Characterization of amine-based CO2 adsorbent for Direct Air Capture

Direct air capture technologies extract CO2 from air at a concentration of as low as 400ppm. The captured CO2 can be used for the production of synthetic methane or liquid fuels. In the literature survey of this thesis, results related to direct air capture by using solid sorbents are presented and critically discussed. In the experimental part, a proprietary amine functionalized resin is characterized for direct air capture. Structural comparison is also made to a commercial resin of similar type. Based on the literature survey, the most important parameters in direct air capture process are low adsorption and desorption temperatures, good cyclic stability in dry and humid conditions, high CO2 outlet purity and a high working capacity. Primary amine functionalized solid sorbents are found to often have good qualities for direct air capture, but overall process performance is rarely studied exhaustively. Based on FTIR spectra, both resin adsorbents are found to be consisted of polystyrene functionalized with primary amine, and capture CO2 by forming carbamate. The commercial resin is more porous, has a slightly higher particle size and contains fewer impurities. Important physical parameters are gained of the proprietary resin, such as internal porosity and median particle size. The resin’s amine group is found to endure thermal treatment reasonably well. CO2 adsorption capacity gained by thermal gravimetry from 400ppm CO2 is highest at 25oC, and is found to be reasonable compared to values presented in literature. Thus, the resin is stated to exhibit promising qualities for direct air capture.

CO2 Laser Cutting of Particleboard, HDF and MDF

The purpose of this thesis is to reveal how the laser cutting parameters influence lasercutting of particleboard, HDF and MDF. The literature review introduces the basic principle of CO2 laser, CO2 laser equipment and its usage in cutting of wood-based materials. The experimental part focuses on the discussion and analysis ofthe test data and attempts to draw conclusions on the influence of various parameters, including laser power, focal length of the lens and cutting gas, on the cutting speed and kerf quality. The tested materials include various thicknesses of particleboard, HDF and MDF samples. A TRUMPF TLF2700 HQ laser equipment was used for the experiments. To obtain valid data, the test samples must be completely cut through without any bonding of wood fibre. The maximum cutting speed is linear dependent on the laser power in thecondition that the other parameters are constant. For each thickness of a specific material type, there is a minimum laser power for cutting. Normally, the topand bottom kerf widths increase with the enhancement of laser power. There may be a critical laser power which can generate the minimum cross-sectional kerf width. Lens of larger focal length may achieve higher cutting speed. As the focal length becomes larger, the top kerf width tends to increase while the bottom andcross-sectional kerf widths to the opposite. Of all cutting gases, oxygen can help achieve higher cutting speed. The gas pressure of nitrogen does not seem to have strong influence on the cutting result. Generally, 2 bar air is more preferable for higher cutting speed. For particleboard and MDF samples of larger thickness than 12 mm, 2 bar argon can be used to reach remarkably higher cutting speed than the 5 bar. Generally, the 190.5 mm lens can produce smallest total kerf width. The kerf sides of thicker samples are darker than the thinner ones. The sample darkness tends to be lower as laser power increased. 63.5 mm lens seemed tocause more darkness than other lens. 5 bar cutting gases can produce less dark side kerfs than 2 bar ones. Oxygen normally causes darker kerfs than other gases. No distinct differences were found between nitrogen and argon.

The effects of some variables on CO2 laser-MAG hybrid welding

The CO2-laser-MAG hybrid welding process has been shown to be a productive choice for the welding industry, being used in e.g. the shipbuilding, pipe and beam manufacturing, and automotive industries. It provides an opportunity to increase the productivity of welding of joints containing air gaps compared with autogenous laser beam welding, with associated reductions in distortion and marked increases in welding speeds and penetration in comparison with both arc and autogenous laser welding. The literature study indicated that the phenomena of laser hybrid welding are mostly being studied using bead-on-plate welding or zero air gap configurations. This study shows it very clearly that the CO2 laser-MAG hybrid welding process is completely different, when there is a groove with an air gap. As in case of industrial use it is excepted that welding is performed for non-zero grooves, this study is of great importance for industrial applications. The results of this study indicate that by using a 6 kW CO2 laser-MAG hybrid welding process, the welding speed may also be increased if an air gap is present in the joint. Experimental trials indicated that the welding speed may be increased by 30-82% when compared with bead-on-plate welding, or welding of a joint with no air gap i.e. a joint prepared as optimum for autogenous laser welding. This study demonstrates very clearly, that the separation of the different processes, as well as the relative configurations of the processes (arc leading or trailing) affect welding performance significantly. These matters influence the droplet size and therefore the metal transfer mode, which in turn determined the resulting weld quality and the ability to bridge air gaps. Welding in bead-onplate mode, or of an I butt joint containing no air gap joint is facilitated by using a leading torch. This is due to the preheating effect of the arc, which increases the absorptivity of the work piece to the laser beam, enabling greater penetration and the use of higher welding speeds. With an air gap present, air gap bridging is more effectively achieved by using a trailing torch because of the lower arc power needed, the wider arc, and the movement of droplets predominantly towards the joint edges. The experiments showed, that the mode of metal transfer has a marked effect on gap bridgeability. Transfer of a single droplet per arc pulse may not be desirable if an air gap is present, because most of the droplets are directed towards the middle of the joint where no base material is present. In such cases, undercut is observed. Pulsed globular and rotational metal transfer modes enable molten metal to also be transferred to the joint edges, and are therefore superior metal transfer modes when bridging air gaps. It was also found very obvious, that process separation is an important factor in gap bridgeability. If process separation is too large, the resulting weld often exhibits sagging, or no weld may be formed at all as a result of the reduced interaction between the component processes. In contrast, if the processes are too close to one another, the processing region contains excess molten metal that may create difficulties for the keyhole to remain open. When the distance is optimised - i.e. a separation of 0-4 mm in this study, depending on the welding speed and beam-arc configuration - the processes act together, creating beneficial synergistic effects. The optimum process separation when using a trailing torch was found to be shorter (0-2 mm) than when a leading torch is used (2-4 mm); a result of the facilitation of weld pool motion when the latter configuration is adopted. This study demonstrates, that the MAG process used has a strong effect on the CO2-laser-MAG hybrid welding process. The laser beam welding component is relatively stable and easy to manage, with only two principal processing parameters (power and welding speed) needing to be adjusted. In contrast, the MAG process has a large number of processing parameters to optimise, all of which play an important role in the interaction between the laser beam and the arc. The parameters used for traditional MAG welding are often not optimal in achieving the most appropriate mode of metal transfer, and weld quality in laser hybrid welding, and must be optimised if the full range of benefits provided by hybrid welding are to be realised.

Novel CO2 Regulated Proteins in Synechocystis PCC 6803

The large biodiversity of cyanobacteria together with the increasing genomics and proteomics metadata provide novel information for finding new commercially valuable metabolites. With the advent of global warming, there is growing interest in the processes that results in efficient CO2 capture through the use of photosynthetic microorganisms such as cyanobacteria. This requires a detailed knowledge of how cyanobacteria respond to the ambient CO2. My study was aimed at understanding the changes in the protein profile of the model organism, Synechocystis PCC 6803 towards the varying CO₂ level. In order to achieve this goal I have employed modern proteomics tools such as iTRAQ and DIGE, recombinant DNA techniques to construct different mutants in cyanobacteria and biophysical methods to study the photosynthetic properties. The proteomics study revealed several novel proteins, apart from the well characterized proteins involved in carbon concentrating mechanisms (CCMs), that were upregulated upon shift of the cells from high CO₂ concentration (3%) to that in air level (0.039%). The unknown proteins, Slr0006 and flavodiiron proteins (FDPs) Sll0217-Flv4 and Sll0219-Flv2, were selected for further characterization. Although slr0006 was substantially upregulated under C_i limiting conditions, inactivation of the gene did not result in any visual phenotype under various environmental conditions indicating that this protein is not essential for cell survival. However, quantitative proteomics showed the induction of novel plasmid and chromosome encoded proteins in deltaslr0006 under air level CO₂ conditions. The expression of the slr0006 gene was found to be strictly dependent on active photosynthetic electron transfer. Slr0006 contains conserved dsRNA binding domain that belongs to the Sua5/YrdC/YciO protein family. Structural modelling of Slr0006 showed an alpha/beta twisted open-sheet structure and a positively charged cavity, indicating a possible binding site for RNA. The 3D model and the co-localization of Slr0006 with ribosomal subunits suggest that it might play a role in translation or ribosome biogenesis. On the other hand, deletions in the sll0217-sll218- sll0219 operon resulted in enhanced photodamage of PSII and distorted energy transfer from phycobilisome (PBS) to PSII, suggesting a dynamic photoprotection role of the operon. Constructed homology models also suggest efficient electron transfer in heterodimeric Flv2/Flv4, apparently involved in PSII photoprotection. Both Slr0006 and FDPs exhibited several common features, including negative regulation by NdhR and ambiguous cellular localization when subjected to different concentrations of divalent ions. This strong association with the membranes remained undisturbed even in the presence of detergent or high salt. My finding brings ample information on three novel proteins and their functions towards carbon limitation. Nevertheless, many pathways and related proteins remain unexplored. The comprehensive understanding of the acclimation processes in cyanobacteria towards varying environmental CO₂ levels will help to uncover adaptive mechanisms in other organisms, including higher plants.

Vegetation and CO2 balance in an abandoned harvested peatland in Aitoneva, southern Finland

Tiivistelmä: Kasvillisuus ja CO2-tase käytöstä vapautuneella turvetuotantoalueella Kihniön Aitonevalla

Germinability of Norway spruce and scots pine pollen exposed to open air

Summary

The effects of prolonged exposure to elevated temperatures and elevated CO2 levels on the growth, yield and dry matter partitioning of field-sown meadow fescue

Selostus: Kohotetun lämpötilan ja kohotetun CO2-pitoisuuden vaikutukset peltoon kylvetyn nurminadan kasvuun, satoon ja kuiva-aineen jakautumiseen