The challenges posed by our limited clean water sources and the well-known global water pollution demand more efficient water purification technologies. Additionally, the increasing environmental awareness has inspired a shift towards eco-friendly and renewable materials and technologies. This thesis is focused on developing effective adsorbent materials from renewable resources to eliminate organic solvents, dyes, and metal ions from water. Cellulose, the most abundant biopolymer in nature, is the main component used to develop new materials in the present study. Its distinctive physical and colloidal properties, in the form of nanocellulose, along with tunable surface chemistry, play key roles in enhancing the effectiveness of the developed materials.

The primary focus of the first part of the thesis was to develop a molecular layer-by-layer modification technique to customize the surface functionality of cellulose aerogels in a uniform and controlled manner. Through the sequential deposition of diamine and triacid monomers, exceeding lythin polyamide coatings were formed on the cellulose aerogels, altering the surface properties from hydrophilic to hydrophobic. This transformation made them well-suited structures for oil-water separation.

Following this, a biohybrid aerogel was developed based on cellulose nanofibrils (CNFs) and amyloid nanofibrils (ANFs), the latter derived by heat treatment of β-lactoglobulin proteins. The pH-tunable surface charge of the aerogel, controlled by the amphiphilicity of the protein, allowed for the adsorption of both cationic and anionic contaminants by adjusting the pH of the solutions. Furthermore, the aerogels exhibited remarkable selectivity for lead (II) ions and they could also be regenerated and reused after each adsorption cycle without a significant loss of their adsorption capacity. This was to a large extent possible due to the excellent wet stability of these aerogels, which was achieved by crosslinking the CNFs during freezing and ice templating, eliminating the need for freeze-drying. However, a solvent exchange to acetone after melting was still necessary to reduce the influence of the capillary forces during drying to avoid the collapse of the aerogels. In a consecutive study, the foaming characteristics of the heat-treated β-lactoglobulin system were exploited to create highly stable Pickering foams with the aid of using CNFs as stabilizers and to physically lock the system through a controlled pH reduction. Interestingly, these Pickering foams could be directly oven-dried without collapsing, yielding low-density foams. Furthermore, it was demonstrated that the foams can be chemically crosslinked by incorporating chemical crosslinkers in the formulation or by pre-functionalizing the CNFs with dialdehydes. This crosslinking naturally also provided wet stability to the oven-dried foams.

Finally, an innovative and environmentally friendly method was introduced to increase the charge of cellulose fibers by radical polymerization of acrylic acid from the fibers, enabling the preparation of fibers with an exceptionally high charge of 6.7 mmol/g. The introduction of these charged groups significantly enhanced the interaction of the fibers with methylene blue as a model dye and lead (II), Copper (II), and Zinc (II) ions as model metal ions, showing the huge potential of these fibers as building blocks for a wide range of adsorbent applications. Overall, this thesis demonstrates the development and characterization of several bio-based adsorbents for water remediation.

De utmaningar som vi ställs inför på grund av den begränsade tillgången på rent vatten och de globala vattenföroreningarna har ökat behovet av nya och effektivare vattenreningstekniker. Dessutom har vårt ökade miljömedvetande uppmuntrat till en utveckling av miljövänliga och förnybara material och processer. Arbetet i denna avhandling har därför fokuserats på att utveckla effektiva adsorptionsmaterial, ifrån förnybara råvaror, för att eliminera organiska lösningsmedel, färgämnen och metalljoner ifrån olika vattenströmmar. Vi har valt att använda cellulosa, naturens vanligaste biopolymer, som basråvara i de nya material som utvecklats. Cellulosans utmärkta fysikaliska och kolloidala egenskaper, i form av nano-cellulosa, i kombination med en kontrollerbar ytkemi, har varit en grundförutsättning för att styra och kontrollera effektiviteten hos de utvecklade materialen.

Det primära syftet med den första delen av avhandlingen var att utveckla en molekylär skikt-för-skikt-modifieringsmetodik för att styra ytfunktionaliteten hos cellulosaaerogeler på ett jämt och kontrollerat sätt. Genom att sekventiellt belägga aerogelen med molekylära skikt av trimesoyl klorid(TMC) and m-xylylen diamin (MXD) skapades ytterst tunna polyamidbeläggningar på cellulosaaerogelerna, vilket omvandlade ytorna ifrån att vara hydrofila till att vara hydrofoba. De modifierade materialen visade sig väl lämpade att separera olja ifrån blandningar av vatten och olja.

Efter detta utvecklades en biohybridaerogel bestående av dels cellulosananofibriller (CNF) och dels av amyloidnanofibriller (ANF) som kunde prepareras genom en enkel värmebehandling av β-laktoglobulinprotein. Dessa aerogeler har en ytladdning som enkelt kan styras genom en pH-ändring och som beror av amfifiliteten hos det protein som används för att tillverka de ANF som används. Detta, i sin tur, gör det möjligt att adsorbera både katjoniska och anjoniska föroreningar och den mängd som kan adsorberas går att styra genom att ändra lösningarnas pH. Dessutom visade aerogelerna en anmärkningsvärd selektivitet för bly (II)-joner. Det visade sig också vara möjligt att regenerera och återanvända aerogelerna efter varje adsorptionscykel utan någon större förlust av deras adsorptionsförmåga. Grunden till detta var den utmärkta våtstabiliteten hos aerogelerna som skapdes genom att tvärbinda CNF:erna via en enkel frysning och smältning av vattenfasen, vilket eliminerade behovet av en kostsam frystorkning. För att minska inverkan av kapillärkrafterna under torkningen och för att undvika kollaps av aerogelerna visade det sig emellertid nödvändigt att använda ett lösningsmedelsutbyte till aceton efter smältningen. I en efterföljande undersökning utnyttjades skumningsegenskaperna hos det värmebehandlade β-laktoglobulinsystemet för att skapa mycket stabila sk. Pickering-skum genom att använda CNF:er som stabilisatorer och för att fysiskt låsa skummet genom en kontrollerad pH-sänkning. Intressant nog visade det sig också vara möjligt att ugnstorka dessa Pickering-skum utan att kollapsa strukturen, vilket resulterade i skummer med lågdensitet. Det visade sig också vara möjligt att kovalent låsa skummet genom att inkorporera kemiska tvärbindare i skum-formuleringen eller genom att förse den CNF som användes med dialdehydfunktionalitet. Denna tvärbindning gav också våtstabilitet åt de ugnstorkade skummerna.

Slutligen utvecklades en innovativ och miljövänlig metod för att öka laddningen hos cellulosarika fibrer och för att samtidigt skräddarsy fibrerna för en följande ymppolymerisation av akrylsyra till demodifierade fibrerna. Detta gjorde det möjligt att preparera fibrer med en exceptionellt hög laddning av 6,7 mmol/g. Med hjälp av denna höga laddningstäthet visade det sig att fibrerna hade en utmärkt förmåga att adsorbera metylenblått, som modellfärgämne, och bly (II), koppar (II) och zink (II) joner som modellmetalljoner. Detta visar också på den enorma användarpotential dessa högmodifierade fibrer har i olika typer av adsorbentapplikationer.

The advent of diffraction-limited storage rings (DLSRs) has boosted the brilliance or coherent flux by one to two orders of magnitude with respect to the previous generation. One consequence of this brilliance enhancement is an increase in the flux density or number of photons per unit of area and time, which opens new possibilities for the spatiotemporal resolution of X-ray imaging techniques. This paper studies the time-resolved microscopy capabilities of such facilities by benchmarking the ForMAX beamline at the MAX IV storage ring. It is demonstrated that this enhanced flux density using a single harmonic of the source allows micrometre-resolution time-resolved imaging at 2000 tomograms per second and 1.1 MHz 2D acquisition rates using the full dynamic range of the detector system.

Achieving a sustainable foam production requires a complete substitution of synthetic components with natural and renewable alternatives, as well as development of an environment-friendly production process. This work demonstrates a synergetic combination of heat-treated beta-lactoglobulin proteins and cellulose nanofibrils (CNFs) to create fully bio-based and highly-stable wet foams. Furthermore, a gradual reduction in the pH, enabled oven-drying of the wet foams without any major structural collapse of the foam, resulting in the preparation of lightweight solid foams with the density of 10.2 kg.m(-3). First, the foaming behavior of heat-treated beta-lactoglobulin systems (HBSs) containing amyloid nanofibrils (ANFs) and non-converted peptides was investigated at different pHs. Subsequently, the HBS foams were stabilized using CNFs, followed by a gradual acidification of the system to a final pH of 4.5. To gain a deeper understanding of the stabilization mechanism of the foam, the interactions between the foam's components, their positioning in the foam structure, and the viscoelasticity of the fibrillar network were investigated using quartz crystal microgravimetry, confocal microscopy and rheology. The analysis of the obtained data suggests that the stability of the foams was associated with the accumulation of CNFs and ANFs at the air-water interface, and that the concomitant formation of an intertwined network surrounding the air bubbles. This together resulted in a significant decrease in drainage rate of the liquid in the foam lamellae, bubble coarsening and bubble coalescence within the foams. The results also show that the major surface-active component participating in the creation of the foam is the free peptide left in solution after the formation of the ANFs. A slow reduction in pH to 4.5 lead to further gelation of the fibrillar network and an improved storage modulus of the foam lamellae. This resulted in a strong coherent structure that could withstand oven-drying without collapse. The density, porosity, microstructure and compressive mechanical properties of such prepared dry foams were assessed. Overall, the results demonstrate the potential of HBSs to replace synthetic surfactants and outlines a sustainable preparation protocol for the preparation of light-weight porous composite structures of ANFs and CNFs.

The fabrication of reusable, sustainable adsorbents from low-cost, renewable resources via energy efficient methods is challenging. This paper presents wet-stable, carboxymethylated cellulose nanofibril (CNF) and amyloid nanofibril (ANF) based aerogel-like adsorbents prepared through efficient and green processes for the removal of metal ions and dyes from water. The aerogels exhibit tunable densities (18-28 kg m-3), wet resilience, and an interconnected porous structure (99% porosity), with a pH controllable surface charge for adsorption of both cationic (methylene blue and Pb(II)) and anionic (brilliant blue, congo red, and Cr(VI)) model contaminants. The Langmuir saturation adsorption capacity of the aerogel was calculated to be 68, 79, and 42 mg g-1for brilliant blue, Pb(II), and Cr(VI), respectively. Adsorption kinetic studies for the adsorption of brilliant blue as a model contaminant demonstrated that a pseudo-second-order model best fitted the experimental data and that an intraparticle diffusion model suggests that there are three adsorption stages in the adsorption of brilliant blue on the aerogel. Following three cycles of adsorption and regeneration, the aerogels maintained nearly 97 and 96% of their adsorption capacity for methylene blue and Pb(II) as cationic contaminants and 89 and 80% for brilliant blue and Cr(VI) as anionic contaminants. Moreover, the aerogels showed remarkable selectivity for Pb(II) in the presence of calcium and magnesium as background ions, with a selectivity coefficient more than 2 orders of magnitude higher than calcium and magnesium. Overall, the energy-efficient and sustainable fabrication procedure, along with good structural stability, reusability, and selectivity, makes these aerogels very promising for water purification applications.

Cellulose nanofibril-based aerogels have promising applicability in various fields; however, developing an effi-cient technique to functionalize and tune their surface properties is challenging. In this study, physically and covalently crosslinked cellulose nanofibril-based aerogel-like structures were prepared and modified by a mo-lecular layer-by-layer (m-LBL) deposition method. Following three m-LBL depositions, an ultrathin polyamide layer was formed throughout the aerogel and its structure and chemical composition was studied in detail. Analysis of model cellulose surfaces showed that the thickness of the deposited layer after three m-LBLs was approximately 1 nm. Although the deposited layer was extremely thin, it led to a 2.6-fold increase in the wet specific modulus, improved the acid-base resistance, and changed the aerogels from hydrophilic to hydrophobic making them suitable materials for oil absorption with the absorption capacity of 16-36 g/g. Thus, demon-strating m-LBL assembly is a powerful technique for tailoring surface properties and functionality of cellulose substrates.