Deep eutectic solvent with Lewis acid for highly efficient biohydrogen production from corn straw

Innovative liquid embolic agents based on deep eutectic solvent: Rapid gelation in situ via solvent exchange with water for endovascular embolization

Current liquid embolic agents face several challenges, including poor biocompatibility and vascular recanalization. Herein, we propose an innovative liquid embolic agent composed of a coenzyme-based polymer (poly lipoic acid, PLA) and a biocompatible solvent (deep eutectic solvent, DES). The agent undergoes phase transformation to form a stable hydrogel in situ through solvent exchange with water, thereby enabling safe and effective embolization. First, DES is obtained by heating a mixture of choline chloride (ChCl) and glycerol (Gly). Subsequently, lipoic acid (LA) is incorporated into the DES and heated to produce the PLA/DES complex. Owing to the strong hydrogen bonding between the DES and PLA, the DES acts as a solvent while also inhibiting PLA depolymerization. Upon contact with blood, most of the DES exchange with water, whereas some amount of ChCl integrates within the PLA via strong hydrogen bonding. This hydrogen bonding not only prevents PLA depolymerization but also reinforces the PLA network, resulting in a stable PLA hydrogel rather than depolymerized LA monomers. Furthermore, liquid-metal (LM) nanoparticles are incorporated to fabricate radiopaque PLA/LM/DES. PLA/LM/DES shows better in vitro hemocompatibility and cytocompatibility, milder inflammatory response in a rat model, and more effective and safer embolization in a rabbit model than a commercial embolic agent (Onyx). Thus, this work provides an innovative liquid embolic agent and broadens the biomedical applications of DES.

Metal chloride mediated choline chloride-lactic acid deep eutectic solvent pretreatment of bamboo for improved cellulose saccharification and lignin recovery

The cost and recycling efficiency of solvents are critical factors determining the practicality of pretreatment process. In this work, effects of metal chlorides FeCl3, AlCl3 and CuCl2 on pretreatment efficiency and recyclability of choline chloride-lactic acid (ChCl-LA) deep eutectic solvent are comparatively studied. The results show that metal chloride mediation significantly enhances pretreatment efficiency of ChCl-LA, improving delignification, lignin recovery and enzymatic saccharification of cellulose after pretreatment. Among the tested metal chlorides, CuCl2 is found to be most effective as comparing to FeCl3 and AlCl3. 87.3 % delignification and 60 % enzymatic saccharification of cellulose are obtained as the maximum after pretreatment of bamboo with ChCl-LA-CuCl2. These are 1.22- and 2.58-times as that obtained via ChCl-LA pretreatment, respectively. Besides, yield of lignin increases from 25.3 % to 82.6 % companying with increment of purity from 83.9 % to 97.7 %. In terms of recyclability, ChCl-LA-FeCl3 exhibits notable reusability. Taking three cycles into consideration, the enzymatic conversion of cellulose after ChCl-LA-FeCl3 pretreatment is 1.8 and 1.2 times higher than which after ChCl-LA and ChCl-LA-CuCl2 pretreatments, respectively. This research contributes to advancing the practical application of ChCl-LA and has the potential to lower solvent costs.

Enhancement of hydrogen production in dark fermentation of corn stover hydrolysates through composite electric field pretreatment: Improving enzymatic efficiency and regulating microbial metabolic balance

This study investigates the effects of composite electric field pretreatment (CEP) on hydrogen production from corn stover enzymatic hydrolysates in dark fermentation. The findings reveal that under optimal conditions, the CEP group achieved a cumulative hydrogen yield of 77.3  ±  2.6 mL/g TS, marking a 55.3 % increase compared to the control group without the electric field. CEP significantly enhances the fermentation capacity of enzymatic hydrolysates during the acid-stage of dark fermentation by disrupting the lignin structure and optimizing cellulase hydrolysis efficiency. Additionally, pH self-regulation is facilitated through the interaction between volatile fatty acids (VFAs) and ammonia nitrogen. Microbial community analysis revealed that CEP shifts the metabolic balance between Clostridium_sensu_stricto_1 and Lactococcus, leading to increased hydrogen yield and concentration during acid fermentation. Notably, Terrisporobacter exhibited a superior acid-producing capability compared to Bacteroides during the dark fermentation of enzymatic hydrolysates. This study provides a new perspective for the practical application of corn stover.

Preparation of straw/PLA composites with excellent flame retardancy based on deep eutectic solvent sulfonation

There have been numerous studies on flame retardant modification of natural fiber/PLA composite materials due to the demand for applications. However, the existing flame retardant modification methods mostly involve adding flame retardants, which have a negative impact on the mechanical properties. Based on this, this study aims to introduce sulfonic groups into the cellulose of straw fibers via modification with a sulfamic acid-based deep eutectic solvent (SDES), thereby achieving flame retardance without affecting the inherent mechanical properties of the composite material. The performance enhancement of DS/PLA is manifested in the following specific aspects: the LOI reaches 36.53 %, the thermal stability is improved from 7.8 % of the residual carbon of PS/PLA to 38.4 %, and the tensile modulus is increased by 69.5 %. The preparation scheme for straw/PLA composite materials in this study is simple, economical, and efficient, and the flame retardant performance of the composite material is excellent, providing valuable references for flame retardant modification of natural fiber/plastic composite materials.

Improved biohydrogen production by co-fermentation of corn straw and excess sludge: Insights into biochemical process, microbial community and metabolic genes

The global climate change mainly caused by fossil fuels combustion promotes that zero-carbon hydrogen production through eco-friendly methods has attracted attention in recent years. This investigation explored the biohydrogen production by co-fermentation of corn straw (CS) and excess sludge (ES), as well as comprehensively analyzed the internal mechanism. The results showed that the optimal ratio of CS to ES was 9:1 (TS) with the biohydrogen yield of 101.8 mL/g VS, which was higher than that from the mono-fermentation of CS by 1.0-fold. The pattern of volatile fatty acids (VFAs) indicated that the acetate was the most preponderant by-product in all fermentation systems during the biohydrogen production process, and its yield was improved by adding appropriate dosage of ES. In addition, the content of soluble COD (SCOD) was reduced as increasing ES, while concentration of NH4+-N showed an opposite tendency. Microbial community analysis revealed that the microbial composition in different samples showed a significant divergence. Trichococcus was the most dominant bacterial genus in the optimal ratio of 9:1 (CS/ES) fermentation system and its abundance was as high as 41.8%. The functional genes prediction found that the dominant metabolic genes and hydrogen-producing related genes had not been significantly increased in co-fermentation system (CS/ES = 9:1) compared to that in the mono-fermentation of CS, implying that enhancement of biohydrogen production by adding ES mainly relied on balancing nutrients and adjusting microbial community in this study. Further redundancy analysis (RDA) confirmed that biohydrogen yield was closely correlated with the enrichment of Trichococcus.

Novel ternary deep eutectic solvent fractionation for effective utilization of willow

A novel ternary deep eutectic solvent (TDES), consisting of zinc chloride, ethylene glycol and alpha hydroxy carboxylic acids (i.e., glycolic acid, citric acid and malic acid), was first proposed to effectively fractionate and convert willow (Salix matsudana cv. Zhuliu) into fermentable sugar. In particular, the zinc chloride/ethylene glycol/malic acid (ZnCl2/EG/MA) TDES system showed remarkable fractionation performance with 91.66 % xylan and 90.12 % lignin removals at 130 °C for 1.5 h, resulting in 96.01 % glucose yield in the subsequent enzymatic hydrolysis stage. Moreover, the regenerated lignin showed regular nanoparticle morphology and good antioxidant properties. Even after four recycling, the TDES showed 70.16 % of delignification and 83.70 % glucose yield with the TDES pretreated willow. Overall, this study demonstrated an effective solvent fractionation approach to maximize the utilization of total lignocellulose under mild conditions.

Hydrogen-transfer strategy in lignin refinery: Towards sustainable and versatile value-added biochemicals

Lignin, the most prevalent natural source of polyphenols on Earth, offers substantial possibilities for the conversion into aromatic compounds, which is critical for attaining sustainability and carbon neutrality. The hydrogen-transfer method has garnered significant interest owing to its environmental compatibility and economic viability. The efficacy of this approach is contingent upon the careful selection of catalytic and hydrogen-donating systems that decisively affect the yield and selectivity of the monomeric products resulting from lignin degradation. This paper highlights the hydrogen-transfer technique in lignin refinery, with a specific focus on the influence of hydrogen donors on the depolymerization pathways of lignin. It delineates the correlation between the structure and activity of catalytic hydrogen-transfer arrangements and the gamut of lignin-derived biochemicals, utilizing data from lignin model compounds, separated lignin, and lignocellulosic biomass. Additionally, the paper delves into the advantages and future directions of employing the hydrogen-transfer approach for lignin conversion. In essence, this concept investigation illuminates the efficacy of the hydrogen-transfer paradigm in lignin valorization, offering key insights and strategic directives to maximize lignin's value sustainably.

Corn straw-saccharification fiber improved the reproductive performance of sows in the late gestation and lactation via lipid metabolism

With the development of animal husbandry, the shortage of animal feedstuffs has become serious. Dietary fiber plays a crucial role in regulating animal health and production performance. The aim of this study was to investigate the effects of three kinds of corn straw-saccharification fibers (CSSF) such as high-fiber and low-saccharification (HFLS), medium-fiber and medium-saccharification (MFMS), low-fiber and high-saccharification (LFHS) CSSF on the reproductive performance of sows. Thirty-two primiparous Yorkshire sows were randomly assigned to 4 groups, 8 sows for each group. Group A was the basal diet as the control group; groups B - D were added with 6% HFLSCSSF, 6% MFMSCSSF and 6% LFHSCSSF to replace some parts of corn meal and wheat bran in the basal diet, respectively. The experimental period was from day 85 of gestation to the end of lactation (day 25 post-farrowing). The results showed that 6% LFHSCSSF addition significantly increased number of total born (alive) piglets, litter weight at birth (p < 0.05), whereas three kinds of CSSF significantly decreased backfat thickness of sows during gestation (p < 0.001), compared with the control group. Furthermore, CSSF improved the digestibility of crude protein, ether extract and fiber for sows. In addition, the levels of total cholesterol, total triglycerides, and high-density lipoprotein cholesterol in serum of sows were decreased by different kinds of CSSF. Further analysis revealed that CSSF regulated lipid metabolism through adjusting the serum metabolites such as 4-pyridoxic acid, phosphatidyl cholines and L-tyrosine. In summary, CSSF addition to the diets of sows during late gestation and lactation regulated lipid metabolism and improved reproductive performance of sows. This study provided a theoretical basis for the application of corn straw in sow diets.

Combined sulfuric acid and choline chloride/glycerol pretreatment for efficiently enhancing enzymatic saccharification of reed stalk

In this study, an efficient combination of pretreatment solvents involving Choline chloride/Glycerol (ChCl/Gly) and H2SO4 was firstly developed to assess the pretreatment performance and determine optimal pretreatment conditions. The results illustrated that the H2SO4-[ChCl/Gly] combination efficiently removed lignin (52.6%) and xylan (80.5%) from the pretreated reed stalk, and subsequent enzymatic hydrolysis yielded 91.1% of glucose. Furthermore, several characterizations were conducted to examine the structural and morphological changes of the reed stalk, revealing apparently enhanced accessibility (128.4 to 522.6 mg/g), reduced lignin surface area (357.9 to 229.5 m2/g), and substantial changes on biomass surface. Based on the aforementioned study, possible mechanisms for the H2SO4-[ChCl/Gly] pretreatment of reed stalks were proposed. The comprehensive understanding of combined H2SO4-[ChCl/Gly] pretreatment system for enhancing the saccharification of the reed stalk was interpreted in this work. Overall, this novel approach could be efficiently applied to pretreat and saccharify reed stalks, empowering the biomass refining industry.

Thermally modified tourmaline enhances hydrogen production by influencing hydrolysis acidification in two stages during dark fermentation of corn stover

This study investigated the influence of thermally modified tourmaline (Tur) on hydrogen production during the dark fermentation of corn stover. Single-factor experimental results revealed influencing factors of particle size, mass, and temperature. Optimization of the experimental process was achieved using the Box-Behnken design, reaching optimum at conditions of 407 °C, 910-mesh, and 6.2 g. The principle analysis experiment showed that the Tur-enhanced group (Tur_En) amplified cumulative hydrogen production by elevating hydrogen production during the sugar-production stage. The Tur_En group's cumulative hydrogen production was measured at 396.2 ± 40.3 (mL/g VS), marking a 34.2% increase compared to the control group. Analysis of microbial diversity indicated that Firmicutes and Bacteroidota emerged as dominant colonies in both stages. Tur facilitated hydrogen production by stimulating the activity of Firmicutes. This study suggests a highly effective Tur-enhanced technology for hydrogen production from corn stover and elucidates the principles underpinning this method from two stages.

Microwave-assisted choline chloride/1,2-propanediol/methyl isobutyl ketone biphasic system for one-pot fractionation and valorization of Eucalyptus biomass

The developing of pretreatment method to break the biomass barrier of lignocellulosic is a challenging task for achieve high value utilization. A fast microwave-assisted choline chloride/1,2-propanediol/methyl isobutyl ketone biphasic system was constructed for pretreating Eucalyptus to the production of furfural and cellulose-rich residues and the extraction of lignin. Results showed that the combination of AlCl₃·6H₂O and HCl had the best catalytic ability for furfural production among the examined catalysts. Under the optimal conditions (140 °C, 15 min, 0.075 M AlCl₃·6H₂O, 0.05 M HCl), the furfural yield of 55.4 %, the glucose yield of 90.3 % and the delignification rate of 92.4 % could be achieved. Moreover, the extracted lignin samples with a low polydispersity (1.55-1.73) and molecular weight (1380-2040 g/mol) are promising to act as precursor for the value-add products processing. These findings demonstrated an ultrafast pretreatment process with excellent results in biomass fractionation and comprehensive utilization of biomass components.

Fight for carbon neutrality with state-of-the-art negative carbon emission technologies

After the Industrial Revolution, the ever-increasing atmospheric CO2 concentration has resulted in significant problems for human beings. Nearly all countries in the world are actively taking measures to fight for carbon neutrality. In recent years, negative carbon emission technologies have attracted much attention due to their ability to reduce or recycle excess CO2 in the atmosphere. This review summarizes the state-of-the-art negative carbon emission technologies, from the artificial enhancement of natural carbon sink technology to the physical, chemical, or biological methods for carbon capture, as well as CO2 utilization and conversion. Finally, we expound on the challenges and outlook for improving negative carbon emission technology to accelerate the pace of achieving carbon neutrality.