We investigate in this paper the potential of Raman spectroscopy for the quantification of protic ionic liquid components (acid and base) and water, in ionic liquid/water mixtures, taking 1.5-Diazabicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]) as a case study. We show that the combination of Raman spectroscopy and chemometrics is quite successful for the quantitative analysis of the ionic liquid components and water in mixtures over wide concentration ranges. The finding of the present work suggest that Raman spectroscopy should be considered more universally for the in-line monitoring and control of processes involving ionic liquid/H 2 O mixtures.

One of the main issues associated with ionic liquids (ILs) is their recyclability. Viable recycling concepts can only be developed if one knows what is in the IL mixtures and solutions. In our previous work, we showed that it is possible to quantify water and 1.5-diazabicyclo[4.3.0]non-5-enium acetate [DBNH][OAc] IL components in liquid mixtures using Raman spectroscopy. In this regard, we considered Raman spectroscopy as a promising analytical method for the inline monitoring and control of the Ioncell ® process. In the present work, we push the limits of this analytical method further by extending it to more complex and realistic liquid mixtures including the hydrolysis product 1-(3-aminopropyl)-2-pyrrolidone (APP) that can be formed upon the reaction of 5-diazabicyclo[4.3.0]non-5-ene (DBN) with water. Quantifying APP is important in order to measure the extent of the hydrolysis reaction and apply the right corrective measures to reverse the reaction and to maintain the process within the optimal working conditions. The simultaneous quantification of the four components (Acetic acid, DBN, APP and H 2 O) in typical Ioncell ® liquid streams is investigated using Raman spectroscopy. The sensitivity of the Raman method in quantifying APP is also highlighted in comparison with refractometry, which is widely applied to measure IL concentration in aqueous mixtures. Finally, we propose simple modifications on the multivariate partial least square regression model based on a variable selection algorithm to enhance the accuracy of the predicted calibration values.

Ioncell is a Lyocell-based process that utilizes protic superbase-based ionic liquids (ILs) to produce man-made cellulose fibers. This process comprises a dry-jet wet spinning technology, in which ...

Ioncell is a Lyocell based technology for the production of man-made cellulose fibers. This technology exploits the intrinsic dissolution power of superbase-based ionic liquids (ILs) toward cellulose and the ability to form spinnable cellulose solutions. The regenerated fibers are produced via a dry-jet wet spinning process in which the cellulose filaments are stretched in an air gap before regenerating in an aqueous coagulation medium. For the commercialization of this process, it is essential to demonstrate the quantitative recovery of the solvent from the coagulation bath without impairing its solvation power. This study reports on the spinnability and recyclability of the IL 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate ([mTBDH][OAc]) over five cycles in comparison to 1,5-diaza-bicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]). The aqueous IL solutions were recovered from the coagulation bath by successive thermal treatments under reduced pressure. Accordingly, the recycled ILs were utilized to dissolve 13 wt % cellulose pulp in each cycle without the addition of make-up IL. While using [mTBDH][OAc], the pulp was completely dissolved and processed into easily spinnable cellulose solutions during all five cycles, whereas the ability to dissolve pulp was completely lost after the first recovery cycle when using [DBNH][OAc]. The composition of the recovered ILs and extent of side-products generated in the adopted process was analyzed in detail. This includes characterization of the rheological properties of the solutions as well as the macromolecular and mechanical properties of the regenerated fibers. In addition, we review the toxicity of both solvents using Vibrio fischeri bacteria. Finally, the spun fibers from all [mTBDH][OAc] spinning trials were combined to produce a demonstration dress (Paju), designed and sewn by Marimekko Design House in Finland.

This Review discusses novel catalytic pathways of lignocellulosic biomass to value‐added chemicals including biomass‐derived sugar alcohols, organic acids, furans and biohydrocarbons. These production approaches are undertaken by biological, chemical and thermochemical transformations or a combination of them. Nevertheless, the majority of research in this area is focused on the design of heterogeneous catalysts to convert value‐added products from holocellulosic biomass. Biorefineries represent the peak of biomass processes in order to produce valuable chemicals and liquid fuels avoiding the utilization of corroding and toxic elements. The aim of the present Review is to offer the readers a broad overview of recent holocellulosic‐based chemical and fuels production technologies via heterogeneous catalysis. There is also an overview of the economic aspects to efficiently produce these platform chemicals at industrial scale. To summarize this Review, an outlook and conclusions of the reported processes to date is provided.

Furfural (FUR) was produced from xylose using a biphasic batch reaction system. Water-immiscible organic solvents such as isophorone, 2-methyltetrahydrofuran (2-MTHF) and cyclopentyl methyl ether (CPME) were used to promptly extract FUR from the aqueous phase in order to avoid the degradation to humins as largely as possible. The effect of time, temperature, organic solvent and organic-to-aqueous ratio on xylose conversion and FUR yield were investigated in auto-catalyzed conditions. Experiments at three temperatures (170, 190 and 210 degrees C) were carried out in a stirred microwave-assisted batch reactor, which established the optimal conditions for achieving the highest FUR yield. The maximum FUR yields from xylose were 78 mol% when using CPME, 48 mol% using isophorone and 71 mol% in the case of 2-MTHF at an aqueous to organic phase ratio of 1:1 (v/v). Birch hydrolysate was also used to show the high furfural yield that can be obtained in the biphasic system under optimized conditions. The present study suggests that CPME can be used as a green and efficient extraction solvent for the conversion of xylose into furfural without salt addition. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

The production of furfural (FUR) from xylose was carried out using sulfated zirconia (SZ) on cordierite, alumina on cordierite and commercially-available polymeric solid catalysts (Amberlyst DT and Nafion NR40) to provide insights into the reaction pathways and kinetics for the dehydration of xylose in aqueous phase. Experiments conducted at three temperatures were investigated (170, 190 and 210 degrees C) in a stirred microwave-assisted batch reactor, which established the optimal conditions to obtain the highest FUR yield as well as extensive and fast xylose conversion. The maximum FUR yields obtained from xylose were 41 mol% when using SZ on cordierite in 2 min (at 210 degrees C), 43 mol% when using alumina on cordierite in 30 min (at 210 degrees C) and 48 mol% for an auto catalyzed system in 60 min (at 210 degrees C). Based on the experimental results, a reaction mechanism was proposed considering the formation of an intermediate from xylose when solid acid catalysts were added. After five reusability cycles using SZ on cordierite, this catalyst can be regenerated with a similar performance and similar FUR yield on the 6th cycle.

In a long development of solvents for cellulose dissolution and fiber spinning, ionic liquids represent the youngest category with great potential both from an environmental and technical point of view. Herein, we report on 1,5-diazabicyclo[4.3.0]non-5-ene-1-ium acetate – a nonimidazolium based ionic liquid – as excellent solvent for a wide set of lignocellulosic solutes to prepare composite fibers of cellulose, hemicellulose, and lignin. The viscoelastic properties of the polymer solutions that are governed by the cellulosic constituents have to be within defined limits to assure good spinnability. The solutions are processed in a Lyocell-type dry-jet wet spinning procedure that allows for a filament draw in the air gap. The draw was found to be a major factor controlling the mechanical properties of the resulting fibers. However, the effect of the draw was dependent on the solute composition. With a high share of cellulose, a small draw led already to high tensile strength and modulus. All fibers showed high tenacities and moduli even when containing a high share of noncellulosics. The elongation at break was affected significantly only at high lignin content. A distinct relationship was found between the cellulose content and the mechanical properties.

Both IONCELL-P(ulp) and IONCELL-F(iber) are emerging new cellulose processing technologies utilizing ionic liquids (ILs). IONCELL-P is upgrading paper pulp into dissolving pulp with mixtures of IL and water. IONCELL-F is an IL based cellulose fiber spinning technology. In this work, these two processes were combined using the same ionic liquid, 1,5-diazabicyclo[4.3.0]non-5-ene acetate [DBNH][OAc], in both processes. In the IONCELL-P to achieve dissolving pulp quality cellulose (hemicellulose content below 5%) from birch kraft pulp, different pretreatments and optimization steps, such as targeted enzymatic predegradation of the xylans, preadjusting the viscosity of the pulp, and decreased pulp consistency (2%) in the fractionation, were implemented. From the obtained cellulose fraction containing 4.2% xylan, a dope was prepared from which high tenacity (50 cN/tex) and Young's modulus (23.6 GPa) fibers were spun with IONCELL-F dry jet wet spinning. The produced fibers surpassed the mechanical properties of commercially available viscose and Lyocell fibers.

A new chemical recycling method for waste cotton is presented that allows the production of virgin textile fibers of substantially higher quality than that from the mechanical recycling methods that are used currently. Cotton postconsumer textile wastes were solubilized fully in the cellulose-dissolving ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) to be processed into continuous filaments. As a result of the heterogeneous raw material that had a different molar mass distribution and degree of polymerization, pretreatment to adjust the cellulose degree of polymerization by acid hydrolysis, enzyme hydrolysis, or blending the waste cotton with birch prehydrolyzed kraft pulp was necessary to ensure spinnability. The physical properties of the spun fibers and the effect of the processing parameters on the ultrastructural changes of the fibers were measured. Fibers with a tenacity (tensile strength) of up to 58 cN tex-1 (870 MPa) were prepared, which exceeds that of native cotton and commercial man-made cellulosic fibers.

An experimental work has been performed to study the relevance of xylulose as an intermediate during non-catalyzed and acid-catalyzed xylose conversions to furfural in aqueous solution at the temperature range from 180 to 220 °C.

In this work, chromatographic recovery of hydroxy acids and cooking alkali (NaOH) from spent pulping liquor using size-exclusion chromatography (SEC) is investigated. Ultrafiltered black liquors from soda cooking of hardwood and softwood were used as feed and Sephadex G-10 as the stationary phase. Hydroxy acids were successfully separated from sodium hydroxide and the lignin content of the product fraction was reduced significantly. Fouling did not reduce the separation capability of the separation medium in extended runs with more than 40 consecutive injections. High column loadings, up to 25% of the bed volume, were found applicable for separation of authentic solutions without compromising the resolution. This was attributed to size-exclusion of individual ions which leads to co-operative sorption of NaOH in the presence of the sodium salts of hydroxy acids. The proposed mechanism was verified using data from experiments with model solutions. (C) 2013 Elsevier B.V. All rights reserved.

Evaporation rates play a key role in evaporation crystallization and the drying of crystal products. Raman analysis was used to study the effect of the evaporation rate on the polymorphs of indomethacin at room temperature. The studied solvents were highly volatile ethanol, acetone, and ethyl acetate. The approach was based on a mass transfer model of evaporation, and experimental flux measurements were used for model evaluation. Evaporation rates from porous carriers were also investigated. The studied mesoporous silicon microparticles can be used in oral dosage forms of poorly soluble active pharmaceutical ingredients. Evaporation rates of dimethyl sulfoxide from a pure solvent, from indomethacin solutions, and from solutions containing microparticles were measured at 100 °C. An evaporation rate model of porous particles was used and the predicted results were compared with the experimental results obtained.

•A separation process for recovering hydroxy acids from black liquor was developed.•No precipitation of lignin by neutralization of the black liquor is required.•Key steps are membrane filtration, chromatographic separation and ion exchange.•Hydroxy acid fractions with high purity were produced.

Separation of sulphuric acid and glucose using steady-state recycling chromatography (SSR) was investigated experimentally and by simulations. The application is relevant for the recovery of fermentable monosaccharides from lignocellulosic hydrolysates. Choosing appropriate cut times beforehand was found to be challenging because of complex phase equilibrium behavior. An empirical isotherm model that accounts for co-operative sorption was used in simulations. SSR provided 60% higher productivity with 45% lower eluent consumption than batch when equal flow rates were used. Productivity of SSR was strongly improved without a significant increase in eluent consumption by simultaneously increasing flow rate and injection volume.