| 1. |
- Abdelhamid, Hani Nasser, et al.
(författare)
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Template-free and room temperature synthesis of hierarchical porous zeolitic imidazolate framework nanoparticles and their dye and CO2 sorption
- 2018
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 20:5, s. 1074-1084
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Tidskriftsartikel (refereegranskat)abstract
- Hierarchical porous zeolitic imidazolate framework ZIF-8 nanoparticles have been synthesized using zinc nitrate, 2-methylimidazole (Hmim), and sodium hydroxide. Zinc hydroxide nitrate nanosheets were formed as intermediates that further transformed to hierarchical porous ZIF-8 after the addition of Hmim. These intermediates serve as in situ sacrificial templates and promote the formation of hierarchical porous ZIF-8 without the need for any other templates. The surface area and mesoporosity of the materials can be tuned by adjusting the concentration of NaOH. This method offers a fast and template-free approach for the synthesis of pure hierarchical porous ZIF-8 at room temperature with tunable porosity. The approach has been applied to synthesize two-dimensional ZIF leaf-like materials, ZIF-L. The synthesis of ZIF-8 and ZIF-L can be scaled up with high yields (>80%). The resulting ZIF-8 and ZIF-L materials show very good CO2 sorption properties. ZIF-8 nanoparticles show fast (<5 min), selective, and high efficiency (>95%) uptake of methyl blue in aqueous solution both without and in the presence of other dyes. The results open a new avenue for the understanding of the self-assembly and the formation of hierarchical porous ZIFs.
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| 2. |
- Arshadi, Mehrdad, et al.
(författare)
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Impact of supercritical extraction on solid fuel wood pellet properties and off-gassing during storage
- 2016
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 18, s. 2682-2690
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Tidskriftsartikel (refereegranskat)abstract
- Biofuel pellets derived from wood raw material are an important carbon neutral source of energy. Their storage and bulk transportation can lead to serious hazards as a result of off-gassing (CO, CO2, CH4 combined with serious oxygen (O-2) depletion). Herein, supercritical carbon dioxide extraction (scCO(2)) has been demonstrated as an efficient tool in significantly reducing these emissions from wood pellets. 84% of the lipids and resin acids have been removed from the sawdust prior to pelletisation. Crucially, this work reports the first off-gassing measurements associated with lipid autoxidation in wood pellets post scCO(2) extraction of the sawdust. These off-gassing processes were considerably reduced for scCO(2)-extracted sawdust pellets, when compared to pellets prepared from virgin untreated sawdust (reference pellets). Significant reductions in the levels of CO, CO2 and CH4 (85, 85, and 94% respectively) were observed. A slight reduction in O-2 concentration (20% to 19.3%) was observed for the scCO(2)-pellets, while an 8% decrease (reduction in O-2 concentration from 20% to 12%) was observed for the reference. The results support a connection between the amount of lipids/resin acids and intermediate products of autoxidation (i.e. 71% reduction in aldehydes) and the off-gassing of CO, CO2 and CH4. Finally, there was low impact on the production, durability, calorific values and density of scCO(2) pellets compared to the reference pellets. This work demonstrated that scCO(2) extraction is effective as a pre-treatment technology for wood based pelletised fuels, considerably reducing the risks associated with off-gassing and oxygen depletion, while also highlighting potential chemicals and biofuels which could be generated from extracts.
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| 3. |
- Arshadi, Mehrdad, et al.
(författare)
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Pre-treatment and extraction techniques for recovery of added value compounds from wastes throughout the agri-food chain
- 2016
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Ingår i: Green Chemistry. - 1463-9262 .- 1463-9270. ; 18, s. 6160-6204
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Forskningsöversikt (refereegranskat)abstract
- The enormous quantity of food wastes discarded annually forces a look into alternatives for this interesting feedstock. Thus, food bio-waste valorisation is one of the current imperatives of society. This review is the most comprehensive overview of currently existing technologies and processes in this field. It tackles classical and innovative physical, physico-chemical and chemical methods of food waste pre-treatment and extraction for the recovery of added value compounds and detection by modern technologies and is an outcome of the COST Action EUBIS, TD1203 Food Waste Valorisation for Sustainable Chemicals, Materials and Fuels.
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| 4. |
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| 5. |
- Axelsson, Anton, 1991, et al.
(författare)
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Organocatalytic valorisation of glycerol via a dual NHC-catalysed telescoped reaction
- 2017
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Ingår i: Green Chemistry. - 1463-9262 .- 1463-9270. ; 19:11, s. 2477-2481
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Tidskriftsartikel (refereegranskat)abstract
- A general telescoped reaction for the NHC-catalysed carbonation and aerobic esterification of glycerol and 2-amino-2-methylpropane-1,3-diol has been developed. The reaction provides highly functionalised glycerol derivatives in good to excellent yields (up to 95%) using low catalyst loadings and ambient conditions.
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| 6. |
- Bansal, Namita, et al.
(författare)
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Cell wall-associated transition metals improve alkaline-oxidative pretreatment in diverse hardwoods
- 2016
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 18:5, s. 1405-1415
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Tidskriftsartikel (refereegranskat)abstract
- The responses of four diverse hardwoods (hybrid poplar, silver birch, hybrid aspen, and sugar maple) to alkaline hydrogen peroxide (AHP) pretreated at ambient temperature and pressure were analyzed to gain a deeper understanding of the cell wall properties that contribute to differences in enzymatic hydrolysis efficacy following alkaline-oxidative pretreatment. The enzymatic hydrolysis yields of these diverse hardwoods increased significantly with increasing the cell wall-associated, redox-active transition metal content. These increases in hydrolysis yields were directly correlated with improved delignification. Furthermore, we demonstrated that these improvements in hydrolysis yields could be achieved either through elevated levels of naturally-occurring metals, namely Cu, Fe, and Mn, or by the addition of a homogeneous transition metal catalyst (e.g. Cu 2,2′-bipyridine complexes) capable of penetrating into the cell wall matrix. Removal of naturally-occurring cell wall-associated transition metals by chelation resulted in substantial decreases in the hydrolysis yields following AHP pretreatment, while re-addition of metals in the form of Cu 2,2′-bipyridine complexes and to a limited extent Fe 2,2′-bipyridine complexes prior to pretreatment restored the improved hydrolysis yields. Glycome profiles showed improved extractability of xylan, xyloglucan, and pectin epitopes with increasing hydrolysis yields for the diverse hardwoods subjected to the alkaline-oxidative pretreatment, demonstrating that the strength of association between cell wall matrix polymers decreased as a consequence of improved delignification
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| 7. |
- Benselfelt, Tobias, et al.
(författare)
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Supramolecular double networks of cellulose nanofibrils and algal polysaccharides with excellent wet mechanical properties
- 2018
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Ingår i: Green Chemistry. - : ROYAL SOC CHEMISTRY. - 1463-9262 .- 1463-9270. ; 20:11, s. 2558-2570
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Tidskriftsartikel (refereegranskat)abstract
- Supramolecular double network films, consisting of cellulose nanofibrils (CNF) entangled with the algal polysaccharides alginate or carrageenan, were prepared using a rapid vacuum filtration process to achieve water-resistant CNF nanopapers with excellent mechanical properties in both the wet and dry states following the locking of the structures using Ca2+. The rigid network of calcium alginate was more efficient than the more flexible network of calcium carrageenan and 10% by weight of alginate was sufficient to form a network that suppressed the swelling of the CNF film by over 95%. The resulting material could be compared to a stiff rubber with a Young's modulus of 135 MPa, a tensile strength of 17 MPa, a strain-at-break above 55%, and a work of fracture close to 5 MJ m(-3) in the wet state, which was both significantly stronger and more ductile than the calcium-treated CNF reference nanopaper. It was shown that the state in which Ca2+ was introduced is crucial, and it is also hypothesized that the alginate works as a sacrificial network that prevents the CNF from aligning during loading and that this leads to the increased toughness. The material maintained its barrier properties at elevated relative humidities and the extensibility and ductility made possible hygroplastic forming into three-dimensional shapes. It is suggested that the attractive force in the CNF part of the double network in the presence of multivalent ions is due to the ion-ion correlation forces generated by the fluctuating counter-ion cloud, since no significant ion coordination was observed using FTIR.
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| 8. |
- Deb, Somdatta, et al.
(författare)
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Application of mild autohydrolysis to facilitate the dissolution of wood chips in direct-dissolution solvents
- 2016
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 18:11, s. 3286-3294
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Tidskriftsartikel (refereegranskat)abstract
- Wood is not fully soluble in current non-derivatising direct-dissolution solvents, contrary to the many reports in the literature quoting wood 'dissolution' in ionic liquids. Herein, we demonstrate that the application of autohydrolysis, as a green and economical wood pre-treatment method, allows for a massive increase in solubility compared to untreated wood. This is demonstrated by the application of two derivitising methods (phosphitylation and acetylation), followed by NMR analysis, in the cellulose-dissolving ionic liquids 1-allyl-3-methylimidazolium chloride ([amim]Cl) and 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]. In addition, the non-derivitising tetrabutylphosphonium acetate ([P-4444][OAc]) : DMSO-d6 electrolyte also allowed for dissolution of the autohydrolysed wood samples. By combination of different particle sizes and P-factors (autohydrolysis intensity), it has been clearly demonstrated that the solubility of even wood chips can be drastically increased by application of autohydrolysis. The physiochemical factors affecting wood solubility after autohydrolysis are also discussed.
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| 9. |
- Duval, Antoine, et al.
(författare)
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Reversible crosslinking of lignin via the furan-maleimide Diels-Alder reaction
- 2015
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 17:11, s. 4991-5000
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Tidskriftsartikel (refereegranskat)abstract
- Two distinct functionalization schemes for Kraft lignin (KL) were developed to selectively incorporate furan and/or maleimide motifs as chain ends. The incorporation of furan functionalities was carried out by the selective and quantitative reaction of the lignin's phenolic OH groups with furfuryl glycidyl ether (FGE). Maleimide groups were introduced by esterifying the lignin's aliphatic and phenolic OH groups with 6 maleimidohexanoic acid (6-MHA), offering a high loading despite a somewhat incomplete conversion. Furan-and maleimide-functionalized lignins were subsequently combined to generate crosslinking via the Diels-Alder (DA) [4 + 2] cycloaddition reaction. The formation of the DA adduct was confirmed by H-1 NMR. Under appropriate conditions, the formation of a gel was apparent, which turned back into the liquid state after performing the corresponding retro-DA reaction upon heating to 120 degrees C. This study reveals the significant versatility and potential of the developed strategy for the utilization of lignin-based recyclable networks.
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| 10. |
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