Solvent Pretreatment Research Articles

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.

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.

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 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.

Efficient conversion of corn stover to glucose using alkaline DBU synergized glycerol-based deep eutectic solvent under mild conditions

Efficient pretreatment is crucial for the high-value and effective conversion of lignocellulose. However, the current glycerol-based deep eutectic solvent (DES-Gly) pretreatment method requires high reaction temperatures, considerable solvent usage, and yields low conversion efficiency. In this study, we investigated the pretreatment of corn stover with 1,8-diazobicyclic [5.4.0] undeca-7-ene (DBU) synergized with DES-Gly, which significantly enhances the glucose yield from corn stover. The strong synergistic effect of DBU and DES-Gly effectively removes lignin and substantially increases glucose yield. Under optimal conditions, 95.27 % glucose conversion could be achieved, even with the addition of only 2 FPU/mL of cellulase. The physicochemical properties of the DES-Gly solution and pretreated corn stover were analyzed using FTIR, XRD, SEM, TGA, and 1 H NMR characterization techniques. In addition, DES-Gly and DBU synergy mechanisms are further explored. Our work provides a mild, efficient and low-cost DES-Gly-based pretreatment method, introducing a new way for the catalytic conversion of lignocellulose to sugar production.

Imidazole ionic liquid effects on coal swelling behavior and pyrolysis characteristics: Experiment and molecular simulation

In view of low-rank coal conventional swelling solvent large pollution and the clean efficient utilization of coal, the effects of imidazole ionic liquid (IL) pretreatment with different anion groups as green solvent on coal thermal expansion and pyrolysis performance were investigated. IL interacts with coal molecules, destroying the hydrogen bonds, resulting coal expansion. Different anion groups have different modification effects, [Bmim]Cl has the best swelling effect, which is 17.37 % higher than raw coal, and the best modification time is 24 h. In addition, IL modification has a catalytic effect on coal pyrolysis, which can significantly reduce the maximum weight loss temperature and increase tar content. Coal solvent pretreatment provides a good theoretical basis for application of swelling and pyrolysis. The reduction of thermochemical reaction temperature not only reduces the content of heavy groups in pyrolysis products, but also provides new ideas for carbon emission reduction.

Efficient binary diol-based deep eutectic solvent pretreatment for enhancing enzymatic saccharification and lignin fractionation from eucalyptus

An innovative binary biol-based deep eutectic solvent (DES), specifically ethylamine hydrochloride-ethylene glycol (EaCl-EG), was developed for efficient pretreatment of eucalyptus biomass. This DES exhibited superior performance in achieving high delignification (85.0%) and xylan removal (80.0%), while preserving a significant amount of cellulose (94.5%) compared to choline chloride-based DES. Notably, the pretreated eucalyptus residues showed a remarkable glucose yield of over 92.5%, representing a substantial enhancement of up to 15 times compared to untreated eucalyptus. Furthermore, the pretreated liquor yielded high-purity lignin with a yield of 97.8%, characterized by well-preserved β-O-4 structure and nanoscale dimensions. These lignin nanoparticles (LNPs) were subsequently self-assembled into lignin nanobottles (LNBs), adding further value to the pretreatment process. The proposed novel binary EaCl-EG DES presented great potential as an efficient pretreatment solvent for future biomass fractionation processes.

Electro-driven deep eutectic solvent pretreatment of wheat straw with enhancive component fractionation and hydrogen evolution at room temperature

Electro-driven deep eutectic solvent pretreatment of wheat straw with enhancive component fractionation and hydrogen evolution at room temperature

Nanocellulose separation from barley straw via ultrasound-assisted choline chloride – Formic acid deep eutectic solvent pretreatment and high-intensity ultrasonication

The present study aims at investigating the application of ultrasound assisted choline chloride (ChCl) – formic acid (FA) deep eutectic solvent (DES) pretreatment of Barley straw. In addition, the efficiency of a wet grinding followed by high intensity ultrasound (HIUS) treatment for production of cellulose nanofibers (CNF) has been evaluated. The DES (using ChCl: FA at 1:9 M ratio) treatment at 45 kHz ultrasound frequency and 3 h of treatment duration resulted in 84.68 ± 1.02 % and 82.96 ± 0.79 % of lignin and hemicellulose solubilisation, respectively. The purification of DES treated solid residue resulted in cellulose with more than 90 % purity. Further, 10 min of wet grinding followed by 40 min of HIUS treatment resulted in more than 80 % nano-fibrillation efficiency. The produced CNF had diameters less than 100 nm in number size distribution and type I cellulose structure. This study confirmed that the developed process offers a sustainable method for producing nanocellulose from agricultural waste.

Multifunctional composite film of curcumin Pickering emulsion stabilized by lignocellulose nanofibrils isolated from bamboo shoot shells for monitoring shrimp freshness

Concerns about food safety and environmental impact from chemical surfactants have prompted interest in natural lignocellulosic materials as alternatives. In this study, we combined hydrated deep eutectic solvent (DES) pretreatment with ultrasound treatment to prepare lignocellulosic nanofibrils (LCNF) from bamboo shoot shells with appropriate surface properties for stabilizing Pickering emulsions. The pretreatment intensity effectively modulated the surface characteristics of LCNF, achieving desirable wettability through lignin retention and in-situ esterification. The resulting LCNF/curcumin Pickering emulsion (CPE) demonstrated curcumin protection and pH-responsive color changes, while the ensuing CPE/PVA composite film exhibited ultraviolet shielding, mechanical strength, oxygen barrier, and antioxidant properties. Furthermore, the CPE/PVA film showed promise as a real-time indicator for monitoring shrimp freshness, maintaining sensitivity to spoilage even after six months of storage. These findings advance the advancement of green LCNF technologies, providing eco-friendly solutions for valorizing bamboo shoot shells and enhancing the application of LCNF in Pickering emulsions.

Textile waste pretreatment for anaerobic digestion: a review and technology feasibility study

AbstractThe increasing volume of textile waste in landfills and incineration poses severe environmental challenges. Waste valorisation of textile waste via anaerobic digestion (AD) is preferable, as it offers economic and environmental benefits, but it is hindered by textile complexity, necessitating effective pretreatment technologies to improve biogas production. This study aims to evaluate various pretreatment technologies for biogas production from textile fibres via AD. A weighted‐scoring analysis (WSA) assessed pretreatment methods based on technical, economic, environmental and operational criteria. Hydrothermal pretreatment emerged as the most technically effective method, scoring 140 owing to its substantial methane enhancement. Economically, shredding was the most viable option, scoring 125, as a consequence of low capital and O&amp;M cost. Environmentally, hydrothermal and deep eutectic solvent (DES) pretreatments were top performers with 100 points owing to low environmental impact and positive heat reactions. In a case study conducted in the Auckland region, the potential environmental impact (PEI) obtained from hydrothermal and DES were 169 and 92 per year, respectively, resulting in minimal environmental impact. Operationally, ultrasonic and biological pretreatments scored highest owing to their ease of operation, and minimal health and safety requirements. Overall, hydrothermal pretreatment achieved the highest WSA score of 340, reflecting its balanced performance across all criteria. Hydrothermal pretreatment is the most promising technology for enhancing biogas production from textile waste. Its technical efficiency, economic feasibility and environmental benefits regarding the WSA score make it suitable for upscaling and providing a viable solution for managing textile waste in the AD plant. © 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry (SCI).

Current status and future prospects of pretreatment for tobacco stalk lignocellulose.

With the growing demand for sustainable development, tobacco stalks, as a resource-rich and low-cost renewable resource, hold the potential for producing high-value chemicals and materials within a circular economy. Due to the complex and unique structure of tobacco stalk biomass, traditional methods are ineffective in its utilization, making the pretreatment of tobacco stalk lignocellulose a crucial step in obtaining high-value products. This paper reviews recent advancements in various pretreatment technologies for tobacco stalk lignocellulosic biomass, including hydrothermal, steam explosion, acid, alkaline, organic solvent, ionic liquid, and deep eutectic solvent pretreatment. It emphasizes the impact and efficiency of these pretreatment methods on the conversion of tobacco stalk biomass and discusses the advantages and disadvantages of each technique. Finally, the paper forecasts future research directions in the pretreatment of tobacco stalk lignocellulose, providing new insights and methods for enhancing its efficient utilization.

Zero-waste biorefining co-products from ultrasonically assisted deep eutectic solvent-pretreated Chlorella biomass: Sustainable production of biodiesel and bio-fertilizer

Microalgal biomass is gaining increasing attention to produce high-value co-products. This study proposes integrating Chlorella microalgal biomass into a zero-waste biorefining system, aiming to produce biodiesel and biofertilizer. It investigates optimal conditions for ultrasound-assisted deep eutectic solvent (DES) pretreatment and lipid recovery to enhance the extraction of lipids. Optimal DES pretreatment was identified as a 1.6:1 acetic acid-to-choline chloride molar ratio, 0.36 g biomass loading, and 2.50 min of pretreatment. Lipid recovery succeeded with a 10-minute extraction time and a 1:3 methanol-to-butanol volume ratio. These conditions yielded biodiesel-quality lipids at 139.52 mg/g microalgal biomass with superior fuel characteristics. The de-oiled microalgal biomass residue exhibited promise as a lettuce biofertilizer, enhancing photosynthetic pigments but potentially reducing yields by 40 %. The study also notes changes in rhizosphere microbial communities, indicating both stimulatory and inhibitory effects on beneficial microbes. This study has the potential to enhance sustainability in energy, agriculture, and the environment.

Temperature-responsive deep eutectic solvent-based microextraction for the determination of bisphenols in beverages by HPLC-FLD

In this work, a homogeneous liquid-liquid microextraction approach based on temperature-responsive deep eutectic solvent for pretreatment of beverages was developed for the first time. The procedure assumed the heating of the homogeneous solution, consisting of sample, precursors of temperature-responsive deep eutectic solvent (amphiphilic amine and carboxylic acid) and salting-out agent in a disposable polyethylene pipette. The heating of extraction system induced the change of acid-base properties of the precursors, and thus it attributed to in situ formation of microdroplets of deep eutectic solvent in beverage sample. The significant difference in densities of aqueous sample phase and the extraction solvent allowed to obtain spontaneous phase separation, while the presence of a thin capillary on top of the pipette facilitated microvolume sampling of the resulting extract. The approach was utilized for the determination of bisphenols (bisphenol A, bisphenol C, bisphenol E and bisphenol F) in beverages by high-performance liquid chromatography with fluorometric detection. The temperature-responsive deep eutectic solvent based on lidocaine and heptanoic acid provided the highest preconcentration of analytes (enrichment factor – 22). Under optimal conditions, the RSD in terms of inter-day precision was < 11 %, limits of detection for bisphenols were 0.01–0.03 μg L−1.

Enhancing lead-free photovoltaic performance: Minimizing buried surface voids in tin perovskite films through weakly polar solvent pre-treatment strategy

Buried interfacial voids have always been a notorious phenomenon observed in the fabrication of lead perovskite films. The existence of interfacial voids at the buried interface will capture the carrier, suppress carrier transport efficiencies, and affect the stability of photovoltaic devices. However, the impact of these buried interfacial voids on tin perovskites, a promising avenue for advancing lead-free photovoltaics, has been largely overlooked. Here, we utilize an innovative weakly polar solvent pre-treatment strategy (WPSPS) to mitigate buried interfacial voids of tin perovskites. Our investigation reveals the presence of numerous voids in tin perovskites during annealing, attributed to trapped dimethyl sulfoxide (DMSO) used in film formation. The WPSPS method facilitates accelerated DMSO evaporation, effectively reducing residual DMSO. Interestingly, the WPSPS shifts the energy level of PEDOT:PSS downward, making it more aligned with the perovskite. This alignment enhances the efficiency of charge carrier transport. As the result, tin perovskite film quality is significantly improved, achieving a maximum power conversion efficiency approaching 12% with only an 8.3% efficiency loss after 1700 h of stability tests, which compares well with the state-of-the-art stability of tin-based perovskite solar cells.

A HPLC method based on deep eutectic solvents to analyze high concentration of TATB

TATB as an insensitive high explosive, has wide applications in both civil and military areas. High performance liquid chromatography (HPLC) is a crucial tool to analyze the purity for quality control of TATB. However, current HPLC method for TATB has several drawbacks resulted by its poor solubility. A deep eutectic solvent (CS-1) has high solubility toward TATB, so it has been used as the pretreatment solvent and mobile phase to develop a new HPLC method for TATB in this work. When CS-1 was used as the pretreatment solvent for TATB prior to HPLC analysis, it displayed greater efficiency, less dosage, and shorter time compared to conventional solvents such as dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF). Compared to the pretreatment time of 240 min by using DMSO, the pretreatment time of TATB by using CS-1 is significantly shortened to 20 min. Meanwhile, the carrying capacity of mobile phase for TATB became stronger after CS-1 was added into the mobile phase. The concentration of TATB with 40 mg·100 mL−1 is successfully analyzed by the HPLC based on the mobile phase containing CS-1, which is 10 times higher than that of DMSO with 4.0 mg·100 mL−1. Therefore, a new HPLC method based on CS-1 as one of the deep eutectic solvents is first established to improve the efficiency and representation of analyzing high concentration of TATB.