This PhD study presents the investigations carried out on the reaction chemistry of plasmas with liquids. A plasma-induced liquid chemistry (PiLC) system has been developed and used to identify the reaction chemi~try of plasma interacting with water. The PiLC system is characterized by breakdown voltage and voltage-time dependent measurements. Temperature, pH and conductivity of water are also studied under the influence of plasma at different processing conditions and dissolved oxygen and hydrogen peroxide (H20 2) produced in the water are measured. An initial attempt at an analytical model leading to the description of the reaction chemistry of plasma with \ water has been presented. The PiLC system is then used to synthesize gold nanoparticles (AuNPs) of various sizes (5 nm to several hundreds of nanometers) and shapes (spherical, hexagonal, pentagonal, triangular, etc.) without using any surfactants. It is found that H20 2 plays the role of reductant to synthesize AuNPs. Silver nanostructures (AgNSs) are synthesized without using any surfactants and the effect of precursor concentration on AgNSs size and absorption characteristics has been examined. Reaction mechanisms of AgNSs synthesis have been analysed and it is found that addition of ethanol, methanol and iodine to the silver precursor during plasma processing affects the reaction chemistry of AgNSs. Plasma treatment of BaTi03 nanoparticles (BT-NPs) in ethanol is performed. It is found that plasma-treatment introduces negative charges on surface of BT-NPs and oxygen bondings on the surface have become more prominent. Absorption results indicate that the band gap of BT -NPs reduces after the plasma treatment and it may be correlated to the increased oxygen bondings on the surface. Graphene oxide (GO) is reduced via plasma-treatment in water. Absorption results indicate the red shift in the characteristic (C-C) peak of GO and Raman analysis shows that 0 and G Raman bands are blue shifted after plasma processing which confirms the reduction of GO.

No description available.

The objectives of this work were to attempt to elucidate the initial hydrolysis reaction mechanism when LiH is exposed to water vapour (or air) under specific environmental conditions. Specifically, the work sought to determine whether the initial hydrolysis reaction product was Li₂0 or LiOH, which is an important question that must be answered if an accurate predictive model of LiH hydrolysis is to be developed, which was the underlying driver for this work.

The identification of models of chemical reaction networks is of importance in the safe, economic and environmentally sensitive development of chemical products. Qualitative models of a network of interactions are used in the design of drugs and other therapies. Quantitative models of the behaviour of reaction networks are the foundation of the science of reaction engineering (e.g. see Levenspiel, 1999); allowing the use of simulation software in the rapid development of commercial scale production processes. This work extends the existing methods reported by Burnham et al. (2006); adopting the global basis fonction method first applied to this problem by Crampin et al. (2004a).

Since micro channel flow was developed, single phase Microchannel flow has been notorious for chemical reaction because of its low Re. Mixing in micro channel network utilizing chaos theory has shown that the potential but optimum mixing efficiency only can be achieved when Re~ 70, while usually microfluidic flow has Re~ 10. The most important advantages of liquid-liquid slug flow operation in micro channel are the absolute control volume and well mixing behaviour. Preliminary result shows that the synnge pump operating with a synnge above total nominal flowrate of 1 OO~lJhr, giving infusion accuracy of ~ 1.5%. When operating with two syringes simultaneously, average deviation of flow fraction is ~5%. From qualitative analysis from experimental images, disperse phase slug break up at T-junction is driven by a combination of hydrodynamic force and capillary force as well as shear force. Hydrodynamic force is developed from Hagen Poiseulle equation while capillary force is developed from Young-Laplace equation. During slug formation, magnitudes of shear forces were exerted on the interface by the continuous phase because of varying volume in the T-junction available for the continuous phase flow. However, shear force generated just before break up is the most important force. For designing purpose, if the clean snap off of slug break up at the T-junction is desired, narrower micro channel is required. At low Weeff, the disperse phase slug break up occurs at the T-junction with a clean snap off, dominated by a combination of continuous phase upstream pressure and capillary force. At intermediate Weeff, the slug was broken from a disperse phase connecting neck, driven by both combination of forces and shear force. A disperse phase laminar flow region was formed in the micro channel at high Weeffi in which slug break up from the front of the laminar flow region. The break up is dominated by shear force applied by the continuous phase flow on the laminar flow region. A dimensionless number, Rj, which is the ratio of shear force to the combination of hydrodynamic force and capillary force is used for characterizing the importance of forces during slug break up. For Acetonitrile/tetradecane system, slug break up from the front of the disperse phase laminar flow region when Rj> 3.5e-6. The role of shear force in break up becoming more important as Weeff increases, this is because of increasing contact area available for shear. However, estimation of area available for shear from 2D experimental images is difficult. Empirical equations were developed in relating the disperse phase slug length to the frequency of slug formation, in which the threshold slug length is equivalent to disperse phase channel width. The properties of the immisible liquid-liquid systems are more important in characterizing slug break up operation in the micro channel network. Both Weeff and Caeff can be used to characterize the slug length, depends on the region in which researchers interested in.

This investigation explores the use of environmentally friendly solid acid catalysts based on immobilised Lewis acids in liquid phase organic reaction using the spinning disc reactor. The reaction studied was the rearrangement of a-pinene oxide to campholenic aldehyde, which is an important intermediate used by the fragrance industry in the synthesis of santalol (sandalwood). By focusing on liquid phase reactions and by addressing the particular problems associated with catalysis for such reaction systems the aim of this work is to develop new catalytic technology of value to the highly successful UK fine and speciality chemical industries, where acid catalysis is widely used but normally involves the use of corrosive and toxic reagents, unselective processes and the production of unacceptable levels of hazardous waste. The performance of a compact catalytic spinning disc reactor (SDR) with good heat and mass transfer characteristics for continuous conversion of a-pinene oxide to campholenic aldehyde using supported Zn(OTf)2 catalysts was studied. The spinning disc runs were performed at various conditions and conversion and selectivity were monitored. A 100% conversion of a-pinene oxide was easily achieved for most of the conditions. Lower residence time enhanced selectivity towards aldehyde up to a maximum of 82%, at 60% conversion. SDR empirical models were developed and activation energies determined for each catalyst used. Comparison of SDR with batch process is also made. Results suggest that the catalytic SDR can significantly enhance the reaction rates, reaction selectivity and improve process safety whilst eliminating the loss of catalyst. The findings of this investigation indicate that the vision of realising a truly intensified plant using green chemistry to achieve greener technology is a real possibility.

No description available.

Silica functionalised with PAMAM dendrimer chains has been investigated as a support for anchoring chiral salen complexes in both an axial and covalent fashion. It was found that using a high dendrimer chain density resulted in very low enantioselectivity in the epoxidation of styrene, 1-methyl-1-cyclohexene and α-methylstyrene. Through a thorough series of tests the poor performance was attributed to both interactions with the surface and with neighbouring dendrimer chains. It was found that the system could be improved by decreasing the dendrimer chain density and pacifying the surface by capping the remaining surface hydroxyl groups on the silica. This resulted in the epoxidation of α-methylstyrene with a considerably improved enantioselectivity. Dendritically functionalised silica and silica coated magnetic nanoparticles were also investigated as supports for the immobilisation of an achiral salen complex. High epoxide selectivity was achieved with α-pinene and 1-methyl-1-cyclohexene, while more moderate selectivity was achieved with cyclohexene and limonene as substrates. The heterogeneous catalysts could generally be used 3 times with no apparent loss in activity or selectivity. Both enantiomers of α-pinene and limonene were used to investigate immobilised chiral salen complexes. Results indicate that the diastereomeric excess produced is independent of the configuration or presence of stereogenic centres in the complex. Instead the stereoselectivity appears to be controlled by the nature of the substrate alone. These results call into question the use of such substrates for the investigation of immobilised chiral salen complexes.

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