Solvent Pretreatment Research Articles

A strong, excellent water resistance, and anti-ultraviolet poly(vinyl alcohol)/lignocellulose/poly(butylene adipate-co-terephthalate) composite with "sandwich" structure.

Renewable materials derived from lignocellulose are promising materials for different practical applications, including biomedical, food, and agricultural fields. However, the poor mechanical performance and wet stability restrict their applications. Herein, we fabricated PVA/lignocellulose/PBAT (PVA/CLM/PBAT) composite with a "sandwich" structure. Cellulose-lignin mixture (CLM) was prepared by deep eutectic solvent (DES) pretreatment of corn straw. It served as a reinforcing scaffold of Poly (Vinyl Alcohol) (PVA) film for improving mechanical properties, UV blocking and decrease water permeability. Poly (butylene adipate-co-terephthalate) (PBAT) was used as "protector" with PVA/CLM composites by solvent coating method. The tensile strength of PVA/CLM/PBAT is 63.92MPa. The results show that 27.93MPa of tensile strength and 179.98% of elongation at break of PVA/CLM/PBAT are achieved after immersing in water for 2h, which was remarkable higher than that of PVA/CLM without PBAT coating (4.78MPa and 111.43%, respectively). The bonding strength of PVA/CLM/PBAT is 2.44±0.06N/15mm. The hydrogen bonds, π-π interaction between PBAT, PVA, and CLM enhance the bonding strength of PVA/CLM/PBAT composites. The water absorption rate of PVA/CLM/PBAT is only 4.4% after 20h, which showed a remarkable water resistance. 25wt% CLM content in PVA/CLM/PBAT composite can fully shield ultraviolet at 200-800nm, indicating that the remarkable UV shielding capability.

Rapid microwave-assisted deep eutectic solvent pretreatment for highly efficient saccharification and biohydrogen production from corn straw

Rapid microwave-assisted deep eutectic solvent pretreatment for highly efficient saccharification and biohydrogen production from corn straw

A ternary deep eutectic solvent for efficient biomass fractionation and lignin stabilization.

The efficient isolation and lignin stabilization are critical to the fractionation process of lignocellulosic biomass, enabling the subsequent valorization of both carbohydrates and lignin. In this study, a ternary deep eutectic solvent pretreatment system with outstanding reusability has been developed. Under optimal conditions (ChCl: MT: p-TsOH=1:1:0.5, 120°C, 60min), the system efficiently removed 94.66% of hemicellulose and 95.74% of lignin while retaining 84.50% of cellulose. Glucose was obtained from the cellulose-rich solid residue via enzymatic hydrolysis, achieving an 87.12% yield. This DES system inhibits lignin condensation through a dual mechanism of α-etherification and intermolecular forces (π-π stacking and hydrophobic interaction). The recovered lignin exhibits a low molecular weight (922-1049g/mol), high phenolic hydroxyl content (2.57-3.37mmol/g), low polydispersity (1.54-1.61), and high purity (93.02%). Combined with its superior antioxidant activity and UV shielding properties, this lignin represents a promising new resource with potential applications.

Effects of Multiple Treatments of Formic Acid on the Chemical Properties and Structural Features of Bamboo Powder.

Under mild conditions, formic acid effectively separates the components of lignocellulose, removing the majority of the hemicellulose and lignin from the cellulose. However, it has not yet been determined if multiple treatments with fresh formic acid may totally remove hemicellulose and lignin. In this study, fresh formic acid was used to repeatedly pretreat the bamboo powder, and the effect of multiple treatments on the physicochemical structure of the bamboo powder was investigated using changes in fractions, enzymatic hydrolysis, hydrophilicity, cellulose crystallinity, and lignin structure. Although the hydrophilicity of the powder rose as the number of treatments increased and the number of β-O-4 links in the lignin decreased, it was found that the bamboo powder still contained 5.4% lignin and 2.5% hemicellulose. The 48 h enzymatic yield increased with the number of treatments, with a 59.3% yield obtained at the fifth cycle. This study can serve as a foundation for further research into the mechanism of the influence of organic solvent pretreatment on lignocellulose structural integrity.

Preparation of peanut shell lignin nanocellulose by aluminum trichloride acid deep eutectic solvent pretreatment

Preparation of peanut shell lignin nanocellulose by aluminum trichloride acid deep eutectic solvent pretreatment

Acidic and alkaline deep eutectic solvents pretreatment of Macadamia nutshells for production of cellulose nanofibrils and lignin nanoparticles.

This study explored a facile method for converting macadamia nutshells into bio-based nanomaterials, including cellulose nanofibers (CNFs) and lignin nanoparticles (LNPs), through deep eutectic solvent (DES) pretreatment coupled with a nanofabrication strategy. Comparisons of the physicochemical, morphological, and structural properties of the CNF and LNPs produced through acidic choline chloride/oxalic acid dihydrate (ACDES) and alkaline K2CO3/glycerol DES (ALDES) pretreatments were conducted using SEM, TEM, FTIR, XRD, TGA, GPC and 2D NMR. The CNFs obtained from ACDES pretreatment (ACCNFs) exhibited uniform and long filament-like structures with shorter whisker-like nanocrystals. Conversely, the CNFs produced with the ALDES pretreatment (ALCNFs) displayed irregular aggregates and nanofibril bundles. Additionally, the ACCNFs demonstrated higher crystallinity and contained small amounts of the oxalate half-ester compare to ALCNFs. During ACDES pretreatment, a large proportion of β-O-4, β-5, and β-β linkages in lignin disrupted and re-condensed to form lignin substructures, resulting in the assembly of cluster-like lignin nanoparticles pretreated with ACDES (ACLNP) aggregates. In contrast, lignin nanoparticles pretreated with ALDES (ALLNP) exhibited uniform nanospherical shapes because of the preservation of β linkages in lignin during the ALDES pretreatment. This work not only broadens the fabrication strategies for CNF and LNPs but also offered a promising approach for the valorization of lignocellulosic agricultural wastes.

Efficient isolation of cellulose from chestnut burs using deep eutectic solvent pretreatment

Efficient isolation of cellulose from chestnut burs using deep eutectic solvent pretreatment

Deep eutectic solvent pretreatment of oil palm biomass: Promoted lignin pyrolysis and enzymatic digestibility of solid residues.

Herein, choline chloride/oxalic acid (ChCl/OA) and choline chloride/oxalic acid/ethylene glycol (ChCl/OA/EG) pretreatments of oil palm empty fruit bunches (EFB) and mesocarp fibers (MSF) were conducted to achieve protection of the lignin structure, while improving the enzymatic efficiency of the solid residues. Under the operating conditions of 90 °C and 6 h, ChCl/OA/EG demonstrated a higher lignin extraction selectivity and obtained solid residues with higher hemicellulose content compared to ChCl/OA. The digestibility of glucan and xylan in solid residues obtained using ChCl/OA/EG achieved 98.56 % and 95.63 %, respectively, for EFB and 75.95 % and 88.60 %, for MSF. Uncondensed lignin enriched with 71.79-81.61 % of β-O-4 bonds was obtained from EFB and MSF using ChCl/OA/EG. 2D HSQC NMR and the density functional theory calculation confirmed that substituting the lignin Cα position by ethylene glycol changed the local potentials of the β-O-4 bonds, impeding the attack of protons (H+). The higher β-O-4 linkage content in ChCl/OA/EG-Ls led to the formation of several oxygenated alkyl methoxy phenols and alkyl methoxy phenols were promoted during the pyrolysis. Moreover, molecular dynamics simulations showed that the main factor affecting lignin extraction and dissolution in this study was the diffusion coefficient of lignin in DESs.

Biomass-based strong adhesive based on supramolecular deep eutectic solvents pretreatment

Biomass-based strong adhesive based on supramolecular deep eutectic solvents pretreatment

Efficient production of xylobiose and xylotriose from xylan in moso bamboo by the combination of pH-controlled lactic acid and xylanase hydrolysis.

Short-chain xylo-oligosaccharides (XOS) such as xylobiose (X2) and xylotriose (X3) have higher biological activities. Therefore, it is interesting to produce highly active XOS enriched with X2 and X3. In this work, pH-controlled lactic acid (LA) hydrolysis was used to produce XOS from xylan in moso bamboo and xylanase was used to convert high DP XOS into low DP XOS to increase the percentage of X2+X3 in XOS. A 33.1% XOS yield was obtained from 2% LA hydrolysis (pH=3.2). After xylanase hydrolysis of the LA hydrolysate, the total XOS yield reached 64.1%, with X2+X3 yield reaching 58.4%. The percentage of X2+X3 increased from 52.3% to a high level of 91.0%. The deep eutectic solvent pretreatment removed 87.2% lignin from the residue and the glucose yield of the delignified residue hydrolyzed by cellulase was 96.9%. The results suggested that the integrated process of LA and xylanase hydrolysis could effectively produce X2+X3 from xylan in moso bamboo.

A combination of acetic acid and deep eutectic solvent pretreatment on poplar for coproduction of bioethanol, bio-oil and energy recovery

This work proposed an acetic acid (AC) pre-hydrolysis and a deep eutectic solvent (DES) post-delignification strategy for efficient fractionation of hemicellulose and lignin from lignocellulosic biomass, providing an easily hydrolyzed cellulose, which could be effectively converted to ethanol through semi-simultaneous saccharification and fermentation (SSSF) process. Results showed that, 11.20 kg xylo-oligosaccharides (XOSs), 19.91 kg ethanol and 25.89 kg lignin could be produced from lignocellulosic biorefinery based on the AC-DES pretreatment of 100 kg poplar. In addition, the lignin recovered from DES showed the potential as feedstock for production of hydrocarbon enriched bio-oil by pyrolysis. Higher heating values (HHV) of 27.19 MJ/kg and 31.56 MJ/kg for oil were measured, after pyrolysis of DES lignin and DES lignin/low-density polyethylene (LDPE) with ratio of 7:3, respectively. Finally, mass balance and energy analysis revealed that, lignocellulosic biorefinery based on AC-DES combined pretreatment to co-produce XOSs, bioerthanol and DES lignin could achieve an energy recovery of 78 %.

Integrated approach for cellulosic ethanol and succinic acid production: Gamma valerolactone-based pretreatment and co-fermentation of peanut shells.

The inability to utilize pentose poses as a significant limitation to the production of cellulosic ethanol. To attain efficient raw material conversion and mitigate carbon dioxide emissions during cellulosic ethanol synthesis, a integrated approach focused on the co-processing of ethanol and succinic acid (SA) from peanut shells was proposed. The results demonstrated that the GVL system, containing 30 % water and catalyzed by dilute sulfuric acid, exhibited remarkable efficiency in pretreatment, boosting glucose yield sixfold relative to the untreated raw material. Under optimal conditions of 82 mM sulfuric acid, 141 °C, 56 min, and a solid-to-liquid ratio of 0.07, the glucose yield of the pretreated peanut shell reached 79.0 ± 0.22 %. Through recycling the pretreatment solvent, Tween 80-assisted enzymatic catalysis, and coupling of saccharification and co-fermentation processes, the complete utilization of lignocellulosic feedstocks and sustainable production of high titers of SA (86.1 g/kg) and ethanol (66.4 g/kg) were achieved. This study developed a novel integrated procedure for the efficient co-production of SA and ethanol from peanut shells, offering a new perspective for the efficient biorefinery of lignocellulosic biomass.

Varying extractability of petrogenic and pyrogenic polycyclic aromatic hydrocarbons (PAH) in urban soils: Evaluation of sample preparation and extraction of 71 PAH and alkylated PAH

PAH extraction methods have been widely studied over the last decades. However, there is still no consistent method for contaminated soils. Here, for the first time, PAH source characteristics in soils were considered for the investigation of different pretreatment methods, extraction techniques and solvents in nine petrogenic to primarily pyrogenic urban soils. Sources were identified by macroscopic identification of source substrates and analysis of 71 PAH and alkylation patterns.The comparison of extraction solvents revealed that a combined sequential extraction using dichloromethane (for petrogenic PAH) and toluene:methanol (6:1) led to the highest extraction efficiencies for all samples and is therefore best suited for PAH analysis of unknown samples. Acetone:n-hexane led to the lowest extraction efficiencies for all samples and is not recommended as extraction solvent. The comparison of extraction techniques showed that Pressurized Solvent Extraction is more efficient than ultrasonic extraction especially for petrogenic PAH, but also for pyrogenic PAH. Grinding increased PAH extractability considerably but mainly for petrogenic PAH from bituminous coal particles. In mixed to primarily pyrogenic samples with a smaller proportion of coal, the enhanced extractability of coal leads to a more petrogenic PAH distribution and consequently a decrease in the source identifying PAH Alkylation Index.It is concluded that PAH contents in unknown (urban) soils, where pyrogenic and petrogenic PAH can be present, cannot generally be compared if different extraction techniques, different extraction solvents and grinding or no grinding are applied. As extraction efficiency increases with more effective methods and solvents for bituminous coals, it is recommended to define a specific extraction technique and solvent mixture for improved comparability in future PAH analyses.

Loblolly pine needles processing with deep eutectic solvents to develop porous structure

This work focused on the removal of lignin from pine needles, leaving oriented porous cellulose. Deep eutectic solvent (DES) pretreatment of loblolly pine needles allowed for the removal of lignin from the biomass, leading to the exposure of the desired cellulose structure. Heating under reflux and microwave heating methods were used to pretreat loblolly pine needles with 12:1 lactic acid:choline chloride DES, 2:1 formic acid:choline chloride DES, and 1:2 oxalic acid:choline chloride DES. Characterization of the untreated and pretreated pine needles was done by Brunauer–Emmett–Teller analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy, and ultraviolet–visible spectroscopy. Fiber analysis was also performed on the untreated and pretreated pine needles. The DES pretreated pine needles showed significant enhancements in both specific surface area and pore volume, with microwave pretreatment giving the best results. The oxalic acid:choline chloride DES was the most efficient at eliminating acid-soluble lignin. The optimal duration for conductive heat pretreatment to enhance specific surface area and pore volume was found to be 80 min. For microwave treatment, the formic acid:choline chloride DES was found to be most effective to increase the overall cellulose to lignin ratio.

Comparative study of alkaline, acidic, and deep eutectic solvent pretreatments on lignocellulosic biomass for enhanced enzymatic hydrolysis

Comparative study of alkaline, acidic, and deep eutectic solvent pretreatments on lignocellulosic biomass for enhanced enzymatic hydrolysis

Comparing the improvement of enzymatic hydrolysis effect of Celtis sinensis leaves residue by hydrophilic or hydrophobic deep eutectic solvent pretreatment

Comparing the improvement of enzymatic hydrolysis effect of Celtis sinensis leaves residue by hydrophilic or hydrophobic deep eutectic solvent pretreatment

A new co-production (biogas& biodiesel) plant under a microalgae-to-biofuel process designed under a hydrothermal disintegration/ deep eutectic solvent process

Microalgae-to-biofuel process can be introduced as one of the promising alternatives to non-renewable resources due to its outstanding advantages. However, the industrial feasibility of employing deep eutectic solvents (DESs) for pretreatment of microalgae remains a relatively uncharted territory, which had been acknowledged as a noteworthy research gap in the literature. The purpose of the article is to develop life cycle and energetic analyzes of a co-production (biogas& biodiesel) plant under a microalgae-to-biofuel process. The proposed biofuel production process is based on a hydrothermal disintegration (HD)/DES cycle. An in-depth analysis and comparison between HD/DES of microalgae for the concurrent production and the conventional HD process is developed. Additionally, the effectiveness of recrystallization and membrane filtration for DES recovery was developed. Finally, the sensitivity analyses, focusing on variables like lipid recovery, DES usage quantity, the efficiency of DES recovery, and biogas yield, are provided. When compared to traditional HD, the incorporation of DES during HD led to a substantial 36.8 % improvement in energy output. However, this came at the cost of higher energy input, resulting in a rise in ratio of net energy by 28 %, primarily due to the energy-intensive nature of DES synthesis. Additionally, the introduction of DES contributed to a slight increase in overall released GHG, from −25.86–25.72 g CO2 (eq.) per MJ. Notably, a combination approach involving both membrane filtration and recrystallization yielded promising results, achieving a low ratio of net energy of 0.46 and even negative overall released GHG. The sensitivity analyses findings emphasized the need for reducing energy utilization in DES synthesis and addressing more energy-efficient recovery processes to further enhance the HD/DES process's environmental performance and energy efficiency. This study provides valuable insights into optimizing the co-production plant under a microalgae-to-biofuel process through HD/DES, highlighting avenues for sustainability improvements in this promising approach.

Enhancing the biorefinery of brewery spent grain by deep eutectic solvent pretreatment: Optimisation of polysaccharide enrichment through a response surface methodology

One of the main challenges in biorefinery is the efficient fractionation and use of lignocellulosic biomass. In this sense, pretreatment with deep eutectic solvents (DES) is highlighted as a clean and effective separation method, due to its selective solubilisation of hemicellulose and lignin fractions while preserving cellulose. This study presents a process of the enrichment of polysaccharide content and the improvement of enzymatic digestibility using choline chloride (ChCl) and lactic acid (LA) or glycerol (Gly) in brewery spent grain (BSG) pretreatment. Additionally, it describes how improvements can be made in obtaining polysaccharide-rich material through a response surface methodology, this by means of analysing the operational conditions (temperature, reaction time, and molar ratio) using ChCl:LA. The optimised operational conditions (130 °C, 90 min, and 1:8 mol/mol) generate a 75 % enrichment of polysaccharide fraction and the removal of 77.13 %, 50.70 %, and 100 % of acid-soluble lignin, xylan, and arabinan, respectively. Moreover, the process enhances the saccharification of glucan and xylan to almost 70 % using Cellic CTec2, and to 80 % of glucan and 40 % of xylan using A. niger CECT 2700 enzymatic extract. This constitutes a promising approach to the fractioning of cellulose and lignin from BSG through DES pretreatment, which is unfeasible using traditional pretreatment methods.

Promoted lignocellulose fractionation and improved enzymatic hydrolysis of corn stalks through cationic surfactant combined with deep eutectic solvent pretreatment

The efficient conversion of lignocellulose relies on the implementation of an effective pretreatment strategy. Cationic surfactants combined with deep eutectic solvent ([Betaine][LA] was employed as a novel pretreatment strategy for treating corn stalks. Valuable insights were provided on the impact of the surfactant hydrophobic segment length on pretreatment efficacy. The specific pretreatment conditions were optimized by single factor and orthogonal experiment. Octadecyl trimethyl ammonium bromide (OTAB, 1.5 wt%) with the longest hydrophobic part combined with [Betaine][LA] (Betaine-to-LA molar ratio 1:4) achieved the best pretreatment effect (delignification 92.8 %, xylan elimination 91.1 %) when severity factor reached 4.26, meanwhile, 1.7 g/L xylo-oligosaccharides and 4.4 g/L furfural were detected in pretreatment liquid due to the hydrolysis of hemicellulose in corn stalks with acidic deep eutectic solvent [Betaine][LA]. The relative saccharification activity reached 2.7 times of raw material, while the lignin surface area significantly decreased, leading to enhanced cellulose accessibility. Additionally, molecular perspective provided by molecular dynamics showed the elimination of lignin and xylan was facilitated by strong interaction of hydrogen-bond and van der Waals force between lignin and hemicellulose with [Betaine][LA] + OTAB. Overall, the effectiveness and potential of cationic surfactant combined deep eutectic solvent pretreatment strategy for lignocellulose pretreatment was revealed.

Impact of filtration at elevated temperature and solvent pre-treatment on crosslinked polyvinylidene difluoride and polyimide solvent-resistant nanofiltration membranes

The high temperature filtration performance of crosslinked polyvinylidene difluoride (XL-PVDF) and polyimide (XL-PI) membranes in solvent-resistant nanofiltration (SRNF) applications was studied. The membranes were tested in four industry-relevant, apolar solvents (toluene, xylene, chloroform, and n-butyl acetate) over a temperature range from 25 °C to 80 °C. The temperature effect on membrane performance was evaluated using a polar probe molecule (5,10,15,20-tetrakis(3,5-di-tert-butyl phenyl)porphyrin (TBPP), 1064 Da), showing that permeance increased with rising temperature due to the anticipating reduced solvent viscosity and enhanced flexibility of the membrane polymer chains. This effect varied clearly between the two polymer systems. After the high-temperature filtration, room-temperature (RT) filtrations demonstrated stable retention in xylene, BuOAc, and toluene, but a decrease in chloroform The membranes exhibited excellent long-term stability, retaining their quasi-intact filtration performance over a full week of operation. To investigate the impact of a pre-filtration solvent treatment, Sudan black (SB)/chloroform filtrations were done before and after exposure to toluene, xylene, BuOAc, and chloroform. Quite surprisingly, such solvent treatment resulted in a polymer-specific impact: an increased permeation for XL-PVDF and a decreased permeation for XL-PI. Retentions were constant for XL-PVDF but slightly increased for XL-PI. Overall, both membrane types showed excellent thermal and solvent stability, but the impact was very different.