Solvent Pretreatment Research Articles

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

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.

Novel ternary deep eutectic solvents pretreatment of corn stalk to realize high-value utilization

The high-valued utilization of biomass components through pretreatment technology can effectively alleviate the pressure of energy and environment. In this study, a ternary deep eutectic solvent (TDES) was prepared by using glycolic acid (GA) and ethylene glycol (EG) as double hydrogen donors and benzyl trimethyl ammonium chloride (TMBAC) as hydrogen acceptor. The corn stalk was separated by TDES to obtain cellulose-rich solid residue and low-condensed lignin. Moreover, the solid residue was converted into bio-oil by rapid pyrolysis, and the low-condensed lignin was converted into fluorescent lignin by grafting luminol for information encryption. The results showed that under the pretreatment condition of 150℃ for 3 h, TDES with the molar ratio of 1:1:2 had a lignin removal ratio of 90.60 %, and the yield of levoglucosan obtained from solid residue pyrolysis bio-oil reached 36.38 %. Furthermore, TDES prevented lignin from forming a C-C polycondensation structure and endowed it with polyhydroxy properties, which was beneficial to graft luminolto enhance the fluorescence intensity efficiently. The high-intensity fluorescent grafted lignin was used for information encryption of various materials. The mechanism of TDES pretreatment and luminol grafting were explored, and the mass balance of corn stalk during pretreatment was described. This study provides a green, environmentally friendly, and efficient pretreatment process for the high-value utilization of biomass.

Deep eutectic solvent (DES) pretreatment and lignin regeneration for the development of a bamboo leaf-based bioplastic.

The excessive utilization of petroleum-based plastic products has led to a pervasive environmental and human health threat. In response, the adoption of bioplastics derived from biomass has emerged as the foremost alternative to conventional plastics, owing to their inherent biodegradability and sustainability. The present study demonstrates the preparation of a biodegradable and cost-effective lignocellulosic bioplastic by utilizing dissolving bamboo leaf powder with deep eutectic solvents (DES) and regenerating lignin in situ. The DES was synthesized through a one-step heating and stirring method using choline chloride (ChCl) and anhydrous oxalic acid. The crystallinity of the bioplastics is enhanced by DES pretreatment, thereby improving the internal structural order of the material. Moreover, lignin regeneration reduces the pore size within the bioplastics and contributes to a more compact internal structure. The prepared lignocellulosic bioplastics exhibit remarkable mechanical strength, with a tensile strength of 113MPa. Additionally, they demonstrate good water stability, as evidenced by a contact angle of 55.52°. Moreover, these bioplastics possess an exceptional biodegradability with a degradation rate exceeding 98% after 60days. This study presents an innovative approach for the high-value utilization of bamboo leaf resources.

A miniaturized feedstocks-to-fuels pipeline for screening the efficiency of deconstruction and microbial conversion of lignocellulosic biomass.

Sustainably grown biomass is a promising alternative to produce fuels and chemicals and reduce the dependency on fossil energy sources. However, the efficient conversion of lignocellulosic biomass into biofuels and bioproducts often requires extensive testing of components and reaction conditions used in the pretreatment, saccharification, and bioconversion steps. This restriction can result in a significant and unwieldy number of combinations of biomass types, solvents, microbial strains, and operational parameters that need to be characterized, turning these efforts into a daunting and time-consuming task. Here we developed a high-throughput feedstocks-to-fuels screening platform to address these challenges. The result is a miniaturized semi-automated platform that leverages the capabilities of a solid handling robot, a liquid handling robot, analytical instruments, and a centralized data repository, adapted to operate as an ionic-liquid-based biomass conversion pipeline. The pipeline was tested by using sorghum as feedstock, the biocompatible ionic liquid cholinium phosphate as pretreatment solvent, a "one-pot" process configuration that does not require ionic liquid removal after pretreatment, and an engineered strain of the yeast Rhodosporidium toruloides that produces the jet-fuel precursor bisabolene as a conversion microbe. By the simultaneous processing of 48 samples, we show that this configuration and reaction conditions result in sugar yields (~70%) and bisabolene titers (~1500 mg/L) that are comparable to the efficiencies observed at larger scales but require only a fraction of the time. We expect that this Feedstocks-to-Fuels pipeline will become an effective tool to screen thousands of bioenergy crop and feedstock samples and assist process optimization efforts and the development of predictive deconstruction approaches.

Deep eutectic solvent pretreatment for enhanced enzymatic hydrolysis of pineapple biomass via Response Surface Methodology

Deep eutectic solvent pretreatment for enhanced enzymatic hydrolysis of pineapple biomass via Response Surface Methodology

Impact of deep eutectic solvent pre-treatment on the extraction of cellulose nanofibers

Deep Eutectic Solvents (DESs) have emerged as promising eco-friendly pre-treatment agents for lignocellulosic biomass, offering considerable advantages for the nanofibrillation process. This study investigates the impact of DESs on cellulose fibers morphology, focusing on solubilization phenomena in the amorphous regions that may facilitate cellulose nanofiber production. The pre-treatment process combining a DES (triethylmethylammonium chloride and imidazole, TEMA:IMD) with microwave (MW) energy was optimized to enhance the solubility of cellulosic fibers. A response surface methodology (RSM) was employed to optimize the DES-MW-assisted pre-treatment. Results show that the reaction time and the temperature significantly influence the solubility of cellulosic fibers. The optimized conditions resulted in cellulose fibers with low content of hemicellulose and lignin, high crystallinity index, and improved thermal stability. The effectiveness of DES-MW pre-treatment in producing cellulose nanofibers (CNFs) from native and pre-treated fibers was investigated. Cellulose fibers pre-treated with a DES yielded CNFs with a narrower diameter distribution. Overall, optimized DES-MW pre-treatment offers a promising strategy for the efficient and sustainable extraction of CNFs.

Understanding the role of porous particle characteristics and water state distribution at multi-scale variation on cellulase hydrolysis of lignocellulosic biomass

Porous particle characteristics of lignocellulosic biomass and the water state distribution surrounding particles determine enzyme/solute transfer, while inherently affecting the liquefaction and hydrolysis reactions. For submillimeter biomass particles (<500 μm), deep eutectic solvent pretreatment tended to create additional macropores (∼4%, pore volume of 4.3 mL/g) and micropores (∼3%, pore area of 2.26 m2/g) at the extragranular and cell wall scales, simultaneously with reducing particle size by 15%. The pretreated biomass exhibited preferential rapid liquefaction over sugar production, leading to a ∼70% reduction in particle size only after 3 h hydrolysis. This further increased particle porosity (∼85% after 12 h hydrolysis) with the transition from large surface-pores to interior micropores. The increases in the tissue/cell-scale pore size and intraparticle area had greater significance for improving hydrolysis performance than particle size reduction. Additionally, particle liquefaction released constrained water in capillary pores and enhanced slurry fluidity; capillary water and free water became main transfer carriers during the hydrolysis. Free water activity was positively related to sugar production (r = 0.80–0.85), and integrating it with particle component and porosity allowed for accurate prediction of hydrolysis yields (R2 = 0.98–0.99). Inspired by particle liquefaction, a short-time feeding strategy was proposed to reconstruct high-solid hydrolysis.