An introduction and overview of the work is given in Chapter 1. In Chapter 2, a description of the equipment and the kinetics modelling used in this thesis is explained in detail. Chapter 3 includes an overview of traditional solvents and shows the kinetics and mass transfer results of the absorption of CO2 in amine solvents. Chapter 4 starts with a literature review on organic solvents and hybrid solutions (organic-amine aqueous solutions) and includes the mass transfer and kinetic results of the absorption of CO2 in selected hybrid solvents containing amines. Chapters 3 and 4 sum up the 11 solutions tested for the absorption of CO2 and include their physical characterization (density, viscosity and N2O solubility), at unloaded and loaded conditions and from 298 to 353K. Chapter 5 is focused on the thermodynamic modelling of new amine solvents in ASPEN PLUS and Chapter 6 includes the modelling at pilot plant scale of absorber and desorber. Every chapter includes conclusions and final remarks are given at the end of this thesis. Chapter 7 presents the conclusions of the whole thesis and recommendations for future work.

This work considers the extent to which the virial expansion can describe the structure and phase behaviour of several model fluids. These are the hard-sphere fluid, inverse-power potential fluids, the Lennard-Jones fluid and two kinds of 'square-shoulder' potential. The first novel contribution to knowledge that this work makes is in using virials to obtain the direct correlation function of a hard-core inverse-power potential fluid at densities close to freezing. Predicted radial distribution functions for the fluid at these densities are found that agree well with integral equation theory and simulation data. For softer-core potentials, a convergent direct correlation function is obtained at densities up to those at which a convergent virial expansion is known to exist. The study then extends to a Lennard-Jones fluid. At super-critical temperatures, a convergent direct correlation function is found as before. However, at sub-critical temperatures, the direct correlation function is found to diverge at all points for densities below criticality. Several recently-proposed re-summations of the pressure virial expansion are studied to improve its convergence at high densities. Some promise is shown in improving the accuracy of the virial expansion at high densities, but a re-summed virial expansion is found to be unable to fully capture the true behaviour of the system at densities close to criticality. A second novel contribution to knowledge is made by the reporting of virial coefficient data for several dissipative particle dynamics and penetrative square well potential forms. This is used to study the effect of re-summing the virial expansion for these systems in order to improve its convergence at high densities. The virial expansions of these potentials are found to perform increasingly poorly in the proximity of a vapour-liquid phase transition. This is in agreement with the results of investigating the Lennard-Jones fluid. Thirdly, this investigation considers the whether the virial expansion can describe the freezing of a hard sphere fluid and therefore predict the entire phase diagram for this system. This is investigated using a virial expansion to model the excess contribution to the Helmholtz energy functional. The virial expansion is not found to be able to accurately the point of phase transition, most likely due to questions remaining over the choice of a Gaussian basis set to describe lattice.

No description available.

The transformation of carbon dioxide into added value chemicals by a plasma-activated catalytic process was studied. First of all, the current status of CO2 reutilisation by plasma-assisted technologies was reviewed. Followed by an in-depth study on the process of plasma-catalysis, the effects of dilution gas (i.e. argon and nitrogen) addition and operating parameters in CO2 dissociation were systematically investigated in non-thermal atmospheric pressure plasma barium titanate (BaTiO3) packed-bed reactor from both an engineering and scientific point of view. The extensive experimental and modelling study provided an insight into the relationship between the operating parameters, plasma electrical properties and electron-induced reaction processes in the discharge and the effect of the dilution gases on the product formation and reaction mechanism. The results showed that there was a higher CO2 conversion and energy efficiency in the studied packed-bed reactor than the dielectric barrier discharge (DBD) reactor with and without packed materials using electrodes covered by dielectric layers. Based on the above research work, an in-depth study of the complex mechanism of plasma-catalysis interface reaction was carried out. A new model catalyst (Ni/α-Al2O3 nanocatalyst) with a minimum of physical and chemical variables was specifically designed and synthesised for plasma-assisted reactions to help directly understand the intrinsic role of catalytic active sites during the plasma-catalytic process. In situ time-resolved tuneable lead salt diode laser (TDL) diagnostics of carbon dioxide decomposition over the model catalysts in a planar dielectric barrier discharge (DBD), non-thermal atmospheric pressure plasma reactor demonstrated that the active Ni metal sites do enhance the plasma-catalytic reaction in a similar way as that in conventional catalytic processes. Finally, demonstration of a novel catalysis concept of in situ capture-catalytic system was made for the plasma-assisted catalytic water gas shift reaction. This was investigated in a barium titanate (BaTiO3) packed-bed, non-thermal atmospheric pressure plasma reactor operating at 298 K. The results showed that the packed-bed reactor with CuBTC metal-organic framework (MOF) addition enhanced the CO conversion up to 43%. The comprehensive characterisation of the CuBTC MOF shows that CuBTC MOF exhibited sustainably good physical and chemical stabilities during 4 h long term continuous plasma reaction. The research work in this thesis showed that the BaTiO3 ferroelectric, packed-bed, non-thermal plasma reactor is a potential and powerful environmental solution for CO2 dissociation and other similar pollution treatments with a much higher conversion and energy efficiency at a high specific input energy, more mature and cheaper reactor configuration to scale-up without the need for dielectric barriers. As catalyst introduced into the plasma-assisted process, the demonstrated similar catalytic role of catalytic active sites in plasma-catalytic processes as in conventional thermal catalytic processes opened the gate to apply the catalysts and basic catalytic theories in conventional thermal catalysis field into the non-thermal and atmospheric plasma processes. The boundary of catalysis has been further extended, especially for the non-thermal atmospheric catalytic processes. The catalysis concept for the combination of plasma-catalytic process and conventional thermal catalytic process to enhance the adsorption process of the reactant and then catalyse it simultaneously over the active sites at room temperature and atmospheric pressure could be realised, as demonstrated by using the MOFs with a large gas capture capacity to catalyse water gas shift reaction in non-thermal atmospheric plasma.

The aim of this study was to develop a microbial fuel cell (MFC) wastewater treatment system with a reduced production of sludge; whilst generating electricity as a product. Addition of a graphite intercalated compound, Nyex, provided an opportunity to add an adsorbent system for removal of micropollutants and dyes. Electrochemical analysis, effluent analysis and biofilm analysis provided detail on power generation and wastewater treatment ability and understanding of the biofilm. An 800ml capacity two-chamber MFC was developed and operated using anaerobic wastewater sludge as the anodic inoculum, acetate based artificial waste water as an anolyte and buffered DI water as a catholyte. Separation was provided by a proton exchange membrane, Nafion 117. Nyex was incorporated into the base design using 6 different configurations. Of those, the system with 100g of Nyex loose around each electrode saw the best overall performance. Producing a maximum power density of 0.054W m-2 and current density of 0.35A m-2, an increase of 500% and 312%, respectively, compared to the base fuel cell after 60 days of operation. This is due to a reduction in internal resistance of 86%. Scanning electron microscopy of biofilm indicated species rapidly form links between electrode material to facilitate electron transfer. 16s rRNA gene analysis of used anodic biofilm in the base fuel cell identified two dominant species; P,putida and P.caeni, neither had been used as a pure MFC inoculum. When used as pure cultures and in binary combination all MFCs generated voltage, indicating the species are exoelectrogenic. P.putida produced a current density of 0.0179A m-2, a 258% increase on P.caeni alone, 99% increase on the binary inoculum and a 49% increase on the mixed sludge used for the same time period in the same cell setup. Its maximum power density was 0.0018W m-2; a 167% increase on P.caeni, a 157% increase on the binary inoculum and a 100% increase on the mixed sludge inoculum. COD removal saw a decrease of 62.2% for P.caeni, 61.6% for the binary inoculum, 50.8% for P.caeni, treating 400mL of feed and 34% for the mixed culture treating 1L of feed during the same time period with the same maturity. Based on the results of this study, using the Nyex fuel cell with loose Nyex on both sides generates a power density of 0.054W m-2 when treating 1L of artificial wastewater. Using this system to treat the 11 billion litres of wastewater generated in the UK everyday [1] would result in a total power output of 9.5MW per day. Assuming that the benefits of modifying the fuel cell configuration and modifying the biofilm are independent, their improvements on cell performance can be assumed to be cumulative. Therefore, taking the 0.054W m-2 from the mixed culture Nyex cell and accounting for the 100% power density improvement when using P.putida, the potential power density is 0.108W m-2. Which when applied to the 11 billion litres of wastewater being treated daily within the UK would produce a total power output of 19MW per day.

The development of modern chemical and environmental industry requires novel reactor concepts to enable the transfer of catalysts developed in laboratories into the industrial context. The applications of structured reactors/catalysts such as cellular foams are one of the most promising technologies that can facilitate this crucial step. Open-cell foams with stochastically interconnected cells and high porosities (>60%) can promote the low pressure drop during operation and improve the transport phenomena, overtaking the conventional fixed beds for continuous flow catalysis. In this PhD project, silicon carbide (SiC) cellular foams were investigated to evaluate the potential for developing heterogeneous catalysis using foam-based catalysts in continuous flow regime, due to the good compatibility with framework catalyst coatings and features of the cellular structure. The work was carried out by (i) studying morphological and structural features of SiC foams using X-ray computed tomography technique in relation to their implications for applications in chemical engineering; (ii) developing a microwave-assisted method based on the microwave absorbing feature of SiC for fast yet selective synthesis of zeolite (ZSM- 5) coatings on SiC foams; (iii) developing Fe-ZSM-5/SiC structured catalysts using a chemical vapour deposition method and subsequently studying their application as the foam bed reactor in the catalytic wet peroxide oxidation (CWPO) reaction (using phenol as the model compound); and (iv) developing intra-framework Fe-ZSM-5 catalyst on SiC foams (ferrisilicate/SiC) to address the Fe leaching issue from the Fe-ZSM-5/SiC catalyst. Satisfactory results were obtained through the systematic study of the SiC foam based catalysts, showing the potential of using SiC foams to develop structured catalysts for continuous flow environmental catalysis.

Loss of solubility and aggregation of proteins are important bottlenecks in modern bioprocessing pipelines, where formulation and large-scale production of therapeutic proteins such as antibodies is achieved. The mechanistic basis of protein aggregation propensity and solubility are actively investigated using experimental and computational techniques. A significant part of research in this field involves efforts to understand how sequence- and structure-based properties enable proteins to remain functional under conditions and conditions relevant to physiology and delivery of biotherapeutic agents. Using sequence-based and structural features as well as physico-chemical properties, a model was developed to study how such descriptors can be used in a predictive capacity to separate soluble and insoluble proteins. Therapeutic protein datasets including antibody derivatives and non-antibody biologics were constructed so that their solubility could be studied using the descriptors. Surface charge, polarity, and sequence composition were tested against established thresholds for solubility of E. coli proteins. Surface non-polarity was verified as a consistent feature for separating soluble and insoluble therapeutics, in line with its established role as a key player for determining aggregation propensity in the broader scientific community. The ratio of lysine to arginine composition emerged as a novel sequence-based feature that contributes to solubility, where higher lysine composition is favourable for the solubility. There is potential to use this as a method for engineering proteins for higher solubility with minimal disruption to functionality. The predictive model was subsequently expanded to include a broad array of sequence-based and 3D structural features. Quantitative proteomics studies with high-throughput data for protein solubility, abundance and concentration were used to construct datasets. Web accessible repositories of protein abundance in several species and plasma protein concentration were used to augment the data used to validate the model. Our findings reiterate previously established studies regarding protein length, charge-based properties and surface non-polarity as important descriptors for discriminating soluble and insoluble proteins. The sequence-level lysine/arginine ratio offers a novel perspective on potentially simple ways of protecting proteins against aggregation, which could prove useful for bioprocessing pipelines. Protein-excipient interactions were studied using a dot product metric to measure the association of a set of crystallisation screen ligands with proteins in the PDB database. Enrichment for predicted small molecule (sugars and buffers) binding sites was observed, although the underlying reasons remain unclear without more sophisticated structure-based techniques.

The problem of third phase formation plays a key role in the plutonium and uranium extraction process (PUREX). This process is responsible for the recycling of used nuclear fuel in order to save fuel usage and more importantly to reduce the amount of waste created (and afterwards disposed or stored) after the end of a nuclear fuel cycle. Understanding the role and behaviour of its components in the aqueous and organic phase, and more in depth on the process' extractant tributyl phosphate (TBP), will help give a better understanding of what causes the phase separation of the organic phase and the interactions occuring at that interface. The focus of this project is on the mean activity coefficients of aqueous uranyl nitrate (and other salts) under varying concentrations using the Statistical Associating Fluid Theory (SAFT). Also, apart from the thermodynamic aspect of the above, molecular dynamic simulations were performed on tributyl phosphate and its interactions with other third phase components to study the effects on the structure and behaviour of TBP. By studying TBP in dodecane mixtures it was found that TBP forms aggregates and filament structuring throughout the organic diluent at most TBP concentrations. Also nitric acid hinders this formation by contacting the polar group (P=O) of TBP via intermolecular forces; its action is physical (based on intermolecular interactions) as opposed to chemical. It is expected that this structuring of TBP in the organic phase has an important effect in the transport of metal nitrates from the aqueous to the organic phase in the PUREX process.

Polyhydroxybutyrate (PHB) is a biodegradable, linear polyester that has potential as a promising alternative to petrochemical derived plastics as it possesses the same properties as several current and widely used synthetic, non-biodegradable petrochemical-based plastics. PHB is a natural polyester which is accumulated by many bacteria as an intracellular store of energy and carbon, under stress conditions; limited in one or more essential nutrient, with the carbon source in excess. Currently the PHB production cost is far greater than that of petroleum based plastics. Recent research, therefore, has focused on improving the cost- effective synthesis of PHB from different substrates and microorganisms. The improvement of fermentation processes and strains allowing for PHB to be produced from an inexpensive carbon source is required to compete with synthetic plastics and to mimic their desired properties. The goal of the work reported in this thesis is to assess the suitability of using waste date seed as a feedstock for PHB production under various stress conditions. Date seeds have The novelty of this study The results include fructose hydrolysis from date seeds and the development of a mass transfer model to describe the process, demonstrating that the high nutrient content of date seeds makes them a promising raw material for microbial growth and that a meaningful amount of PHB can be produced. Using fructose rich waste date seed derived medium, with an initial fructose concentration of 10.8 g/l, maximum dry cell weight and PHB concentrations of 6.3 g/l and 4.6 g/l, respectively, were obtained, giving a PHB content of 73%. An investigation into the suitability of using waste date seed oil extract as an alternative carbon source for PHB synthesis was also carried out. This date seed oil was used as the sole carbon source in a series of microbial fermentation experiments, and the results demonstrate that date seed oil is a feasible substrate for PHB production. A maximum dry cell weight (DCW) of 14.35 g/l was obtained, with a PHB content of 82%, using 20 g/l of date seed oil. Subsequently, the effect of using mixed-substrate (date seed hydrolysate media and date seed extracted oil) on PHB synthesis was investigated using various ratios of substrate feeding. A ratio of 1:1 fructose to oil produced the highest biomass and PHB concentrations of 15.22 g/l and 12.36 g/l, with PHB content 84.1%, respectively. Solid state fermentation using polyurethane foam (PUF) as inert solid support also proved to be a successful alternative for traditional SSF method for PHB production with ease. The maximum PHB production was 0.169±0.03 g/g PUF and biomass was 0.4±0.003 g/g PUF. This work results demonstrate that the use of a generic waste date seed medium as a feedstock for PHB synthesis is technically feasible. It is shown that waste date seed provides a novel approach to produce value added products, in this case biopolymer (PHB). The specific studies carried out lead to the wider outlook that a general feedstock derived from date palm by-product, seeds, has potential to be utilised to synthesise a wide range of products based on the microorganism used. More improvement of this process to develop the efficient production of nutrients as well as improve product yields and subsequently, integration of the process into a broader biorefining process would be an essential contribution in the improvement of the sustainable bio-products industries. ï¿1⁄4 a high nutrient content, are available in large quantities and are relatively cheap. lies in the fact that waste date seed can be used as the feedstock for biopolymer production, based on the development of various techniques to make these nutrients bioavailable for the bacterium, Cupriavidus necator for PHB accumulation.

This research focuses on improving direct methanol fuel cell (DMFC) performance by using graphene based materials in their membrane electrode assembly (MEA). The main obstacles of commercialization, poor electrode kinetics and the fuel crossover are addressed by using reduced graphene oxide (rGO) in the cathode microporous layer and single layer graphene (SLG) as an anode barrier layer. In the microporous layer work, an rGO (by hydroiodic acid (HI) reduction of graphene oxide) coated electrode exhibited higher conductivity than conventionally used Ketjen Black electrode (standard). The MEA containing rGO produced peak power density of 79 ± 3 mW cm-2 compared to the standard MEA performance of 55 ± 3 mW cm-2 (44 % improvement) at 70 °C, 1 M methanol fuel cell operating conditions. Doping rGO with boron (B-rGO) or nitrogen (N-rGO) by boric acid and nitric acid treatment and utilizing them as electrodes produced peak power density of 90 ± 3 mW cm-2 for B-rGO (63 % improvement) and 101 ± 3 mW cm-2 for N-rGO (84 % improvement) respectively. This is attributed to the higher conductivity of doped rGO electrodes than rGO, owing to the replacement of heteroatoms in their graphene lattice, with detected boron and nitrogen levels at 2 at% and 6 at%, evidenced by x-ray photoelectron spectroscopy (XPS), aiding in improved electron transfer. In the barrier layer work, SLG added onto the anode side of the MEA, reduced methanol permeation from 1.72 ± 0.1 x 10-7 mol cm-2 s-1 (for the standard) to 1.21 ± 0.1 x 10-7 mol cm-2 s-1, with negligible resistance to protons observed at 70 °C, leading to 45 % improvement in power density (77 ± 1 mW cm-2), caused by the dense carbon lattice packing and single layer nature of SLG. Preliminary results using hexagonal boron nitride (hBN), showed that the cell performance improved by 18 %. Overall, it is evident from the performance improvement results that these graphene materials (first ever reported to have used in the MEA of a DMFC) hold great promise for paving the way towards DMFC commercialization by increasing the electrode kinetics (in case of rGO usage) and reducing methanol permeation (in case of SLG usage).