| 1. |
- Abitbol, Tiffany, et al.
(author)
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Cellulose nanocrystal/low methoxyl pectin gels produced by internal ionotropic gelation.
- 2021
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In: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 260
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Journal article (peer-reviewed)abstract
- The biotechnological applications of cellulose nanocrystals (CNCs) continue to grow due to their sustainable nature, impressive mechanical, rheological, and emulsifying properties, upscaled production capacity, and compatibility with other materials, such as protein and polysaccharides. In this study, hydrogels from CNCs and pectin, a plant cell wall polysaccharide broadly used in food and pharma, were produced by calcium ion-mediated internal ionotropic gelation (IG). In the absence of pectin, a minimum of 4 wt% CNC was needed to produce self-supporting gels by internal IG, whereas the addition of pectin at 0.5 wt% enabled hydrogel formation at CNC contents as low as 0.5 wt%. Experimental data indicate that CNCs and pectin interact to give robust and self-supporting hydrogels at solid contents below 2.5 %. Potential applications of these gels could be as carriers for controlled release, scaffolds for cell growth, or wherever else distinct and porous network morphologies are required.
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| 2. |
- Abitbol, Tiffany, et al.
(author)
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Isolation of Mixed Compositions of Cellulose Nanocrystals, Microcrystalline Cellulose, and Lignin Nanoparticles from Wood Pulps
- 2023
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In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:24, s. 21474-21484
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Journal article (peer-reviewed)abstract
- From a circular economyperspective, one-pot strategies for theisolation of cellulose nanomaterials at a high yield and with multifunctionalproperties are attractive. Here, the effects of lignin content (bleachedvs unbleached softwood kraft pulp) and sulfuric acid concentrationon the properties of crystalline lignocellulose isolates and theirfilms are explored. Hydrolysis at 58 wt % sulfuric acid resulted inboth cellulose nanocrystals (CNCs) and microcrystalline celluloseat a relatively high yield (>55%), whereas hydrolysis at 64 wt% gaveCNCs at a lower yield (<20%). CNCs from 58 wt % hydrolysis weremore polydisperse and had a higher average aspect ratio (1.5-2x),a lower surface charge (2x), and a higher shear viscosity (100-1000x).Hydrolysis of unbleached pulp additionally yielded spherical nanoparticles(NPs) that were <50 nm in diameter and identified as lignin bynanoscale Fourier transform infrared spectroscopy and IR imaging.Chiral nematic self-organization was observed in films from CNCs isolatedat 64 wt % but not from the more heterogeneous CNC qualities producedat 58 wt %. All films degraded to some extent under simulated sunlighttrials, but these effects were less pronounced in lignin-NP-containingfilms, suggesting a protective feature, but the hemicellulose contentand CNC crystallinity may be implicated as well. Finally, heterogeneousCNC compositions obtained at a high yield and with improved resourceefficiency are suggested for specific nanocellulose uses, for instance,as thickeners or reinforcing fillers, representing a step toward thedevelopment of application-tailored CNC grades.
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| 3. |
- Aldaeus, Fredrik, et al.
(author)
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Characterization of pulp with high enzymatic hydrolyzability
- 2014
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In: 13th European Workshop on Lignocellulosics and Pulp (EWLP 2014) book of abstracts.
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Conference paper (other academic/artistic)abstract
- Conversion of biomass to biofuels is currently an area that attracts large interest, and lignocellulosic biomass offers the abundance and environmental attributes that can potentially support large-scale biofuel production as an alternative to petroleum-based transportation fuel.In a recent project, Innventia has developed wood based pulps optimized for conversion to biofuels. These novel pulps were produced to target a high level of enzymatic hydrolyzability. To assess the hydrolyzability of these pulps, a laboratory protocol has been established usingan enzyme mixture containing Celluclast 1.5L and Novozyme 188 with an activity of 10 FPU/g pulp (Andersen 2007). Results obtained using this protocol are assumed to be relevant for industrial conditions. In addition to assessment of the produced pulps, the results havebeen compared to commercial cellulose substrates and pulps of a variety of grades.Furthermore, supramolecular properties – specific surface area and average pore size – were determined by an in-house method utilizing solid state nuclear magnetic resonance (Larsson et al. 2013). Kappa numbers, limiting viscosities, ISO-brightness and carbohydrate compositions were determined using standard methods. Molecular mass distributions of cellulose tricarbanilates were determined by size exclusion chromatography with tetrahydrofuran mobile phase (Drechsler et al. 2000).The presentation will discuss the influence of chemical, macromolecular and supramolecular properties of commercial and novel pulp grades on the enzymatic hydrolyzability. Theprotocol used to assess of enzymatic hydrolyzability will be proposed as a benchmark test.
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| 4. |
- Aldaeus, Fredrik, et al.
(author)
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Miniaturized determination of ash content in kraft lignin samples using oxidative thermogravimetric analysis
- 2017
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In: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 32:2, s. 280-282
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Journal article (peer-reviewed)abstract
- A study has been made of several aspects of determination of ash content in kraft lignin samples using thermogravimetric analysis (TGA). Three different methods were used; with the main differences between the methods being that two have a temperature hold at 250 deg C to remove volatiles and that the three methods use different maximum temperatures, namely 525, 550 and 575 deg C, respectively. The three kraft lignins used were produced using the LignoBoost lignin isolation process. It has been demonstrated that the results obtained by the different temperature programmes showed no significant difference. The results were comparable with those from using oven ignition. Moreover, the limit of quantification was several orders of magnitude lower than when using oven ignition. It has been recommended that if TGA is used for determination of ash content, a temperature programme from a standard method should be used, which should be mentioned together with the results. The temperature programme in method one (corresponding to ISO 1762) was the shortest and the preferable method. A well as requiring less labour due to fewer movements in the analytical protocol, the TGA methods enabled a high sample throughput due to autosampling possibilities.
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| 5. |
- Aldaeus, Fredrik, et al.
(author)
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Miniaturized determination of ash content in kraft lignin samples using thermogravimetric analysis
- 2015
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In: 18th International Symposium on Wood, Fiber and Pulping Chemistry, September 9-11, 2015, Vienna. ; , s. 352-354
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Conference paper (other academic/artistic)abstract
- Thermogravimetric analysis (TGA) in oxidative conditions is a promising alternative to ignition in oven for the determination of inorganic residue, commonly referred to as ash. It is here shown that TGA can be used with temperature programs resembling those in standardized methods for oven ignition, and obtainequivalent results even though the sample amount is several orders of magnitude lower. The precision and limit of quantification of TGA is also discussed.
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| 6. |
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| 7. |
- Aldaeus, Fredrik, et al.
(author)
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The supramolecular structure of cellulose-rich wood and wheat straw pulps can be a determinative factor for enzymatic hydrolysability
- 2016
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In: The 7th Workshop on cellulose, regenerated cellulose and cellulose derivatives. ; , s. 39-39
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Conference paper (other academic/artistic)abstract
- Conversion of biomass to biofuels and other products is a research area that is currently attracting a great amount of interest, particularly because such production may be envisaged as a key part of any bio-based economy. Lignocellulosic biomass is abundant and sustainable, and can therefore potentially support large-scale production of biofuel as an alternative to petroleum-based fuel.The enzymatic hydrolysability of three industrial pulps, five lab made pulps, and one microcrystalline cellulose powder was assessed using commercial cellulolytic enzymes. To gain insight into the factors that influence the hydrolysability, a thorough characterization of the samples was done, including their chemical properties (cellulose content, hemicellulose content, lignin content, and kappa number), their macromolecular properties (peak molar mass, number-average molar mass, weight-average molar mass, polydispersity, and limiting viscosity) and their supramolecular properties (fibre saturation point, specific surface area, average pore size, and crystallinity). The hydrolysability was assessed by determination of initial conversion rate and final conversion yield, with conversion yield defined as the amount of glucose in solution per unit of glucose in the substrate. Multivariate data analysis revealed that for the investigated samples the conversion of cellulose to glucose was mainly dependent on the supramolecular properties, such as specific surface area and average pore size. The molar mass distribution, the crystallinity, and the lignin content of the pulps had no significant effect on the hydrolysability of the investigated samples.In addition, experiments were carried out aiming at identifying suitable conditions for pre-treatment of wheat straw, for the purpose of making cellulose rich pulps with improved enzymatic reactivity. Two sets of conditions for pre-treatment of wheat straw were identified; a combination of low temperature alkaline washing and acid pre-hydrolysis, or high temperature acid pre-hydrolysis. Both bleached wheat straw pulps showed similar enzymatic reactivity. However, the enzymatic reactivity of both bleached wheat straw pulps was found to be significantly less than what has been achieved for wood pulps. A probable explanation for the low enzymatic reactivity of the bleached wheat straw pulp can be the small pore size, limiting the access for enzymes to the cellulose surfaces in the fibre wall interior.Text, figures and tables in an extended abstract (< 4 pages with title and references).
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| 8. |
- Aldaeus, Fredrik, et al.
(author)
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The supramolecular structure of cellulose-rich wood pulps can be a determinative factor for enzymatic hydrolysability
- 2015
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In: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 22:6, s. 3991-4002
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Journal article (peer-reviewed)abstract
- The enzymatic hydrolysability of three industrial pulps, five lab made pulps, and one microcrystalline cellulose powder was assessed using commercial cellulolytic enzymes. To gain insight into the factors that influence the hydrolysability, a thorough characterization of the samples was done, including their chemical properties (cellulose content, hemicellulose content, lignin content, and kappa number), their macromolecular properties (peak molar mass, number-average molar mass, weight-average molar mass, polydispersity, and limiting viscosity) and their supramolecular properties (fibre saturation point, specific surface area, average pore size, and crystallinity). The hydrolysability was assessed by determination of initial conversion rate and final conversion yield, with conversion yield defined as the amount of glucose in solution per unit of glucose in the substrate. Multivariate data analysis revealed that for the investigated samples the conversion of cellulose to glucose was mainly dependent on the supramolecular properties, such as specific surface area and average pore size. The molar mass distribution, the crystallinity, and the lignin content of the pulps had no significant effect on the hydrolysability of the investigated samples.
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| 9. |
- Brännvall, Elisabet, 1961-, et al.
(author)
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Changes in the cellulose fiber wall supramolecular structure during the initial stages of chemical treatments of wood evaluated by NMR and X-ray scattering
- 2021
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In: Cellulose. - : Springer Science and Business Media B.V.. - 0969-0239 .- 1572-882X. ; 28, s. 3951-3965
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Journal article (peer-reviewed)abstract
- The effect of initial stages of pulping of spruce, resembling prehydrolysis and alkaline cooking was studied using CP/MAS 13C-NMR, X-ray scattering, FSP and carbohydrate composition in order to study the impact of the pre-treatments on the fiber wall nanostructure. Removal of fiber wall components, hemicellulose and lignin, increased the fiber wall porosity and induced cellulose fibril aggregation. The effect of temperature and pH in the treatment on cellulose fibril aggregate size appears to be secondary. It is the removal of hemicellulose that has a profound effect on the supramolecular structure of the cellulose fiber wall. As the amount of hemicellulose dissolved from wood increases, the fibril aggregate size determined by NMR increases as well, ranging from 16 to 28 nm. Specifically, a good correlation between the amount of glucomannan in the fiber wall and the fibril aggregate size is seen. The lower the amount of glucomannan, the larger the aggregate size. Glucomannan thus seems to prevent aggregation as it acts as a very efficient spacer between fibrils. Elemental fibril size determined by NMR, was quite similar for all samples, ranging from 3.6 to 4.1 nm. By combining measurement methods, a more well-resolved picture of the structural changes occurring during was obtained. © 2021, The Author(s).
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| 10. |
- Chinga Carrasco, Gary, et al.
(author)
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Carboxylated nanocellulose for wound healing applications – Increase of washing efficiency after chemical pre-treatment and stability of homogenized gels over 10 months
- 2023
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In: Carbohydrate Polymers. - : Elsevier Ltd. - 0144-8617 .- 1879-1344. ; 314
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Journal article (peer-reviewed)abstract
- To commercialize a biomedical product as a medical device, reproducibility of production and time-stability are important parameters. Studies of reproducibility are lacking in the literature. Additionally, chemical pre-treatments of wood fibres to produce highly fibrillated cellulose nanofibrils (CNF) seem to be demanding in terms of production efficiency, being a bottleneck for industrial upscaling. In this study, we evaluated the effect of pH on the dewatering time and washing steps of 2,2,6,6-Tetramethylpiperidinyloxy (TEMPO)-mediated oxidized wood fibres when applying 3.8 mmol NaClO/g cellulose. The results indicate that the method does not affect the carboxylation of the nanocelluloses, and levels of approximately 1390 μmol/g were obtained with good reproducibility. The washing time of a Low-pH sample was reduced to 1/5 of the time required for washing a Control sample. Additionally, the stability of the CNF samples was assessed over 10 months and changes were quantified, the most pronounced were the increase of potential residual fibre aggregates, reduction of viscosity and increase of carboxylic acid content. The cytotoxicity and skin irritation potential were not affected by the detected differences between the Control and Low-pH samples. Importantly, the antibacterial effect of the carboxylated CNFs against S. aureus and P. aeruginosa was confirmed. © 2023 The Authors
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