Kinetic and Thermodynamic Characteristics of Torrefied Acer palmatum.

The goal of this research was to investigate the effects of torrefying temperature (220, 260, and 300 °C) on the physicochemical properties, kinetics, thermodynamic parameters, and reaction processes of Acer palmatum (AP) during the pyrolysis process. The kinetics of raw materials and torrefied biomass were studied by using three kinetic models, and the main function graph approach was employed to find the reaction mechanism. The torrefied biomass produced at temperatures of 220 °C (AP-220), 260 °C (AP-260), and 300 °C (AP-300) was thermogravimetrically analyzed at four different heating rates (5, 10, 15, and 20 °C/min). In comparison to the raw material, the average activation energy of torrefied biomass declined with increasing temperature, from 174.13 to 84.67 kJ/mol (FWO), 172.52 to 81.24 kJ/mol (KAS and DAEM). The volatile contents of AP and AP-220 are higher than those of AP-260 and AP-300, indicating that the random nucleation model occupies the central position. Compared with the raw biomass, the average Gibbs free energy (ΔG) of torrefied biomass increased from 157.97 to 195.38 kJ/mol. The mean enthalpy change (ΔH) during the torrefaction process is positive, while the mean entropy change (ΔS) of the torrefaction of biomass is negative, decreasing from 16.93 to -151.53 kJ/mol (FWO) and from 14.36 to -156.06 kJ/mol (KAS and DAEM). Overall, the findings provide a comprehensive understanding of the kinetics and improved features of torrefied biomass as a high-quality solid fuel.

The synergistic regulation of sewage sludge biodrying and greenhouse gas reduction by additives.

As a dewatering method of high moisture solid waste sludge, biodrying still faces environmental problems such as material loss and greenhouse gas emission in the process of treatment. In this study, biochar and magnesium chloride were used to explore the synergistic effect of enhancing sludge biodrying and reducing greenhouse gas emissions. The highest temperature of biodrying was raised to 68.2 °C within 3 days, extending the longest high-temperature period to 5 days, which reduced the water content to 28.8 % in the single addition of biochar treatment. The complex addition increased the NH4+-N content of materials by 57.49 % and decreased the NO3--N content of materials by 40.62 %. The use of additives significantly reduced the emissions of CO2, CH4, and N2O compared to the no-addition treatment. The increase in dominant Actinomycetes and Chloroflexibacter was the main reason for the reduction in gas emissions.

Enzymolytic Lignin-Derived N-S Codoped Porous Carbon Nanocomposites as Electrocatalysts for Oxygen Reduction Reactions.

Currently, the development of nonmetallic oxygen reduction reaction (ORR) catalysts based on heteroatomic-doped carbon materials is receiving increaseing attention in the field of fuel cells. Here, we used enzymolytic lignin (EL), melamine, and thiourea as carbon, nitrogen, and sulfur sources and NH4Cl as an activator to prepare N- and S-codoped lignin-based polyporous carbon (ELC) by one-step pyrolysis. The prepared lignin-derived biocarbon material (ELC-1-900) possessed a high specific surface area (844 m2 g-1), abundant mesoporous structure, and a large pore volume (0.587 cm3 g-1). The XPS results showed that ELC-1-900 was successfully doped with N and S. ELC-1-900 exhibited extremely high activity and stability in alkaline media for the ORR, with a half-wave potential (E1/2 = 0.88 V) and starting potential (Eonset = 0.98 V) superior to those of Pt/C catalysts and most non-noble-metal catalysts reported in recent studies. In addition, ELC-1-900 showed better ORR stability and methanol tolerance in alkaline media than commercial Pt/C catalysts.

Influences of the Reaction Temperature and Catalysts on the Pyrolysis Product Distribution of Lignocellulosic Biomass (Aspen Wood and Rice Husk).

It is important to clarify the distribution of pyrolysis products from lignocellulosic biomass for its thermal transformation to produce high-quality bio-oil. Influences of the reaction temperature and catalysts on the pyrolysis product distribution from aspen wood (AW) and rice husk (RH) were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The difference in components from the lignocellulosic biomass results in different pyrolysis characteristics of the biomass raw materials. The reaction temperature significantly influences the product distribution from AW and RH pyrolysis. In all AW catalysis experiments, acids (8.35%), ketones (3.79%), phenols (4.73%), and esters (1.50%) have the lowest content while carbohydrates (48.75%) demonstrate the highest content when taking zinc chloride (ZnCl2) as the catalyst; the HZSM-5 molecular sieve (HZSM-5) promotes the generation of esters (7.97%) and N-compounds (22.43%) while inhibiting production of aldehydes (2.41%); addition of an MCM-41 molecular sieve (MCM-41) is conducive to increasing the contents of aldehydes (21.29%), furans (5.88%), ketones (22.30%), acids (20.46%), and hydrocarbons (4.85%), while reducing the contents of alcohols (0) and carbohydrates (0). In all RH catalysis experiments, the addition of ZnCl2 helps increase the content of carbohydrates (39.16%) and decrease the contents of ketones (3.89%), phenols (5.20%), alcohols (2.34%), esters (1.13%), and N-compounds (3.09%); when applying HZSM-5 as the catalyst, hydrocarbons (18.28%) and alcohols (6.66%) reach their highest content while acids (13.21%) have the lowest content; MCM-41 promotes the generation of aldehydes (25.33%) and furans (5.55%) while inhibiting that of carbohydrates (1.42%).

Enhanced degradation of VOCs from biomass gasification catalyzed by Ni/HZSM-5 series catalyst.

Volatile organic compounds (VOCs) evolved from biomass gasification plays a positive role in the formation of PM2.5 and odor pollution. In order to improve the removal rate of various VOCs produced by biomass gasification, a nickel-based supported HZSM-5 cataly st (Ni/HZSM-5 and Ni-Ca-Co/HZSM-5) was prepared by different auxiliary methods, Ni loadings, and pyrolysis temperatures. The catalytic cracking performance of Ni/HZSM-5 catalysts for different VOCs model compounds such as toluene, phenol, furan, acetic acid and cyclohexane were studied in a fixed-bed reactor. The catalysts were further characterized and analyzed by XRD, SEM, XPS and BET. The results showed that the Ni/HZSM--C-Co5 catalyst prepared by ultrasonic-assisted excess impregnation method with Ni loading of 8 wt%, Ca loading of 4 wt%, Co loading of 0.1 wt% had strong catalytic activity for VOCs degradation. With the increase of the cracking temperature, the conversion rate and gas yield of from model compound cracking improved significantly. At 800 °C, the conversion of each model compound was more than 90%, accompanied by the generation of cracking gases such as H2 and CH4. The selectivity of H2 and CH4 from toluene cracking reached 93%, and cyclohexane reached 98%. The models with higher oxygen content and lower bond energy were more likely to undergo reforming reaction to form small molecular gas. Model compounds with large molecular weight and high carbon content provided more carbon sources. Under the conversion degree towards the gas direction was high. This study provides a new idea on the removal of VOCs for the efficient utilization of biomass resources.

Pretreatment of Arundo donax L. for photo-fermentative biohydrogen production by ultrasonication and ionic liquid.

Combined pretreatment methods were assumed to further enhance photo-fermentative biohydrogen production (PFHP) from lignocellulosic biomass. For this purpose, an ultrasonication assisted ionic liquid pretreatment was applied to Arundo donax L. biomass for PFHP. The optimal condition for the combined pretreatment was 16 g/L of 1-Butyl-3-methylimidazolium Hydrogen Sulfate ([Bmim]HSO4) combined with ultrasonication at a solid to liquid ratio (SLR) of 1:10 for 1.5 h under 60 °C. Under this condition, the maximum delignification of 22.9 % was obtained, in addition, the hydrogen yield (HY) and energy conversion efficiency (ECE) were enhanced by 1.5-fold and 46.4 % (p < 0.05) compared to untreated biomass, respectively. Moreover, heat map analysis was performed to evaluate the correlation between pretreatment conditions and corresponding results, suggesting pretreatment temperature had the strongest (absolute value of Pearson's r was 0.97) linear correlation with HY. Combined multiple energy production approaches might be useful for further improved ECE.

Impact of Different Lignin Sources on Nitrogen-Doped Porous Carbon toward the Electrocatalytic Oxygen Reduction Reaction.

Lignin is an ideal carbon source material, and lignin-based carbon materials have been widely used in electrochemical energy storage, catalysis, and other fields. To investigate the effects of different lignin sources on the performance of electrocatalytic oxygen reduction, different lignin-based nitrogen-doped porous carbon catalysts were prepared using enzymolytic lignin (EL), alkaline lignin (AL) and dealkaline lignin (DL) as carbon sources and melamine as a nitrogen source. The surface functional groups and thermal degradation properties of the three lignin samples were characterized, and the specific surface area, pore distribution, crystal structure, defect degree, N content, and configuration of the prepared carbon-based catalysts were also analyzed. The electrocatalytic results showed that the electrocatalytic oxygen reduction performance of the three lignin-based carbon catalysts was different, and the catalytic performance of N-DLC was poor, while the electrocatalytic performance of N-ELC was similar to that of N-ALC, both of which were excellent. The half-wave potential (E1/2) of N-ELC was 0.82 V, reaching more than 95% of the catalytic performance of commercial Pt/C (E1/2 = 0.86 V) and proving that EL can be used as an excellent carbon-based electrocatalyst material, similar to AL.

In-situ synthesis of Pt nanoparticles/reduced graphene oxide/cellulose nanohybrid for nonenzymatic glucose sensing.

In recent years, nanocellulose-based bioinorganic nanohybrids have been exploited in numerous applications due to their unique nanostructure, excellent catalytic properties, and good biocompatibility. To the best of our knowledge, this is the first report on the simple and effective synthesis of graphene/cellulose (RGO/CNC) matrix-supported platinum nanoparticles (Pt NPs) for nonenzymatic electrochemical glucose sensing. The Pt/RGO/CNC nanohybrid presented a porous network structure, in which Pt NPs, RGO, and CNCs were integrated well. Here, cellulose nanocrystals act as a biocompatible framework for wrapped RGO and monodispersed Pt nanoparticles, effectively preventing the restacking of graphene during reduction. The superior glucose sensing performance of Pt/RGO/CNC modified glass carbon electrode (GCE) was achieved with a linear concentration range from 0.005 to 8.5 mM and a low detection limit of 2.1 µM. Moreover, the Pt/RGO/CNC/GCE showed remarkable sensitivity, selectivity, durability, and reproducibility. The obtained results indicate that the CNCs-based bioinorganic nanohybrids could be a promising electrode material in electrochemical biosensors.

Research Priorities and Trends on Bioenergy: Insights from Bibliometric Analysis.

Replacing fossil fuels with bioenergy is crucial to achieving sustainable development and carbon neutrality. To determine the priorities and developing trends of bioenergy technology, related publications from 2000 to 2020 were analyzed using bibliometric method. Results demonstrated that the number of publications on bioenergy increased rapidly since 2005, and the average growth rate from 2005 to 2011 reached a maximum of 20% per year. In terms of publication quantity, impact, and international collaboration, the USA had been leading the research of bioenergy technology, followed by China and European countries. Co-occurrence analysis using author keywords identified six clusters about this topic, which are "biodiesel and transesterification", "biogas and anaerobic digestion", "bioethanol and fermentation", "bio-oil and pyrolysis", "microalgae and lipid", and "biohydrogen and gasification or dark fermentation". Among the six clusters, three of them relate to liquid biofuel, attributing that the liquid products of biomass are exceptional alternatives to fossil fuels for heavy transportation and aviation. Lignocellulose and microalgae were identified as the most promising raw materials, and pretreating technologies and efficient catalysts have received special attention. The sharp increase of "pyrolysis" and "gasification" from 2011 to 2020 suggested that those technologies about thermochemical conversion have been well studied in recent years. Some new research trends, such as applying nanoparticles in transesterification, and hydrothermal liquefaction in producing bio-oil from microalgae, will get a breakthrough in the coming years.

Effect of Evolution of Carbon Structure during Torrefaction in Woody Biomass on Thermal Degradation.

Torrefaction is an effective method for upgrading biomass. Cedar torrefaction is carried out in a fixed bed reactor at the temperature of 200-300 °C. The structural parameters are obtained from elemental analysis and 13C nuclear magnetic resonance (NMR). Thermal degradation behavior of raw and torrefied cedar is monitored by thermogravimetry analysis. The results show that carbon structure varied during torrefaction has a significant effect on thermal degradation of cedar. Some unstable oxygen functional groups, such as C1 of hemicellulose, ß-O-4 linked bonds, and amorphous C6 of cellulose, are decomposed at mild torrefaction of torrefied temperature ≤ 200 °C. The temperature of maximum weight loss rate increases from 348 °C of raw cedar to 373 °C of C-200. The amorphous cellulose is partly re-crystallized at moderate torrefaction of torrefied temperature 200-250 °C. The aromaticity of torrefied cedar increases from 0.45 of C-200 to 0.73 of C-250. The covalent bond in the side chain of aromatic rings in cedar was further broken during torrefaction at severe torrefaction of torrefied temperature 250-300 °C. The area percentage of DTG mainly signed at 387 °C of C-300. The proton aromatic carbon increases from 12.35% of C-250 to 21.69% of C-300. These results will further facilitate the utilization of biomass for replacing fossil fuel to drive carbon neutrality.

Fast Pyrolysis of Cellulose and the Effect of a Catalyst on Product Distribution.

Fast pyrolysis of microcrystalline cellulose (MC) was carried out by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The effects of temperature, time, and a catalyst on the distribution of the pyrolysis products were analyzed. The reaction temperature and time can significantly affect the types and yields of compounds produced by cellulose pyrolysis. A pyrolysis temperature of 500-600 °C and pyrolysis time of 20 s optimized the yield of volatile liquid in the pyrolysis products of cellulose. In all catalytic experiments, the relative contents of alcohols (1.97%), acids (2.32%), and esters (4.52%) were highest when K2SO4 was used as a catalyst. HZSM-5 promoted the production of carbohydrates (92.35%) and hydrocarbons (2.20%), while it inhibited the production of aldehydes (0.30%) and ketones (1.80%). MCM-41 had an obvious catalytic effect on cellulose, increasing the contents of aldehydes (41.58%), ketones (24.51%), phenols (1.82%), furans (8.90%), and N-compounds (12.40%) and decreasing those of carbohydrates (5.38%) and alcohols (0%).

Co-Thermal Oxidation of Lignite and Rice Straw for Synthetization of Composite Humic Substances: Parametric Optimization via Response Surface Methodology.

In this study, Baoqing lignite (BL) and rice straw (RS), which were the representatives of low-rank coal and biomass, were co-thermally oxidized to produce composite humic substances (HS), including humic acid (HA) and fulvic acid (FA). Taking HS content as the output response, the co-thermally oxidizing conditions were optimized through single factor experiment and response surface methodology (RSM). The structures of HA and FA prepared under optimized conditions were analyzed by SEM, UV, and FTIR. Results showed that HS content was clearly influenced by the material ratio, oxidation time, and oxidation temperature, as well as their interactions. The optimized co-thermal oxidization condition was as follows: BL and RS pretreated with a material ratio of 0.53, oxidation time of 59.50 min, and oxidation temperature of 75.63 °C. Through verification, the experimental value (62.37%) had a small relative error compared to the predicted value (62.27%), which indicated that the developed models were fit and accurate. The obtained HA had a tightly packed block structure; FA had a loosely spherical shape. The molecular weight of FA was 2487 Da and HA was 20,904 Da; both had a smaller molecular weight than that reported in other literature. FA showed strong bands at 1720 cm-1, thus confirming the presence of more oxygen-containing functional groups. The appearance of double peaks at 2900~2980 cm-1 indicated that HA contains more aliphatic chains. The co-thermal oxidation of BL and RS gives a new method for the synthesis of HS, and the optimization of co-thermal oxidation conditions will provide fundamental information for the industrialization of composite HS.

Effect of 5-HMF and furfural additives on bio-hydrogen production by photo-fermentation from giant reed.

Substances harmful to photo-fermentative biological hydrogen production (PFHP) were produced during cellulose hydrolysis. This study aimed to evaluate the effect of by-products (5-hydroxymethylfurfural (5-HMF) and furfural) released from lignocellulose during enzymatic hydrolysis process on PFHP. The exist of 5-HMF inhibited the hydrogen production. However, 0.2 g/L furfural improved the hydrogen production by 19 % compared to no addition (511.6 mL) with a maximum concentration of nitrogenase (109.96 IU/L) at 96 h. Furthermore, a 18.7 % enhancement of hydrogen production was also observed when 0.2 g/L 5-HMF and furfural were mixed at a ratio of 1:1, while decrement of hydrogen production at higher addition was observed as well. Through the scatter matrix analysis, it was concluded that 5-HMF and furfural additives had significant effects on PFHP. This study gave an insight into effect of lignocellulosic by-products on biohydrogen production.

Comparison of three ionic liquids pretreatment of Arundo donax L. For enhanced photo-fermentative hydrogen production.

Ionic liquids (ILs) pretreatment has been regarded as a promising green way to treat lignocellulosic biomass. 1-Butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4), 1-allyl-3-methylimidazolium chloride ([Amim]Cl), and 1-Butyl-3-methylimidazolium Hydrogen Sulfate ([Bmim]HSO4) with different loadings (2, 4, 8, and 16 g/L) were adopted to pretreat the Arundo donax L.. 16 g/L [Bmim]HSO4 pretreated Arundo donax L. obtained the highest sugar yield of 7.9 g/L during the enzymatic hydrolysis and hydrogen yield of 106.1 mL/g TS during the photo-fermentation, which were 68.8 % and 35.3 % higher than those of untreated Arundo donax L., respectively. Moreover, volatile fatty acids (VFAs) distribution revealed that acetic acid was the main by-product during hydrogen production process with ILs pretreated Arundo donax L.. Besides, the relationship between sugar yield and hydrogen yield was the closest based on scatter matrix analysis. This study helps to understand of correlation between ILs pretreatment with the behavior of bioenergy production.

Towards high light conversion efficiency from photo-fermentative hydrogen production of Arundo donax L. By light-dark duration alternation strategy.

Suitable illumination project would help in achieving high light conversion efficiency (LCE) for photo-fermentation. This study proposed an improvement strategy for LCE of photo-fermentative hydrogen production (PFHP) with a photosynthetic consortium by adopting light-dark duration alternation. For this purpose, 6 projects (continues light, 24 h light + 24 h dark, 24 h dark + 24 h light, 48 h light + 48 h light, 48 h dark + 48 h light, and continues dark) light disturbances were carried out to estimate the strategy. The fluctuation of cell growth (OD660) was corresponded to the light-dark alternation. 24 h dark + 24 h light alternation achieved the maximum hydrogen yield (HY) of 390.9 mL/g TS cell (6.7 % higher than continuous light) and maximum improvement of LCE of 114.7%. Moreover, heat map analysis revealed that the light period after inoculation had the closest relation (Pearson's r = 1) with the average hydrogen production rate (HPR) of photo-fermentation. Besides, decreased dark period after inoculation would increase the hydrogen yield of photo-fermentation.

Fabrication of Carbon-Alumina Composites via Catalytic Pyrolysis of Pine Sawdust on Aluminum Dross for Cr(VI) Removal.

Carbon-alumina composites are prepared for the efficient removal of Cr(VI) from wastewater. Pristine and acid-treated alumina dross (AD and AAD) are copyrolyzed with pine sawdust to form the respective composites, ADPC and AADPC. Excellent absorption properties with Cr(VI) removal efficiency of 95.08% are demonstrated at 60 °C for an initial concentration of 6 µg/mL. The composites combine the merits of char, which provides a high surface-to-volume ratio with abundant functional groups on the surface, and alumina, which provides metal ions for coprecipitation. Carbon structures of pine, char, and composite were analyzed semiquantitatively using 13C NMR by a curve-fitting method. Cr(VI) adsorption is accurately described with chemisorption by the Langmuir isotherm model and a pseudo-second-order kinetic model. The results show that AADPC has more alcohol hydroxyl groups substituted to glucosyl units in amorphous cellulose assigned to the peak at 80 ppm and hemicellulose assigned to peaks at 97 and 101 ppm. Also, it has more phenolic groups in lignin distributed at syringyl units assigned to peaks at 129 and 146 ppm. These oxygen-containing functional groups have a significant influence on Cr(VI) adsorption and reduction to Cr(III) governed by the mechanisms of diffusion, adsorption, complexation, reduction, and coprecipitation. The results of this work provide a new direction for the reuse of biomass and industrial solid wastes to fabricate higher value-added products, i.e., adsorption materials for Cr(VI) removal and stabilization.

Oxidative Esterification of 5-Hydroxymethylfurfural with an N-doped Carbon-supported CoCu Bimetallic Catalyst.

The direct fabrication of furan-2,5-dimethylcarboxylate (FDMC), a promising renewable monomer, from biomass-derived 5-hydroxymethylfurfural (HMF) is a cutting-edge process. In this contribution, an elaborately designed N-doped carbon-supported CoCu bimetallic catalyst (Cox Cuy -NC; x/y=9:1, 7:3, 4:6, which represents the designed molar ratio of Co and Cu in the catalyst), which could offer a desirable FDMC yield of 95 % under mild and base-free conditions (Co7 Cu3 -NC, 2 bar O2 , 80 °C, 4 h) is described for the oxidative esterification of HMF. Notably, an FDMC formation rate of 6.1 molFDMC molCo -1 h-1 was achieved over Co7 Cu3 -NC, which represents the highest catalytic efficiency so far among Co-based catalytic systems. It has been demonstrated that Cu-doping in Co7 Cu3 -NC catalyst brings about more active sites (Co-Nx species) with stronger molecular oxygen activation ability. The increase of surface N content of Co7 Cu3 -NC also improves basicity of the catalyst, which favors the hydrogen abstraction process during the HMF oxidative esterification reaction. These findings may pave an efficient and green way for the synthesis of sustainable bio-based polymer monomers.

Fast corn stalk pyrolysis and the influence of catalysts on product distribution.

Fast pyrolysis of corn stalk (CS) was performed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and the product distribution was measured as a function of temperature, time, and catalyst. The types and yields of product compounds were influenced dramatically by temperature, while the duration of the reaction had little effect on the type of compound. Three primary components in the biomass interacted during pyrolysis. The maximum proportions of aldehydes (27.26%), furans (5.93%), and olefins (6.46%), and the minimum proportions of alcohols (0%) and carbohydrates (0.74%) were obtained over MCM-41. HZSM-5 improved the selectivity of aromatic hydrocarbons while inhibiting acid formation. The proportion of N-compounds was maximal (23.39%) over ZrO2. ZnCl2 tended to generate the least amounts of ketones (2.02%), phenols (9.08%), and esters (2.16%), but the greatest amount of carbohydrates (37.31%). K2SO4 promoted the formation of acids, ketones, alcohols, and phenols, while reducing the production of N-compounds and aldehydes.

Cellulose nanocrystal driven microphase separated nanocomposites: Enhanced mechanical performance and nanostructured morphology.

The interest in the modification of cellulose nanocrystals (CNCs) lies in the potential to homogenously disperse CNCs in hydrophobic polymer matrices and to promote interfacial adhesion. In this work, poly(methyl methacrylate) (PMMA) and poly(butyl acrylate) (PBA) were grafted onto CNCs, thereby imparting their hydrophobic traits. The successful grafting modification led to the increased thermal stability of modified CNCs (MCNCs), and the hydrophobic surface modification was integrated with crystalline structure and morphology of CNCs. The nanocomposites with 7 wt% MCNCs/PBA-co-PMMA had an increase in Young's modulus of >25-fold and in tensile strength at about 3 times compared to these of neat PBA-co-PMMA copolymer. In addition, a micro-phase separated morphology (PBA soft domains, and PMMA and CNC hard domains) of MCNCs/PBA-co-PMMA nanocomposites was observed. The large increase in the storage moduli (glass transition temperatures) and organized morphology of MCNCs/PBA-co-PMMA nanocomposites also elucidated the relationship between mechanical properties and micro-phase separated morphology. Therefore, the MCNCs are effective reinforcing agents for the PBA-co-PMMA thermoplastic elastomers, opening up opportunities for their wide-spread applications in polymer composites.

Synthesis of MCM-41-Supported Metal Catalysts in Deep Eutectic Solvent for the Conversion of Carbohydrates into 5-Hydroxymethylfurfural.

A series of MCM-41 supported metal catalysts (denoted M/D41) were prepared by using the deep eutectic solvent (DES)-mediated ionothermal synthesis strategy. Al/D41 was found to have excellent performance in the conversion of carbohydrates into 5-hydroxymethylfurfural (HMF). Furthermore, the production of HMF from glucose could be performed at high concentrations in choline chloride aqueous solution (CAS; 32 wt %, relative to the reaction phase) and as a result, CAS is a more promising solvent than water and DES for HMF production.