Processing of solutions containing phenolics by adsorption–desorption enables the recovery and purification of bioactive compounds or fractions from plant. This work reviews the equilibrium and ...kinetic principles of adsorption, as well as the adsorption/desorption processing of solutions containing phenolic compounds. The description of relevant applications such as food-oriented processes, detoxification of fermentation media, color removal, and purification of sugar solutions and microbial metabolites is included.
•A concentrate containing hemicellulosic saccharides (HS) was obtained from wood.•HS was employed as a substrate for furfural manufacture.•An Acidic Ionic Liquid was employed as a solvent and as a ...catalyst.•Operation was carried out in the presence of a co-solvent (dioxane).•The optimal furfural conversion (59.1%) was achieved at 160°C.
Eucalyptus globulus wood samples were treated with hot, compressed water to separate hemicelluloses (as soluble saccharides) from a solid phase mainly made up of cellulose and lignin. The liquid phase was dehydrated, and the resulting solids (containing pentoses as well as poly- and oligo- saccharides made up of pentoses) were dissolved and reacted in media containing an Acidic Ionic Liquid (1-butyl-3-methylimidazolium hydrogen sulfate) and a co-solvent (dioxane). The effects of the reaction time on the product distribution were studied at temperatures in the range 120–170°C for reaction times up to 8h, and operational conditions leading to 59.1% conversion of the potential substrates (including pentoses and pentose structural units in oligo- and poly- saccharides) into furfural were identified.
Furfural production using ionic liquids: A review Peleteiro, Susana; Rivas, Sandra; Alonso, José Luis ...
Bioresource technology,
February 2016, 2016-Feb, 2016-02-00, 20160201, Letnik:
202
Journal Article
Recenzirano
•Furfural is a renewable platform chemical with a bright future.•Technologies based on ionic liquids (ILs) are suitable for furfural production.•ILs can be used as additives, catalysts or reaction ...media for furfural manufacture.•Acidic ionic liquids may perform at once as reaction media and catalysts.
Furfural, a platform chemical with a bright future, is commercially obtained by acidic processing of xylan-containing biomass in aqueous media. Ionic liquids (ILs) can be employed in processed for furfural manufacture as additives, as catalysts and/or as reaction media. Depending on the IL utilized, externally added catalysts (usually, Lewis acids, Brönsted acids and/or solid acid catalysts) can be necessary to achieve high reaction yields. Oppositely, acidic ionic liquids (AILs) can perform as both solvents and catalysts, enabling the direct conversion of suitable substrates (pentoses, pentosans or xylan-containing biomass) into furfural. Operating in IL-containing media, the furfural yields can be improved when the product is continuously removed along the reaction (for example, by stripping or extraction), to avoid unwanted side-reactions leading to furfural consumption. These topics are reviewed, as well as the major challenges involved in the large scale utilization of ILs for furfural production.
This work provides an assessment on the fractionation of
Eucalyptus globulus wood by sequential stages of autohydrolysis (to cause the solubilization of hemicelluloses) and organosolv pulping (to ...dissolve lignin, leaving solids enriched in cellulose). With this approach, valuable products (hemicellulose-derived saccharides, sulphur-free lignin fragments and cellulosic substrates with low contents of residual hemicelluloses) are obtained in separate streams, according to the biomass refinery approach. Autohydrolysis was carried out under optimized operational conditions, and organosolv pulping was performed using uncatalyzed ethanol–water solutions. The effects of the most influential operational variables (autohydrolysis severity, delignification temperature and ethanol concentration in the organosolv stage) on solid yield, solid composition, cellulose susceptibility and recovery of the various fractions was assessed using statistical methods, which enabled the identification of the most favourable operational conditions.
The acidic 1-butyl-3-methylimidazolium hydrogen sulfate (bmimHSO4) ionic liquid was explored as both a reaction medium and a catalyst in the furfural production from xylose. Preliminary experiments ...were carried out at 100–140 °C for 15–480 min in systems containing just xylose dissolved in bmimHSO4 in the absence of externally added catalysts. More than 95% xylose conversion was achieved when operating at 120 or 140 °C for 300 and 90 min, respectively; but just 36.7% of the initial xylose was converted to furfural. Operation in biphasic reaction systems (in the presence of toluene, methyl-isobutyl ketone or dioxane as extraction solvents) at 140 °C under selected conditions resulted in improved furfural production (73.8%, 80.3%, and 82.2% xylose conversion to furfural for the cited extraction solvents, respectively).
Eucalyptus globulus wood samples were pretreated in aqueous media under non-isothermal conditions to reach maximal temperatures (
T
MAX) in the range 195–250
°C, in order to assess the effects of the ...pre-treatment severity on the fractionation of wood and on the susceptibility of processed samples toward enzymatic hydrolysis. Both the fraction of cellulose susceptible to hydrolysis and the hydrolysis rate increased with the severity of the pre-treatments, but the overall glucose yield decreased for substrates pretreated at
T
MAX above 220
°C owing to cellulose losses. Using substrates pretreated at
T
MAX
=
220
°C, up to 94% of polysaccharides were recovered in the hydrolysis media as mono- or oligo-saccharides. High glucose to ethanol conversions were obtained operating at low enzyme charges in Simultaneous Saccharification and Fermentation mode.
Recent developments on the manufacture, purification and biological effects of xylo-oligosaccharides are reviewed. Xylo-oligosaccharides (XO) can be produced by chemical and/or enzymatic methods from ...a variety of xylan-containing raw materials, and then refined by physicochemical treatments. Considered as food ingredients, xylo-oligosaccharides have favourable technological properties and cause prebiotic effects derived from their ability to modulate the intestinal function. Besides the effects related to their effects in the large bowel, a range of additional biological activities have been reported for XO. Other topic discussed include the utilization of XO in synbiotic preparations, their technological properties and market perspectives.
•Peanut Shells (PS) were tested for bioactive compounds obtention for the first time.•Autohydrolysis is efficient to recover oligosaccharides and antioxidants from PS.•The refined oligosaccharides ...were characterized by HPLC, MALDI TOF MS and FTIR.•Environmentally friendly technologies were used to valorize peanut shells.
Peanut shells were subjected to non-isothermal aqueous treatments to cause the partial breakdown of hemicelluloses into soluble oligosaccharides and lignin-derived compounds with high antioxidant activity. The effects of temperature on the chemical composition of the substrate and soluble reaction products were assessed. Under selected conditions (210°C, severity=4.09), the overall amount of poly- and oligo- saccharides present in the liquid phase reached 9.8g/L. This solution was refined by consecutive stages of discontinuous diafiltration, yielding a refined product containing about 72.4wt% of oligomers at a global yield of 8.5kg/100kg oven-dry PS. The purified products were characterized by HPLC, MALDI-TOF-MS and FTIR, confirming the major reaction products were saccharides made up of xylose with degrees of polymerization up to 17, substituted with acetyl and methylglucuronosyl groups, for which a number of pharmaceutical and food applications have been proposed. Solubilization of hemicelluloses in the treatments resulted in the production of solids enriched in cellulose and lignin suitable for further applications.
► This work deals with the utilization of Eucalyptus globulus as substrate for 2nd generation biofuels production. ► Eucalyptus globulus was pretreated in aqueous media and then subjected to ...Simultaneous Saccharification and Fermentation. ► The operational conditions were optimized on the basis of a Response Surface Methodology assessment. ► The whole processing scheme resulted in high ethanol yields, even in operation at high substrate loading.
Eucalyptus globulus wood samples were subjected to non-isothermal autohydrolysis in order to solubilize hemicelluloses, leading to treated solids of increased cellulose content and enzyme digestibility. Autohydrolyzed solids obtained under a variety of operational conditions were assayed as substrates for bioethanol production by Simultaneous Saccharification and Fermentation (SSF). SSF was optimized using the Response Surface Methodology. The experimental plan included as independent variables the autohydrolysis severity (So defined as the logarithm of the severity factor), the liquor to solid ratio and the enzyme to substrate ratio. The dependent variables considered were the maximum ethanol concentration achieved in individual experiments, the volumetric productivity, the maximum ethanol conversion, the yield of solids after SSF and the cellulose recovery in solids coming from SSF. Operating at high solids loading (So=4.67, LSR=4g/g, ESR=16FPU/g), media containing up to 67.4g ethanol/L and corresponding to 91% of the stoichiometric amount calculated from the cellulose content of wood were obtained. Wood processing resulted in the generation of soluble products from hemicelluloses, in the generation of up to 291L ethanol/1000kg oven-dry wood from cellulose, and in a solid material mainly made up of lignin.
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