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- Fijoł, Natalia, 1994-
(författare)
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3D printing of Green Water Purification Filters : Design towards Sustainable and Scalable Biocomposite Materials
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The globally escalating water pollution and water scarcity necessitates the development of efficient and sustainable water treatment technologies. This thesis investigates the feasibility of utilizing renewable and waste materials in the form of green composites for the fabrication of water purification filters via Fused Deposition Modelling (FDM).The first system studied within this thesis is based on the biobased thermoplastic polymer - polylactic acid (PLA), which serves as a composite matrix that is reinforced and functionalized with an array of green materials including fish-scale extracted hydroxyapatite (HAp), 2,2,6,6 – tetramethylpiperdine-1-oxyl (TEMPO) - oxidized cellulose nanofibers (TCNF), chitin nanofibers (ChNF), and bioinspired metal-organic framework – SU-101. All the developed PLA-based biocomposites exhibited great design flexibility and excellent printability, leading to the development of high surface-finish quality water purification filters of various geometries and porosity architectures. The developed filters successfully removed various contaminants from water. High capability for removal of metal ions from both, model solutions (reaching removal capacity towards Cu2+ ions of 208 mg/gNF and 234 mg/gNF for ChNF/PLA and TCNF/PLA filters, respectively, compared to only 4 mg/g for PLA filters), as well as from an actual mine effluent, reaching removal efficiency towards i.a. Mn2+ ions of over 50 % was demonstrated. Moreover, the developed TCNF/PLA and ChNF/PLA filters successfully removed microplastics from laundry effluent with over 70 % separation efficiency. The PLA-based biocomposite filters surface-functionalized with SU-101 were also suitable for the removal of cationic dye, methylene blue (MB), from water with removal efficiencies of over 40 %.The second composite system explored the possibility of using post-consumer polycotton textile waste as a functional entity for the polyethylene terephthalate glycol (PETG) matrix, for the fabrication of 3D printing filaments, which can be further processed into highly functional water purification filters by the FDM. The conducted TEMPO-mediated oxidation of the polycotton garments introduced negatively charged carboxylic groups onto the 3D printing filament’s surface and consequently, onto the 3D printed structures, yielding filters suitable for removal of cationic dyes, such as MB, from water.Apart from being evaluated for their ability to remove various contaminants from water, the filters have been subjected to a series of tests to assess the homogeneity of the filler dispersion in the polymer matrix as well as the filters’ permeability and mechanical stability. The high throughput character of the filters was demonstrated, as e.g., for the HAp/PLA filters the calculated flux reached 2x106 Lm-2h-1bar-1. The reinforcing impact of the nanospecies on the polymer matrix in the gradient porosity filters was investigated and so, it was shown that the addition of ChNF and TCNF fibers into PLA increases their Young’s modulus value from 550.7 ± 2.8 MPa, to 622.7 ± 1.6 MPa and 702.9 ± 5.4 MPa, respectively. Moreover, the lifespan of the filters was assessed by subjecting them to an accelerated ageing procedure in water, which have shown that the TCNF/PLA and ChNF/PLA filters could serve up to eight and five months, respectively, while maintaining their functionality and good mechanical performance. Furthermore, the study revealed that the filters are indeed biodegradable, as after prolonged exposure to water at elevated temperatures, they have fully disintegrated.Overall, the obtained results demonstrate the feasibility of combining renewable and recycled materials with 3D printing technology to create water purification filters suitable for the removal of a wide variety of contaminants from water.
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| 2. |
- Hadi, Seyed Ehsan, 1993-
(författare)
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Colloidal Processing and Alignment of Wood-Based Dispersions and Hybrid Functional Foams
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents novel methods and approaches for designing, preparing/fabricating, and characterizing wood-based nanomaterials. It investigates how modifications in structure, process variables, and composition can enhance functional properties. It employs advanced characterization techniques to analyze process-structure-property relationships and utilizes innovative colloidal processing approaches such as controlled nanoparticle incorporation, Layer-by-Layer self-assembly, and unidirectional ice-templating to improve the functional properties of wood-based nanomaterials.A novel approach has been developed to fabricate lightweight, highly porous hybrid foams using iron oxide nanoparticles (IONP) and TEMPO-oxidized cellulose nanofibers (TOCNF). The addition of tannic acid (TA) and the application of a magnetic field-enhanced unidirectional ice-templating technique (MFUIT) enhanced processability, mechanical, and magnetic characteristics of the foams. The hybrid foam containing 87% IONPs exhibited a saturation magnetization of 83.2 emu g–1, which is equivalent to 95% of the magnetization value observed in bulk magnetite.Hybrid, anisotropic foams have been prepared by incorporation of reduced graphene oxide (rGO) onto the macropore-walls of anisotropic TOCNF foams using a liquid-phase Layer-by-Layer self-assembly method. These hierarchical rGO-TOCNF foams exhibit lower radial thermal conductivity (λr) across a wide range of relative humidity compared to control TOCNF foams.The shear-induced orientations and relaxations of multi-component dispersions containing cellulose nanocrystals (CNC) and montmorillonite nanoplatelets (MNT) have been studied by rheological small-angle X-ray scattering (Rheo-SAXS). The addition of MNT resulted in gelation and changes in flow behavior, shear responses, and relaxation dynamics. Rheo-SAXS measurements showed that CNC and MNT aligned under shear, creating aligned structures that relaxed upon shear removal. Gaining insights into shear-induced orientations and relaxation dynamics can aid in the development of advanced wood-based nanocomposite materials.Transmission Electron Microscopy (TEM) was employed to characterize lignin oleate nanoparticles (OLNPs) derived from abundant lignin waste. TEM analysis revealed that the OLNPs had a spherical shape and a core-shell structure. Upon drying, the particles tended to agglomerate due to the loss of electrostatic repulsion forces. This agglomeration behavior indirectly supports the hypothesis that oleate chains act as a hydration barrier, preventing water permeation into the particles. Finally, a comprehensive study showed that TEMPO-oxidized lignocellulose nanofibers (TOLCNF)-based foams made from unbleached pulp can be used to prepare anisotropic, light-weight ice-templated foams with high mechanical strength. TOLCNF foams utilize lignin and hemicellulose to enhance properties while require less energy for production compared to TOCNF-based foams. This study emphasizes the potential for developing sustainable wood-based nanomaterials using TOLCNF.The results presented in this thesis offer valuable insights for further advancements of wood-based nanomaterials.
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| 3. |
- Schiele, Carina, 1993-
(författare)
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Multifunctional Foams Based on Nanomaterials from Plants and Textile Waste
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nanoparticles extracted from plants or textile waste are promising candidates for the design of sustainable materials. In this thesis, I explored how nanoparticles extracted from trees and from Kevlar and cotton textile wastes can be processed to form lightweight composite foams. The heat transfer and other functional properties such as electromagnetic shielding have been related to the structure, composition, and processing of the composite foams. Specifically, upcycled aramid nanofibers (upANFA) with a small diameter were derived from Kevlar yarn. The upANFA could be combined with wood-based cellulose nanofibrils (CNF) to produce moisture-resilient anisotropic foams with a very low thermal conductivity perpendicular to the aligned nanofibrils. The very low radial thermal conductivity was related to the strong interfacial phonon scattering between the very thin upANFA and CNF in the hybrid foam walls. Aqueous dispersions of multiwalled carbon nanotubes (MWCNT) and cellulose nanocrystals (CNC) were used to form anisotropic foams with an anisotropic heat transport and orientation-dependent electromagnetic interference shielding efficiency (EMI-SE). The low-density (31 kg m–3) CNC-MWCNT hybrid foams with 22 wt% MWCNT were mechanically robust along the axial direction (Young’s Modulus of 1200 kPa). The foams displayed an absorption-dominated EMI-SE of up to 41–48 dB and transferred heat favorably along the axial direction compared to the radial, meaning that this material could be useful in devices that require directional heat management and electromagnetic shielding.A novel wet-foaming with subsequent freeze-casting process was developed to produce air- and ice-templated foams based on methylcellulose, CNF, and tannic acid. The air- and ice-templated foams displayed a high specific compression stiffness compared with other CNF-based materials while maintaining good insulation properties. Hybrid foams based on CNC extruded from cotton textile waste and wood-based CNF were prepared by freeze-casting in combination with two different solvent removal routes: supercritical drying and freeze drying. The nanoparticles in the foam walls of the freeze-dried foams were more densely packed, and the foams were mechanically stiffer and more resistant to moisture, whereas the supercritically dried foams displayed a significantly larger surface area. This highlights how the processing techniques govern the structure of a material, which in turn affects its properties.
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