[dipl] Kemian tekniikan korkeakoulu / CHEM

Permanent URI for this collection

Browse

Recent Submissions

Now showing 1 - 20 of 2094
  • Item
    Assessment of technical and environmental solutions for developing reusable kitchen sponges. Case of the innovative start-up INGA
    (2024-08-29) Redureau, Alice; Tehrani, Ali; Lívia De Almeida, Maria; Kemian tekniikan korkeakoulu; Dessbesell, Luana
    This master’s thesis explores INGA, a company focused on durable, reusable household items, and the financial and technical challenges it faces. The study emphasizes the role of start-ups in promoting sustainability by transforming single-use products into reusable ones. An analysis of each stage of the life cycle of INGA’s sponge reveals opportunities for reducing environmental impact, such as through the use of more sustainable materials like PLA and lignin. However, economic and technical obstacles currently hinder immediate adoption. According to this research, a theoretical sponge has been created, which aims to be greener. A comparative streamlined LCA shows that INGA’s washable sponge and the theoretical version with greener materials have lower environmental impacts than disposable sponges. However, this simplified LCA had underlined the limitations of the study because of the lack of data. Overall, the LCA provides valuable insights, aiding INGA’s sustainability efforts and marketing, and investor relations. Despite obstacles, INGA is committed to enhancing the sustainability of its products through ongoing research and investment.
  • Item
    Hydrogels with tailorable anisotropic microporous architecture for bone engineering
    (2024-08-29) Abousharabia, Ibrahim; Keerakkara Arumughan, Vishnu; Kemian tekniikan korkeakoulu; Kontturi, Eero
    This thesis delves into the innovative development of anisotropic hydrogels tailored for bone regeneration, utilizing surface-deacetylated chitin nano-fibers (SDA-ChNFs) through a systematic freeze-casting process. By utilizing a 1.25% concentration of SDA-ChNFs and crosslinking with sodium tripolyphosphate (STP), I enhanced the mechanical and morphological properties of the hydrogels. Notably, freezing the hydrogels at -20°C, as opposed to -196°C, resulted in the formation of larger, uniformly aniso-tropic pores while preserving comparable mechanical integrity. These enhanced pore structures are vital for promoting cell growth, nutrient diffusion, and waste elimination, closely emulating the natural bone environment. In addition, thawing at refrigerator temperatures (4°C) further refined pore uniformity and improved structural strength. Biomineralization assessments using simulated body fluid (SBF) affirmed the hydrogels' proficiency in supporting mineral deposition, thereby highlighting their promise in bone tissue engineering. In this thesis I will outline the pathway to creating these anisotropic hydrogels, focusing on optimizing the concentration of SDA-ChNFs, selecting the ideal crosslinker, and fine-tuning the freezing and thawing conditions. The impact of these parameters was evaluated through comprehensive morphological, mechanical, and rheological analyses. By emphasizing the critical importance of material and process optimization, this thesis gives insights into the development of hydrogels with compatible porosity and pore sizes for bone and tissue engineering.
  • Item
    Enzyme encapsulation into Archeaoglobus fulgidus ferritin
    (2024-08-29) Rosenlöf, Lotta; Zhou, Yu; Kemian tekniikan korkeakoulu; Kostiainen, Mauri
    Ferritins are ubiquitous protein nanocages with a hollow structure that can be loaded with cargo molecules. Ferritins offer significant potential in technological and medical applications due to their many favorable characteristics, including stability, modifiability, and ability to encapsulate cargo. Proteins are susceptible to denaturation, but their crystalline form could offer improved bioavailability and stability. Protein crystallization is a critical tool in structural biology and pharmaceuticals, yet it remains poorly understood. Encapsulating a protein within a ferritin cage followed by crystallization may provide additional stability to the cargo. Whether enzymatic activity is retained in encapsulated enzymes after crystallization remains unclear. Thus, the aim of the thesis is to assemble photo-responsive crystals from ferritin cages that have encapsulated an enzyme. Ideally, the enzyme would be protected from the surrounding environment by the cage or subsequently by the crystals. The encapsulation efficiency was evaluated using SDS-PAGE, UV-vis spectroscopy, and transmission electron microscopy (TEM). The crystallization was studied with dynamic light scattering (DLS), TEM, and optical microscopy. Although photo-responsive crystals were not achieved, enzyme encapsulation within the ferritin cages was done successfully. Furthermore, the assembled complexes could be disassembled upon UV light irradiation. These results suggest that photo-responsive crystals with enzymatic activity could be assembled. However, further research is needed to optimize the host-guest ratio for encapsulation and to refine the crystallization conditions for the assembly of highly organized structures. New applications in drug delivery may arise if the protein crystals can preserve the enzymatic activity under various conditions.
  • Item
    Design and assessment of alkaline kraft lignin valorization routes for high-added value applications
    (2024-08-29) Zandonadi Nunes, Caio; Karpale, Juho-Matti; Kemian tekniikan korkeakoulu; Dessbesell, Luana
    Lignin, a biopolymer found in plant tissues, represents the most abundant source of renewable aromatics, accounting for approximately 20-30% of the dry weight of woody species. Despite its abundance, lignin is often underutilized, typically considered a low-value by-product in the pulp and paper industry, and burned for steam and electricity generation. This limited utilization presents an opportunity for the bioeconomy, as the valorization of lignin into high-added value products can address environmental concerns and also stimulate economic growth. Phenol-formaldehyde resins, traditionally derived from petroleum-based phenol and formaldehyde, can be effectively produced using lignin as a substitute for the phenol. Similarly, polyurethane foams, which also come from petroleum-based chemicals, can incorporate lignin-based polyols to achieve comparable mechanical properties and thermal insulation. In the first part of this thesis, an LCA was con-ducted to assess the environmental impact of extracting lignin using the novel Large Pore Membrane Filtration (LPMF) technology on a pilot scale. The second part assesses the economic feasibility of using this lignin in two different process-es, producing either lignin-based phenol-formaldehyde resins or rigid polyurethane foams. The LCA used mainly primary data and Ecoinvent v3.10 as a data-base, and the software Aspen Plus v.14 was used for process simulation and eco-nomic evaluation. The process simulations include detailed design and sensitivity analyses to assess the impact of raw material and product price fluctuations. The LCA results showed a cradle-to-gate climate change impact of 0.22 kg CO2/kg lignin, which is comparable to other lignin extraction processes. The TEA indicate that lignin-based phenol-formaldehyde resins and polyurethane foams are eco-nomically viable. For both industries operating a capacity of 15kton of lignin per year, payback periods of 4.06 and 2.08 years were found for phenol-formaldehyde resins and polyurethane, respectively. In addition, a replacement ratio of 30% (wt% of phenol or polyol) can potentially lead to a reduction in CO2 emissions of 17.2% in the case of phenolic resins and 11.5% for the polyurethane one. Future research should focus on increasing the replacement ratio and development of improved functionalities.
  • Item
    Towards the biomimetic total synthesis of (±)-haloxine
    (2024-08-29) Tong, Linh; Siitonen, Juha; Kemian tekniikan korkeakoulu; Siitonen, Juha
    Natural products (secondary metabolites) have been the leading source of drug discoveries. Many biologically active products often exist in extremely low quantities in nature, making their extraction and isolation challenging and thus leading to low yields. Total synthesis allows chemists to produce these compounds in sufficient quantities for further studies and potential therapeutic applications. The process of total synthesis also provides educational values such as problem-solving skills and techniques that are essential for the training of new chemists. Throughout the history of total synthesis, the field has evolved from merely determining whether molecules could be synthesized in laboratory settings to optimizing the process to achieve the shortest steps with the highest yields, adhering to green chemistry principles. By mimicking processes in nature, biomimetic synthesis has become a powerful tool to replicate chemical reactions of natural compounds based on proposed biosynthesis within a laboratory setting. This approach has enabled the successful synthesis of several complex compounds. Despite nearly 60 years since its isolation, no synthetic studies on haloxine have been reported. This thesis aims to establish the first total synthesis of haloxine by proposing its biosynthetic origin and employing biomimetic strategies. The lack of available spectral data for haloxine added complexity to the synthesis and characterization efforts. Nevertheless, four approaches based on the key biomimetic cascade reactions were explored, leading to the syntheses of five new compounds. Due to time limits, the target natural product was not achieved. This thesis highlights the importance of biomimetic strategies in the synthesis of complex natural products and their potential to inspire innovative methodologies in synthetic chemistry.
  • Item
    A study on optimization of graphite separation in lithium-ion battery waste recycling via froth flotation and selective flocculation: A response surface methodology approach
    (2024-08-29) Esmaeilzadeh Dilmaghani, Sevda; Araya Gómez, Natalia; Saeed, Mohazzam; Kemian tekniikan korkeakoulu; Serna Guerrero, Rodrigo
    The growing demand for lithium-ion batteries (LIBs) necessitates effective recycling methods to recover valuable materials and mitigate environmental impact. This study investigates the optimization of graphite separation from LIB waste using froth flotation and selective flocculation. Flotation is utilized due to the natural hydrophobicity of graphite compared to the hydrophilic nature of cathode materials, making it a suitable method for separation. Selective flocculation is explored to enhance the efficiency of this process by promoting the aggregation of target particles. Key flotation parameters, including solid content, impeller tip speed, conditioning time, and flocculant dosage, were systematically varied and analyzed using a Response Surface Methodology (RSM) approach. Results indicated that employing ultrafine cathode particles (<10 µm) in the model black mass feed achieved a graphite concentrate grade of 98.63% with a recovery rate of 71.98% in a single-stage flotation process. Among the parameters studied, solid content was found to have the most significant impact on graphite grade, while impeller tip speed and flocculant dosage most influenced graphite recovery. Through response optimization, it was determined that optimal conditions include a solid content of 20 g/L, a conditioning time of 13 min, and an impeller tip speed of 1040 rpm, resulting in a graphite grade of 99.02% and a graphite recovery of 74.54%. This study highlights the potential of combining froth flotation with RSM to enhance the efficiency and effectiveness of graphite separation in LIB recycling processes. Future research should explore alternative pH levels, flocculants, and multi-stage flotation processes to further improve separation performance.
  • Item
    Life cycle assessment (LCA) of end-of-life photovoltaic panels
    (2024-08-29) Song, Yutong; Aromaa-Stubb, Riina; Kemian tekniikan korkeakoulu; Lundström, Mari
    With the transition to clean and renewable energy worldwide, photovoltaic (PV) technologies have been increasingly utilized, and crystalline silicon (c-Si) PV panels are expected to remain dominant for a long time. The amount of EOL PV panels is predicted to reach millions of tons by 2050 globally. It has been proved that the recycling of PV panels has lower environmental burdens than other EOL disposal methods, and the recovery of secondary raw materials such as high-purity silicon and metals from them provides additional environmental and economic benefits. It is therefore essential to find the most efficient and environmentally friendly recycling methodologies. In this thesis, two recycling scenarios are designed to recover metallurgical grade silicon, copper and silver from EOL c-Si PVs based on a literature review on the state-of-art recycling technologies. In the first recycling scenario (SCE1), a combination of thermal and mechanical treatment is applied, and in the second scenario (SCE2), the pretreatment only involves a mechanical processing based on electro-hydraulic fragmentation (EHF) technology. The material recovery after pretreatment in both scenarios is achieved by hydrometallurgical processing. A unit-level life cycle inventory (LCI) has been complied for both recycling scenarios with the mass and energy data obtained from process simulation using HSC Sim software and data collected from literature. The environmental impacts of two recycling scenarios were then subjected to a gate-to-gate life cycle assessment (LCA) in openLCA software. Six impact indicators are evaluated: freshwater eutrophication (EP), global warming (GWP), photochemical ozone creation potential (POCP), ozone depletion potential (ODP), terrestrial acidification potential (AP), freshwater consumption (FC). The LCA results indicate that SCE2 overall performs better than SCE1. SCE2 shows lower impacts than SCE1 in all the evaluated impact categories except GWP, though the GWP of SCE2 is still lower than that of the primary production of equivalent amounts of products by 36%. For EP, POCP, AP and FC, the avoided environmental burdens in SCE2 range from 88% to 99% of the equivalent primary production. The subdivided impacts of SCE2 allocated to MG-Si either by mass or by value are lower than the impacts of the equivalent primary production by 30% - 96% for all the evaluated impact indicators. Sensitivity and uncertainty analyses were also conducted for each recycling scenario, which showed that both scenarios are most sensitive to nitric acid consumption. Further LCA uncertainty analysis was performed via Monte Carlo simulation that indicated relative standard deviations of 21% to 32% (SCE1) and 23% to 26% (SCE2), respectively. According to the results of this work, both designed recycling scenarios have scope for improvement. For SCE1, efforts should be made to manage the thermal treatment emissions of organic compounds and nitrogen dioxide and to decrease acid/alkali consumption. For SCE2, further research is required to scale up the application of EHF technology on EOL PVs and to develop effective methods for recovering and purifying silicon afterward.
  • Item
    Scaling up innovative sustainable bio-based products: Case of Aalto University
    (2024-08-29) Hardjono, Vida; Ginting-Szczesny , Bernadetta; Kemian tekniikan korkeakoulu; Dessbesell, Luana
    Beyond its role in widespread education and research, academia has an important role in driving impact and creating positive changes in society. One vehicle for universities to create impact is through the creation of university spin-offs (USOs). With the global need for more sustainable, better alternatives for the current fossil products on the rise, the focus on exploring bio-innovations as alternatives is imminent. This study uncovers the academic research commercialization process, identifying pathway and the barriers and enablers of USOs manufacturing bio-based products to spinout. A cross-sectional qualitative study of seven bio-based USOs from Aalto University is done. Inductive-thematic analysis is used to analyze fourteen in-depth interviews with 7 Aalto University’s bio-based USOs are selected through the university’s research innovation services database. The findings confirms that the development process follows the 4-stage journey of spin-off theory, which includes 4 milestones: research, opportunity framing, finalizing venture projects and launching of spin-off firms. There are twenty-four identified barriers and enablers, with most are dominated by factors related to the business side of innovation commercialization. Barriers and enablers surround multidisciplinary teams, funding, market entry, and business models. Factors that are special in the case of bio-based innovations are the long development timeline, research and development challenges, and gap of funding for commercialization to scale-up manufacturing. LCA is mentioned as one of the enablers to communicate to investors and to align USOs with sustainable values. Factors that are found to emerge as important bottlenecks to tackle are challenges in IPR handling and funding gap they are correlated other identified barriers, such as hindrance in research and development, scaling up and market entrance. Acknowledging the technical complexity of bio-based innovations, through pre-incubation while supporting the development of technology-driven sustainability assessments is recommended to increase the chances of USOs in overcoming barriers in spinning out.
  • Item
    Oxidative precipitation of manganese from battery waste
    (2024-08-29) Tran, Hau; Vänskä, Jere; Budhathoki, Roshan; Kemian tekniikan korkeakoulu; Lundström, Mari
    As the number of electric vehicles has increased, the recycling of lithium-ion batteries has become an important process in promoting the circular economy. In hydrometallurgy, precious metals, such as cobalt, nickel, and lithium, have received wide attention, whereas manganese has been less studied. Recently, battery-grade manganese was added to the European Critical Raw Materials Act in 2023 to lessen the dependence on external supplies for this material. Therefore, this thesis presents an approach for the recovery of manganese from synthetic LIBs leaching solution by utilizing the SO2/O2 gas mixture. The application of this oxidizing mixture could enable a selective and low-cost removal of Mn. A range of parameters was examined, and the experiments were divided into two series to investigate the effect of high and low manganese concentrations (15.6 g/L and 4.5 g/L, respectively). The results of the study showed that 1) the kinetics was generally slow; 2) the parameters, namely SO2/O2 gas ratio, SO2/Mn molar ratio (and consequently, gas flowrates), addition of sodium persulfate, and Mn concentration affected the kinetics of Mn precipitation; 3) the redox from 900 to 950mV was where the oxidative precipitation took place; 4) under condition of 4% (v/v) SO2/O2 gas ratio, SO2/Mn ratio of 1.58, S2O8/Mn ratio of 1, pH of 3, and at 45°C, highest removal of Mn was obtained; 5) The kinetics of experiment drastically decreased when Mn concentration fell between 3900 and 4000 mg/L; and finally 6) the precipitates were amorphous and contained birnessite MnO2 (sigma-MnO2), and the co-precipitations of Co and Ni were ascribed to the adsorbing ability of MnO2. It should be noted that the pH of the solution was not constant due to manual pH adjustment, and it could have a significant impact on the kinetics of the precipitation.
  • Item
    Optimizing single-cell RNA sequencing atlas integration: A pipeline approach
    (2024-08-29) Assaf, Nour; Kilpinen, Helena; Puigdevall, Pau; Kemian tekniikan korkeakoulu; Lähdesmäki, Harri
    Single RNA-sequencing (scRNA-seq) has revolutionized our understanding of cellular diversity across various organisms and models. With the exponential rise in scRNA-seq data, the need for effective integration has become essential. However, challenges such as batch effects, computational limitations, and the lack of consensus on integration methodologies complicate the process. This thesis addresses these limitations to create a comprehensive neurodevelopmental atlas of fetal, 2D- and 3D-derived induced pluripotent stem cell (iPSC) neuronal populations. To achieve this atlas, this work evaluates and benchmarks various state-of-the-art integration tools to determine the most effective strategies for data integration while maintaining biological integrity using neuronal cell datasets from Velmeshev et al. 2023. We propose a combined pipeline that leverages both scVI and scPoli generative model methods to effectively mitigate batch effects while preserving biological signals. The final atlas resulted in well-integrated datasets with accurate cell type annotations, enabling downstream analysis on cell type composition in our neuronal differentiation protocol (Shi et al. 2012). Finally, this integration also allowed for the comparison of in vitro iPSC models to in vivo fetal data in terms gene expression, thus enhancing our understanding of the applicability of the models.
  • Item
    Comparative evaluation of antibacterial activity of chitosan-treated cellulosic non-woven
    (2024-08-29) Shrestha, Rekha; Tarhini, Ali; Kemian tekniikan korkeakoulu; Tehrani, Ali
    The treatment of nonwoven with bio-based antimicrobial agents such as chitosan has undergone intense investigation in recent times for a sustainable solution to combat pathogenic microorganisms. Furthermore, analyzing the antibacterial efficacy of treated textiles following standard test protocol with reproducible results is a bottleneck to evaluating the correlation of different molecular weights with varying concentrations of chitosan applied to surface treatment of cellulosic nonwoven. Thus, the purpose of this research study was to explore and compare the antimicrobial efficiency of nonwoven fabrics Escherichia coli strain ATCC 25922, treated with chitosan of low (30 kDa), medium (250 kDa), and high molecular weight (2,100 kDa) at four different concentrations (1, 5, 10, and 15 g/l) by pad-dry and dip-dry methods based on different standardized antimicrobial test methods for textiles. The deposition of chitosan onto the surface of cellulosic nonwoven was confirmed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The qualitative analysis of treated nonwoven was performed based on agar diffusion and quantitative antibacterial activity was calculated based on log reduction in bacterial colonies in control and treated samples after 24 hours of incubation time. The experimental results showed that chitosan is a non-leaching agent and cannot diffuse through agar while applied on cellulosic nonwoven fabric. All the tested samples showed excellent antimicrobial activity except pad-dry LMW 1g/l treated sample.
  • Item
    Development of solid oxide fuel cell and electrolyser system simulation tools
    (2024-08-29) Karvetti, Kai; Lehtinen, Timo; Kemian tekniikan korkeakoulu; Alopaeus, Ville
    The shift away from fossil fuels is necessary to avoid greenhouse gas emissions that cause climate change and damage to the environment. An attractive opinion towards carbon-free society is hydrogen economy. However, in today’s world, majority of hydrogen is produced from fossil fuels. Essential element towards widespread green hydrogen economy are efficient electrolysis and fuel cell technologies to sustainably produce, use and refine hydrogen. Solid oxide is among the most promising and up-and-coming fuel cell and electrolysis technologies due to high efficiency and effective process integration. In this thesis, solid oxide electrolysis system simulations were built to study the performance, heat balance and mass balance of the systems. The goal of the thesis was to validate a process simulation software, DWSIM, based on experimental data with another simulation software, Aspen Plus, and to create steady state simulation models of various solid oxide electrolysis system concepts with DWSIM. The results showed that both simulation software present very similar results and the differences were minimal. Therefore, it can be concluded that DWSIM is an appropriate tool for steady state simulation of solid oxide electrolysis systems. The simulation of the electrolysis system concepts displayed system efficiencies of 81%-91%, which are corresponding to commercially available solid oxide electrolysis systems.
  • Item
    Exploring the re-emergence of the lignin bioeconomy through systematic integration of business and technology practices
    (2024-08-29) Muratova, Madina; Stuart, Paul; Kemian tekniikan korkeakoulu; Dessbesell, Luana
    Lignin production and the advancement of lignin-based products at the commercial scale has slowed in recent years, however, will inevitably return in the context of the many valuable lessons learned in recent years. In this thesis, we capture the state-of-the-art related to the emerging lignin bioeconomy and describe a systematic methodology for developing a strategy to produce and valorize lignin at a kraft pulp or pulp and paper mill. We examine a policy scenario of green procurement for renewables in asphalt having a sunset date, concepts of rapid market analysis and phased implementation for reduced technology and market risk are placed in perspective. The systematic methodology is applied to a hypothetical case, where the importance of tailoring lignin to optimize its market value is highlighted, and the MetGen METNIN™ technology is used as a best-in-class technology to achieve this goal, and where phenol-formaldehyde (PF) resins substitution is a critical application for the near-term. The strategy includes transitioning from lignin as renewables in asphalt to PF resins, to a portfolio of ligninbased products, resulting in a robust lignin strategy resilient to technological and market shifts while seeking strong margins.
  • Item
    Recovery of caustic soda and side-products from the washing filtrates of the novel dissolving pulp process “StExCell” (steam-exploded cellulose pulp)
    (2024-08-29) Kuruppu Arachchige Dona, Udani Anupama; Sixta, Herbert; Lê, Huy Quang; Kemian tekniikan korkeakoulu; Hummel, Michael
    Steam explosion can be defined as an innovative pre -treatment technique of pulping that exposes wood chips to high pressure steam followed by rapid decompression to disrupt the cell wall structure, thus effectively extracting the hemicellulose and improving the accessibility of cellulose fibres to pulping chemicals in the subsequent stages. After steam explosion of the birch wood chips under pre-optimized conditions, the residual solid fraction was subjected to washing to extract the degraded, water-soluble wood components. The washing procedure of the steam-exploded wood was assessed and optimized by the Nordén model. The wash filtrate was analysed and further treated to isolate and valorize the extracted compounds. Rotary evaporation at 130 mbar and 60 °C to a target distillate collection of 35 wt.% was optimal for the furfural separation. The evaporated liquor was subjected to activated carbon adsorption with an optimum dose of 2 wt.% for the efficient removal of low molecular weight, reactive lignin fraction. The furfural and lignin-lean residue was subjected to acidic dehydration treatment (optimized at 200 °C for 7 minutes in 0.1M H2SO4) to degrade the remaining monomeric and oligomeric xylose to furfural, which was then isolated by another rotary evaporation. The steam exploded wood was subjected to mild caustic extraction (80 °C, 100 kg NaOH/t for 1 hour). A subsequent washing sequence was applied to primarily remove lignin which dissolves well in alkaline mediums. Membrane filtration with 0.5 kDa membranes was conducted to separate unreacted NaOH and lignin from the wash filtrate. Most of the extracted lignin remained in the retentate, while all NaOH had transferred to the permeate phase indicating a successful separation.
  • Item
    Characterising the effect of green fluorescent protein fusion on recombinant spider silk fibres
    (2024-08-29) Ahlberg, Martin; Sammalisto, Fred-Eric; Kemian tekniikan korkeakoulu; Linder, Markus
    Renewable biomimetic and bio-based materials are gathering increased interest as sustainable replacements for fossil man-made materials. Spider silk is a natural protein-based fibre that outperforms synthetic fibres, making it attractive for many applications. Industrial production of spider silk requires the use of recombinant protein technology, and functionalizing recombinant silk relies on the design of artificial silk proteins that form fibres on par with native silk. This requires knowledge about mechanisms underlying fibre assembly and how sequence structure relates to assembly and performance. Fluorescent marker proteins are sometimes used in such efforts, but the spinnability and mechanical properties of fusions are seldom tested. Moreover, developing silk with unique properties, like built-in colour at the molecular level, without hampering performance, would further boost its value. Three previously developed recombinant spider silk constructs were fused with the commonly used marker protein enhanced green fluorescent protein (eGFP). The three eGFP silk constructs were produced alongside their corresponding non-eGFP constructs either in shake flasks or in a bioreactor to assess the possibility of scale- up. Constructs were biomimetically spun into fibres with a wet spinning approach that only uses aqueous solutions, and fibres were tensile tested to compare the mechanical properties and behaviour of eGFP silk to non-eGFP silk. Spinning parameters were toggled to assess how eGFP silk behaves in different conditions and to evaluate if its performance could be improved by minor protocol alterations. The specific impact of eGFP on fibre structure and performance was evaluated. The eGFP silk variants were spinnable just as their corresponding non-eGFP variants and spinning yielded visibly green eGFP fibres. Mechanical testing revealed that eGFP silk behaves differently than non-eGFP silk and has inferior mechanical properties. Tweaking spinning conditions resulted in stronger eGFP fibres, but they were still weaker than non-eGFP ones. Reasons for differences could be dissimilar parameters used in spinning, which makes results demanding to compare, but also divergence in secondary structure, unfavourable intermolecular interactions, and steric hindrance, resulting from eGFP fusion.
  • Item
    Hydrogen and carbon production by thermo-catalytic decomposition of methane: catalyst and support optimisation
    (2024-08-29) Sonphasit, Jasmin; Kupila, Riikka; Kemian tekniikan korkeakoulu; Karppinen, Maarit
    The thermo-catalytic decomposition of methane presents a zero-emission and clean hydrogen source for various industries. The by-product, carbon, has potential applications in diverse fields, including batteries and composites. The use of catalysts significantly reduces the reaction temperatures, thereby decreasing the energy required for heating. This study examined the effects of calcination temperature, metal loading, and supports on the thermo-catalytic decomposition of methane. Twelve catalysts, with varying calcination temperatures, metal loadings, and supports, were analysed using temperature-programmed reduction (TPR) and X-ray diffraction (XRD). The produced carbon was examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Among the twelve catalysts, only one failed to produce any carbon. The calcination temperature influenced certain properties in a similar manner, such as crystallinity and particle size distribution. However, depending on the out-come of TCD reactions, the diameter, defects, and purity of the carbon nanofibers varied depending on the calcination and support used. The addition of a promoter metal caused the reduction to occur at lower temperatures and increased the diameter of the grown fibre. The promoter metal formed alloys with the main metal, resulting in full carbon nanofibers that were larger than those grown from the main metal, which had hollow tunnels. The study proved that none of the twelve catalysts were definitively superior, but some catalysts exhibited specific characteristics that made them suitable for certain carbon applications. From this perspective, the optimal catalysts and their proper-ties were selected to either produce the highest yield, least defected, purest, or a specific diameter of carbon nanofiber. In conclusion, this thesis provides insights into the effects of preparation parameters based on existing literature and completed research.
  • Item
    Development of low-CO2 emission cementitious composites using biochar
    (2024-08-29) Aura, Sarah; Hanafi, Mohamad; Kemian tekniikan korkeakoulu; Bordoloi, Sanandam
    Cement is a highly CO2 intensive material, with its production accounting for 7-8% of total global anthropogenic CO2 emissions (Andrew, 2019). In Finland, 90% of consumed cement is utilized for soil stabilization ground improvement applications (Kivi, 2021). Because Finnish soft clays are often characterized by low shear strength, soil stabilization is a necessary precursor to urbanization and infrastructure development. The purpose of this study was to explore the possibility of creating a low emission or even a CO2 neutral cementitious composite that still possesses necessary mechanical properties for soil stabilization applications. There were three main objectives for this research. First, the effect of binder type on compressive strength and CO2 absorption capacity of stabilized clay was assessed. Second, the effect of biochar type and binder replacement rate on compressive strength and CO2 absorption of stabilized clay was assessed. Third, the amount of CO2 which can be physio-chemically absorbed in the stabilized clay matrix through accelerated carbonation curing (ACC) treatment was measured. In this research, soft clay soil was combined with standard and low CO2 emission commercial binders to stabilize clay. These binders included KC50, the industry standard; as well as GTC and CEM III/B, which are relatively less carbon intensive. Different types of biochar were introduced as partial replacements for these binders to reduce their CO2 intensity. Half of the samples were carbonated by exposure to pressurized CO2 and the potential of CO2 sequestration was studied through a series of physiochemical tests. The samples were cured for varying lengths of time, either 7 or 28 days. After curing time was complete, unconfined compressive strength (UCS) testing followed by pH measurements and thermo-gravimetric analysis (TGA) were performed. The UCS results helped to determine the mechanical effects of carbonation on the undrained shear strength (Cu). A life cycle analysis (LCA) was completed to assess the life cycle stages with varying binder compositions as applied to an example case study. In this research, it was shown that biochar from beetle infested spruce trunks exhibited both greater strength qualities and sequestration potential than the biochars derived from waste wood or municipal sludge. Tree biochar also performed best with ACC treatment. This is likely due to its chemical composition which is rich in CaO when compared to the other biochars. The strength of samples containing GTC or CEM III/B were most negatively affected by ACC treatment. When these samples were analyzed visually after curing, they exhibited clear cracks in the surface which may have inhibited their internal curing ability. The completed LCA covered the different life cycle phases for an in-situ soil stabilization example. The results highlighted the strong impact of the binder emissions on the total net emissions.
  • Item
    Unwanted conversion of monoterpenes during industrially relevant conditions
    (2024-08-29) Ishtiaq, Shadab; Dou, Jinze; Kyllönen, Pia; Kemian tekniikan korkeakoulu; Vuorinen, Tapani
    Methanol is a widely used fuel that can be produced from renewable sources such as biomass, helping to reduce fossil fuel consumption and environmental impact. However, the purification of raw methanol produced during kraft pulping poses some challenges. Therefore, this thesis investigated the unwanted conversion of monoterpenes during the methanol purification process in a kraft pulp mill. In the experimental part, native from deposits were obtained and analysed, along with deposits produced at the laboratory scale. Soxhlet extraction yielded 46% of acetone-soluble deposits. Native and acetone-soluble deposits were analysed using NMR and GC-MS, which identified the presence of monoterpenes such as alpha-pinene incorporated by sulphur and nitrogen containing compounds. It shows non-volatile organic compounds (VOCs) might play important role in polymerization. Elemental analysis, XPS and FTIR provided complementary information indicating the presence of carbon-nitrogen and carbon-sulphur bonds. Solubility tests revealed that the precipitates have moderate polarity, and black precipitates were reproduced at the laboratory scale using in-methanol sample from the mill. Based on the analytical results and literature study, it is hypothesized that a general reaction mechanism involving the acid-catalysed polymerization of monoterpenes in the presence of H2SO4. The mechanism involves protonation, nucleophilic attack by sulphur compounds, oxidation, and nitrogen incorporation. Key parameters in the polymerization process include the presence of nucleophile, acidity, and residence time. Results indicated that monoterpenes, such as alpha-pinene, incorporated with nitrogen and sulphur, are the main precursors for the unwanted precipitates formed during the methanol purification process. These findings can further help in developing strategies to mitigate polymerization and optimize the process.
  • Item
    Implementation of modified quasichemical model to HSC Chemistry and validation
    (2024-08-29) Piironen, Jonna; Kruskropf, Ari; Malan, Willem; Kemian tekniikan korkeakoulu; Lindberg, Daniel
    The demand of metals is increasing, but at the same time the quality and quantity of the ores decreases. One way to address this issue is to advance already existing processes to decrease metal losses. Smelting processes experience dissolution of the metal to slag. This is an implicit aspect of the process, and it is dictated by the thermodynamic equilibrium of the system. The thermodynamic equilibrium of complex multicomponent solution can be modeled using Calphad methodology. This methodology utilizes solution models to optimize thermodynamic property data of the system. In this work, the Modified Quasichemical model is chosen as the solution model, since it allows description of short-range ordering and has adequate amount of assessed parameters for copper smelting available. Modified quasichemical model is implemented to the HSC Chemistry, and validated through relevant studies. The aim of this thesis is to model complex solutions of copper smelting, with elements that have more than one oxidation state in metal phase. This thesis does not address other phases or miscability gaps. This work elaborates on the activity calculation of binary solution. The activity coefficient of KCl in KCl-MgCl2 binary system was calculated in Excel, and the required equations are shown in this thesis. The calculation was validated with F*A*C*T calculation and emf measurement points from literature studies. Moreover, Cu-Fe-O-S and it's subsystems are modeled in metal phase and validated with literature studies. Calculating the activity coefficient of KCl and modeling the Cu-Fe-O-S system was successful.
  • Item
    Behaviour of trace elements in copper smelting operations
    (2024-08-29) Finnholm, Tessa; Klemettinen, Lassi; Tammela, Joonas; Kemian tekniikan korkeakoulu; Lindberg, Daniel
    Copper has a vital role in various industrial sectors, particularly in construction and electronics, driven by the escalating demand spurred by electrification. The increased focus on extracting higher-grade ores to enhance efficiency has led to a global decline in copper ore grades. Simultaneously, a rise in trace element concentration presents challenges for mines and smelters, necessitating a deeper understanding of trace element behaviour in copper smelting processes. This knowledge is deemed essential for optimizing operations, ensuring efficient recovery of valuable components, and eliminating harmful impurities. In addition, recognizing the geological background of raw materials is crucial for anticipating future challenges. In this thesis, the behaviour of trace elements in copper smelting operations was studied during flash smelting, converting, and anode furnace processes. In addition, the relation of raw materials to the geological origin was reviewed to identify potential future challenges faced by smelters. Focus will be on the distribution of trace elements (As, Pb, Zn, Se, Sb, Bi, and Co) between the matte and slag or blister and slag. Industrial samples were taken from Boliden Harjavalta smelter, and they were analysed in laboratories in Aalto University and Geological Survey of Finland. The microstructures of the samples were defined with scanning electron microscope with energy dispersive spectrometry (SEM-EDS), and the trace element concentrations were identified with electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The distribution coefficients were determined using the results from LA-ICP-MS. Zinc and cobalt showed strongest distribution to slag especially during converting, with coefficients of 0.04–0.1 and 0.39–0.43 in the FSF, 0.01–0.0008 and 0.2–0.0004 in the converter, and 0.001 and 0.001 in the anode furnace, respectively. Arsenic distributed quite evenly between matte/blister and slag in the FSF and anode furnace, with coefficients of 0.29–0.37 and 0.33, but more strongly to the matte in the converter (12.2–374). Lead also distributed evenly in the FSF with a coefficient 0.34–0.42, but more strongly to the slag in the converter and anode furnace, with coefficients of 0.005–0.58 and 0.001, respectively. Antimony deported to the slag in the FSF and anode furnace with distribution coefficients of 0.06–0.07 and 0.03, but more to the matte during converting, depending on the slag blow, with coefficients of 0.2–29. Bismuth deported to the matte in the FSF and converter (3.55–6.72 and 4.18–539), but somewhat evenly between blister and slag in the anode furnace (0.11). None of the distribution coefficients for selenium are exact due to some spot measurements being below detection limits, but it was confirmed that selenium distributes strongly in the matte in FSF and converter, and quite evenly between blister and slag in the anode furnace.