[diss] Kemian tekniikan korkeakoulu / CHEM
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Item Influence of viscosity on crystallization of sugars and sugar alcohols from aqueous solutions(Aalto University, 2024) Zaykovskaya, Anna; Louhi-Kultanen, Marjatta, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Chemical Engineering in Aqueous Systems; Kemian tekniikan korkeakoulu; School of Chemical Technology; Louhi-Kultanen, Marjatta, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, FinlandThis dissertation presents a detailed study on the crystallization of sugars and sugar alcohols, with a particular focus on the crucial role of viscosity in influencing process efficiency, crystal morphology, and product purity. The research covers various crystallization techniques, including cooling, evaporative, and antisolvent methods, applied to substances such as xylitol, α-D-galactose, glucose, erythritol, and xylose. High viscosity, especially in xylitol solutions, was found to impede crystallization by slowing nucleation and crystal growth. The addition of ethanol as an antisolvent effectively reduced viscosity by up to 40%, leading to more uniform crystals and improved filterability. In a laboratory-scale stirred reactor, optimal crystallization conditions for xylitol included a tip speed of 0.90 m/s and a temperature range of 40 °C to 25 °C. For α-D-galactose, a stepwise cooling method was most effective in managing high-viscosity industrial side streams. Moreover, the research expanded its focus to include other sugars and sugar alcohols, such as glucose, xylose, and erythritol, providing a broader understanding of how different viscosities impact crystallization dynamics. The stark contrast between lower viscosity of erythritol and xylitol's higher viscosity illustrated the direct correlation between viscosity and crystallization efficiency. Simulations demonstrated how elevated viscosity can reduce mass transfer rates and extend micromixing times. VisiMix simulations further provided valuable insights into the scale-up process, showing how changes in reactor size and mixing conditions influence crystallization dynamics in substances with varying viscosities. The dissertation also tackled the challenges of directly crystallizing xylitol from impure, viscous fermentation broths. Despite the complexities introduced by high viscosity due to impurities, the study developed effective methodologies, achieving xylitol crystal purity levels of up to 99% using chromatographic separation pretreatment. Overall, this dissertation emphasizes the importance of viscosity management in crystallization processes, offering insights that bridge the gap between laboratory research and industrial application. The findings highlight the critical role of viscosity in achieving efficient, high-purity crystallization in biorefinery applications.Item Electrodialysis for upgrading water streams in Kraft pulp mills(Aalto University, 2024) Gonzalez-Vogel, Alvaro; Joutsimo, Olli, Dr., Bioforest SpA., Chile; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Biobased Colloids and Materials; Kemian tekniikan korkeakoulu; School of Chemical Technology; Rojas, Orlando, Prof., Aalto University, Department of Bioproducts and Biosystems, FinlandThe sustainability of water resources has emerged as a relevant driving force in our economy, particularly for large industries. This concern is especially pertinent to water and energy-intensive mills, such as cellulose pulp industrial plants. Water scarcity is becoming increasingly prevalent, and prioritizing its consumption, along with adhering to stringent environmental regulations, makes this issue challenging to address. It remains essential to properly treat substantial volumes of effluents in these plants before discharging them, to minimize the environmental impact of such operations. To achieve this, mechanical and biological treatments are typically employed. Other water treatment technologies are often cost-prohibitive. However, in certain cases, it remains necessary to incorporate additional treatments for achieving water recirculation and chemical recovery. Otherwise, detrimental non-process elements could accumulate in the pulping process if water is recirculated. Alternatively, salts may be disposed of in water bodies or landfills unless they are converted into useful chemicals. Among various water treatment options, electrodialysis (ED) is a versatile technology capable of demineralizing effluent and internal streams, storing and recovering energy, and transforming salts into useful chemicals for reuse. However, ED encounters compatibility issues when treating effluents from cellulose pulp industrial plants, as organics in these streams cause fouling problems. In this thesis, additive manufacturing was used to improve hydraulics of ED systems, while power electronics was employed to address the fouling issue, enhancing the compatibility of ED for upgrading the water resources of Kraft pulp mills. New techniques allow the application of polarity reversal pulses on the order of kHz. By applying high-frequency pulses, turbulence mediated by electric fields are promoted, overcoming the system's limits imposed by the depletion of ions on the surface of the membranes, reducing not only fouling occurrence, but also membrane area requirement. ED and its variants were tested at both laboratory and pilot scale in industrial facilities, in conjunction with a device called the Asymmetric Bipolar Switch (ABS), which enabled the application of high-frequency pulses. Two variations of electrodialysis were tested at pilot scale, when coupled with the ABS, demonstrating improved operation by decreasing fouling over time and increasing productivity. The operations proved to be more robust when using the high-frequency pulses during tests spanning several weeks, enhancing ED compatibility. This advancement represents a significant step in surpassing the technical and cost barriers associated with electrodialysis in the effluent treatment of cellulose pulp industrial plants.Item Selective gold recovery from complex solutions via electrochemical deposition with redox replacement(Aalto University, 2024) Korolev, Ivan; Yliniemi, Kirsi, Senior University Lecturer, Aalto University, Department of Chemistry and Materials Science, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Hydrometallurgy and Corrosion; Kemian tekniikan korkeakoulu; School of Chemical Technology; Lundström, Mari, Assoc. Prof., Aalto University, Department of Chemical and Metallurgical Engineering, FinlandGlobal transition toward a carbon-neutral economy and broader use of renewable energy increases demand for raw materials and metals in particular, including gold. Despite gold cyanidation being the de facto industrial standard, concerns about its adverse effects on the environment and human health stimulated the search for alternatives. The electrodeposition-redox replacement (EDRR) method provides a unique possibility for selective, additive-free, and fully electrified metal recovery from complex industrial process streams. This dissertation investigates the recovery of gold from multimetal chloride solution by EDRR as a basis for non-cyanide technology for processing refractory gold ores. Initial EDRR experiments aimed to outline the detailed reaction mechanism of EDRR and study the effect of process variables using model gold and copper chloride solutions. Electroanalytical techniques, such as cyclic voltammetry, electrochemical quartz crystal microbalance, and rotating ring-disk electrode, were employed for this purpose. The quantity and quality of the produced gold deposits were analyzed with scanning electron microscopy, X-ray photoelectron spectroscopy and inductively coupled plasma mass spectrometry. The experiments with two-component solutions demonstrated the viability of EDRR: gold recovery of 94.4% was achieved in an 8.5-hour experiment, with the purity of the final product reaching 93.7 wt% Au. As part of the process upscaling effort, four alloys were evaluated as potential cathode materials for a large-scale process. The high corrosion resistance of the cathode material in the chloride leaching solution was found to inversely correlate with gold recovery and energy efficiency of the EDRR process due to electrode surface passivation. In a trade-off between performance and durability under typical EDRR conditions, the highly alloyed superaustenitic stainless steel 654SMO was selected as the optimal cathode material. In order to validate EDRR as a relevant gold recovery process, a continuous mini-pilot test was conducted involving leaching of refractory gold ore, filtration of the leach solution, recovery of metallic gold by EDRR and recycling of spent electrolyte. After 150 h of continuous operation, about 83% of the dissolved gold was recovered from solution onto the cathode. According to the process simulation results obtained using HSC Chemistry 10 software, the recirculation of intermediate streams within the flowsheet would increase the total gold recovery from the ore to the cathode up to 84%, exceeding that of the conventional cyanidation process. With the increasing affordability and availability of renewable energy, electrochemical metal recovery methods such as EDRR will become a feasible option to advance cyanide-free gold extraction technologies and reduce the carbon footprint of the extractive industry.Item Strategies to enhance the carbon yield from cellulose-based precursor fiber through blending with other bio-based polymers as charring agents(Aalto University, 2024) Zahra, Hilda; Sawada, Daisuke, Dr., Aalto University, Department of Bioproducts and Biosystems, Finland; Guizani, Chamseddine, Dr., Aalto University, Department of Bioproducts and Biosystems, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Biopolymer Chemistry and Engineering; Kemian tekniikan korkeakoulu; School of Chemical Technology; Hummel, Michael, Assoc. Prof., Aalto University, Department of Bioproducts and Biosystems, FinlandThe intrinsically low carbon yield upon cellulose pyrolysis is one major challenge in producing carbon fibers from cellulosic precursors. In this dissertation, chitosan and keratin, natural amino group−containing biopolymers, are utilized as natural charring agents to increase the yield of cellulose−based carbon fibers. Cellulose pulp was co−dissolved with chitosan or keratin in the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate, and then dry−jet wet spun via the so-called Ioncell® process. Thermogravimetric analysis showed that chitosan and keratin incorporation increased the char yield by >100 wt% and ~53 wt%, at ~21 wt% and ~30 wt% incorporation level, respectively. The role of chitosan and keratin as dehydration catalysts during cellulose pyrolysis up to 900 °C was confirmed through analysis of the volatile products. There was an enhanced production of water, CO2, and a reduced formation of levoglucosan. The change in the cellulose pyrolysis products was further seen in the increased production of several furanic compounds and acetic acid due to chitosan or keratin incorporation in the composite fibers. Mere physical contact between cellulose pulp and biopolymer powder did not alter the cellulose pyrolysis products, suggesting that close packing of the biopolymers in the composite fibers is needed for a synergistic interaction between cellulose and the additives during pyrolysis. Structural analyses revealed that chitosan was distributed homogeneously in the composite matrix. By contrast, keratin aggregates and open voids were found in the keratin composite fibers, leading to a suboptimum interaction between keratin and cellulose and, hence, a lower dehydration activity of keratin than chitosan. The same defects also led to a decrease in the mechanical properties of keratin-cellulose fibers. Chitosan and keratin introduced nitrogen to the composite- and resulting carbon fibers, respectively. The nitrogen might induce in-plane disorders in the aromatic carbon cluster, particularly at pyrolysis temperatures from 500 to 700 °C, but also promote the formation of crosslink structures due to the enhancement of the dehydration reaction. The cross-links increased the mechanical properties of carbon fibers derived from chitosan composite fibers, which can still be improved by further heat treatment such as higher carbonization temperatures. Open pores in the keratin composite fibers were also present in the resulting carbon fibers, resulting in fiber brittleness. However, nitrogen and open pores in carbon materials can be beneficial for electrochemical applications, with the possibility to tune them through tailored heat treatment protocols.Item Nanocellulose-Derived Hydrogels and Aerogels: Advanced Applications in Sustainable Technologies(Aalto University, 2024) Al Haj, Yazan; Kemian ja materiaalitieteen laitos; Department of Chemistry and Materials Science; Multifunctional Materials Design; Kemian tekniikan korkeakoulu; School of Chemical Technology; Vapaavuori, Jaana, Asst. Prof., Aalto University, Department of Chemistry and Materials Science, FinlandThe escalating demand for sustainable technologies in response to global environmental challenges necessitates the exploration of renewable resources. This thesis investigates the transformative potential of nanocellulose, a renewable, biodegradable material, by converting it into hydrogels and aerogels for advanced technological applications. Initial studies focus on processing techniques such as cross-linking, which enhances the mechanical and chemical properties of nanocellulose, enabling the fabrication of structures optimized for modern technologies. Subsequent experiments demonstrate that nanocellulose-derived materials substantially improve the performance of supercapacitors. By optimizing the electrode's pore structure and surface area, these materials enhance ion transport and charge retention, with a primary focus on the role of the anion. Empirical performance metrics indicate a significant increase in energy storage capacity compared to conventional materials. The same carbon material is further showcased in capacitive pressure sensors, where its inherent flexibility and sensitivity enhance real-time monitoring capabilities. A follow-up study develops hydrogel electrolytes using nanocellulose, where selecting the appropriate cation improves the mechanical properties of the electrolyte. Additionally, the unique acoustic absorption properties of nanocellulose cryogels open new avenues in noise reduction, effectively combining high performance with environmental sustainability. In conclusion, this research underscores the potential of nanocellulose in advancing material science and contributing to environmental sustainability. The use of renewable resources highlights nanocellulose's capability in transforming energy storage, real-time monitoring, and sound insulation. Despite challenges such as scalability and integration with existing manufacturing processes, the findings pave the way for future innovations in sustainable technology.Item Tailoring the Electrocatalytic and Supercapacitor Performance Through Materials Design and Nano-engineering(Aalto University, 2024) Soliman, Ahmed; Deska, Jan, Prof., Department of Chemistry, University of Helsinki, Finland; Kemian ja materiaalitieteen laitos; Department of Chemistry and Materials Science; NanoChemistry and NanoEngineering; Kemian tekniikan korkeakoulu; School of Chemical Technology; Elbahri, Mady, Prof., Aalto University, Department of Chemistry and Materials Science, FinlandThe development of efficient energy conversion and storage systems using electrochemical solutions heavily depends on selecting the right electrode material. This involves meticulously designing and tailoring the material's functionality to achieve the necessary surface and intrinsic interfacial characteristics. The aim of this thesis is to provide insights into electroactive material design criteria and offer a range of catalyst preparation methods to achieve this goal. The study has also delved into several fundamental catalysis and material synthesis aspects. In this context, we have demonstrated the versatile use of Lewis base-containing porous organic polymers as a dual-function support and stabilizer for a Pt single atomic/ionic active sites-based hydrogen evolution electrocatalyst, resulting in superior catalyst mass activity and utilization. Additionally, a highly efficient synergistic graphene-supported Ni(OH)2/Zr(OH)4 nano clusters-based oxygen evolution electrocatalyst was developed through the use of a sacrificial metal-organic framework as a pre-catalyst to regulate the release of active catalyst precursors. The thesis also explored the ability of Ag/PCA organic-inorganic hybrid catalyst material to control the oxygen reduction reaction pathway with enhanced selectivity towards peroxide formation, where such hybrid material was obtained through a novel bio-nanosynthesis route. The significant role of particle dispersity and proximity effects in evaluating CuO nanostructure-based electrocatalysts with pristine surfaces, obtained through the superior Leidenfrost nano synthesis technique, was also addressed. The studies in this work also investigated the overlooked role of the conjugate anions in controlling the nanocellulose-derived carbon aerogel microstructures and their impact on performance in EDLC electrodes. Furthermore, the study revisited the important role of surface wettability and the correlation between electrolyte selection and aerogel microstructure and surface characteristics in defining the EDLC active material performance.Item Applications of virtual laboratories in chemical engineering education(Aalto University, 2024) Viitaharju, Panu; Yliniemi, Kirsi Senior University Lecturer, Aalto University, Department of Chemistry and Materials Science, Finland; Nieminen, Minna-Hanna, University Lecturer, Aalto University, Department of Chemistry and Materials Science, Finland; Kemian ja materiaalitieteen laitos; Department of Chemistry and Materials Science; Inorganic Materials Modelling; Kemian tekniikan korkeakoulu; School of Chemical Technology; Karttunen, Antti, Prof., Aalto University, Department of Chemistry and Materials Science, FinlandThis doctoral thesis explores the use of virtual laboratories in chemical engineering education through various study setups including linearly and nonlinearly progressing virtual laboratories, expert interviews, and virtual laboratory experiences consumed through a VR headset. Results indicate that these virtual environments can enhance immersion and student motivation, yet do not necessarily lead to improved learning outcomes. In addition, students appear to have a faster boredom response towards virtual laboratory experiences when compared to traditional laboratory training. The findings reveal that virtual laboratories are not highly effective in replacing real-life laboratory education or in saving teaching resources but should be viewed as having potential for enhancing and enriching existing teaching practices. Virtual laboratories increase engagement, although the increase of immersion level might serve as a distraction rather than enhance learning outcomes. Furthermore, due to the cross-discipline requirements, financial commitments and sophisticated technical skills required for creating virtual laboratories, major resource challenges exist. The lack of established platforms and technological standards raises the threshold for developing and implementing these virtual labs on a wide scale. Additionally, the thesis identified a disagreement between some experts' views regarding the advantages of saving teaching resources against frequently quoted literature. Experts proposed diverse applications for virtual laboratories, from enhancing existing real-life laboratories to creating novel, otherwise impossible learning experiences. Therefore, it may be concluded that virtual laboratories should be considered not as a substitute, but as a complementary tool to traditional laboratory training. In the longer-term perspective, with rapid technological advancements and further research, virtual laboratories could offer more holistic and immersive virtual experiences, which might significantly contribute to the field of chemical engineering education.Item Stabilized Nickel Rich Layered Oxide Electrodes for High Performance Lithium-Ion Batteries(Aalto University, 2024) Ahaliabadeh, Zahra; Miikkulainen, Ville, Asst. Prof., Aalto University, Department of Chemistry and Materials Science, Finland; Mäntymäki, Miia, Dr., Helsinki University, Finland; Kemian ja materiaalitieteen laitos; Department of Chemistry and Materials Science; Electrochemical and Energy Conversion; Kemian tekniikan korkeakoulu; School of Chemical Technology; Kallio, Tanja, Prof. Aalto University, Department of Chemistry and Materials Science, FinlandThe rapid evolution of battery technology necessitates the exploration of innovative strategies to improve the electrochemical performance and lifespan of cathode materials in lithium-ion batteries. Nickel-rich layered transition metal oxides have emerged as promising candidates due to their high energy densities. However, practical application is hindered by issues such as accelerated degradation and capacity fade during cycling, attributed to structural changes and the reactivity of Ni4+ ions. This doctoral thesis focuses on optimizing coating strategies to overcome challenges associated with Ni-rich cathode materials in lithium-ion batteries. It highlights the significance of surface modifications in minimizing side reactions, boosting stability, and enhancing conductivity. Various coating techniques, including atomic layer deposition, physical vapor deposition, and wet chemistry approaches, are explored for their ability to create tailored conformal coatings. The research reveals the impact of atomic layer deposition coating characteristics, such as porosity, lithium diffusivity, chemical stability, and thickness, on the electrochemical performance of Ni-rich cathode materials. Experimental analyses and electrochemical experiments are conducted to develop and fine-tune coatings like Li fluoride, metal oxide, Li-containing metal oxide, and hybrid organic-inorganic films. These coatings aim to boost interfacial stability, suppress parasitic reactions, and improve lithium-ion diffusion of positive electrode materials. Key findings demonstrate that coatings with lithium and a 3D structure, coupled with increased porosity, exhibit superior performance in facilitating lithium-ion diffusion and mitigating capacity fade. Molecular layer deposition emerges as a promising technique for creating flexible coatings capable of accommodating volume changes in the electrode during cycling, thus enhancing battery longevity. Overall, this thesis introduces coating strategies for Ni-rich cathode materials for lithium-ion batteries, providing insights into revolutionary solutions for battery performance and next-generation energy storage systems. The research underscores the critical role of surface modifications in enhancing the efficiency, stability, and longevity of lithium-ion batteries, thereby addressing key challenges in transitioning to sustainable energy solutionsItem Synthesis of cellulose based self-sterilizing materials via solid-state reactions(Aalto University, 2024) Langerreiter, Daniel; Anaya-Plaza, Eduardo, Dr., Aalto University, Department of Bioproducts and Biosystems, Finland; Kaabel, Sandra, Prof., Aalto University, Department of Chemistry and Materials Science, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Biohybrid Materials; Kemian tekniikan korkeakoulu; School of Chemical Technology; Kostiainen, Mauri, Prof., Aalto University, Department of Bioproducts and Biosystems, FinlandAccording to the World Health Organization, antimicrobial resistance has become a major threat to global health, food security and social development in the past decades. Among the recently developed strategies to combat antimicrobial resistance, photodynamic inactivation shows a high potential due to its multi-organism efficiency, and ubiquitous activation via visible light. Single-use antimicrobial materials are particularly valuable in situations such as natural disasters, where power sources can be impossible to access. However, such materials rely on the sustainable synthesis of photosensitizers and their immobilization on suitable polymer matrices. Mechanochemistry, a method where solvent use is drastically reduced, offers environmentally friendly synthesis approaches to achieve these goals. Light-mediated self-sterilizing hybrid materials were developed in publication I. In two different synthesis approaches, toluidine blue was either covalently conjugated or physically adsorbed on (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibers. The results demonstrated that the covalent linked version outperforms the physically adsorbed one within the first 15 minutes under simulated sun irradiation. Next, an environmentally friendly method for chemical modification of cellulose nanocrystals (CNC) was developed in publication II. A mechanochemical approach allowed for the fast tosylation of both uncharged and charged CNCs, yielding a reactive cellulose intermediate that could be substituted with a nucleophile in a solid-state reaction, resulting in amine and ester derivates of CNCs. Incorporating both tosylation and nucleophilic substitution into a one-step mechanochemical method was beneficial for the esterification of cellulose, allowing to reduce the synthesis time to one hour and reduce the solvent usage by at least 10-fold. In publication III, a new method for synthesis of phthalocyanines, which are commonly used as photosensitizers, was developed. The method is based on solid-state synthesis, in which the crucial parameters were investigated systematically. This allows efficient upscaling and to reduce the amount of the high-boiling point organic solvents up to 100- fold. Overall, this thesis explored different aspects of developing a photoactive hybrid material and a production process of its components, with subsequent projects building upon one another. The results provide a comparison of cellulosic hybrid materials prepared via covalent linkage and physical adsorption, which can be used against multi resistant organisms. By using solid-state reactions and mechanochemistry, a new modification method for cellulose and a synthesis pathway for phthalocyanines were developed.Item Assembly of silk-like proteins towards functional bio-inspired materials(Aalto University, 2024) Yin, Yin; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Group of Biomolecular Materials; Kemian tekniikan korkeakoulu; School of Chemical Technology; Linder, Markus, Prof., Aalto University, Department of Bioproducts and Biosystems, FinlandProtein assembly plays a crucial role in the development of functional materials, leveraging the natural properties of proteins to create sophisticated, sustainable, and high-performance materials that meet the demands of diverse applications. Nature offers numerous examples of protein assembly into functional materials, such as silk and collagen. As a prevalent phenomenon in nature, liquid-liquid phase separation (LLPS) has been found involved in the organization and function of living cells and the formation of functional materials outside cells. LLPS is a process where certain mixtures undergo demixing, resulting in a solute-rich dense phase and a solute-poor dilute phase. The dense phase is often referred to as coacervates or condensates. LLPS has gained increasing attention for its significant implications for the design of biological materials. Understanding and exploiting the principles underlying protein assembly through LLPS are therefore important for the design and engineering of bioinspired materials in synthetic biosystems. This thesis work utilized recombinant silk-like proteins as the main building blocks and incorporated other components using the powerful SpyCatcher-SpyTag protein pair to develop strategies and provide insights for functional materials development through LLPS. Publication I investigated the role of coacervates and 3,4-dihydroxyphenylalanine (DOPA), two key features of marine mussel adhesion, on adhesion. This was achieved by incorporating silk-like proteins with mussel foot proteins, resulting in the development of a strong and tough adhesive. Publication II provided strategies for selective condensates that utilize the intrinsically disordered sequence derived from spider silk as a tag for recruiting client proteins into silk-like protein-based condensates. Publication III explored the effect of phosphate, an important element involved in spider silk formation, on silk-like proteins. This study revealed that phosphate induced β-sheet formation in silk-like proteins, stiffening the protein layers and reducing their ability to form new interactions, thereby impeding fiber formation for phosphate-induced coacervates. Publication IV further investigated the assemblies involved in LLPS for longer silk-like proteins and provided insights into the assembly pathway of these proteins. The results of this thesis provided strategies and insights for creating functional silk-like protein-based materials with specific properties, such as strong adhesives, selective condensates, and fibers. This research paves the way for future developments in biomaterials inspired by nature, highlighting the potential of protein-based materials in various applications.Item A step towards a circular economy: Processing waste effluents to acid and alkaline using ion exchange membrane electrodialysis(Aalto University, 2024) Kuldeep, Kuldeep; Kauranen, Pertti, Prof., LUT University, Finland; Kemian ja materiaalitieteen laitos; Department of Chemistry and Materials Science; Kemian tekniikan korkeakoulu; School of Chemical Technology; Murtomäki, Lasse, Prof., Aalto University, Department of Chemistry and Materials Science, FinlandThe rising global energy demand has boosted industrial production to new heights, especially in battery production sectors, which relies heavily on raw materials from the metallurgical and mining sectors. These sectors use sulfuric acid and sodium hydroxide in processing, thus generating large quantities of sodium sulfate as waste. This kind of effluent is not exclusive to hydrometal-lurgical or mining industries; precursors for cathode active material (pCAM) manufacturers are also producing it as a by-product, compounding environ-mental concerns if discharged improperly. Similar issues arise in the pulp & paper industry, where the kraft pulping process produces green liquor, con-taining chemicals like sodium carbonate (Na2CO3), sodium sulfide (Na2S), and NaOH. Addressing these effluents through salt valorization technologies (SVT) such as electrodialysis (ED) and bipolar membrane electrodialysis (BPED) is crucial for recycling valuable chemicals and supporting water reuse strategies, aligning with circular economy principles. These processes, however, are not completely novel in the field of industrial effluent treatment but still require further engineering and research to become more sustainable in long-term usage. In this perspective, thesis is focused on studies of ion exchange mem-branes, especially BPED of electrolytes containing sodium, sulfate, and car-bonate ions. To better understand the ionic transport across the ion exchange membrane, a finite element modelling tool is employed to reveal some novel insights at the macro-scale level that are impossible to discover from a large-scale system. This dissertation considers mainly four topics: (i) ion exchange membrane simulations, (ii) the importance of diffusion coefficients and their calculation for strong and weak electrolytes, (iii) streaming potential studies across the membranes and other porous materials, and (iv) finally the BPED technology.Item Rational design of nickel-based perovskite-type cathode for improved performance of protonic ceramic fuel cells(Aalto University, 2024) Yao, Penghui; Zhao, Yicheng, Prof., Tianjin University, China; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Research Group of Industrial Chemistry; Kemian tekniikan korkeakoulu; School of Chemical Technology; Li, Yongdan, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, FinlandProtonic ceramic fuel cells (PCFCs) are highly efficient and promising de-vices for energy conversion, offering a way to transform chemical energy directly into electricity. PCFCs operate at a temperature range 550-700 °C. However, PCFCs face numerous challenges. One of the most significant challenges is the slow oxygen reduction reaction (ORR) kinetics. Additionally, protons react with oxygen to produce water at the cathode. Thus, proton transfer is also necessary for cathode. To accelerate ORR kinetics and proton transfer of cathodes simultaneously, traditional perovskite materi-als are modified and optimized in this work. Some improvements have been achieved: Ni-doped La0.5Sr0.5MnO3-δ (LSM) cathode was synthesized with glycine sol-gel technique. The PCFC with La0.5Sr0.5Mn0.9Ni0.1O3-δ (LSMNi) cathode delivers a peak power density (Pmax) of 1.1 W cm-2 at 700 °C compared to LSM cathode (788 mW cm-2). LSMNi as cathode demonstrates promising stability over 220 h. Simulation results revealed Ni doping LSM cathode accelerated in both ORR kinetics and proton transfer. Ni-doped PrBaFe1.9Mo0.1O6-δ (PBFMN) cathode was prepared with EDTA-citric acid sol-gel technique. PBFMN consists of a predominant perovskite phase and a minor NiO phase. The composite cathode demonstrates exceptional catalytic activity and stability. The simulations reveal that the perovskite phase enhances oxygen vacancy and facilitates proton transfer, while the NiO phase enhances oxygen adsorption and dissociation. The fuel cell with PBFMN delivers a Pmax of 1230 W cm-2 at 700 °C. La0.8Sr0.2Co0.7Ni0.3O3-δ (LSCN) cathode was prepared through glycine sol-gel technique and evaluated as a cathode for PCFC. A single cell with LSCN cathode delivers a Pmax of 1620 mW cm-2 at 700 °C. The LSCN cathode also shows a good durability. La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) is widely used as cathode of SOFCs due to its high mixed ionic-electronic conductivity, but it faces challenges in PCFC due to slow proton transfer and sluggish ORR kinetics. The Pr2Ni0.5Co0.5O4−δ (PNC), consisting of a perovskite phase and a PrO2 phase, was impregnated onto LSCF surface to enhance the ORR activity and proton transfer. The PCFC with PNC-impregnated LSCF cathode delivers a Pmax of 1857 mW cm−2 at 700 °C. In this thesis, the traditional perovskite materials were modified and optimized to significantly improve the ORR kinetics of cathode in PCFC.Item Prospective life cycle assessment of hydrometallurgical cobalt processes for the battery value chain(Aalto University, 2024) Rinne, Marja; Elomaa, Heini, D.Sc., Metso, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Hydrometallurgy and Corrosion; Kemian tekniikan korkeakoulu; School of Chemical Technology; Lundström, Mari, Assoc. Prof., Aalto University, Department of Chemical and Metallurgical Engineering, FinlandThe environmental impact of electrification has been debated due to the considerable increase in consumption of metals such as cobalt, nickel, manganese, and lithium. Although cobalt can be partly substituted in electric vehicle batteries with metals such as nickel, it remains a critical metal for energy transition and its demand is projected to increase. The sustainable supply of cobalt is dependent on the diversification of sources, including both mining and recycling. The goal of this study was to assess the impacts of emerging primary cobalt and lithium-ion battery recycling processes using a simulation-based life cycle assessment approach, which enables the modeling of prospective scenarios in high detail. In this thesis, life cycle inventory data was obtained by simulating the selected flowsheets with HSC Sim software, and the impacts were calculated using GaBi. Scenario, contribution, and sensitivity analyses were used to aid interpretation of the results. Overall, six primary cobalt and four lithium-ion battery recycling scenarios were simulated based on several preliminary simulations that were used to guide flowsheet development. To be potentially industrially relevant, all scenarios utilize hydrometallurgical processing in sulfuric acid solutions. According to the results, higher grade feeds result in lower impacts during hydrometallurgical processing, and optimizing the leaching conditions may effectively decrease the impacts. Although maximizing cobalt recovery is recommended for primary cobalt, it was observed for lithium-ion battery recycling processes that some valuable losses may be justifiable if this means that milder conditions can be applied. The results also suggest that solvent extraction chemicals may contribute more significantly to the environmental impacts than previously thought, and there is a critical need for primary life cycle inventory data from extractant manufacturers. Simulation-based life cycle assessment was used to assess the impacts of the hydrometallurgical processing of cobalt-bearing raw materials in this research, but it is a suitable method for the evaluation of a wider array of raw materials and processes. The strength of the methodology lies in the ability to create high resolution inventories from limited experimental or literature data. However, it requires both metallurgical and life cycle assessment expertise to correctly justify assumptions and interpret the results for informed decision-making. This thesis presents the effect of some of the assumptions and process parameters in the impacts of hydrometallurgical processing and suggests improvements to further develop the studied processes.Item Innovations in Li-ion Battery Recycling: Advanced Physical Separation, Characterization, and Industrial Process Integration(Aalto University, 2024) Rinne, Tommi; Serna-Guerrero, Rodrigo, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Mineral Processing and Recycling; Kemian tekniikan korkeakoulu; School of Chemical Technology; Serna-Guerrero, Rodrigo, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, FinlandThe exponential growth in the electric vehicle market and the rising demand for sustainable energy storage solutions have resulted in a significant increase in the production rates of lithium-ion batteries (LIBs). Consequently, the demand for critical raw materials needed for LIB manufacturing (e.g., Co, Ni, Cu, graphite, and Li) is projected to increase rapidly in the coming years. Current industrial-scale recycling technologies, namely pyrometallurgy and hydrometallurgy, face limitations in processing end-of-life LIBs and recovering valuables from their active component mixtures (a.k.a., black mass). To overcome these limitations, this Thesis investigated the potential of froth flotation as a separation process for direct recycling of LIBs, an approach aimed at preserving the structural and chemical integrity of the anode and cathode active minerals (CAMs). The research comprised multiple campaigns ranging from fundamental understanding of flotation mechanisms to the integration of flotation in industrial processes. Firstly, a novel tomographybased methodology was developed to characterize flotation froths, thus providing insights into the extraction mechanisms of solid particles. A previously overlooked phenomenon was uncovered, where binder-free lithium cobalt oxide (LCO) particles were observed to be hydrophobized by a common oily collector – indicating a lack of collector selectivity. Another campaign focused on flocculation of CAMs, specifically demonstrating the potential for selectively flocculating LCO particles in mixtures with graphite. Building on these insights, a combined approach of selective flocculation and froth flotation was studied, showing promise in improving the selectivity of graphite separation from black mass through a CAM-selective flocculation pretreatment. Lastly, the integration of LIB recycling into existing industrial slag cleaning processes was studied. It was demonstrated that, in the presence of binder polymers, flotation can effectively separate an industrial black mass into a froth concentrate rich in active minerals and an underflow concentrate comprising current collector metals. Furthermore, the refining of these concentrates was successfully integrated with industrial Ni slag cleaning and Cu slag cleaning processes, revealing synergistic benefits. The integrated processes were found to be chemically self-sustaining, requiring no additional reductants for refining valuable metals Cu, Co, Ni, and Fe, although loss of Li, Al, and Mn to the slag phase was observed. In summary, this thesis presents a comprehensive investigation into advanced characterization and physical separation techniques for LIB recycling, with perspectives on industrial process integration. The findings contribute to the development of more efficient, cost-effective, and environmentally sustainable recycling methods. The studied methods are expected to address existing concerns associated with the growing demand for critical battery materials.Item Pectin Based Multifunctional Porous Materials and Polymer Composites(Aalto University, 2024) Dong, Yujiao; Vapaavuori, Jaana, Prof., Aalto University, Department of Chemistry and Materials Science, Finland; Kemian ja materiaalitieteen laitos; Department of Chemistry and Materials Science; Multifunctional Materials Design; Kemian tekniikan korkeakoulu; School of Chemical Technology; Vapaavuori, Jaana, Prof., Aalto University, Department of Chemistry and Materials Science, FinlandNowadays, the several environmental problems caused by urbanization and industrialization have become global issues. The request to develop more sustainable and economically viable materials and investigate the functional materials from sustainable resources has been growing steadily. The aim of this thesis is to investigate pectin as a raw material to fabricate multifunctional porous mate-rials and polymer composite, by deepening the understanding of pectin and consequently, broadening the potential application fields of pectin-based materials. The fundamental investigation of the correlation between the structure and properties of ionically crosslinked pectin hydrogels and aerogels with a minimal number of cations revealed what happens when the ionic crosslinking and junction zones start to be introduced in pectin solutions. A green and simple method, freeze-casting followed by freeze-drying was utilized to fabricate anisotropic pectin cryogels. Furthermore, the influence of preparation parameters, including pectin concentration, freezing temperature, and salt concentration, on the morphologies and properties of pectin cryogels was investigated. Furthermore, the functional performance of pectin-based porous materials and polymer composites was demonstrated. The anisotropic pectin cryogel exhibits good sound absorption with low thermal conductivity and outstanding mechanical properties. In addition, the freeze-casted anisotropic pectin cryogel is utilized as a matrix to infiltrate polymer solution. Anisotropic pectin cryogel infiltrated with poly(methyl methacrylate) resulted in an optically transparent composite with UV-blocking ability and thermal insulation properties. Infiltrating with phase change material (polyethylene glycol), on the other hand, leads to a pectin/polymer composite with energy storage ability and good optical properties. Combining the fundamental investigation and functional performance in this work, the great potential of pectin as a raw material towards practical applications, such as in the construction industry, has been illustrated.Item Modelling and simulation of biorefinery processes Case study: Kraft pulping process(Aalto University, 2024) Bijok, Nicolaus; Jakobsson, Kaj, D.Sc., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; School of Chemical Engineering; Kemian tekniikan korkeakoulu; School of Chemical Technology; Alopaeus, Ville, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, FinlandIn the pursuit of a sustainable economy, the transition from petroleum-based to renewable feedstocks like lignocellulose demands a profound understanding of its inherent complex character during chemical processing. However, established modelling approaches for the kraft pulping process omit certain aspects of the hierarchical complexity of the feedstocks in use. Hence, these models must be revisited and gradually substituted by more rigorous approaches that capture the variability across multiple scales. They often overlook the intrinsic variability in feedstock properties, such as chemical composition. While some models exist, they typically focus on predicting average behaviour, e.g., the resulting pulp's kappa number, neglecting the distributed nature of initially presented chemical components within the wood and differences in its fragmentation kinetics. This work proposes novel modelling frameworks to address these limitations, introducing the concept of the distributed character for the chemical components within wood chips and investigating the resulting non-uniform delignification at a fibre level regarding individual fibre kappa number distribution. Furthermore, the frameworks incorporate the threedimensional properties of the anisotropic raw material structure and distinguish between different regions within the wood chip, e.g. early- and latewood regions. Resulting of adjustments regarding the kinetics of the well-established Purdue kraft pulping kinetics, a new kinetic model was developed, considering the heterogeneous nature of the lignin macromolecule with its diverse structures on a monolignol resolution using a graph and network structure, which allows a deeper understanding of the processes during fragmentation. Ultimately, this research aims to contribute to developing more efficient and targetoriented processes for producing bioenergy and biomaterials. Leveraging advanced modelling techniques and discussing the modelling results in the context of recent experimental findings offers insights that can help in decision-making and drive the transition towards a more sustainable future.Item Sugar transport in Trichoderma reesei(Aalto University, 2024) Havukainen, Sami; Landowski, Christopher P., PhD, CTO, Onego Bio Ltd, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Kemian tekniikan korkeakoulu; School of Chemical Technology; Frey, Alexander D., Prof., Aalto University School of Chemical Engineering, Department of Bioproducts and Biosystems, FinlandFilamentous fungus Trichoderma reesei is well known for its high capacity to secrete proteins and is considered one of the most important fungal production hosts in the biotechnological industry. T. reesei has evolved to produce biomass-degrading enzymes as part of its saprotrophic lifestyle. These enzymes can be used in the production of second generation biofuels, which have been intensively studied as an alternative to fossil fuels. Similarly, the biomass-degrading enzymes of T. reesei and the improvement of their production, have been the subject of numerous studies. Less attention, however, has been paid to understand how T. reesei obtains nutrients, such as the various sugars released from the biomass by the aforementioned enzymes, from its environment. Transport of sugars across the cell membrane is crucial for many living organisms. Since sugars cannot simply diffuse through the membrane, their import is mediated by specialized transporter proteins. Although the genome of T. reesei has been predicted to code for many such proteins, only handful have been characterized in the literature. Given the wide variety of sugars derived from the biomass, many different sugar transporting activities are needed. Understanding of these processes would provide further insight into the physiology of this organism. Since the availability of sugars affects the production of biomass-degrading enzymes by T. reesei, the manipulation of sugar transport processes could be applied for strain improvement. The aim of this thesis was to characterize the most important members of T. reesei sugar transportome. Phylogenetics was employed to identify transporters for functional studies. Transporters were functionally characterized with two heterologous expression systems: yeast Saccharomyces cerevisiae and Xenopus laevis oocytes. Additionally, we manipulated the expression of some transporters in the native host to study their role in its physiology. This methodology allowed us to functionally characterize multiple T. reesei sugar transporters, including three which had not been described before. Importantly, we could demonstrate transport function for protein called CRT1, which has been shown to play a crucial role in the production of biomass-degrading enzymes. Another transporter, XLT1, was highly specific for L-arabinose and thus it could be potentially utilized for metabolic engineering of yeast for more efficient utilization of this sugar. Although expression of fungal sugar transporters in yeast is well-established, X. laevis oocytes have been seldomly used for this purpose. However, our results demonstrate that electrophysiological measurements which utilize X. laevis oocytes are powerful method for studying fungal sugar transporters. The obtained results provide valuable information about fungal sugar transporters. Unfortunately, we were not able to extend our analysis to study the roles of many of the identified transporters in T. reesei, or their applications to yeast metabolic engineering. There indeed remain many open questions to be answered by future studies.Item Interfacial Adsorption and Stabilization of Nanopolysaccharides in Multifunctional Emulsion Systems(Aalto University, 2024) Zhu, Ya; Rojas, Orlando, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland; Bai, Long, Dr., Aalto University, Finland; Siqi, Huan, Dr., Aalto University, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Kemian tekniikan korkeakoulu; School of Chemical Technology; Rojas, Orlando, Prof., Aalto University, Department of Bioproducts and Biosystems, FinlandThis thesis explores the roles of biobased polysaccharide nanoparticles, including cellulose nanofibrils (CNF), cellulose II nanospheres (NPcats) and chitin nanofibrils (NCh), as stabilizers of emulsion systems. We demonstrate the potential application of these emulsions in the development of advanced materials. The thesis discusses phenomena relevant to colloidal behaviors and adsorption of nanopolysaccharides at oil/water and water/water interfaces, in the form of Pickering emulsions. Variables relevant to the emulsion behaviors, including the particle's interfacial wetting properties, hydrophilicity, functional groups, electrostatic charge, axial aspect ratio and entanglement were evaluated by complementary characterization platforms. The complexation of two oppositely charged nanopolysaccharides, CNF and NCh, were demonstrated to effectively stabilize oil-in-water Pickering emulsions with adjustable droplet size and stability against creaming and oiling-off, imparting long-term stability and remarkable environmental tolerance. Likewise, driven by electrostatic interactions, tuning the mass and charge ratio of NPcat and bovine serum albumin (BSA), the formation of a soft and dense NPcat/BSA layer, is shown to enable the formation of dense NPcat/BSA interfacial layers, stabilizing water-in-water emulsions. Furthermore, NCh was used to formulate high internal phase Pickering emulsions (HIPPEs) through pre-emulsification followed by continuous oil feeding that facilitated a "scaffold" with high elasticity, which arrested droplet mobility and coarsening, achieving edible oil-in-water emulsions with a high internal phase volume fraction (as high as 88%). These green Pickering emulsions offer potential in applications relevant to foodstuff, pharmaceutical, and cosmetic formulations. Direct ink writing (DIW) was applied as a platform to engineer biobased Pickering emulsions to extend their applications. The HIPPEs were easily textured by leveraging their elastic behavior and resilience to compositional changes, making them suitable for 3D printing edible functional foods via DIW. Additionally, we structured emulsion stabilized by NCh (50% oil fraction) through onestep processing into hierarchically and spatially-controlled porous structures defined by emulsion droplet size, ice templating, and DIW infill density. The obtained scaffolds are demonstrated for their excellent modulation of cell adhesion, proliferation, and differentiation, as tested with mouse dermal fibroblast expressing green fluorescent proteins. Taken together, the findings in this thesis are of interest in developing and understanding fundamental emulsion stabilization mechanisms and advancing practical applications. The obtained green Pickering emulsion systems are expected to have an important role in food emulsions, encapsulation, pharmaceuticals, (bio)catalysis, and advanced synthetic cell mimetics.Item Evaluation of in vitro degradation and associated risks of novel biomaterials for implants(Aalto University, 2024) Bordbar-Khiabani, Aydin; Gasik, Michael, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Materials Processing and Powder Metallurgy; Kemian tekniikan korkeakoulu; School of Chemical Technology; Gasik, Michael, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, FinlandThe thesis explores innovative approaches to enhance the performance of orthopaedic metallic alloys by addressing the electrochemical behavior related to simulated post-implantation inflammatory conditions. The work comprises a detailed comparison between commercial purity titanium (Ti Group 2 alloy), Ti–6Al–4V alloy (Group 23) and novel Ti–Nb–Zr–Si (TNZS) alloy. Electrochemical studies include open circuit potential analysis, potentiodynamic polarization test, and electrochemical impedance spectroscopy (EIS), conducted in various media, mimicking normal, inflammatory, and severe inflammatory conditions. The major media differences were mimicked by varying concentration of H2O2, albumin, and lactate. The outcomes indicate i.a. a superior corrosion resistance of TNZS attributed to the presence of silicide phases. In addition, for Group 2 and Group 23 alloys this work examines the electrochemical behavior of additively manufactured (3D printed) patterned titanium layers made of titanium powder of the same composition. For this case, the results reveal an improved corrosion resistance in 3D patterned specimens compared to untreated titanium alloys surfaces. For analysis of more innovative methods of the improvement of the corrosion behavior of metallic alloys tantalum coated with trimanganese tetraoxide (Mn3O4) nanoparticles and 3D patterned titanium with alginate hydrogels laden with octacalcium phosphate (OCaP) particles were studies in these simulated inflammatory media. It was observed that electrophoretic deposition of Mn3O4 nanoparticles on anodized tantalum demonstrates superior corrosion protection for implants in acidic inflammatory conditions, and potential corrosion protection mechanism has been suggested, highlighting nanoparticles' catalytic activity and sealing role, offering valuable insights for developing corrosion-resistant implant materials. For hydrogel-coated titanium alloys, improved hydrophilicity and OCaP phase crystallinity were observed and an effective reduction of corrosion current density has been found, emphasizing the potential of such coatings to mitigate inflammatory-associated corrosion. This comprehensive work provides a combined understanding of metal alloys electrochemical behavior and corrosion resistance, offering novel insights and indicating potential advancements in biomedical materials for orthopedic and dental applications. The work was supported by EU Horizon 2020 project MSCA ITN "PREMUROSA" and has resulted in several peer-reviewed publications.Item Conformality of atomic layer deposition analysed via experiments and modelling: case study of zinc oxide for catalytic applications(Aalto University, 2024) Yim, Jihong; Puurunen, Riikka L., Assoc. Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Karinen, Reetta, D.Sc. (Tech.), Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Catalysis Research; Kemian tekniikan korkeakoulu; School of Chemical Technology; Puurunen, Riikka L., Assoc. Prof., Aalto University, Department of Chemical and Metallurgical Engineering, FinlandAtomic layer deposition (ALD) has been used in various applications including microelectronics and heterogeneous catalysts. Ideally, ALD enables the growth of homogeneously distributed materials on solid supports including high aspect ratio (HAR) structures. However, to ob-tain conformal ALD coatings on HAR structures, process conditions should be optimized. The goals of this work were (i) to develop and apply a zinc oxide ALD process to prepare diverse copper-zinc oxide on zirconia catalysts for carbon dioxide hydrogenation into methanol and (ii) to investigate the effect of various process parameters on ALD conformality. Zinc oxide was added on mesoporous zirconia and alumina particles by the reaction of zinc acetylacetonate in a fixed bed ALD reactor. After the reaction, the remaining acac ligands were oxidatively removed in synthetic air at elevated temperatures. The reaction of zinc acetylacetonate on zirconia showed self-terminating behavior with the areal number density of zinc of approximately two atoms per square nanometer. The steric hindrance of bulky acac ligands was likely a saturation-determining factor for zinc obtained by ALD. Meanwhile, an eggshell-type zinc coating was obtained on alumina, and the zinc loading increased when the reactant dose increased. A diffusion–reaction model adapted to spherical supports was used to simulate the effect of reactant exposure on zinc loading. In the simulation, the zinc loading increased with an increase in the reactant exposure. The simulation results fit well with the experimental results. The zinc-after-copper catalyst was superior compared to other copper-after-zinc or copper-only catalysts for carbon dioxide hydrogenation into methanol. The current research showed the importance of tuning of the interaction of zinc and copper for catalytic performance and demonstrated the potential of zinc acetylacetonate as an ALD reactant. For future ALD conformality studies, a benchmark was proposed using an archetypical trimethylaluminum-water process on lateral HAR microchannels. The effect of process parameters on ALD thickness profiles was investigated using a diffusion–reaction model. For example, penetration depth into microchannels decreased with an increase in the molar mass of ALD reactant and growth per cycle (GPC). The trends of ALD thickness profiles in the free molecular flow regime and transition flow regime were illustrated. This work proposes that the free molecular flow regime and channel filling of less than 5% are the conditions required to obtain fingerprint thickness profile characteristics.