Water hyacinth (Eichhornia crassipes, (Mart) Solms), a floating aquatic plant, has long been recognised as a potential commercial resource but, despite many attempts, its conversion from a nuisance into an asset has not been achieved on a significant scale. The thesis is an analysis and assessment of the options for overcoming the many difficulties encountered in the use of water hyacinth. Following a literature survey, from which a process flow path for optimum use of water hyacinth is devised, the thesis leads to an evaluation of the key components of the proposed system for use of water hyacinth as a large-scale energy resource. The principle component of a system to produce energy from water hyacinth is the anaerobic digester. Trials with high-rate anaerobic digesters were conducted in Bangladesh and Thailand. In Bangladesh, with the assistance of senior personnel from the Department of Chemistry of Dhaka University, an 8.3 cubic metre, multi-stage, upflow anaerobic digester was built within the grounds of the Housing and Building Research Institute in Dhaka. Trials with this unit, and associated laboratory work, demonstrated and quantified both the need and the scope for pre-treatment of raw water hyacinth prior to anaerobic digestion. Initial experimentation in Bangladesh laid down the foundations for an understanding of water hyacinth and led to the experimental programme performed in Thailand. In Thailand, following an extensive search and selection of suitable juicing apparatus, a series of batch reactors were run with juice made from separate parts of the whole plant. These results were compared with each other and with a reactor running on juice made from whole plant. The conclusion drawn from this experimentation was that, when mechanically pre-treated, the root section of the plant will contribute more to gas production than will the stem portion. In many previous trials the root has been discarded because of its resistance to anaerobic digestion in a raw form. A multi-stage upflow anaerobic digester was conceived with inclined weir plates, intended to resist blocking of the flow paths by insoluble solids in water hyacinth juice. A series of four of these units were built on a laboratory scale and trials carried out over a period of one month. These trials demonstrated that the proposal to juice water hyacinth prior to low-solids, high-rate anaerobic digestion is one that is technically feasible. The final sections of the thesis use an economic model of the proposed system to conclude that small-scale (3 m3 biogas per day) and medium- scale (1,000 m3 biogas per day) utilisation of water hyacinth will be difficult to achieve in a commercial setting. Large-scale (above 100,000 m3 biogas per day) utilisation of water hyacinth, however, is concluded to be of significant commercial potential.

ẞ +glass sialon materials are prepared with an Nd203 sintering additive. These materials exhibit similar property characteristics to equivalent ¥203-based compositions. With the absence of an Nd phase equivalent to YAG, phase relationships in the Nd-Si-Al-O-N system are examined to identify alternative grain boundary devitrification products. Materials in which the residual glass after sintering is recrystallised to give a mixture of Nd-N-O wollastonite and NdA103 are shown to exhibit high temperature property characteristics comparable to the conventional ẞ'+YAG sialon materials. The glass forming region in the Nd-sialon system is more extensive than for yttrium and new phases have been identified within the expanded volume. These also offer potential as fully crystalline matrix devitrification products. The most significant of these has the composition Nd3Si3Al30i2N2• B'«Nd3Si3Al30i2N2 materials are prepared and found to exhibit excellent properties up to * 1300°C. The preparation of pure a' and α +β’sialon materials by transient liquid phase sintering is particularly sensitive to starting composition. The fabrication of α +’β +glass materials allows greater flexibility but high temperature properties are still sensitive to the chemistry and concentration of the liquid sintering additives and to post sintering heat treatments. α +’β +glass materials are developed with a very minor amount of residual glass of a composition which allows full devitrification to form mainly YAG. Upon annealing, the a' species is particularly receptive to the non-stoichiometric elements which results in removal of the intergranular residual glass and subsequently increased solid/solid contact. To alleviate the interfacial energy anisotropy the YAG crystals are diffusively rearranged to an isolated equiaxed morphology. The limitations on high temperature use are mitigated by the discontinuous nature of this YAG phase. Component field trials and the potential of this new range of generic sialon materials are discussed.

The conditions under which poly(styrene) standards up to m/z = 12 000 can be analysed by matrix-assisted laser desorption/ionisation (MALDI) have been optimised using 9-nitroanthracene as the matrix material in conjunction with silver tri- fluoroacetate addition. The development of such conditions permitted the analysis of a range of polymeric materials including poly(sulfide) samples and novel poly(isobutylene)samples containing aromatic ring functions of molecular masses up to 1000 Da. A series of calculations were carried out in order to assess the accuracy of molecular mass statistics for a range of PMMA and poly( styrene) standards of low poly(dispersity) values up to masses of 12 000 Da obtained by MALDI. It was found that data obtained were in good agreement with those derived from size exclusion chromatography measurements. Electrospray sample preparation was investigated as a method of increasing reproducibilities and signal-to-noise values in MALDI experiments. Electrospraying low mass poly(styrene) samples (up to 3000 Da) increased intensities, however, higher mass samples could not be detected using this method. Moreover, the traditional spotting method worked much better at higher masses. Post-source decay (PSD) experiments have been performed on poly(ethylene glycol), poly( styrene) and the novel poly(isobutylene) samples previously investigated by MALDI using instruments fitted with curved-field and two-stage reflectrons. The type of information obtained using this method compared with tandem mass spectrometry techniques has been investigated. The effect of laser power and pressure has been studied. Ions formed by PSD processes were found to be the same as those formed by low energy CID processes. A range of standard peptide residues were also investigated as part of this work to highlight calibration difficulties associated with PSD analysis using a curved field reflectron. Emitter activation and field desorption mass spectrometry experiments were attempted in order to study polymer materials with little success. Problems and difficulties associated with these experiments have briefly been described.

The electrochemistry of oxygen and methanol at solid polymer electrolyte (SPE)-based amperometric sensors, fabricated according to an all-planar design concept, has been investigated. The solid protonic conductors used were Nafion®-117 membranes and Polybenzimidazole (PBI) films. The working and counter electrodes were non-porous gold and/or platinum layers (300-1500 nm thick), sputtered on the same face of the solid electrolyte, separated by a gap of the ionic conductor (10-1 mm wide) and in contact with the gas sample. Such all-planar solid-state devices could offer potential advantages over sandwich-type gas sensors namely, reduction in precious metal electrode area and simplified fabrication. Sensors based on both materials exhibited near-linear response to oxygen concentration changes (in the 0.1-21% v/v range) and response times comparable to those of commercially available sensors, irrespective to sample relative humidity, but the magnitude of the signal did depend on the latter even after ohmic correction or at low currents. A systematic study of the effect of humidity on oxygen reduction and gold surface electrochemistry reveals, that the fall in the oxygen signal with decreasing humidity cannot be explained simply in terms of decreasing membrane conductivity and increased ohmic losses, but is related to the effect of water on the number of electro active sites, their catalytic activity and oxygen reduction mechanism in general. The latter is further supported by the unusually high Tafel slopes obtained both on gold and platinum electrodes with decreasing levels of test gas humidification. The shape of the oxygen reduction current-potential curves observed at open all-planar gold-based devices and the magnitude of current at both gold-and platinum-based ones, when compared to those of sandwich-and capillary-type arrangements, point to high mass transport rates and a thin or porous mass transport barrier. Current distribution considerations supported by surface electrochemistry estimates suggest that parts of the deposit closer to the reference and counter electrodes contribute more to the observed currents. Further experimentation by varying the deposit thickness and progressive masking of working electrode areas, revealed that the test gas reacted both at the line formed by the gas/solid electrolyte/metal layer interface (diffusion from the gas phase) and underneath the deposit (diffusion from the back of the sensor and through the Nafion® membrane), but not through the metal layer. For monitoring of dissolved methanol (0.5-3 M) in acidic solutions using bare platinum micro disc electrodes and of methanol vapours (in eqUilibrium with 2-10% w/w or ca. 0.6-3 M aqueous solutions of methanol) using Nafion®-based all-planar platinum sensors, a simple amperometric method was developed. For both types of sensors a clear voltarnmetric picture was obtained with a good separation of methanol oxidation and oxygen reduction curves. The amperometric response could be correlated to the variations in methanol concentration, demonstrating the suitability of the method for crude monitoring of dissolved methanol levels in a range applicable to the feed of direct methanol fuel cells.

Low carbon economy has emerged as an important task in China since the energy intensity and carbon intensity reduction targets were clearly prescribed in its recent Twelfth Five-Year Plan during 2011-2015. While the largest enterprises have undertaken initial initiative to reduce their energy consumption, small and medium-sized enterprises (SMEs) will need to share the responsibilities in meeting the nation’s targets. However, there is no established structure for helping SMEs to reduce their efficiency gap and hence the implementation of energy-saving measures in SMEs still remains patchy. Addressing this issue, this thesis seeks to understand the critical barriers faced by SMEs and aims to develop proprietary methodologies that can facilitate manufacturing SMEs to close their efficiency gap. Process parameters optimisation is perceived to be an effective “no-cost” strategy which can be conducted by SMEs to realise energy efficiency improvement. A unique design of experiment (DOE) introduced by Dorian Shainin offers a simplistic framework to study process optimisation, but its application is not widespread and being criticised over its working principles. In order to address the inherent limitations of the Shainin’s method, it was integrated with the multivariate statistical methods and the signal-response system in the empirical study. The nature of the research aim also requires a theoretical approach to evaluate the economic performance of the energy efficiency investment. Hence, a spreadsheet-based decision support system (file SERP.xlsm) was created via dynamic programming (DP) method. The main contributions of this thesis can be subdivided into empirical level and theoretical level. At the empirical level, a technically feasible yet economically viable approach called “multi-response dynamic Shainin DOE” was developed. An empirical study on the injection moulding process was presented to examine the validity of this novel integrated methodology. The emphasis has been on the integration of multivariate techniques and signal-response analysis. The former successfully identified the critical factors to energy consumption and moulded parts’ impact performance regardless of the great fluctuation in the impact response. The latter enables the end-user to achieve different performance output based on the particular intent. At the theoretical level, the “DP-based spreadsheet solution” provides a convenient platform to help the rationally-behaved decision makers evaluate the energy efficiency investments. A simple hypothetical case study on the injection moulding industry was illustrated how the decision-making process for equipment replacement can evolve over time. To sum up, both proprietary methodologies enhance the dynamicity in the optimisation process to support injection moulding industry in closing their efficiency gap. The study at the empirical level was limited by the absence of real industrial case study where it is important to justify the practicality of the proposed methodology. Regarding the theoretical level, the dataset for initial validation on the spreadsheet solution was not available. Finally, it is important to continue the future work on the research limitations in order to increase the cogency of the proprietary methodologies for common use in the industry.

Pyrolysis is an attractive alternative for the conversion of solid fuels to valuable chemicals and bio-fuels. In order to obtain more H2 and syngas from pyrolysis of coal and biomass, microwave has been adopted to enhance the co-pyrolysis of coal and biomass, which has been investigated systematically in this study. Firstly, conventional pyrolysis of coal and biomass was carried out using a vertical tube furnace. Characterizations of pyrolytic gas, liquid and solid products were conducted to study the different properties of products from the pyrolysis of coal and biomass. More gas products were produced at higher temperatures and biomass samples produced more H2 and syngas than coals. Bio-oils produced from conventional pyrolysis of biomass samples have relatively simpler compositions compared with those produced from conventional pyrolysis of coals. Char samples produced from conventional pyrolysis of coal and biomass samples show different morphologies due to the different nature of original coal and biomass. Secondly, microwave-induced pyrolysis of coal and biomass was carried out and compared with the results of conventional pyrolysis. Microwave-induced pyrolysis was found to produce pyrolytic gas products with higher contents of H2 and syngas than conventional pyrolysis. The bio-oils produced from microwave-induced pyrolysis were not as complicated as those from conventional pyrolysis. The reason for this is believed to be that both microwave irradiation and the longer residence time favour more complete decomposition of large hydrocarbon molecules in coal and biomass, which subsequently results in less complicated composition compared with bio-oil produced via conventional pyrolysis. Char samples from microwave-induced pyrolysis undergo more complete pyrolysis than char samples from conventional pyrolysis, and results in less volatiles remaining. Because of the thermal annealing process by microwave at the later stage of pyrolysis, char samples produced by microwave-induced pyrolysis have higher peak temperatures and burnout temperatures than those produced by conventional pyrolysis. In char samples prepared via microwave-induced pyrolysis of coal and biomass, special structures are found, such as nano-scale fibers in char samples from gumwood and pine, spheres in char samples from coals as well as coal and biomass blends. Based on the analysis of energy balance, it is evident that microwave-induced pyrolysis is a cost-effective and energy saving method for solid fuel conversion.

Currently, solid-state nuclear magnetic resonance (NMR) methodology is still evolving. However, this thesis focuses on the application of NMR methods to improving the understanding of solid-state hydrogen storage materials. In particular, this thesis demonstrates how NMR can provide a unique perspective on materials from a molecular level, complementary to other analytical techniques. All of this work has been done in collaboration with other research groups, so effort has been made to interpret the NMR results recorded here in the context of the synthetic methods used and results obtained from other analytical techniques. Firstly, chapter 1 contains a review on the necessity and challenges of storing hydrogen. Then a complete review of the relevant NMR theory and methodology will be given in chapter 2, before turning attention to its application to specific hydrogen storage systems in subsequent chapters. Chapter 3 studies the metal organic frameworks (MOF): NOTT-207, NOTT-201 and NOTT-209 as potential storage systems. Static 7Li studies elucidated the change in the lithium co-ordination environment upon desolvation, necessarily unblocking the pores for gas sorption. Chapter 4 contains a multi-nuclear study on the LiBH4/MgH2 system. In the first part, static 7Li NMR reveals the effects of ball milling (particle grain size reduction) on lithium ion diffusion; for the hexagonal (high temperature) structure of LiBH4. Evidence is also found for significant lithium ion diffusion in the orthorhombic (low temperature) structure. Then in the second part of chapter 4, 1H, 6Li, 7Li, 11B and 25Mg ex situ magic angle spinning experiments were used to follow the route of decomposition, analysing the effects of varying reaction temperature, pressure and sample stoichiometry. The different phases present at different stages in the amorphous intermediates and products were elucidated, in particular it was possible to show the necessary thermodynamic conditions for the [B12H12]2-intermediate formation. Chapter 5 uses static 7Li NMR to study the Li-N-H system. Firstly, Li3N nanowires are characterised in terms of lithium ion diffusion, with an improvement to diffusion being found upon nano-structuring. Then bulk Li2NH and dual phase Li2NH/LiNH2 are also characterised with respect to lithium ion diffusion, and analysis suggests hopping occurs between tetrahedral sites. Since the three systems studied in this thesis are different, each chapter will contain all the background scientfic information and conclusions relevant to the NMR results of the system under consideration. Finally, chapter 6 will summarise and conclude as a whole in the context of the technological importance of this work.

Pyrolysis of biomass is a promising and sustainable approach to produce value-added chemicals and biofuels. In order to achieve a high yield of hydrogen-rich syngas from pyrolysis of biomass, the microwave-enhanced pyrolysis of biomass coupled with catalytic reforming was studied systematically in this research. Firstly, microwave-enhanced pyrolysis of biomass was carried out and compared with conventional pyrolysis under the same processing conditions. Characterisations of biomass, pyrolytic char, bio-oil and biogas were conducted to investigate the differences between microwave-enhanced and conventional pyrolysis. It was found that certain types of carbon nano materials were formed on the surface of microwave pyrolytic chars. More biogas was produced via microwave heating, in which the highest H2 content reached 48.2vol.% during the course of microwave-enhanced pyrolysis of bamboo at 800°C. Most of the syngas contents produced from microwave-enhanced pyrolysis of biomass were above 80vol.% at 800°C. Generally, biomass could be converted into biofuel efficiently with microwave-enhanced process. Secondly, in order to increase hydrogen production, microwave-enhanced pyrolysis coupled with catalytic reforming (MPCCR) at 600°C was studied. In catalyst screening, Ni and Fe were applied as active compounds loaded onto different supports such as molecular sieves (13X), Al2O3 and natural minerals. In addition, activated carbon was employed as a reforming agent. It was found that Ni-13X catalyst resulted in a low yield of bio-oil and high yield of biogas around 75wt.%, which was the highest among all the catalysts investigated. It was also observed that activated carbon played a significant role in increasing biogas product and reducing bio-oil yield to less than 1wt.% in both conventional and microwave-enhanced pyrolysis coupled with reforming. MPCCR with Ni-13X and activated carbon enhanced cracking reactions of bio-oil, and subsequently lowed bio-oil yields and narrowed products distribution simultaneously. The maximum H2 content reached 55vol.% by MPCCR of bamboo using activated carbon as the reforming agent. Compared with conventional reforming, there was a sharp increase of H2 yield via microwave-enhanced reforming, resulting in a hydrogen-rich syngas with a high ratio of H2 to CO. Therefore, it is concluded that microwave irradiation enhances the reforming process. Finally, in this study, a novel method for catalyst-free synthesis of multi-walled carbon nanotubes (MWCNTs) from biomass was developed. MWCNTs with a diameter of 50 nm and a wall thickness around 5 nm have been successfully prepared via microwave-enhanced pyrolysis of gumwood at 500 °C. The mechanism for the growth of such carbon nanotubes (CNTs) was proposed as follows: volatiles were released from the biomass and left behind char particles; these char particles then acted as substrates, mineral matter in char particles (originating from biomass) acted as the catalyst, and the volatiles released act as the carbon source gas; the volatiles then underwent thermal and/or catalytic cracking on the surface of char to form amorphous carbon nanospheres; the carbon nanospheres subsequently self-assembled to form multi-walled CNTs under the effects of microwave irradiation. In summary, microwave-enhanced pyrolysis of biomass has the potential to produce high yield of hydrogen-rich syngas not only at high temperatures but also at low temperatures when it is coupled with catalytic reforming processes. It has also been demonstrated that microwave-enhanced pyrolysis of biomass could be used to produce MWCNTs at low temperatures. It can therefore be concluded that microwave-enhanced pyrolysis of biomass is an effective and efficient approach for the conversion of biomass into value-added products under mild conditions.

There is great need for the widespread use of indoor gas monitors as modern hermetically-sealed domestic buildings increasingly suffer from indoor air pollution. However, neither modern technologies of gas sensors nor analytical instruments are ideally suited to this purpose. The problems of gas sensors are poor selectivity and the fact that normally they can detect only one gas, and analytical instruments suffer from their large size and high price. Therefore, the aim of the project is "to develop a novel gas sensor with low cost, low power consumption, high reliability, which can detect multiple gases with excellent selectivity" for indoor gas monitoring. In the first part of the project, an SOI-CMOS micro-hotplate with a single crystal silicon (SCS) resistive heater was proposed, fabricated and characterised. The design obviates issues of traditional heater materials i.e. platinum is not CMOS compatible and polysilicon is not thermally stable due to its polycrystalline structure. The SCS micro-hotplate was found to have an ultra low power consumption of 11.6 mW to operate at 500°C, and an excellent reliability with less than 1% drift after 500 hour operation at 500°C. In the second part, a novel temperature modulation technique for a carbon black/polymer composite sensor was theoretically derived based upon linear solvation and Fickian diffusion. The processing technique comprises only two steps; summing the off and on transient conductance signals from a temperature-stepped sensor, and subtracting the steady-state signal. The technique was demonstrated by applying to a carbon black/polyvinylpyrrolidone composite sensor employing the novel micro-hotplate. Identification of water. methanol and ethanol vapours was successfully demonstrated using the peak time of the resultant curve. Furthermore, quantification of those vapours was found to be possible using the height of the peaks, which was linearly proportional to the concentration. In conclusion, a novel low-cost gas sensor has been realised that is capable of detecting more than one gas with a single sensing element and thermal modulation. This has the potential for commercial exploitation in the area of indoor air pollution monitoring.

The increasing use of fossil fuels and the impending depletion of their reserves worldwide are driving alternative energy sources as one of the foremost consideration for research in energy, fuel, and power technology. Additionally, the increasing rate of harmful emissions especially carbon dioxide from the increased usage of fossil fuels have led to the need for more environmentally friendly replacement fuels. Presently, bio-oil originating from biomass has been proposed as an alternative fuel to fossil diesel. The aim of this research project is to optimally produce bio-oil in terms of quantity and quality from Jatropha curcas waste by using conventional and fast pyrolysis methods. Jatropha curcas shrub, which can be planted economically in tropical regions like Malaysia, is typically planted as a source of inedible oil for biodiesel production. The leftover pressed cake after oil extraction is an agricultural waste, which can be upgraded into fuel via pyrolysis. In this project, the pyrolysis parameters to achieve optimum quantity and quality of bio-oil from Jatropha curcas waste were determined. To achieve this, two fixed-bed pyrolysis rigs for conventional and fast pyrolysis processes were designed and fabricated, and a corresponding Design of Experiment was performed. By considering yield, calorific value, water content and acidity, the results from both methods were mathematically modelled after comparison and the optimum parameters for both methods were determined. The validated models of conventional and fast pyrolysis showed that optimum combined quantity and quality of bio-oil occur at reaction temperatures of 800 K and 747 K respectively but at the same nitrogen linear velocity of 0.0078 cm/s. At these optimum conditions, conventional and fast pyrolysis yield 50.08 wt% and 40.08 wt% of bio-oil with gross calorific values of 15.12 MJ/kg and 16.92 MJ/kg, water contents of 28.34 wt% and 28.02 wt%, and pH values of 6.77 and 7.01, respectively. The produced bio-oils from both rigs at their optimum points were dehydrated, and the physicochemical characteristics of the dehydrated bio-oils from both rigs were compared to standard specifications for burner biofuels. Based on ASTM D7554-10 standard for burner biofuel specifications, by reducing the sulphur contents, both dehydrated bio-oils can be used as burner fuel without any further processes. Finally, both 10% of optimised and dehydrated bio-oils emulsified in 90% diesel were tested and compared to EN590, the European standards for diesel used in commercial diesel engines and ASTM D6751-01, the standard biodiesel specifications. In addition to sulphur content, if the water content of both of these emulsified dehydrated bio-oils are removed, they can be commercially used as diesel fuel in diesel engines because their solid content, kinematic viscosity, ash content, flash point, cetane number and copper corrosion strip test results are within the range of EN590 standard.