Publications
51 results found
Prado R, Brandt A, Erdocia X, et al., 2016, Depolymerisation of lignin by oxidation in ionic liquids, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Brandt A, Chen L, van Dongen BE, et al., 2015, Structural changes in lignins isolated using an acidic ionic liquid water mixture, Green Chemistry, Vol: 17, Pages: 5019-5034, ISSN: 1463-9262
Recently, acidic ionic liquid water mixtures based on the hydrogen sulfate anion have been shown to effectively extract lignin from lignocellulosic biomass. This study analyses Miscanthus giganteus lignin isolated after extraction with the protic ionic liquid 1-butylimidazolium hydrogen sulfate ([HC4im][HSO4]) followed by precipitation with the antisolvent water. Several analytical techniques were employed, such as quantitative 13C-NMR, 1H–13C HSQC NMR, 31P-NMR, Py-GC-MS, GPC and elemental analysis. The analysis shows that the ionic liquid pretreatment breaks lignin-hemicellulose linkages and depolymerizes the lignin through the cleavage of glycosidic, ester and β-O-4 ether bonds. This is accompanied by solubilization of the newly generated lignin fragments. At longer pretreatment times, repolymerization of lignin fragments through condensation reactions occurs. The isolated lignins were carbohydrate-free, had low sulfur contents, low molecular weights. Early stage lignins were structurally similar to ball-milled lignin, while more treated lignins were enriched in p-hydroxyphenyl and guaiacyl units and had a high phenolic hydroxyl group content. We conclude that, depending on the treatment conditions, lignins with a variety of characteristics can be isolated using this type of ionic liquid solution.
Prado R, Brandt A, Erdocia X, et al., 2015, Lignin oxidation and depolymerisation in ionic liquids, Green Chemistry, Vol: 18, Pages: 834-841, ISSN: 1463-9262
The depolymerisation of lignin directly in the black liquor was studied, comparing two ionic liquids as extracting solvents (butylimidazolium hydrogen sulphate and triethylammonium hydrogen sulphate), under oxidising conditions. H2O2 was chosen as the oxidant agent. It was observed that lignins derived from butylimidazolium hydrogen sulphate were more susceptible to degradation. The main degradation products found in the extracted oils were aromatic acids, such as vanillic acid, benzoic acid and 1,2-benzenedicarboxylic acid.
Brandt A, Hallett JP, 2015, Low-cost ionic liquids for wood fractionation, Pages: 462-466
Pretreatment of lignocellulosic biomass is the first step in the production of chemicals and fuels from woody biomass. It is also of the most expensive steps and has many implications on down-stream processes. Hence pretreatment technologies must be developed that are have low cost and provide high-quality substrates for subsequent chemical and biological transformations. To optimise cost, valorisation of all components contained in the lignocellulosic feedstock is required, including the hemicellulose and the lignin. A novel pretreatment technology is the application of low-cost ionic liquid water mixtures.
George A, Brandt A, Tran K, et al., 2014, Design of low-cost ionic liquids for lignocellulosic biomass pretreatment, Green Chemistry, Vol: 17, Pages: 1728-1734, ISSN: 1744-1560
The cost of ionic liquids (ILs) is one of the main impediments to IL utilization in the cellulosic biorefinery, especially in the pretreatment step. In this study, a number of ionic liquids were synthesized with the goal of optimizing solvent cost and stability whilst demonstrating promising processing potential. To achieve this, inexpensive feedstocks such as sulfuric acid and simple amines were combined into a range of protic ionic liquids containing the hydrogen sulfate [HSO4]− anion. The performance of these ionic liquids was compared to a benchmark system containing the IL 1-ethyl-3-methylimidazolium acetate [C2C1im][OAc]. The highest saccharification yields were observed for the triethylammonium hydrogen sulfate IL, which was 75% as effective as the benchmark system. Techno-economic modeling revealed that this promising and yet to be optimized yield was achieved at a fraction of the processing cost. This study demonstrates that some ILs can compete with the cheapest pretreatment chemicals, such as ammonia, in terms of effectiveness and process cost, removing IL cost as a barrier to the economic viability of IL-based biorefineries.
Brandt-Talbot A, Murphy R, Leak D, et al., 2014, Treatment, US2014073016 (A1)
The present invention relates to a method for treating a lignocellulose biomass in order to dissolve the lignin therein, while the cellulose does not dissolve. The cellulose pulp obtained can be used to produce glucose. In addition the lignin can be isolated for subsequent use in the renewable chemical industry as a source for aromatic platform chemicals.
Verdia P, Brandt A, Hallett JP, et al., 2014, Fractionation of lignocellulosic biomass with the ionic liquid 1-butylimidazolium hydrogen sulfate, Green Chemistry, Vol: 16, Pages: 1617-1627, ISSN: 1744-1560
The application of the protic ionic liquid 1-butylimidazolium hydrogen sulfate in the deconstruction (aka pretreatment) and fractionation of lignocellulosic biomass has been investigated. A cellulose rich pulp and a lignin fraction were produced. The pulp was subjected to enzymatic saccharification which allowed recovery of up to 90% of the glucan as fermentable glucose. The influence of the solution acidity on the deconstruction of Miscanthus giganteus was examined by varying the 1-butylimidazole to sulfuric acid ratio. Increased acidity led to shorter pretreatment times and resulted in reduced hemicellulose content in the pulp. Addition of water to the ionic liquid resulted in enhanced saccharification yields. The ability to tune acidity through the use of protic ionic liquids offers a significant advantage in flexibility over dialkylimidazolium analogues.
Niedermeyer H, Ashworth C, Brandt A, et al., 2013, A step towards the <i>a priori</i> design of ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 15, Pages: 11566-11578, ISSN: 1463-9076
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- Citations: 55
Brandt A, Grasvik J, Hallett JP, et al., 2013, Deconstruction of lignocellulosic biomass with ionic liquids, Green Chem., Vol: 15, Pages: 550-583-550-583
This paper reviews the application of ionic liquids to the deconstruction and fractionation of lignocellulosic biomass, in a process step that is commonly called pretreatment. It is divided into four parts: the first gives background information on lignocellulosic biomass and ionic liquids; the second focuses on the solubility of lignocellulosic biomass (and the individual biopolymers within it) in ionic liquids; the third emphasises the deconstruction effects brought about by the use of ionic liquids as a solvent; the fourth part deals with practical considerations regarding the design of ionic liquid based deconstruction processes.
Brandt A, Murphy RJ, Leak DJ, et al., 2012, Ionic liquids for pretreating lignocellulosic biomass
The present invention relates to a method for treating a lignocellulose biomass in order to dissolve the lignin therein, while the cellulose does not dissolve. The cellulose pulp obtained can be used to produce glucose. In addition the lignin can be isolated for subsequent use in the renewable chemical industry as a source for aromatic platform chemicals.
Brandt A, Erickson JK, Hallett JP, et al., 2012, Soaking of pine wood chips with ionic liquids for reduced energy input during grinding, Green Chemistry, Vol: 14, Pages: 1079-1085, ISSN: 1463-9262
Ionic liquids are of great interest as potential solvents/catalysts for the production of fuels and chemicals from lignocellulosic biomass. Attention has focused particularly on the pretreatment of lignocellulose to make the cellulose more accessible to enzymatic hydrolysis. Any biomass processing requires a reduction in the size of the harvested biomass by chipping and/or grinding to make it more amenable to chemical and biological treatments. This paper demonstrates that significant energy savings can be achieved in the grinding of pine wood chips when the ionic liquid is added before the grinding operation. We show that this is due to the lubricating properties of the ionic liquids and not to physico-chemical modifications of the biomass. A brief impregnation of the chipped biomass results in higher savings than a longer treatment.
Ab Rani MA, Brandt A, Crowhurst L, et al., 2011, Erratum: Understanding the polarity of ionic liquids (Physical Chemistry Chemical Physics (2011) DOI: 10.1039/c1cp21262a), Physical Chemistry Chemical Physics, Vol: 13, ISSN: 1463-9076
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- Citations: 5
Brandt A, Ray MJ, To TQ, et al., 2011, Ionic liquid pretreatment of lignocellulosic biomass with ionic liquid-water mixtures, Green Chem., Vol: 13, Pages: 2489-2499-2489-2499
Ground lignocellulosic biomass (Miscanthus giganteus, pine (Pinus sylvestris) and willow (Salix viminalis)) was pretreated with ionic liquid-water mixtures of 1-butyl-3-methylimidazolium methyl sulfate and 1-butyl-3-methylimidazolium hydrogen sulfate. A solid fraction enriched in cellulose was recovered, which was subjected to enzymatic hydrolysis. Up to 90% of the glucose and 25% of the hemicellulose contained in the original biomass were released by the combined ionic liquid pretreatment and the enzymatic hydrolysis. After the pretreatment, the ionic liquid liquor contained the majority of the lignin and the hemicellulose. The lignin portion was partially precipitated from the liquor upon dilution with water. The amount of hemicellulose monomers in the ionic liquid liquor and their conversion into furfurals was also examined. The performance of ionic liquid-water mixtures containing 1,3-dialkylimidazolium ionic liquids with acetate, methanesulfonate, trifluoromethanesulfonate and chloride anions was investigated. The applicability of the ionic liquid 1-butylimidazolium hydrogensulfate for lignocellulose pretreatment was also examined. It was found that ionic liquid liquors containing methyl sulfate, hydrogen sulfate and methanesulfonate anions were most effective in terms of lignin/cellulose fractionation and enhancement of cellulose digestibility.
Schrems Michael, Brandt Agnieszka, Welton Tom, et al., 2011, Ionic liquids as media for biomass processing: opportunities and restrictions
Ab Rani MA, Brant A, Crowhurst L, et al., 2011, Understanding the polarity of ionic liquids, Phys. Chem. Chem. Phys., Vol: 13, Pages: 16831-16840-16831-16840
The polarities of a wide range of ionic liquids have been determined using the Kamlet-Taft empirical polarity scales [small alpha], [small beta] and [small pi]*, with the dye set Reichardt’s Dye, N,N-diethyl-4-nitroaniline and 4-nitroaniline. These have been compared to measurements of these parameters with different dye sets and to different polarity scales. The results emphasise the importance of recognising the role that the nature of the solute plays in determining these scales. It is particularly noted that polarity scales based upon charged solutes can give very different values for the polarity of ionic liquids compared to those based upon neutral probes. Finally, the effects of commonplace impurities in ionic liquids are reported.
Ab Rani MA, Brandt A, Crowhurst L, et al., 2011, Understanding the polarity of ionic liquids (vol 13, pg 16831, 2011), PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 13, Pages: 21653-21653, ISSN: 1463-9076
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- Citations: 4
Brandt A, Wojtasiewicz A, Sniezek M, et al., 2010, ChemInform Abstract: Synthesis of Substituted Tetrahydrofurans via Intermolecular Reactions of γ‐Chlorocarbanions of 3‐Substituted 3‐Chloro‐propylphenyl Sulfones with Aldehydes., ChemInform, Vol: 41, ISSN: 0931-7597
<jats:title>Abstract</jats:title><jats:p>Substrates (I), (V) and (IX) are subjected to the title reaction.</jats:p>
Berezina OV, Zakharova NV, Brandt A, et al., 2010, Reconstructing the clostridial n-butanol metabolic pathway in Lactobacillus brevis, Applied Microbiology and Biotechnology, Vol: 87, Pages: 635-646, ISSN: 0175-7598
Brandt A, Wojtasiewicz A, Śnieżek M, et al., 2010, Synthesis of substituted tetrahydrofurans via intermolecular reactions of γ-chlorocarbanions of 3-substituted 3-chloro-propylphenyl sulfones with aldehydes, Tetrahedron, Vol: 66, Pages: 3378-3385, ISSN: 0040-4020
Brandt A, Hallett JP, Leak DJ, et al., 2010, The effect of the ionic liquid anion in the pretreatment of pine wood chips, Green Chem., Vol: 12, Pages: 672-679-672-679
The effect of the anion of ionic liquids on air-dried pine (Pinus radiata) has been investigated. All ionic liquids used in this study contained the 1-butyl-3-methylimidazolium cation; the anions were trifluoromethanesulfonate, methylsulfate, dimethylphosphate, dicyanamide, chloride and acetate. Using a protocol for assessing the ability to swell small wood blocks (10 [times] 10 [times] 5 mm), it was shown that the anion has a profound impact on the ability to promote both swelling and dissolution of biomass. Time course studies showed that viscosity, temperature and water content were also important parameters influencing the swelling process. We used Kamlet-Taft parameters to quantify the solvent polarity of the ionic liquids and found that the anion basicity described by the parameter [small beta] correlated with the ability to expand and dissolve pine lignocellulose. It is shown that 1-butyl-3-methylimidazolium dicyanamide dissolves neither cellulose nor lignocellulosic material.
Berezina OV, Brandt A, Yarotsky S, et al., 2009, Isolation of a new butanol-producing Clostridium strain: High level of hemicellulosic activity and structure of solventogenesis genes of a new Clostridium saccharobutylicum isolate, Systematic and Applied Microbiology, Vol: 32, Pages: 449-459, ISSN: 0723-2020
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