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- Anugwom, I, et al.
(author)
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Ionic liquid assisted extraction of nitrogen and sulphur-containing air pollutants from model oil and regeneration of the spent ionic liquid
- 2011
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In: Journal of Environmental Protection. - : Scientific Research Publishing. - 2152-2197 .- 2152-2219. ; 2:6, s. 796-802
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Journal article (peer-reviewed)abstract
- Removal of air pollutants, such as nitrogen and sulphur containing compounds from a model oil (dodecane) was studied. An ionic liquid (1-ethyl-3-methylimidazolium chloride [C2mim] [Cl]) was used as an extractant. Liquid-liquid extraction by using 1-ethyl-3-methylimidazolium chloride [C2mim] [Cl] was found to be a very promising method for the removal of N- and S-compounds. This was evaluated by using a model oil (dodecane) with indole as a neutral nitrogen compound and pyridine as a basic nitrogen compound. Dibenzothiophene (DBT) was used as a sulphur compound. An extraction capacity of up to 90 wt% was achieved for the model oil containing pyridine, while only 76 wt% of indole in the oil was extracted. The extraction capacity of a model sulphur compound DBT was found to be up to 99 wt%. Regeneration of the spent ionic liquid was carried out with toluene back-extraction. A 1:1 toluene-to-IL wt ratio was performed at room temperature. It was observed that, for the spent ionic liquid containing DBT as a model compound more than 85 wt% (corresponding 3852 mg/kg) could be removed from the oil. After the second regeneration cycle, 86 wt% of the DBT was recovered from the ionic liquid to toluene. In the case of indole as the nitrogen containing species, more than 99 wt%, (corresponding to 2993 mg/kg) of the original indole was transferred from the model oil to the ionic liquid. After the first-regeneration cycle of the spent ionic liquid, 54 wt% of the indole–in-IL was transferred to toluene. Thus, both extractions of nitrogen and sulphur model compounds were successfully carried out from model oil and the back-extraction of these compounds from the ionic liquids to toluene demonstrated the proved the concept of the regeneration point of view.
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- Anugwom, I, et al.
(author)
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Selective Extraction of Hemicelluloses from Spruce using Switchable Ionic Liquids
- 2012
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In: Carbohydrate Polymers. - : Elsevier. - 0144-8617 .- 1879-1344. ; 87:3, s. 2005-2011
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Journal article (peer-reviewed)abstract
- Switchable Ionic Liquids (SILs) made from alcohols, either hexanol or butanol, and CO2 together with an amidine (1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)) were investigated as dissolution/fractionation solvents for wood material. Both native spruce (Picea abies), and pre-extracted spruce were treated with either butanol SIL (SIL1) or hexanol SIL (SIL 2) for 5 days at 55 °C under normal pressure. The SILs were formed by bubbling CO2 through an equimolar mixture of either 1-hexanol or 1-butanol and DBU. The viscosity of the mixture increased from 7.1 mPas to 2980 mPas for SIL 2 and 5.1 to 1600 mPas for SIL 1. Melting points of the SILs 1 and 2 were at 8 and 14 °C, respectively. After the treatment time (5 days), the undissolved fraction contained 38 wt % less hemicelluloses compared to native spruce. There was an increase in the glucose content of the milled spruce treated with both SILs, since the milling step reduced the cellulose crystallinity of the wood and facilitated an easier SIL access into the wood. The solvents were very neutral in terms of lignin removal. Consequently, only about 2% of the lignin was removed from native wood. Moreover, a priori removal of the wood extractives did not influence the lignin removal. Highlights► Switchable Ionic Liquids made from, either hexanol or butanol, and CO2 together with an amidine (DBU) were studies as dissolution/fractionation solvents for spruce wood. ► After the treatment undissolved fraction contained 38 wt-% less hemicelluloses. ► We conclude that Switchable ionic liquids are effective solvent for fractionation of wood material, and they are easily recycled and can be reused.
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- Mäki-Arvela, P, et al.
(author)
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Dissolution of lignocellulosic materials and its constituents using ionic liquids - a review
- 2010
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In: Industrial crops and products (Print). - : Elseier B.V.. - 0926-6690 .- 1872-633X. ; 32:3, s. 175-201
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Journal article (peer-reviewed)abstract
- The state of art from the dissolution of cellulose, lignin and wood using ionic liquids is presented in this work. The emphasis is put on the relationship between the properties of ionic liquids and the dissolution capacity. The impact of the following solvation parameters, namely Hildebrand solubility parameter and hydrogen bond basicity are related to the dissolution of lignocellulosic material. Good solvents for cellulose are 1-butyl- and 1-allyl-3-methylimidazolium chlorides as well as 1-ethyl-3-methylimidazolium acetate, whereas for lignocellulosic material the best solvents are 1-ethyl-3-methylimidazolium acetate and 1-allyl-3-methylimidazolium chloride. In allyl group the ethylene functionality facilitates B-interactions with the aromatic lignin structure. Furthermore, small polarizable anions are also powerful when aiming at dissolution of cellulose. The properties of regenerated cellulose and reconstituted lignin are also given and compared with those of the native materials. Furthermore, the results from the regeneration and reuse of ionic liquids are presented here.
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