The role of metal ions in selective and sustainable processes

Sustainability and recycling are core values in today’s industrial operations. New materials, products and processes need to be designed in such a way as to consume fewer of the diminishing resources we have available and to put as little strain on the environment as possible. An integral part of this is cleaning and recycling. New processes are to be designed to improve the efficiency in this aspect. Wastewater, including municipal wastewaters, is treated in several steps including chemical and mechanical cleaning of waters. Well-cleaned water can be recycled and reused. Clean water for everyone is one of the greatest challenges we are facing today. Ferric sulphate, made by oxidation from ferrous sulphate, is used in water purification. The oxidation of ferrous sulphate, FeSO4, to ferric sulphate in acidic aqueous solutions of H2SO4 over finely dispersed active carbon particles was studied in a vigorously stirred batch reactor. Molecular oxygen was used as the oxidation agent and several catalysts were screened: active carbon, active carbon impregnated with Pt, Rh, Pd and Ru. Both active carbon and noble metal-active carbon catalysts enhanced the oxidation rate considerably. The order of the noble metals according to the effect was: Pt >> Rh > Pd, Ru. By the use of catalysts, the production capacities of existing oxidation units can be considerably increased. Good coagulants have a high charge on a long polymer chain effectively capturing dirty particles of the opposite charge. Analysis of the reaction product indicated that it is possible to obtain polymeric iron-based products with good coagulation properties. Systematic kinetic experiments were carried out at the temperature and pressure ranges of 60B100°C and 4B10 bar, respectively. The results revealed that both non-catalytic and catalytic oxidation of Fe2+ to Fe3+ take place simultaneously. The experimental data were fitted to rate equations, which were based on a plausible reaction mechanism: adsorption of dissolved oxygen on active carbon, electron transfer from Fe2+ ions to adsorbed oxygen and formation of surface hydroxyls. A comparison of the Fe2+ concentrations predicted by the kinetic model with the experimentally observed concentrations indicated that the mechanistic rate equations were able to describe the intrinsic oxidation kinetics of Fe2+ over active carbon and active carbon-noble metal catalysts. Engineering aspects were closely considered and effort was directed to utilizing existing equipment in the production of the new coagulant. Ferrous sulphate can be catalytically oxidized to produce a novel long-chained polymeric iron-based flocculent in an easy and affordable way in existing facilities. The results can be used for modelling the reactors and for scale-up. Ferric iron (Fe3+) was successfully applied for the dissolution of sphalerite. Sphalerite contains indium, gallium and germanium, among others, and the application can promote their recovery. The understanding of the reduction process of ferric to ferrous iron can be used to develop further the understanding of the dissolution mechanisms and oxidation of ferrous sulphate. Indium, gallium and germanium face an ever-increasing demand in the electronics industry, among others. The supply is, however, very limited. The fact that most part of the material is obtained through secondary production means that real production quota depends on the primary material production. This also sets the pricing. The primary production material is in most cases zinc and aluminium. Recycling of scrap material and the utilization of industrial waste, containing indium, gallium and geranium, is a necessity without real options. As a part of this study plausible methods for the recovery of indium, gallium and germanium have been studied. The results were encouraging and provided information about the precipitation of these valuables from highly acidic solutions. Indium and gallium were separated from acidic sulphuric acid solutions by precipitation with basic sulphates such as alunite or they were precipitated as basic sulphates of their own as galliunite and indiunite. Germanium may precipitate as a basic sulphate of a mixed composition. The precipitation is rapid and the selectivity is good. When the solutions contain both indium and gallium then the results show that gallium should be separated before indium to achieve a better selectivity. Germanium was separated from highly acidic sulphuric acid solutions containing other metals as well by precipitating with tannic acid. This is a highly selective method. According to the study other commonly found metals in the solution do not affect germanium precipitation. The reduction of ferric iron to ferrous, the precipitation of indium, gallium and germanium, and the dissolution of the raw materials are strongly depending on temperature and pH. The temperature and pH effect were studied and which contributed to the understanding and design of the different process steps. Increased temperature and reduced pH improve the reduction rate. Finally, the gained understanding in the studied areas can be employed to develop better industrial processes not only on a large scale but also increasingly on a smaller scale. The small amounts of indium, gallium and germanium may favour smaller and more locally bound recovery.

Customer Knowledge Transfer in MNCs

The purpose of this Master’s thesis was to study customer knowledge transfer processes in multinational corporations (MNCs). The main objective was to examine how customer knowledge is transferred in MNCs and what kind of factors enhance or inhibit the knowledge transfer process, and to create a framework on the basis of the existing literature and the empirical findings. In this thesis the factors were organized according to whether they are properties of the unit involved in knowledge management, properties of relationships between the units or properties of the knowledge itself. There are various properties that influence knowledge transfer but in this thesis the focus was on examining the relevant findings from the customer knowledge viewpoint. Empirical results show that internal fragmentation in the MNC seems to be inherent in this type of organization, and may cause many problems in customer knowledge transfer and utilization. These knowledge transfer inhibitors rise from the organization’s properties: it’s absorptive capacity, motivation, organizational culture, and the two dimensions of knowledge. However, in spite of the inherent forces causing internal fragmentation and inhibiting knowledge transfer, moderate customer knowledge and expertise codification, cooperative working practices among the experts, and socialization mechanisms posed by the headquarters seem to help maintain customer knowledge transfer, and value creation in the long-term relationship. This value creation can be seen to be based on accessing and integrating a wide variety of knowledge resources in order to create a coherent product and service offering.

Alternative electron transfer routes involved in photoprotection of cyanobacteria

In oxygenic photosynthesis, the highly oxidizing reactions of water splitting produce reactive oxygen species (ROS) and other radicals that could damage the photosynthetic apparatus and affect cell viability. Under particular environmental conditions, more electrons are produced in water oxidation than can be harmlessly used by photochemical processes for the reduction of metabolic electron sinks. In these circumstances, the excess of electrons can be delivered, for instance, to O2, resulting in the production of ROS. To prevent detrimental reactions, a diversified assortment of photoprotection mechanisms has evolved in oxygenic photosynthetic organisms. In this thesis, I focus on the role of alternative electron transfer routes in photoprotection of the cyanobacterium Synechocystis sp. PCC 6803. Firstly, I discovered a novel subunit of the NDH-1 complex, NdhS, which is necessary for cyclic electron transfer around Photosystem I, and provides tolerance to high light intensities. Cyclic electron transfer is important in modulating the ATP/NADPH ratio under stressful environmental conditions. The NdhS subunit is conserved in many oxygenic phototrophs, such as cyanobacteria and higher plants. NdhS has been shown to link linear electron transfer to cyclic electron transfer by forming a bridge for electrons accumulating in the Ferredoxin pool to reach the NDH-1 complexes. Secondly, I thoroughly investigated the role of the entire flv4-2 operon in the photoprotection of Photosystem II under air level CO2 conditions and varying light intensities. The operon encodes three proteins: two flavodiiron proteins Flv2 and Flv4 and a small Sll0218 protein. Flv2 and Flv4 are involved in a novel electron transport pathway diverting electrons from the QB pocket of Photosystem II to electron acceptors, which still remain unknown. In my work, it is shown that the flv4-2 operon-encoded proteins safeguard Photosystem II activity by sequestering electrons and maintaining the oxidized state of the PQ pool. Further, Flv2/Flv4 was shown to boost Photosystem II activity by accelerating forward electron flow, triggered by an increased redox potential of QB. The Sll0218 protein was shown to be differentially regulated as compared to Flv2 and Flv4. Sll0218 appeared to be essential for Photosystem II accumulation and was assigned a stabilizing role for Photosystem II assembly/repair. It was also shown to be responsible for optimized light-harvesting. Thus, Sll0218 and Flv2/Flv4 cooperate to protect and enhance Photosystem II activity. Sll0218 ensures an increased number of active Photosystem II centers that efficiently capture light energy from antennae, whilst the Flv2/Flv4 heterodimer provides a higher electron sink availability, in turn, promoting a safer and enhanced activity of Photosystem II. This intertwined function was shown to result in lowered singlet oxygen production. The flv4-2 operon-encoded photoprotective mechanism disperses excess excitation pressure in a complimentary manner with the Orange Carotenoid Protein-mediated non-photochemical quenching. Bioinformatics analyses provided evidence for the loss of the flv4-2 operon in the genomes of cyanobacteria that have developed a stress inducible D1 form. However, the occurrence of various mechanisms, which dissipate excitation pressure at the acceptor side of Photosystem II was revealed in evolutionarily distant clades of organisms, i.e. cyanobacteria, algae and plants.

Heat-transfer improvements in an axial-flux permanent-magnet synchronous machine

Axial-flux machines tend to have cooling difficulties since it is difficult to arrange continuous heat path between the stator stack and the frame. One important reason for this is that no shrink fitting of the stator is possible in an axial-flux machine. Using of liquid-cooled end shields does not alone solve this issue. Cooling of the rotor and the end windings may also be difficult at least in case of two-stator-single-rotor construction where air circulation in the rotor and in the end-winding areas may be difficult to arrange. If the rotor has significant losses air circulation via the rotor and behind the stator yokes should be arranged which, again, weakens the stator cooling. In this paper we study a novel way of using copper bars as extra heat transfer paths between the stator teeth and liquid cooling pools in the end shields. After this the end windings still suffer of low thermal conductivity and means for improving this by high-heat-conductance material was also studied. The design principle of each cooling system is presented in details. Thermal models based on Computational Fluid Dynamics (CFD) are used to analyse the temperature distribution in the machine. Measurement results are provided from different versions of the machine. The results show that significant improvements in the cooling can be gained by these steps.

Lean management implementation in Horizontal Technology Transfer projects

The importance of Technology Transfer activities of companies is underpinned by the changes in technological and economic environments. However, there is still a significant gap in defining possible ways for Technology Transfer projects effectiveness improvement. The Master’s Thesis overviews common problems faced by the companies in implementation of Technology Transfer projects and examines Lean management principles as possible way to improve its effectiveness. Based on the analysis of the relevant scientific literature and results of the survey, conducted among the firms of different types, the approach to Technology Transfer projects implementation with the use of Lean management principles is proposed. The approach serves to solve some of the important problems faced by the managers of Technology Transfer projects. It is envisaged that this approach can help to increase overall Technology Transfer projects’ effectiveness.

A reaction engineering approach to homogeneously catalyzed glycerol hydrochlorination

The production of biodiesel through transesterification has created a surplus of glycerol on the international market. In few years, glycerol has become an inexpensive and abundant raw material, subject to numerous plausible valorisation strategies. Glycerol hydrochlorination stands out as an economically attractive alternative to the production of biobased epichlorohydrin, an important raw material for the manufacturing of epoxy resins and plasticizers. Glycerol hydrochlorination using gaseous hydrogen chloride (HCl) was studied from a reaction engineering viewpoint. Firstly, a more general and rigorous kinetic model was derived based on a consistent reaction mechanism proposed in the literature. The model was validated with experimental data reported in the literature as well as with new data of our own. Semi-batch experiments were conducted in which the influence of the stirring speed, HCl partial pressure, catalyst concentration and temperature were thoroughly analysed and discussed. Acetic acid was used as a homogeneous catalyst for the experiments. For the first time, it was demonstrated that the liquid-phase volume undergoes a significant increase due to the accumulation of HCl in the liquid phase. Novel and relevant features concerning hydrochlorination kinetics, HCl solubility and mass transfer were investigated. An extended reaction mechanism was proposed and a new kinetic model was derived. The model was tested with the experimental data by means of regression analysis, in which kinetic and mass transfer parameters were successfully estimated. A dimensionless number, called Catalyst Modulus, was proposed as a tool for corroborating the kinetic model. Reactive flash distillation experiments were conducted to check the commonly accepted hypothesis that removal of water should enhance the glycerol hydrochlorination kinetics. The performance of the reactive flash distillation experiments were compared to the semi-batch data previously obtained. An unforeseen effect was observed once the water was let to be stripped out from the liquid phase, exposing a strong correlation between the HCl liquid uptake and the presence of water in the system. Water has revealed to play an important role also in the HCl dissociation: as water was removed, the dissociation of HCl was diminished, which had a retarding effect on the reaction kinetics. In order to obtain a further insight on the influence of water on the hydrochlorination reaction, extra semi-batch experiments were conducted in which initial amounts of water and the desired product were added. This study revealed the possibility to use the desired product as an ideal “solvent” for the glycerol hydrochlorination process. A co-current bubble column was used to investigate the glycerol hydrochlorination process under continuous operation. The influence of liquid flow rate, gas flow rate, temperature and catalyst concentration on the glycerol conversion and product distribution was studied. The fluid dynamics of the system showed a remarkable behaviour, which was carefully investigated and described. Highspeed camera images and residence time distribution experiments were conducted to collect relevant information about the flow conditions inside the tube. A model based on the axial dispersion concept was proposed and confronted with the experimental data. The kinetic and solubility parameters estimated from the semi-batch experiments were successfully used in the description of mass transfer and fluid dynamics of the bubble column reactor. In light of the results brought by the present work, the glycerol hydrochlorination reaction mechanism has been finally clarified. It has been demonstrated that the reactive distillation technology may cause drawbacks to the glycerol hydrochlorination reaction rate under certain conditions. Furthermore, continuous reactor technology showed a high selectivity towards monochlorohydrins, whilst semibatch technology was demonstrated to be more efficient towards the production of dichlorohydrins. Based on the novel and revealing discoveries brought by the present work, many insightful suggestions are made towards the improvement of the production of αγ-dichlorohydrin on an industrial scale.

Moving lipids : ceramides, glycosphingolipids and the glycolipid transfer protein

Lipid movement in cells occurs by a variety of methods. Lipids diffuse freely along the lateral plane of a membrane and can translocate between the lipid leaflets, either spontaneously or with the help of enzymes. Lipid translocation between the different cellular compartments predominantly takes place through vesicular transport. Specialized lipid transport proteins (LTPs) have also emerged as important players in lipid movement, as well as other cellular processes. In this thesis we have studied the glycolipid transport protein (GLTP), a protein that transports glycosphingolipids (GSLs). While the in vitro properties of GLTP have been well characterized, its cell biological role remains elusive. By altering GSL and GLTP levels in cells, we have extracted clues towards the protein's function. Based on the results presented in this thesis and in previous works, we hypothesize that GLTP is involved in the GSL homeostasis in cells. GLTP most likely functions as a transporter or sensor of newly synthesized glucosylceramide (GlcCer), at or near the site of GlcCer synthesis. GLTP also seems to be involved in the synthesis of globotriacylceramide, perhaps in a manner that is similar to that of the fourphosphate adaptor protein 2, another GlcCer-transporting LTP. Additionally, we have developed and studied a novel method of introducing ceramides to cells, using a solvent-free approach. Ceramides are important lipids that are implicated in several cellular functions. Their role as proapoptotic molecules is particularly evident. Ceramides form stable bilayer structures when complexed with cholesterol phosphocholine (CholPC), a large-headgroup sterol. By adding ceramide/CholPC complexes to the growth medium, various chain length ceramides were successfully delivered to cells in culture. The uptake rate was dependent on the chain length of the ceramide, where shorter lipids were internalized more quickly. The rate of uptake also determined how the cells metabolised the ceramides. Faster uptake favored conversion of ceramide to GlcCer, whereas slower delivery resulted mainly in breakdown of the lipid.

Mass transfer and reaction kinetics in single droplet systems

As reactive extraction grown more and more popular in a variety of technological applications, optimizing its performance becomes more and more important. The process of complex formation is affected by a great number of both physical and chemical properties of all the components involved, and sometimes their interference with one another makes improving the effectiveness of such processes very difficult. In this Master’s Theses, the processes of complex formation between the aqueous phase - represented by copper sulfate water solution, and organic phase – represented by Acorga M5640 solvent extractor, were studied in order to establish the effect these components have on reactive extraction performance and to determine which step is bottlenecking the process the most.