| 1. |
- Anugwom, Ikenna, et al.
(author)
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Switchable ionic liquids (SILs) based on glycerol and acid gases
- 2011
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In: RSC Advances. - : The Royal Society of Chemistry. - 2046-2069. ; 1:3, s. 452-457
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Journal article (peer-reviewed)abstract
- New types of switchable ionic liquids (SILs), containing 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU), glycerol and an acid gas (CO2, SO2), were synthesized and characterized in this study. [DBU][Carbonate] or [sulfonate] were easily synthesized from a non-ionic mixture of molecular organic polyol and amidine base upon bubbling of an acid gas (CO2, SO2). Moreover, they were switched back to the original molecular solvents by flushing out the acid gas (CO2, SO2) by heating and/or bubbling an inert gas such as N2 through it. The structures of the SILs were confirmed by NMR and FTIR. The change from low polarity (molecular solvent) to high polarity (Switchable Ionic Liquid, SIL) was also indicated by the changes in properties, such as viscosity and miscibility with different organic solvents. The decomposition temperatures of the SILs were determined by means of Thermo Gravimetric Analysis (TGA) and gave values in the range of 50 °C and 120 °C for DBU-glycerol-CO2 (SIL1) and DBU-glycerol-SO2 (SIL2), respectively. Due to the reasonable decomposition temperatures, these novel SILs can be employed in multiple applications.
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| 2. |
- Anugwom, Ikenna, et al.
(author)
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Treating birch wood with a switchable 1,8-diazabicyclo-[5.4.0]-undec-7-ene-glycerol carbonate ionic liquid
- 2012
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In: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 66:7, s. 809-815
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Journal article (peer-reviewed)abstract
- The suitability of a new switchable ionic liquid (SIL) has been investigated as a solvent for fractionation of lignocellulosic materials. SIL was prepared from inexpensive chemicals, e. g., glycerol, CO2, and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU). Fresh Nordic birch wood (B. pendula) was treated with the SIL for a time period of 1-5 days at 100 degrees C and under atmospheric pressure. Upon SIL treatment, at best, 57 % of the hemicelluloses were dissolved and 50 % of lignins were dissolved from the native birch. The slightly fibrillated SIL treated chips contained about 55 % cellulose. Up to 76 % of the recovered species removed from the spent SIL liquor was originating from hemicelluloses, mainly from xylan. The spent SILs were reused for fresh wood dissolution in four consecutive cycles and each time the wood dissolution efficiency was similar. SILs could offer affordable (easy-to-synthesize) solvent systems for partial elimination of hemicelluloses and lignin from wood. SILs can also be prepared in-situ and on-site.
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| 3. |
- Damlin, Pia, et al.
(author)
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Characterization of Hardwood-Derived Carboxymethylcellulose by High pH Anion Chromatography Using Pulsed Amperometric Detection
- 2010
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In: Cellulose Chemistry and Technology. - 0576-9787. ; 44:1-3, s. 65-69
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Journal article (peer-reviewed)abstract
- An approach for the quantitative analysis of substituent distribution in carboxymethylcellulose (CMC) is presented. In short, the high-pH anion-exchange chromatography method, coupled to pulsed amperometric detection (PAD), is introduced. Each of the seven derivatives in CMC is presented by a single peak on the PAD trace, thus enabling an easy quantification. New inside information on monomer composition is obtained by this novel method, which is essential for understanding the structure versus property relationships in the CMC samples.
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| 4. |
- Hyvärinen, Sari, et al.
(author)
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Ionic liquid fractionation of woody biomass for fermentable monosaccharides
- 2011
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In: Cellulose Chemistry and Technology. - : Cellulose Chemistry and Technology. - 0576-9787. ; 45:7-8, s. 483-486
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Journal article (peer-reviewed)abstract
- The goal of the present study, devoted to wood fractionation, was to obtain monosaccharides, hexoses and pentoses by means of an ionic liquid (IL) based pre-treatment procedure. Softwood sawdust (maximum particle size of 2 mm) of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) were exposed to ionic liquids – 1-ethyl-3-methylimidazolium acetate (C2mimAce) and 1-ethyl-3-methylimidazolium chloride (C2mimCl) – and thermal treatment (80-150 °C), for various time intervals (0-72 h). Furthermore, cellulose of various origins (plants, wood pulps) was dissolved in C2mimAce and 1-butyl-3-methylimidazolium chloride (C4 mimCl) for the study of the dissolved fractions, stress being laid on monosaccharides and possible by-products, 5-hydroxymethylfurfural and furfural. Knowing the challenges in analysis techniques when ILs and sugars are involved, the present work focuses on the development of suitable analysis methods. To this end, a Hewlett Packard 1100 series HPLC equipped with a refractive index (RI), detector model HP1047 A and a diode array UV detector (DAD) fitted with a carbohydrate column HPX-87K was utilized. Challenges and improvements are discussed.
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| 5. |
- Koyejo, Adefunke O., et al.
(author)
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Cellulose-Based Reduced Nanographene Oxide on Gold Nanoparticle Supports for CO2 Electrocatalysis
- 2020
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In: ChemElectroChem. - : WILEY-V C H VERLAG GMBH. - 2196-0216. ; 7:24, s. 4889-4899
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Journal article (peer-reviewed)abstract
- Cellulose-based reduced graphene oxide materials (r-nGO) were fabricated and anchored onto polyvinyl alcohol stabilized gold nanoparticles. Their potential in applications in the electrocatalytic reduction of CO2 (ER-CO2) is demonstrated. The nGO was synthesized by microwave-assisted cellulose carbonization followed by two different reduction methods, that is, with super-heated water (i) or caffeic acid (ii). These materials, denoted as r-nGO (i) r-nGO-CA (ii), were utilized to immobilize colloidal gold nanoparticles (Au NPs) in an aqueous environment. The two r-nGO-supported Au NP materials were deposited on glassy carbon electrode surfaces and studied as catalysts for ER-CO2. ER-CO2 was investigated at room temperature and pressure (RTP) using ionic liquids (RTILs) or an aprotic solvent acetonitrile (ACN). Tetrabutylammonium hexafluoroborate (TBAPF(6)) was used as an electrolyte salt in the case of ACN. The current response resulting from ER-CO2 was measured under cyclic voltammetric conditions using a one-compartment three-electrode cell. Results showed that, r-nGO-supported gold nanoparticles catalyze ER-CO2 and they significantly reduce the overpotential of CO2 reduction from -1.9 V to -1.6 V vs. Ag/AgCl. Moreover, of all the materials studied, Au/r-nGO was superior in reducing CO2 in both RTILs and TBAPF(6)/ACN. These outcomes serve as grounds for the further development of electrocatalysts from bio-based reduced graphene oxides.
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| 6. |
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| 7. |
- Mikkola, Jyri-Pekka, et al.
(author)
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Ionic liquid-aided carboxymethylation of kraft pulp
- 2010
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In: International Journal of Chemical Reactor Engineering. - : Bepress. - 1542-6580. ; 8:A102
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Journal article (peer-reviewed)abstract
- Different ionic liquids containing the cation such as 1-N-butyl-3-methylimida-zolium (Bmim+) are able to efficiently dissolve cellulose. The ability of ionic liquids to truly dissolve cellulose is significant when cellulose derivatization is attempted. A series of experiments on etherification (carboxymethylation) of cellulose was performed, using both the conventional suspension approach (slurry) with 2-propanol as the principal reaction media and a totally homogenous reaction approach utilizing ionic liquids as a reaction media capable of dissolving cellulose. It was observed that a pre-treatment with the ionic liquid 1-N-butyl-3-methylimidazolium iodide ([Bmim][I]) seems to promote substitution in line with the conventional, heterogeneous suspension process. Under carefully chosen reaction conditions, a higher degree of substitution was obtained when wetting the cellulose with [Bmim][I] prior to classical derivatization than without this pre-treatment. It was also observed that the substitution pattern was changing upon use of the ionic liquid [Bmim][I]. Upon a totally homogenous etherification, it was found that the ionic liquid 1-N-butyl-3-methylimidazolium acetate ([Bmim][oAc]) gave the highest degree of substitution. The product obtained was water-soluble and had a DS (degree of substitution) of 0.59. The substitution pattern of the products obtained from the homogenous reactions follow the same substitution pattern as the products obtained from the conventional suspension process. This indicates that the properties of the products are in line with products prepared via the conventional reaction route.
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| 8. |
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| 9. |
- Salmi, Tapio, et al.
(author)
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Modelling and experimental verification of cellulose substitution kinetics
- 2011
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In: Chemical Engineering Science. - : Elsevier. - 0009-2509 .- 1873-4405. ; 66:2, s. 171-182
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Journal article (peer-reviewed)abstract
- Cellulose and starch derivatives are often prepared by substitution reactions to the hydroxyl groups (OH-2, OH-3 and OH-6) of the corresponding anhydroglucose units. A general kinetic model for the substitution of cellulose and starch was developed. The model assumes different reactivities of the hydroxyl groups and a decrease in the reactivity as the substitution proceeds. Both phenomena are taken into account in the model. The model predicts the detailed distribution of the different mono (2, 3, 6)-, di (23, 26, 36)—and trisubstituted (236) units as a function of the reaction time. The classical Spurlin distribution is obtained as a special case of the general model. Numerical strategies were developed for the solution and computer simulation of the model. Simulation results were shown to be valid for various reactivity ratios of the hydroxyl groups. The modelling concept was verified with experimental data obtained for carboxymethylation of cellulose. It should be emphasized, however, that the same general approach is also applicable in studies of any hemicelluloses or oligo- or monosaccharides. The detailed data, which revealed the non-uniform reactivities of the different hydroxyl groups and the decline of the substitution rate with time, were successfully described by the mathematical model.
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