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Sökning: hsv:(TEKNIK OCH TEKNOLOGIER) hsv:(Kemiteknik) > RISE

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1.
  • Palme, Anna, 1986, et al. (författare)
  • Development of an efficient route for combined recycling of PET and cotton from mixed fabrics
  • 2017
  • Ingår i: Textiles and Clothing Sustainability. - : Springer Science and Business Media LLC. - 2197-9936. ; 3:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Most textile waste is either incinerated or landfilled today, yet, the material could instead be recycled through chemical recycling to new high-quality textiles. A first important step is separation since chemical recycling of textiles requires pure streams. The focus of this paper is on the separation of cotton and PET (poly(ethylene terephthalate), polyester) from mixed textiles, so called polycotton. Polycotton is one of the most common materials in service textiles used in sheets and towels at hospitals and hotels. A straightforward process using 5–15 wt% NaOH in water and temperature in the range between 70 and 90 °C for the hydrolysis of PET was evaluated on the lab-scale. In the process, the PET was degraded to terephthalic acid (TPA) and ethylene glycol (EG). Three product streams were generated from the process. First is the cotton; second, the TPA; and, third, the filtrate containing EG and the process chemicals. The end products and the extent of PET degradation were characterized using light microscopy, UV-spectroscopy, and ATR FT-IR spectroscopy, as well as solution and solid-state NMR spectroscopy. Furthermore, the cotton cellulose degradation was evaluated by analyzing the intrinsic viscosity of the cotton cellulose. The findings show that with the addition of a phase transfer catalyst (benzyltributylammonium chloride (BTBAC)), PET hydrolysis in 10% NaOH solution at 90 °C can be completed within 40 min. Analysis of the degraded PET with NMR spectroscopy showed that no contaminants remained in the recovered TPA, and that the filtrate mainly contained EG and BTBAC (when added). The yield of the cotton cellulose was high, up to 97%, depending on how long the samples were treated. The findings also showed that the separation can be performed without the phase transfer catalyst; however, this requires longer treatment times, which results in more cellulose degradation.
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2.
  • Bergvall, Niklas, et al. (författare)
  • Slurry Hydroconversion of Solid Kraft Lignin to Liquid Products Using Molybdenum- and Iron-Based Catalysts
  • 2022
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 36:17, s. 10226-10242
  • Tidskriftsartikel (refereegranskat)abstract
    • Kraft lignin is an abundantly available and largely underutilized renewable material with potential for production of biobased fuels and chemicals. This study reports the results of a series of slurry hydroprocessing experiments with the aim of converting solid Kraft lignin to liquid products suitable for downstream refining in more conventional reactors. Experiments reported in this study were conducted by feeding a lignin slurry to an already hot, liquid-filled reactor to provide momentaneous heating of the lignin to the reaction temperature. This modified batch procedure provided superior results compared to the regular batch experiments, likely since unwanted repolymerization and condensation reactions of the lignin during the heating phase was avoided, and was therefore used for most of the experiments reported. Experiments were performed using both an unsupported Mo-sulfide catalyst and Fe-based catalysts (bauxite and hematite) at varied reaction temperatures, pressures, and catalyst loadings. The use of Mo-sulfide (0.1% Mo of the entire feed mass) at 425 °C and 50 bar resulted in complete conversion of the Kraft lignin to nonsolid products. Very high conversions (>95%) could also be achieved with both sulfided bauxite or hematite at the same temperature and pressure, but this required much higher catalyst loadings (6.25% bauxite or 4.3% hematite of the total feed mass), and around 99% conversion could be achieved at higher temperatures but at the expense of much higher gas yields. Although requiring much higher loadings, the results in this study suggest that comparatively nonexpensive Fe-based catalysts may be an attractive alternative for a slurry-based process aimed at the hydroconversion of solid lignin to liquid products. Possible implementation strategies for a slurry-based hydroconversion process are proposed and discussed.
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3.
  • Hedayati, Ali, 1984, et al. (författare)
  • Experimental evaluation of manganese ores for chemical looping conversion of synthetic biomass volatiles in a 300 W reactor system
  • 2021
  • Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437 .- 2213-2929. ; 9:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Two manganese ores with different iron content were investigated as oxygen carriers for chemical looping conversion of simulated biomass volatiles. The aim was to study the performance of the oxygen carriers with regards to combustion and potential use for chemical-looping gasification of wood-based biomass. The oxygen carriers were studied in a 300 W chemical-looping reactor system with circulation of oxygen carriers between the fluidized air and fuel reactors. The temperature was 850-900 °C and the fuel flow rates were 0.6-3 Lmin-1. The Mn ore with higher iron content showed significant oxygen release at 900 °C under inert conditions, as well as full conversion of CO, H2 and methane at low fuel flow. The other Mn ore showed little methane conversion and poorer conversion of the other gases when compared at similar fuel flows. However, the gas composition attained was rather similar if compared for a similar overall gas conversion. Nonetheless, a slightly higher syngas fraction and H2 to CO ratio in the product stream was obtained with the Mn ore with lower iron content. In all cases the syngas fraction in the product gas increased with temperature and fuel flow. The formation of fines (attrition rate), particle size distribution, and the bulk density of the oxygen carriers were measured to evaluate their mechanical properties during chemical looping of biomass volatiles.
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4.
  • Hedayati, Ali, 1984, et al. (författare)
  • Thermochemical conversion of biomass volatiles via chemical looping: Comparison of ilmenite and steel converter waste materials as oxygen carriers
  • 2022
  • Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 313
  • Tidskriftsartikel (refereegranskat)abstract
    • Two oxygen carriers were tested with respect to chemical looping combustion (CLC) and chemical looping gasification (CLG). Ilmenite, a natural ore composed mainly of iron–titanium oxide, and LD Slag, an iron-based industrial waste, were investigated at 850 and 900 °C in a continuous operation in a 0.3 kW chemical-looping reactor system using synthetic biomass volatiles as fuel. CLC and CLG conditions were simulated in the fuel reactor by changing the fuel flow rates. In the case of ilmenite the syngas yield and methane conversion increased with fuel flow rate. Consequently, the syngas to hydrocarbon ratio was higher for ilmenite. Methane conversion improved for both tested oxygen carriers with increasing the operating temperature. Oxygen release was observed in the case of LD Slag. The H2/CO ratio was between 0.7 and 0.8 for both oxygen carriers at the higher fuel flows. With respect to CLC, ilmenite showed higher gas conversion than LD slag. Analysis of the particles revealed that ilmenite possessed better mechanical properties and formed less dust compared to LD Slag during the continuous operation with fuel.
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5.
  • Mei, Daofeng, 1986, et al. (författare)
  • Reactivity and lifetime assessment of an oxygen releasable manganese ore with biomass fuels in a 10 kW th pilot rig for chemical looping combustion
  • 2021
  • Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 215
  • Tidskriftsartikel (refereegranskat)abstract
    • Finding a suitable oxygen carrier is crucial for the development of Chemical Looping Combustion (CLC). A new manganese ore was tested with different biomass fuels in a recently commissioned 10 kWth unit. The ore maintains the capability of generating O2 gas in N2 after continuous operations with the fuels, however, the concentration was relatively low within 0.45–1.0 vol% at 820 to 975 °C. Influence of temperature, solids circulation and fuel power was examined for different fuels. Temperature increase enhances the carbon capture and reduces the oxygen demand, while the solids circulation and fuel power should be carefully controlled. Using biomass char the oxygen demand can be lowered to 2.6% while the carbon capture was close to 99%. The manganese ore showed a higher reactivity than the often-used ilmenite. Thus, a decrease of 8–10% in oxygen demand was achieved by using the manganese ore in comparison to ilmenite. During the 42 h of hot operation, defluidisation was not observed. Based on the analysis of the 35 fine samples collected, the initial attrition after first hours of operation was high, but gradually decreased to a relatively stable value of 0.27 and 0.12 wt%/h for hot and fuel operations, respectively, corresponding a lifetime of 370–830 h.
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6.
  • Sauer, Christopher, 1993, et al. (författare)
  • Valorisation of 2,5-dimethylfuran over zeolite catalysts studied by on-line FTIR-MS gas phase analysis
  • 2022
  • Ingår i: Catalysis Science & Technology. - : Royal Society of Chemistry. - 2044-4753 .- 2044-4761. ; 12:3, s. 750-761
  • Tidskriftsartikel (refereegranskat)abstract
    • The valorisation of 2,5-dimethylfuran (2,5-dmf) by catalytic fast pyrolysis (CFP) was studied by on-line FTIR-MS gas phase analysis. Zeolite beta, H-ZSM-5 and Cu-ZSM-5 were characterised and used as catalysts. The on-line analysis enables sufficient time resolution to follow subminute transient phenomena, e.g., the impact of catalyst pretreatment and time on stream (TOS) on the reaction selectivity. The results show, that the initial selectivity towards benzene, toluene and xylene (BTX) aromatics is high but decreases with TOS while the isomerisation rates of 2,5-dmf towards 2,4-dimethylfuran and cyclic ketones increase. This indicates the involvement of specific active sites for the different conversion processes. The formation of BTX compounds is linked to the availability of specific olefins, as supported by temperature programmed desorption experiments, which is indicative of aromatisation stemming directly from the olefin pool rather than via Diels-Alder reactions. 
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7.
  • Andersson, Helene, 1983, et al. (författare)
  • Effects of molecular weight on permeability and microstructure of mixed ethyl-hydroxypropyl-cellulose films
  • 2013
  • Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 48:1-2, s. 240-248
  • Tidskriftsartikel (refereegranskat)abstract
    • Films of ethyl cellulose (EC) and water-soluble hydroxypropyl cellulose (HPC) can be used for extended release coatings in oral formulations. The permeability and microstructure of free EC/HPC films with 30% w/w HPC were studied to investigate effects of EC molecular weight. Phase separation during film spraying and subsequent HPC leaching after immersion in aqueous media cause pore formation in such films. It was found that sprayed films were porous throughout the bulk of the films after water immersion. The molecular weight affected HPC leaching, pore morphology and film permeability; increasing the molecular weight resulted in decreasing permeability. A model to distinguish the major factors contributing to diffusion retardation in porous films showed that the trend in permeability was determined predominantly by factors associated with the geometry and arrangement of pores, independent of the diffusing species. The film with the highest molecular weight did, however, show an additional contribution from pore wall/permeant interactions. In addition, rapid drying and increasing molecular weight resulted in smaller pores, which suggest that phase separation kinetics affects the final microstructure of EC/HPC films. Thus, the molecular weight influences the microstructural features of pores, which are crucial for mass transport in EC/HPC films.
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8.
  • Gårdebjer, Sofie, 1985, et al. (författare)
  • Using Hansen solubility parameters to predict the dispersion of nano-particles in polymeric films
  • 2016
  • Ingår i: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954 .- 1759-9962. ; 7:9, s. 1756-1764
  • Tidskriftsartikel (refereegranskat)abstract
    • We suggest a rough and straightforward method to predict the dispersibility of modified cellulose nanocrystals (CNC) in nanocomposites using Hansen solubility parameters (HSP). The surface of CNC was modified using a novel approach where Y-shaped substituents with two different carbon chain lengths were attached to the surface. Approximate HSP values were calculated for the modified CNC, and dispersions of unmodified and modified CNC in solvents with varying HSPs were studied. The best dispersibility was observed in dichloromethane, when the CNC surface was modified with longer carbon chains. Dichloromethane has HSP similar to low-density polyethylene (LDPE). Nanocomposites with both unmodified and modified CNC were produced. The materials with modified CNC showed increased adhesion between the filler and the matrix, followed by a decreased water permeability compared to unmodified CNC, suggesting a better dispersibility of modified CNC in LDPE and confirming the usefulness of this approach.
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9.
  • Hui, I. S. B., et al. (författare)
  • Biocomposites containing poly(lactic acid) and chitosan for 3D printing - Assessment of mechanical, antibacterial and in vitro biodegradability properties
  • 2023
  • Ingår i: Journal of the Mechanical Behavior of Biomedical Materials. - : Elsevier Ltd. - 1751-6161 .- 1878-0180. ; 147
  • Tidskriftsartikel (refereegranskat)abstract
    • New bone repair materials are needed for treatment of trauma-and disease-related skeletal defects as they still represent a major challenge in clinical practice. Additionally, new strategies are required to combat orthopedic device-related infections (ODRI), given the rising incidence of total joint replacement and fracture fixation surgeries in increasingly elderly populations. Recently, the convergence of additive manufacturing (AM) and bone tissue engineering (BTE) has facilitated the development of bone healthcare to achieve personalized three-dimensional (3D) scaffolds. This study focused on the development of a 3D printable bone repair material, based on the biopolymers poly(lactic acid) (PLA) and chitosan. Two different types of PLA and chitosan differing in their molecular weight (MW) were explored. The novel feature of this research was the successful 3D printing using biocomposite filaments composed of PLA and 10 wt% chitosan, with clear chitosan entrapment within the PLA matrix confirmed by Scanning Electron Microscopy (SEM) images. Tensile testing of injection molded samples indicated an increase in stiffness, compared to pure PLA scaffolds, suggesting potential for improved load-bearing characteristics in bone scaffolds. However, the potential benefit of chitosan on the biocomposite stiffness could not be reproduced in compression testing of 3D printed cylinders. The antibacterial assays confirmed antibacterial activity of chitosan when dissolved in acetic acid. The study also verified the biodegradability of the scaffolds, with a process producing an acidic environment that could potentially be neutralized by chitosan. In conclusion, the study indicated the feasibility of the proposed PLA/chitosan biocomposite for 3D printing, demonstrating adequate mechanical strength, antibacterial properties and biodegradability, which could serve as a new material for bone repair.
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10.
  • Javed, Asif, 1982-, et al. (författare)
  • Lignin-containing coatings for packaging materials—pilot trials
  • 2021
  • Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 13:10
  • Tidskriftsartikel (refereegranskat)abstract
    • One severe weakness of most biopolymers, in terms of their use as packaging materials, is their relatively high solubility in water. The addition of kraft lignin to starch coating formulations has been shown to reduce the water solubility of starch in dry coatings. However, lignin may also migrate into aqueous solutions. For this paper, kraft lignin isolated using the LignoBoost process was used in order to examine the effect of pH level on the solubility of lignin with and without ammonium zirconium carbonate (AZC). Machine-glazed (MG) paper was coated in a pilot coating machine, with the moving substrate at high speed, and laboratory-coated samples were used as a reference when measuring defects (number of pinholes). Kraft lignin became soluble in water at lower pH levels when starch was added to the solution, due to the interactions between starch and lignin. This made it possible to lower the pH of the coating solutions, resulting in increased water stability of the dry samples; that is, the migration of lignin to the model liquids decreased when the pH of the coating solutions was reduced. No significant difference was observed in the water vapor transmission rate (WVTR) between high and low pH for the pilot-coated samples. The addition of AZC to the formulation reduced the migration of lignin from the coatings to the model liquids and led to an increase in the water contact angle, but also increased the number of pinholes in the pilot-coated samples. © 2021 by the authors
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