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Treating ground bagasse or Southern yellow pine in the biodegradable ionic liquid (IL), choline acetate ([Cho][OAc]), at 100°C for 24h led to dissolution of hemicellulose and lignin, while leaving the cellulose pulp undissolved, with a 54.3% (bagasse) or 34.3% (pine) reduction in lignin content. The IL solution of the dissolved biopolymers can be separated from the undissolved particles either by addition of water (20 wt% of IL) followed by filtration or by centrifugation. Hemicellulose (19.0 wt% of original bagasse, 10.2 wt% of original pine, containing 14-18 wt% lignin) and lignin (5.0 wt% of original bagasse, 6.0 wt% of original pine) could be subsequently precipitated. The pulp obtained from [Cho][OAc] treatment can be rapidly dissolved in 1-ethyl-3-methylimidazolium acetate (e.g., 17 h for raw bagasse vs. 7h for pulp), and precipitated as cellulose-rich material (CRM) with a lower lignin content (e.g., 23.6% for raw bagasse vs. 10.6% for CRM)., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Certain ionic liquids have been shown to dissolve cellulose, other biopolymers, and even raw biomass under relatively mild conditions. This particular ability of some ionic liquids, accompanied by a series of concurrent advantages, enables the development of improved processing strategies for the manufacturing of a plethora of biopolymer-based advanced materials. The more recent discoveries of dissolution of lignocellulosic materials (e.g., wood) in ionic liquids, with at least partial separation of the major constituent biopolymers, suggest further paths towards the achievement of a truly sustainable chemical and energy economy based on the concept of a biorefinery which provides chemicals, materials, and energy. Nonetheless, questions remain about the use of ionic liquids and the advisability of introducing any new process which utilizes bulk synthetic chemicals which have to be made, disposed of, and prevented from entering the environment. In this article, we discuss our own journey from the discovery of the dissolution of cellulose in ionic liquids to the cusp of an enabling technology for a true biorefinery and consider some of the key questions which remain.

A well-known polyoxometalate, [PV₂Mo₁₀O₄₀]⁵⁻, in both acidic (acidic POM, H₅[PV₂Mo₁₀O₄₀]) and ionic liquid-compatible form ([C₂mim]POM, [1-ethyl-3-methylimidazolium]₄H[PV₂Mo₁₀O₄₀]), has been studied as a catalyst for the dissolution and delignification of wood in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C(2) mim]OAc). Differences were observed with variables such as the form of POM, POM loading, and reaction conditions. Generally, the addition of POM leads to a faster dissolution, a lower lignin content in the recovered cellulose-rich materials (isolated pulp), and a lower isolated yield of lignin due to its oxidation. Acidic POM decreases the lignin content of the pulp without compromising the yield of the pulp. [C₂mim]POM in the IL facilitates greater delignification (lower lignin content in pulp) than the IL with acidic POM; however, the overall pulp yield is also lower indicating some degradation of the carbohydrates. The POM can be recovered with [C₂mim]OAc after evaporation of the reconstitution solvent (e.g., acetone/water) and can be reused, albeit with some loss of POM and loss of POM activity under the current conditions., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Chemisorption of carbon dioxide by 1‐ethyl‐3‐methylimidazolium acetate ([C2mim][OAc]) provides a route to coagulate chitin and cellulose from [C2mim][OAc] solutions without the use of high‐boiling antisolvents (e.g., water or ethanol). The use of CO2 chemisorption as an alternative coagulating process has the potential to provide an economical and energy‐efficient method for recycling the ionic liquid. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are desirable for use in a large number of applications because of their unique properties; however, compositions comprising only a single IL are expensive to synthesize and difficult to purify, and the widely used chloride-based ILs can be toxic and corrosive. Therefore, there is a need for new IL compositions that minimize common disadvantages encountered with single IL composition and synthetic methods which avoid halide intermediates. In this study, IL mixtures, which are chloride-free, were synthesized by a one-pot process, and the mixtures were used to dissolve biopolymers. The synthesized IL mixtures show high capability to dissolve the two exemplary biopolymers, cellulose and chitin. [ABSTRACT FROM AUTHOR]

Rapid dissolution of bagasse and southern yellow pine has been achieved in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C2mim]OAc) by using a dissolution temperature above the glass transition of lignin (ca.150 °C). When 0.5 g of bagasse or pine is added to 10 g of [C2mim]OAc, complete dissolution can be obtained in 5–15 min for bagasse at a temperature of 175–195 °C, compared to 15–16 h at 110 °C, and over 90% of added pine can be dissolved with heating at 175 °C for 30 min. Upon regeneration in acetone/water, lignin and carbohydrate can be partially separated as lignin and a cellulose-rich material (CRM, pulp). Compared to published methods with lower temperatures and longer times (e.g., 110 °C, 16 h), processing bagasse in [C2mim]OAc at 185 °C for 10 min results in higher yields of both recovered lignin (31% vs.26% of the available lignin) and carbohydrate (carbohydrate yield = 66% vs.63% of the available carbohydrate). In addition, the CRM pulp recovered using the higher temperature method has much lower residual lignin content (6% vs.20%). Similar results were obtained for pine (lignin content in CRM with higher vs.lower temperature method = 16.1% vs.23.5%). The IL was recycled and reused although the efficiency decreased and ca.15% of the IL had degraded after the higher temperature process. These latter results suggest further optimization of the choice of IL and heating conditions might be needed to develop an energy and chemical efficient process. [ABSTRACT FROM AUTHOR]

Rapid dissolution of bagasse and southern yellow pine has been achieved in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C2mim]OAc) by using a dissolution temperature above the glass transition of lignin (ca. 150 °C). When 0.5 g of bagasse or pine is added to 10 g of [C2mim]OAc, complete dissolution can be obtained in 5–15 min for bagasse at a temperature of 175–195 °C, compared to 15–16 h at 110 °C, and over 90% of added pine can be dissolved with heating at 175 °C for 30 min. Upon regeneration in acetone/water, lignin and carbohydrate can be partially separated as lignin and a cellulose-rich material (CRM, pulp). Compared to published methods with lower temperatures and longer times (e.g., 110 °C, 16 h), processing bagasse in [C2mim]OAc at 185 °C for 10 min results in higher yields of both recovered lignin (31% vs. 26% of the available lignin) and carbohydrate (carbohydrate yield = 66% vs. 63% of the available carbohydrate). In addition, the CRM pulp recovered using the higher temperature method has much lower residual lignin content (6% vs. 20%). Similar results were obtained for pine (lignin content in CRM with higher vs. lower temperature method = 16.1% vs. 23.5%). The IL was recycled and reused although the efficiency decreased and ca. 15% of the IL had degraded after the higher temperature process. These latter results suggest further optimization of the choice of IL and heating conditions might be needed to develop an energy and chemical efficient process. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass composite fibers (southern yellow pine and bagasse) were successfully prepared directly from the ionic liquid, 1-ethyl-3-methylimidazolium acetate ([C2mim]OAc) with a dry-jet wet spinning process using short dissolution times (10–30 min) and temperatures above the glass transition temperature of lignin. Fibers could not be spun at all from solutions of pine dissolved using previously reported dissolution methods (110 °C, 16 h), while bagasse fibers spun using the higher temperature/shorter time method were stronger than those obtained using the lower temperature/longer time method. [ABSTRACT FROM AUTHOR]

We present the dissolution of fresh fragrance biomass in ionic liquids for the isolation of essential oils and compare direct distillation with solvent extraction. Orange essential oil was distilled from orange peels dissolved in ionic liquid media, thus allowing a simple, efficient, and mild isolation of fragrance and flavor components with complete recovery of the ionic liquid. [ABSTRACT FROM AUTHOR]

This study demonstrates the use of ionic liquids to successfully extract chitin from different biomass sources and the utilization of the resulting chitins to prepare monofilament fibers. Chitin was extracted from five different biomass sources (processed and raw shrimp shell, crab and lobster shell, and fly larvae) using the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C 2 mim][OAc]). While processed and raw shrimp shell yielded chitin of high purity in quantitative yield, crab and lobster shell resulted in lower yields of chitin. Fly larva provided chitin severely contaminated with proteins. Each extracted chitin was re-dissolved in the same IL and dry wet jet spun into monofilament fibers to determine any trends in mechanical properties vs. biomass source. The concentration needed to spin fibers was not consistent and had to be adjusted individually for each type of chitin obtained. Chitin from raw shrimp shell produced the strongest fibers, while the chitin from the crab and lobster produced weaker fibers, although, the latter were twice as elastic. The use of fly larvae led to the weakest and least elastic fibers. [Display omitted] [ABSTRACT FROM AUTHOR]