20 results found
Vincent S, Prado R, Kuzmina O, et al., 2018, Regenerated cellulose and willow lignin blends as potential renewable precursors for carbon fibers, ACS Sustainable Chemistry and Engineering, Vol: 6, Pages: 5903-5910, ISSN: 2168-0485
We report on the extraction of lignin from willow and its use to manufacture cellulose-lignin fibers as potential precursors for the manufacture of carbon fibers. The lignin from willow was extracted using triethylammonium hydrogen sulfate [Et3NH][HSO4]. The lignin extracted by this process was characterized by ATR-IR and elemental analysis, which indicated a high carbon yield. 1-Ethyl-3-methylimidazolium acetate [C2C1im][OAc] was then used as a common solvent to dissolve cellulose and lignin to manufacture lignin-cellulose fiber blends. The Young’s modulus of a 75:25 lignin/cellulose fiber was found to be 3.0 ± 0.5 GPa, which increased to 5.9 ± 0.6 GPa for a 25:75 lignin/cellulose blend. From a characterization of the surface morphology, using scanning electron microscopy (SEM) and atomic force microscopy (AFM), it was observed that higher lignin content in the fiber blend increased the surface roughness. FT-IR analysis confirmed the presence of aromatic groups related to lignin in the obtained fibers from the presence of peaks located at ∼1505 cm–1 and ∼1607 cm–1. The presence of lignin improves the thermal stability of the fiber blends by allowing them to degrade over a wider temperature range. The presence of lignin also improved the carbon yield during carbonization. Therefore, the lignin-cellulose fibers developed in this work can offer an excellent alternative to pure cellulose or lignin filaments.
Kuzmina O, Bhardwaj J, Vincent SR, et al., 2017, Superbase ionic liquids for effective cellulose processing from dissolution to carbonisation, Green Chemistry, Vol: 19, Pages: 5949-5957, ISSN: 1463-9262
A range of superbase derived ionic liquids (SILs) was synthesised and characterised. Their ability to dissolve cellulose and the characteristics of the produced fibres were correlated to their specific structural and solvent properties. 17 ionic liquids (ILs) (including 9 novel) were analysed and six ILs were selected to produce fibres: 1-ethyl-3-methylimidazolium acetate [C2C1im][OAc], 1-ethyl-3-methylimidazolium diethyl phosphate [C2C1im][DEP] and the SILs 1-ethyl-1,8-diazabicyclo[5.4.0]undec-7-enium diethylphosphate [DBUEt][DEP], 1,8-diazabicyclo[5.4.0]undec-7-enium acetate [DBUH][OAc], 1,5-diazabicyclo[4.3.0]non-5-enium acetate [DBNH][OAc] and 1-ethyl-1,5-diazabicyclo[4.3.0]non-5-enium diethylphsophate [DBNEt][DEP]. The mechanical properties of these fibres were investigated. The obtained fibres were then carbonised to explore possible application as carbon fibre precursors. The fibres obtained using a mixture of 1,5-diazabicyclo[4.3.0]non-5-enium based SILs with acetate and hexanoate anions (9 : 1), [DBNH][OAc][Hex], showed a promising combination of strength, stiffness and strain at failure values for applications in textiles and fibre reinforcement in renewable composites. Using Raman spectroscopy it is demonstrated that these fibres exhibit a relatively high degree of structural order, with fewer defects than the other materials. On the other hand, analogous fibres based on imidazolium cation with acetate and hexanoate anions (9 : 1), [C2C1im][OAc][Hex] showed a decline in the quality of the produced fibres compared to the fibres produced from [C2C1im][OAc], [C2C1im][DEP] or [DBNH][OAc][Hex].
Kuzmina O, Hassan NH, Patel L, et al., 2017, The impact of ionic liquids on the coordination of anions with solvatochromic copper complexes, Dalton Transactions, Vol: 46, Pages: 12185-12200, ISSN: 1477-9234
Solvatochromic transition metal (TM)-complexes with weakly associating counter-anions are often used to evaluate traditional neutral solvent and anion coordination ability. However, when employed in ionic liquids (IL) many of the common assumptions made are no longer reliable. This study investigates the coordinating ability of weakly coordinating IL anions in traditional solvents and within IL solvents employing a range of solvatochromic copper complexes. Complexes of the form [Cu(acac)(tmen)][X] (acac = acetylacetonate, tmen = tetramethylethylenediamine) where [X]− = [ClO4]−, Cl−, [NO3]−, [SCN]−, [OTf]−, [NTf2]− and [PF6]− have been synthesised and characterised both experimentally and computationally. ILs based on these anions and imidazolium and pyrrolidinium cations, some of which are functionalised with hydroxyl and nitrile groups, have been examined. IL-anion coordination has been investigated and compared to typical weakly coordinating anions. We have found there is potential for competition at the Cu-centre and cases of anions traditionally assigned as weakly associating that demonstrate a stronger than expected level of coordinating ability within ILs. [Cu(acac)(tmen)][PF6] is shown to contain the least coordinating anion and is established as the most sensitive probe studied here. Using this probe, the donor numbers (DNs) of ILs have been determined. Relative donor ability is further confirmed based on the UV-Vis of a neutral complex, [Cu(sacsac)2] (sacsac = dithioacetylacetone), and DNs evaluated via23Na NMR spectroscopy. We demonstrate that ILs can span a wide donor range, similar in breadth to conventional solvents.
Kuzmina O, Symianakis E, Godfrey D, et al., 2017, Ionic liquids for metal extraction from chalcopyrite: solid, liquid and gas phase studies, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 19, Pages: 21556-21564, ISSN: 1463-9076
We studied leaching of Cu and Fe from naturally occurring chalcopyrite ore using aqueous solutions of ionic liquids (ILs) based on imidazolium and ethylammonium cations and hydrogensulfate, nitrate, acetate or dicyanamide anions. Liquid, solid and gas phases of the leaching systems were characterised. We have shown that nonoxidative leaching is greatly dependant not only on temperature and pH, but on the anion species of the IL. Solutions of 1-butylimidazolium hydrogen sulfate exhibited the best leaching performance among hydrogen sulphate ILs. We have suggested that the formation of an oxide layer in some ILs may be responsible for a reduced leaching ability. The analysis of the gas phase showed the production of CO2 and CS2 in all leached samples. Our results suggested that the CS2 produced upon leaching could be responsible for decreasing the sulfur, but not oxide, layer on the surface of chalcopyrite samples and therefore more efficient leaching. This is the first study, to our knowledge, to provide a systematic comparison of the leaching performance of ILs composed of different anions and cations and without added oxidants.
Kuzmina O, 2017, CHAPTER 3. cationic and anionic polymerized ionic liquids: properties for applications, Polymerized Ionic Liquids, Publisher: Royal Society of Chemistry, Pages: 83-116, ISBN: 9781782629603
This chapter contains information on the comparison of cationic and anionic polymeric ionic liquids (PILs) as functional materials for emerging applications. Data is tabulated to allow the interested reader to easily find the required information. The structures of the discussed cationic and anionic PILs are collected and reported against their performance in particular areas of application to assist in understanding the effects of structure on the properties of this class of materials. Key similarities in performance, depending on their structure and additives, are included in the studied systems together with a discussion of the research progress in each field of PIL application. Anionic PILs are much less explored than cationic PILs due to their complicated synthesis and the smaller diversity of the available polymerised anions in comparison to the wide variety of polymerised cations and relative simplicity of the synthesis of cationic PILs. Reports on research into the use of anionic PILs as electroconductive and sensing materials and gas-sorbents are found and discussed in this chapter. Their properties are comparable to those of cationic PILs with similar structures of ions, with very promising conductivity results. This chapter may become a source of inspiration for researchers aiming to design novel PILs for specific applications.
Hunt PA, Welton T, Hallett J, et al., 2016, Solubility of Alkali Metal Halides in the Ionic Liquid [C4C1im][OTf], Physical Chemistry Chemical Physics, Vol: 18, Pages: 16161-16168, ISSN: 1463-9084
The solubilities of the metal halides LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbCl, CsCl,CsI, were measured at temperatures ranging from 298.15 to 378.15 K in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4C1im][OTf]). Li+, Na+and K+salts with anionsmatching the ionic liquid have been also investigated to determine how well these cations dissolve in[C4C1im][OTf]. This study compares the influence of metal cation and halide anion on the solubility ofsalts within this ionic liquid. The highest solubility found was for iodide salts and the lowestsolubility, for the three fluoride salts. There is no outstanding difference in the solubility of salts withmatching anions in comparison to halide salts. The experimental data were correlated employingseveral phase equilibria models, including ideal mixtures, van’t Hoff, the λh (Buchowski) equation,the modified Apelblat equation, and the non-random two-liquid model (NRTL). It was found that thevan’t Hoff model gave the best correlation results. On the basis of the experimental data thethermodynamic dissolution parameters (ΔH, ΔS, and ΔG) were determined for the studied systemstogether with computed gas phase metathesis parameters. Dissolution depends on the energydifference between enthalpies of fusion and dissolution of the solute salt. This demonstrates thatovercoming the lattice energy of the solid matrix is the key to the solubility of inorganic salts in ionicliquids.
Albrecht T, Godfrey D, Bannock JH, et al., 2016, A robotic platform for high-throughput electrochemical analysis of chalcopyrite leaching, Green Chemistry, Vol: 18, Pages: 1930-1937, ISSN: 1463-9262
Cu extraction from chalcopyrite ores is typically a slow process that involves aggressive chemical reagents with significant environmental impact. Ionic liquids (IL) have been proposed as a potentially more benign solution, but the sheer number of IL variants complicates the search for the most efficient solvent systems. Here, we present an automated electrochemical platform that allows for screening of 180 and more leaching samples in parallel with minimal solvent consumption. In a proof-of-concept study, we screen 25 samples with different IL and water contents, and find two orders of magnitude difference in leaching performance within this array. The best performing system is then applied in a tank leaching configuration, with real-time electrochemical monitoring of Cu evolution in solution. All electrochemical data is found to be in excellent agreement with off-line ICP-AES data.
Welton T, Griffith J, Clough M, et al., 2016, Enhancing the stability of ionic liquid media for cellulose processing: acetal protection or carbene suppression?, Green Chemistry, Vol: 18, Pages: 3758-3766, ISSN: 1463-9262
Although excellent candidate solvents for cellulose, capa-ble of dissolving 20 wt% of the carbohydrate for electro-spinning processes, dialky-limidazolium carboxylate ionic liquids undergo unde-sirable side reactions with the reducing end of saccharides, terminating in an equilibrium concentration of a 2-(hydroxymethyl)-substituted imidazolium ‘adduct’. The addition of small molar quantities of a benign, non-toxic and inexpensive co-solvent, e.g. glycerol, mini-mises the rate of adduct ac-cumulation, thereby enhanc-ing the long-term thermal stability and recyclability of the expensive ionic liquid component. NMR, UV-vis and mass spectrometry ex-periments reveal that the im-proved stability is likely at-tributable to suppression of the transient dialkylimidazol-2-ylidene carbene, via hy-drogen-donation by the pro-tic co-solvent, rather than by cyclic acetal protection of the carbohydrate. The incor-poration of (up to) 10 wt% of glycerol into the solvent mix-ture does not exacerbate the rate of cellulose depolymeri-sation compared to in the neat ionic liquid, and high solubility of cellulose is main-tained. Furthermore, a col-ourimetric comparison of the recovered solvents, following cellulose re-precipitation, demonstrates that glycerol does not increase the concen-tration of contaminant re-ducing sugars in the organic electrolyte.
Kuzmina O, Welton T, 2016, Physicochemical properties of cellulose-dissolving superbase ionic liquids, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Vincent SR, Prado R, Koutsomitopoulou A, et al., 2016, Fibre spinning of lingo-cellulose biomass using ionic liquids, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Rahatekar S, Zhu C, Eichhorn S, et al., 2016, Manufacturing strong regenerated cellulose nano-composite fibres, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
McIntosh AJS, Grasvik J, Griffith J, 2016, Methods of synthesis and purification of ionic liquids, Application, Purification, and Recovery of Ionic Liquids, Editors: Kuzmina, Hallett, Publisher: Elsevier, ISBN: 9780444637130
The book gives a description of the methods used for recovery and purification of ILs, a summary of the economic aspects of using ILs, and a review on the toxicity data of ILs.
Kuzmina O, Hallett JP, 2016, Application, Purification, and Recovery of Ionic Liquids, ISBN: 9780444637130
Application, Purification, and Recovery of Ionic Liquids provides a comprehensive overview of the usage of ionic liquids (IL). The book gives a description of the methods used for recovery and purification of ILs, a summary of the economic aspects of using ILs, and a review on the toxicity data of ILs. It is written for researchers, scientists, and engineers working with ILs, their properties, and usages. The book not only describes the chemical aspects, but the economic and environmental aspects as well, making it of particular interest to professionals applying this technology. Chapters written by scientists in academia and researchers in industry, ensuring coverage of both the scientific fundaments and industrial applications. A single source of information for a broad collection of recovery and purification methods. Provides information on using ionic liquids as green solvents. Includes economic aspects of recovery and reuse of ionic liquids.
Kuzmina O, Hallett JP, 2016, Introduction, ISBN: 9780444637130
Kuzmina O, Jankowski S, Fabianska A, et al., 2014, PRESWELLING OF CELLULOSE PULP FOR DISSOLUTION IN IONIC LIQUID, CELLULOSE CHEMISTRY AND TECHNOLOGY, Vol: 48, Pages: 45-51, ISSN: 0576-9787
Kuzmina O, Heinze T, Wawro D, 2012, Blending of Cellulose and Chitosan in Alkyl Imidazolium Ionic Liquids, ISRN Polymer Science, Vol: 2012, Pages: 1-9
<jats:p>The production of cellulose/chitosan blends in alkyl imidazolium ionic liquids (ILs) was studied in this work. Selected organic solvents, such as dimethyl sulfoxide, ethyl acetate, and diethyl ether, were used as cosolvents. The addition of cosolvents decreased the viscosity of cellulose/chitosan solutions in ILs and facilitated the dissolution of polysaccharides, thereby decreasing the and polymer aggregates sizes in the solutions. The cellulose/chitosan films were produced from the studied solutions. The presence of one of cosolvent and ILs in the blended films was confirmed by FTIR spectroscopy. The blended film is stronger than pure cellulose film, and the addition of cosolvents has an influence on its mechanical properties.</jats:p>
Kuzmina O, Sashina E, Wawro D, et al., 2010, Dissolved state of cellulose in ionic liquid - the impact of water, FIBRES & TEXTILES in Eastern Europe
Kuzmina O, Sashina E, Novoselov N, et al., 2009, Blends of Cellulose and Silk Fibroin in 1-buthyl-3-methylimidazolium chloride Based Solutions, FIBRES & TEXTILES in Eastern Europe 2009, Vol. 17, No. 6 (77) pp. 36-39.
Novoselov NP, Sashina ES, Kuzmina OG, et al., 2007, Ionic liquids and their use for the dissolution of natural polymers, Russian Journal of General Chemistry, Vol: 77, Pages: 1395-1405, ISSN: 1070-3632
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