Effects of hydrothermal processing on miscanthus × giganteus polysaccharides: a kinetic assessment

Miscanthus × giganteus samples were characterized for composition and treated with hot compressed water (hydrothermal or autohydrolysis treatments) at temperatures in the range of 190–240 °C. The liquid phases from treatments were analyzed to assess the breakdown of susceptible polysaccharides into a scope of soluble intermediates and reaction products. The experimental concentration profiles determined for the target compounds (monosaccharides, higher saccharides, acetic acid and sugar-decomposition products) were interpreted using a pseudohomogeneous kinetic mechanism involving 27 reactions, which were governed by kinetic coefficients showing an Arrhenius-type temperature dependence. The corresponding activation energies were calculated and compared with data from the literature. The kinetic equations allowed a quantitative assessment of the experimental results, providing key information for process simulation and evaluation.Ministerio de Ciencia e Innovación | Ref. IJC2018-037665Ministerio de Ciencia e Innovación | Ref. RYC2021-031964-IXunta de Galicia | Ref. GRC-ED431C 2022/0

Integral fractionation of Arundo donax using biphasic mixtures of solvents derived from biomass: an environmentally friendly approach

Arundo donax, one of the most invasive plants in the world, but also a promising source of lignocellulose materials was employed as a feedstock for a biorefinery process. Water-extracted Arundo donax samples were subjected to one-step biphasic fractionation in catalyzed media containing water and 1-butanol, an environmentally-friendly solvent. The effects of selected operational variables (catalyst concentration, temperature and reaction time) on the measured effects (solid recovery yield and compositions of the solid, aqueous and organic phases resulting from treatments) were assessed using statistical methods. The results allowed a quantitative discussion on aspects regarding the selectivity of component separation (lignin, glucan, and hemicelluloses), the overall recovery of valuable products, and the selection of operational conditions enabling extensive delignification (around to 90 %) and high recovery rates of glucan and hemicellulose-derived sugars (above 80 % and 75 %, respectively). This study provides new insights into biphasic fractionation, highlighting the selective separation of hemicellulose, cellulose and lignin into a single and sustainable process, thereby by enhancing biomass resource while reducing environmental impact.Agencia Estatal de Investigación | Ref. RYC2021-031964-IXunta de Galicia | Ref. ED431F2023/03Universidade de Vigo/CISU

Manufacture of Furfural from Xylan-containing Biomass by Acidic Processing of Hemicellulose-Derived Saccharides in Biphasic Media Using Microwave Heating

Furfural was produced in biphasic media using a microwave-heated reactor. Diverse substrates were considered: xylose (considered as a reference compound) or hemicellulosic saccharides from Eucalyptus globulus wood or corncobs. Operation was carried out at 170°C for the desired reaction time in the presence of an acidic catalyst (sulfuric acid or HCl). The best furfural yields (67.8% and 72.5% from E. globulus wood and corncobs, respectively) were obtained operating for 10 min or 20 min with 1% or 0.5% HCl, respectively. These results were slightly lower than the ones obtained using xylose (a model substrate) under comparable reaction conditions, a fact ascribed to differences in the complexity of substrates and to the presence of contaminants

Ethanol production from fractionated eucalyptus wood

Eucalyptus globulus wood (EGW) is a lignocellulosic material with high cellulose and hemicellulose content, suitable for the simultaneous production of hemicellulosic and cellulosic ethanol. Processing of EGW by autohydrolysis yields a liquid phase rich in hemicellulosic-derived compounds (13.73 kg of xylooligosaccharides/ 100 kg of raw material). The liquid phase was processed by membranes, achieving a concentrated-liquor of 52.9 g of xylooligosaccharides/L. The liquor from membrane processing was hydrolyzed with sulphuric acid, detoxified and fermented. The maximal concentration of ethanol from liquid phase was 19.3 g/L (volumetric productivity Qp=0.19 g/Lh and YP/S=0.38 g/g). The solid phase from autohydrolysis was submitted to delignification organosolv, obtained a solid with 81 kg of cellulose/100 kg of delignified solid. The simultaneous saccharification and fermentation of delignified solid was carried out, achieving 62.7 g/L of ethanol with cellulose to ethanol conversion of 92% (based in a cellulose content of delignified solid)

Arundo donax L processing in catalyzed butanol–water media in the scope of lignocellulose biorefineries

Arundo donax L samples, before or after aqueous extraction to remove extractives, were subjected to chemical fractionation in H2SO4-catalyzed mixtures of 1-butanol and water. The partial miscibility of 1-butanol and water at room temperature allowed the separation of the three major feedstock components in separate streams (lignin, accumulated in the 1-butanol-rich phase; hemicellulose-derived products, accumulated in the aqueous acidic phase; and cellulose, present in the solid phase). The effects of selected variables (temperature, catalyst concentration, reaction time and 1-butanol content of the reaction media) on variables measuring the solid recovery yield and the compositions of phases from fractionation were measured. Using water-extracted A. donax L as a substrate, the best operational conditions enabled 93.2% hemicellulose removal and 85.4% delignification with limited cellulose solubilization (15%). The experimental results provided key information to assess the proposed process in the scope of biorefineries.Ministerio de Ciencia e Innovación | Ref. IJC2018-037665Ministerio de Ciencia e Innovación | Ref. PID2020-116717RB-I00Ministerio de Ciencia e Innovación | Ref. RYC2021-031964-

Effect of hydrothermal pretreatment for fermentable sugars production using brown macroalgae as raw material

Energy high demands and concerns about global climate changes have led to the resurgence of biofuels as bioethanol. The conversion of biomass (macroalgae) into high added-value chemicals (pigments, food supplements, polymers, surfactants and fertilizer) and bioenergy renewable products as bioethanol is essential in order to sustain our present and future. The polysaccharides conversion from macroalgae to fermentable sugars and fuel ethanol production is still to be studied. For that reason, the aim of this work was to evaluate the production of fermentable sugars from brown macroalgae using hydrothermal pretreatment that it is considered an environmentally friendly process. The hydrothermal pretreatment was evaluated in different conditions of time and temperature. The best operating condition for the production of fermentable sugars was at 200 ºC for 30 min, obtaining 0.41 g of total sugars/ g of macroalgae, dry basis. The hydrothermal process proved to be a promising pretreatment to produce fermentable sugars

Jabučni otpaci kao alternativna sirovina u proizvodnji hrane

In order to measure the potential of apple pomace as a raw material for manufacturing food-related products (such as lactic acid, fiber-rich concentrates and pectin), samples from cider industry were assayed for composition and enzymatic digestibility. Alcohol-soluble compounds (monosaccharides, oligosaccharides and malic acid) accounted for 32–45 mass percent of oven-dry pomace. Glucose and fructose were the major components of this fraction. The alcohol-insoluble fraction accounted for 55–68 mass percent of oven-dry pomace and was mainly made up of neutral detergent fiber (62–69 percent of the mass fraction) and pectin (16.2–19.7 percent of the mass fraction). The feedstock content of N, P and metal ions (K, Mg, Fe and Mn) was favourable for further manufacture of lactic acid fermentation media. Apple pomace showed a high susceptibility to enzymatic hydrolysis: in media with a cellulase loading of 8.5 FPU/g of apple pomace and a cellobiase loading of 5 IU/FPU, about 80 % of the total glucan was converted into glucose after 15 h. Considering the low enzyme charge, liquor to solid ratio employed, reaction time needed to achieve the maximal sugars concentration and N, P and metal ion (K, Mg, Fe and Mn) content of samples, it can be concluded that apple pomace is a promising raw material for lactic acid production.Ispitani su sastav i enzimska razgradnja jabučnih otpadaka iz industrijske proizvodnje jabukovače radi mogućnosti njihove primjene u proizvodnji (mliječne kiseline, koncentrata bogatih vlaknima i pektina). Nakon sušenja otpadaka u pećnici, maseni je udio sastojaka topljivih u alkoholu (monosaharidi, oligosaharidi i jabučna kiselina) iznosio 32-45 %, od čega je najviše bilo glukoze i fruktoze. Ostatak od 55 do 68 % čine tvari netopljive u alkoholu, uglavnom neutralna detergentska vlakna (62-69 % masenog udjela) i pektin (16,2-19,7 % masenog udjela). Udio dušika, fosfora i iona metala (K, Mg, Fe i Mn) u sirovini povoljan je za daljnju fermentaciju mliječne kiseline. Jabučni se otpaci iznimno dobro razgrađuju enzimskom hidrolizom. U podlogama s 8,5 FPU celulaze po g jabučnih otpadaka i 5 IU/FPU celobiaze, od 80 % ukupnoga glukana nakon 15 sati dobiva se glukoza. Ako se uzme u obzir mala količina enzima, omjer tekuće i čvrste faze, vrijeme reakcije potrebno da bi se postigla maksimalna koncentracija šećera te udio dušika, fosfora i iona metala (K, Mg, Fe i Mn) u uzorcima, može se zaključiti da su jabučni otpaci prikladna sirovina za proizvodnju mliječne kiseline

A biorefinery cascade conversion of hemicellulose-free Eucalyptus globulus wood: Production of concentrated levulinic acid solutions for γ-valerolactone sustainable preparation

Eucalyptus globulus wood samples were subjected to preliminary aqueous processing to remove water-soluble extractives and hemicelluloses, and the resulting solid (mainly made up of cellulose and lignin) was employed as a substrate for converting the cellulosic fraction into mixtures of levulinic and formic acid through a sulfuric acid-catalyzed reaction. These runs were carried out in a microwave-heated reactor at different temperatures and reaction times, operating in single-batch or cross-flow modes, in order to identify the most favorable operational conditions. Selected liquid phases deriving from these experiments, which resulted in concentrated levulinic acid up to 408 mmol/L, were then employed for γ-valerolactone production by levulinc acid hydrogenation in the presence of the commercial 5% Ru/C catalyst. In order to assess the effects of the main reaction parameters, hydrogenation experiments were performed at different temperatures, reaction times, amounts of ruthenium catalyst and hydrogen pressure. Yields of γ-valerolactone in the range of 85-90 mol % were obtained from the hydrogenation of the wood-derived solutions containing levulinic acid, obtained by single-batch operation or by the cross-flow process. The negative effect of co-produced formic acid present in crude levulinic acid solutions was evidenced and counteracted efficiently by allowing the preliminary thermal decomposition of formic acid itself