. Additionally this stress is a function of the ratio of the powder’s particle size to the magnitude of the auger/tube clearance C. Work presented in Chapter 8 supports this conclusion showing that once C/D90 is greater than 3.5, build-up is not formed.

The purpose of this study was to develop adsorbents from slag materials as a low cost method to purify acid mine drainage of high acidity and toxic metal ions content. The study included adsorbent characterisation and adsorption experiments to understand the adsorption behaviour of a multi-adsorbate system of Cd\(^2\)\(^+\), Co\(^2\)\(^+\), Cu\(^2\)\(^+\), Fe\(^2\)\(^+\) and Mn\(^2\)\(^+\) ions. It was found that the adsorbents had low surface area and unfavourable pore size distribution. The chemical activation of the adsorbents improved the adsorbent properties, and thus increased amounts of metal ions adsorbed. However, the adsorption of multiple metal ions was only effective in dilute solutions, with adsorption efficiency increasing with increase in phase ratio, pH and temperature. The adsorption data was best described by pseudo second order kinetic and double exponential diffusion models. The mechanisms involved adsorption, precipitation and ion exchange. The adsorbent capacities were relatively low, with selectivity proposed as Fe\(^2\)\(^+\)>Cu\(^2\)\(^+\)> Cd\(^2\)\(^+\)>Co\(^2\)\(^+\)>Mn\(^2\)\(^+\). The fixed bed efficiencies were satisfactory but the adsorbents were easily exhausted, which indicated a limited ability for the adsorbent materials to be regenerated. However, desorption of metal ions was favourable, and this may provide an opportunity for metal ions to be recovered and for spent adsorbents to be disposed safely.

The availability of finite resources is uncertain due to the worldwide increase in population growth and global industrialisation. Consequently, there is a pressing need for substitutive replacements and methods of replenishing stocks by recycling. The platinum group metals (PGMs) are rare, expensive elements with an unpredictable supply chain and a wide range of industrial applications for which there are often no substitutes. Mining from primary ores is environmentally damaging; hence recycling is vital to minimise losses and maintain stock at sustainable levels. This work investigates the feasibility of recovering PGMs from secondary waste sources and bioconverting them into new catalysts, circumventing the current environmentally polluting and energy expensive pyrometallurgical processing. Two secondary sources of PGMs were examined: scrap automotive catalysts and spent furnace refractory lining. This study shows a route to improve PGM recycling from secondary waste sources and, further, the potential to produce a catalytically active end product without the need for traditional refining.

Mechanically agitated vessels are widely used for various mixing operations within a wide range of industries including the chemical, pharmaceutical, food and petroleum industries. They are used for liquid blending, solid-liquid mixing, gas dispersion in liquids, heat/mass transfer enhancement and chemical reaction. Mixing is intrinsically a Lagrangian process and, whilst Eulerian data are essential, Lagrangian information is necessary for its complete description. Possible approaches of generating Lagrangian data can, in principle, employ numerical simulations or experimental techniques based on Lagrangian tracking to provide the trajectories of fluid elements or solid particles. In this work a set of tools are developed for the analysis and theoretical validation of Lagrangian single and multi-phase flow data obtained from tracer trajectories in mechanically agitated vessels. Whilst theoretical procedures developed here exploit a large range of mathematical and statistical concepts with Shannon entropy being an example, the computational data analysis often involved handling and sequential processing of multidimensional matrices containing several millions of data points. Computational codes were developed for performing Lagrangian statistical data analysis, Lagrangian-Eulerian data conversion, Shannon entropy analysis, multi-phase mixing studies and detailed Eulerian multi-plane investigations. The implementation and power of these tools are demonstrated by analysing a wide range of measurements acquired using the technique of positron emission particle tracking (PEPT) during the mixing of Newtonian and non-Newtonian fluids, as well as the mixing of highly concentrated solid-liquid systems. These multi-phase suspensions included monodisperse, binary and polydisperse solid-liquid suspensions. Experimental measurements obtained in these systems are unique and valuable in their own right as, for the first time, it has been possible to determine the full 3D velocity and concentration fields of liquid and solid phases within opaque dense slurries of this type containing up to 40 wt% solids.