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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. |
- Ruiz-Caldas, Maria-Ximena, 1991-
(författare)
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Discarded Textiles as an Underexplored Source of Cellulose Nanomaterials : Processing, Properties, and Applications in Lightweight Materials
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The valorization of discarded clothing offers significant economic, social, and environmental benefits by repurposing waste and presents a major opportunity to reduce landfill burden while providing an alternative to virgin raw materials. This thesis explores the potential of discarded garments as a source of cellulose nanomaterials (CNMs).Sulfated cellulose nanocrystals (SCNCs) were extracted from cotton, polyester/cotton, and acrylic/cotton blends via sulfuric acid hydrolysis, with simultaneous recovery of the synthetic fibers. The properties of the highly pure extracted SCNCs were comparable to those from virgin cotton, despite the presence of textile dyes. A life cycle assessment (LCA) revealed a reduced environmental footprint for SCNC production using clothing rather than wood pulp as a feedstock.An alternative route for CNC extraction was developed: citric acid esterification and partial hydrolysis followed by mechanical fibrillation. This yielded citrated cellulose nanocrystals (CitCNCs) with carboxyl and citrated surface moieties, high crystallinity, a needle-like morphology, and a surface charge of 0.9 mmol g−1. The LCA identified the use of citric acid as the environmental hotspot for optimization, highlighting the importance of such assessments for guiding sustainable development from the laboratory scale.The versatility of cotton garments was explored by oxidizing them with NaClO and catalytic amounts of 2,2,6,6-tetramethyl-1-piperidinyloxy/NaBr, yielding TO-Cotton with a surface charge of 1.4 mmol g−1. The NaClO also degraded the cotton fabric dyes. TO-Cotton was treated in two ways to generate distinct CNMs. First, it was hydrolyzed with hydrochloric acid to obtain carboxylated cellulose nanocrystals (TCNCs) with an average surface charge of 1.1 mmol g−1 and a morphology similar to that of SCNCs. Second, TO-Cotton was mechanically fibrillated to yield carboxylated cellulose nanofibrils (TO-CNFs).To investigate the influence of textile functionalization on the final properties of CNFs, cotton garments were cationized using (2,3-epoxypropyl)trimethylammonium chloride to form Cat-Cotton, which was further fibrillated to yield Cat-CNFs. Both Cat-CNFs and TO-CNFs showed high surface charge (>0.9 mmol g−1), small cross-section (<10 nm), and high aspect ratio (>35). TO-CNFs were formed in higher yields and with a greater surface charge compared to Cat-CNFs. However, the Cat-CNFs possessed a higher aspect ratio and maintained colloidal stability over a wider pH range. Both CNFs were used to prepare nanopapers and foams, whose mechanical properties depended on the type of CNF.All three CNC types (SCNCs, CitCNCs, and TCNCs) were used to prepare anisotropic foams in combination with xanthan gum (XG). These foams exhibited minimal shrinkage after freeze-drying, high alignment, and excellent thermal stability. The CNC type influenced the foam properties: SCNC foams had the lowest water uptake, pristine CitCNC foams exhibited the best mechanical properties, and the incorporation of XG significantly enhanced the mechanical properties of TCNC foams.This thesis demonstrates the feasibility and potential of using post-consumer cotton fabrics as a feedstock for CNM production, indicating the versatility of the resulting CNMs in various applications.
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