Distinct effects of dilute acid prehydrolysate inhibitors on enzymatic hydrolysis and yeast fermentation.

The effects of dilute acid prehydrolysate from poplar were investigated and compared in the enzymatic hydrolysis, fermentation, and simultaneous saccharification fermentation (SSF) in this study. The improvement of enzymatic hydrolysis and fermentation with resin adsorption and surfactant addition has also been represented. A total of 16 phenolic alcohols, aldehydes, acids and 3 furan derivatives in the prehydrolysates were identified and quantified by gas chromatography/mass spectrometry (GC/MS). The degree of inhibition from the phenolic compounds (26.55%) in prehydrolysate on the enzymatic hydrolysis was much higher than carbohydrates-derived inhibitors (0.52-4.64%). Around 40% degree of inhibition was eliminated in Avicel enzymatic hydrolysis when 75% of prehydrolysates phenolic compounds were removed by resin adsorption. This showed distinguishing inhibition degrees of various prehydrolysate phenolic compounds. Inhibition of prehydrolysate on enzymatic hydrolysis was more dosage-dependent, while their suppression on the fermentation showed a more complicated mode: fermentation could be terminated by the untreated prehydrolysate, while a small number of prehydrolysate inhibitors even improved the glucose consumption and ethanol production in the fermentation. Correlated with this distinct inhibition modes of prehydrolysate, the improvement of Tween 80 addition in SSF was around 7.10% for the final ethanol yield when the glucose accumulation was promoted by 76.6%.

Transforming municipal cotton waste into a multilayer fibre biocomposite with high strength.

We analyzed the problematic textile fiber waste as potential precursor material to produce multilayer cotton fiber biocomposite. The properties of the products were better than the current dry bearing type particleboards and ordinary dry medium-density fiberboard in terms of the static bending strength (67.86 MPa), internal bonding strength (1.52 MPa) and water expansion rate (9.57%). The three-layer, four-layer and five-layer waste cotton fiber composite (WCFC) were tried in the experiment, the mechanical properties of the three-layer WCFC are insufficient, the five-layer WCFC is too thick and the four-layer WCFC had the best comprehensive performance. The cross-section morphology of the four-layer WCFC shows a dense structure with a high number of adhesives attached to the fiber. The hardness and stiffness of the four-layer cotton fiber composite enhanced by the high crystallinity of cellulose content, and several chemical bondings were presence in the composites. Minimum mass loss (30%) and thermal weight loss rate (0.70%/°C) was found for the four-layer WCFC. Overall, our findings suggested that the use of waste cotton fiber (WCF) to prepare biocomposite with desirable physical and chemical properties is feasible, and which can potentially be used as building material, furniture and automotive applications.

Recent development of metal-organic frameworks and their composites in electromagnetic wave absorption and shielding applications.

With the rapid development of information and communication industries, the usage of electromagnetic waves has caused the hazard of human health and misfunction of devices. The adsorption and shielding of electromagnetic waves have been achieved in various materials. The unique adjustable spatial structure makes metal-organic frameworks (MOFs) promising for electromagnetic shielding and adsorbing. As MOFs research advances, various large-scale MOF-based materials have been developed. For instance, MOFs spatial structure has been expanded from 2D to 3D to load more ligands. Progress in synthetic methods for MOFs and their derivatives is advancing, with priority on large-scale preparation and green synthesis. This review summarizes the methods for synthesizing MOFs and their derivatives, and explores the effects of MOFs spatial structure on electromagnetic interference (EMI) shielding and electromagnetic wave absorption capabilities. At the same time, detailed examples are used to focus on the applications of five different MOFs composites in electromagnetic shielding and electromagnetic wave absorption. Finally, the current challenges and prospects of MOFs in the electromagnetic field are introduced, providing a useful reference for the preparation and design of MOFs and their composites for electromagnetic wave processing applications.

High efficient preparation of low molecular weight galactomannan from Leucaena leucocephala galactomannan through the combination of hydrogen peroxide and oxalic acid.

Researchers have always been interested in polysaccharide degradation because of the increased biological activity and usability following degradation. In this work, low molecular weight galactomannan (LMW-GM) was produced through the degradation of galactomannan by H2O2 and oxalic acid (OA). The optimal reaction conditions were found by conducting the response surface optimization experiment based on single-factor experiment and kinetics analysis. Under these conditions, the LMW-GM yield was 69.48 ± 1.02 %. Ultimately, an analysis of the degradation process revealed that OA attacked GM indiscriminately, and H2O2 has a stronger effect on the removal of branched chains while degrading GM. Hence, the degradation steps were rearranged as H2O2 was added 20 min before OA at a constant total time. The LMW-GM yield was successfully increased to 76.49 ± 1.27 %. The goal of this work is hopefully to give a theoretical foundation for the low-cost preparation and industrial production of the degradation of galactomannan.

Co-production of fermentable sugars and highly active lignin from eucalyptus via a mild preprocessing with diethylene glycol and chromic chloride.

Eucalyptus was pretreated with diethylene glycol catalyzed by 0.02 mol/L CrCl3 for 10 min, resulting in 91 % delignification and 98 % cellulose recovery, with trace fermentation inhibitors generated. After the mild pretreatment, the accessibility and affinity of cellulase to eucalyptus was enhanced, especially since enzyme adsorption rate increased by 1.6-fold. Therefore, glucose yield of pretreated eucalyptus was 7.9-fold higher than that of untreated eucalyptus after hydrolyzed 48 h, in which the maximum glucose concentration reached 62 g/L from eucalyptus by adding Tween 80. According to the characterization analysis, the structure of the eucalyptus lignin-carbohydrate complexes structure was destroyed during the pretreatment, while lignin fragments was likely reacted with diethylene glycol to form the stabilized aromatic ethers. Moreover, the extracted Deg-lignin exhibited better performances than commercial alkali lignin such as higher fluorescence intensity, less negative surface charge, and lower particle size. The mild pretreatment method with diethylene glycol and CrCl3 provided a promising approach for co-production of fermentable sugars and high activity lignin from lignocellulosic biomass.

Phosphoric acid pretreatment of poplar to optimize fermentable sugars production based on orthogonal experimental design.

The recalcitrant structure of raw poplar limited the production of fermentable sugars when applied as the material in the pretreatment of biochemical conversions. Phosphoric acid pretreatment is an efficient method to destroy the compact lignocellulose matrix presence in the poplar. In this study, phosphoric acid pretreatment of poplar was optimised by an orthogonal experimental design [L9(33)] to improve enzymatic digestibility through investigating the effects of reaction temperature, time duration, and phosphoric acid concentration. The optimal conditions were selected based on the variance of chemical compositions, hemicellulose removal ratio, and delignification of the woody material after pretreatment. The optimum enzymatic hydrolysis yield of up to 73.44% was obtained when the phosphoric acid pretreatment performed at 190°C for 150 min under 1.5% of v/v phosphoric acid concentration.

Genomics and nitrogen metabolic characteristics of a novel heterotrophic nitrifying-aerobic denitrifying bacterium Acinetobacter oleivorans AHP123.

A novel aerobic strain of Acinetobacter oleivorans AHP123 was isolated from activated sludge, which could conduct heterotrophic nitrification and denitrification simultaneously. This strain has excellent NH4+-N removal ability, with 97.93% removal rate at 24-hour. To identify the metabolic pathways of this novel strain, genes of gam, glnA, gdhA, gltB, nirB, nasA, nar, nor, glnK and amt were detected by genome analysis. Through RT-qPCR, it was found that the expression of key genes confirmed two possible ways of nitrogen removal in strain AHP123: nitrogen assimilation and heterotrophic nitrification aerobic denitrification (HNAD). However, the absence of some common HNAD genes (amo, nap and nos) suggested that strain AHP123 might have a different HNAD pathway from other HNAD bacteria. Nitrogen balance analysis revealed that strain AHP123 assimilated most of the external nitrogen sources into intracellular nitrogen.

A novel fungal-algal coupling system for slaughterhouse wastewater treatment and lipid production.

In this study, a novel fungal-algal coupling system was established for slaughterhouse wastewater treatment with Chlorella sp. DT025 and a new fungus, Penicillium sp. AHP141. With the optimization of cultivation conditions for the fungal-algal coupling system, the harvest efficiency of Chlorella sp. DT025 reached 99.79%. The mechanism of microalgae harvest of the fungal-algal system was revealed to be related to the morphological characteristics, surface charge, and the secretion of humic acid-like compounds and tryptophan on the surface of the fungi cells. For the original slaughterhouse wastewater treatment, the fungal-algal coupling system had a better removal efficiency of COD, TN, and TP than both monoculture systems. In the high-concentration artificial slaughterhouse wastewater, COD removal of the fungal-algal system reached more than 5350 mg/L. The lipid production of the fungal-algal coupling system in the high-concentration artificial slaughterhouse wastewater treatment was improved by 343.33% to 1.33 g/L compared to the microalgae monoculture treatment.

Nuclear magnetic resonance analysis of ascorbic acid assisted lignocellulose decomposition in dilute acid pretreatment and its stimulation on enzymatic hydrolysis.

The effect of ascorbic acid addition on lignin decomposition in the dilute acid pretreatment and the corresponding cellulose conversion of pretreated biomass have been studied. This enhancement by ascorbic acid addition was dose dependent. Decomposed and residual bulk lignins from pretreated poplar were analyzed by 2D HSQC and 31P NMR spectra. The promotional effect on lignocellulose decomposition with the assistance of ascorbic acid addition was supported by the NMR analysis. The analysis showed that the addition of ascorbic acid has a more significant stimulation on decomposed lignins compared to residual bulk lignins. The stimulatory effect of ascorbic acid in lignocellulose decomposition benefits the cellulose conversion of the corresponding pretreated materials. Poplar pretreatment assisted with ascorbic acid (2-8% w/w) increased the final hydrolysis yield by 7.5%-32.2%. This promotional effect of ascorbic acid on enzyme digestibility was more obvious with higher enzyme loading.

Combined effect of CO2 concentration and low-cost urea repletion/starvation in Chlorella vulgaris for ameliorating growth metrics, total and non-polar lipid accumulation and fatty acid composition.

Different CO2 concentration such as 0.03, 5, 10 and 15% and low-cost urea repletion/starvation in Chlorella vulgaris on growth, total and non-polar lipid content and fatty acid composition was studied. Chlorella vulgaris grown at 0.03% CO2 apparently revealed inferior biomass yield 0.55 g/L on 14th day compared to CO2 supplemented cells. In the case of CO2 supply, 15% CO2 has unveiled higher biomass yield at about 1.83 g/L on day 12 whereas biomass yield for 5 and 10% CO2 supplemented cells was 1.61 and 1.73 g/L, respectively on 12th day of cultivation. The biomass productivity (g) per liter per day was 32 mg in control condition whereas it was 125, 134 and 144 mg/L/d in 5, 10 and 15% CO2 supplied cells, respectively. Lipid content of the strain grown at control, 5, 10 and 15% CO2 was 21.2, 22.1, 23.4 and 24.6%, respectively and however, without CO2 addition in low-cost urea repleted and urea depleted medium grown cells revealed 21.2 and 24.2%, respectively. Interestingly, strain grown at 15% CO2 supply in urea deplete medium yielded 28.7% lipid and contribution of non-polar lipids in total lipids is 69.7%. Further, the fatty acid composition of the strain grown in 15% CO2 supply in urea depleted medium showed C16:0, C16:1, C18:1 and C18:3 in the level of 30.12, 9.98, 23.43, and 11.97%, respectively compared to control and urea amended condition.

New Poplar-Derived Biocomposites via Single-Step Thermoforming Assisted by Phosphoric Acid Pretreatment.

One-step thermoforming represents an effective approach to preparing glue-free biocomposites. This study aimed to produce glue-free biocomposites with high-temperature resistance and mechanical properties using phosphoric acid pretreatments combined with thermoforming. Due to the hot-moulding process, the cell wall was destroyed, which allowed the fibres to adhere closely together. Most hemicelluloses were hydrolysed through pretreatment with phosphoric acid, and the contact area between the cellulose and lignin was significantly increased. The biocomposites prepared by ball milling demonstrated remarkable flexural strength (49.03 MPa) and tensile strength (148.23 MPa). Moreover, they had excellent thermal stability, with the maximum temperature for pyrolysis rate at 374 °C, which was much higher than that of poplar (337 °C). In addition, the material released no formaldehyde during the preparation process, which is in line with the concept of green production.

Latest eco-friendly approaches for pesticides decontamination using microorganisms and consortia microalgae: A comprehensive insights, challenges, and perspectives.

Pesticides are chemical compounds that are considered toxic to many organisms, including humans. Their elimination from polluted sites attracted the attention of Scientifics in the last decade; Among the various methods used to decontaminate pesticides from the environment, the microbial-algae consortium is a promising bioremediation technology, which implies several advantages as an eco-friendly process that generate biomass produced that could be valorized in the form of bioenergy, In this review, we will discuss the latest eco-friendly approaches using microorganisms to remediate sites contaminated by pesticides, and shows the ability of microbial, algae and their consortium to remove pesticides and the role of different enzymes in degradation processes.

Optimization of Different Acid-Catalyzed Pretreatments on Co-Production of Xylooligosaccharides and Glucose from Sorghum Stalk.

There is an increasing emphasis on the transformation of lignocellulosic biomass into versatile products. The feasibility of preparing xylooligosaccharides (XOS) by hydrolysis of sorghum stalk (SS) using organic and inorganic acids was studied. The influences of different acids (gluconic acid, acetic acid, sulfuric acid, and oxalic acid), process time and temperature on the hydrolysis of SS were explored. The findings indicated XOS yield can be maintained at a high level under different conditions with organic acid pretreatments. Optimum yield of XOS (39.4%) was obtained using sulfuric acid (pH 2.2) at 170 °C and 75 min of process time. It is suggested when reaction temperature and time were increased, both X5 and X6 are cracked into XOS with lower molecular mass such as X2, X3, and X4. Moreover, the results based on mass balance showed that up to 110 g (XOS) plus 117 g (glucose) can be recovered from 1000 g of SS. Results will give insights into establishing an efficient acid pretreatment of sorghum stalk to coproduction of XOS and glucose.

Innovative Conversion of Pretreated Buxus sinica into High-Performance Biocomposites for Potential Use as Furniture Material.

Traditional wood-based panels are usually made from large-diameter trees and rely on adhesives for compactness, which negatively impacts the environment and human health. However, the widely distributed small-diameter shrubs are good raw materials for wood-based panels with abundant fibers, but are often under-exploited. This research reports the preparation of self-bonding biocomposites from Buxus sinica by an innovative combined approach of extraction, alkali treatment, and hot molding. The resulted biocomposites show better mechanical properties in which the flexural modulus (7.79 GPa) and the tensile modulus (4.33 GPa) were 5 times and 1.7 times higher than the conventional fiberboard, respectively, and also demonstrated better hydrophobicity than fiberboard, which could be due to the layer of lignin that formed on its surface preventing the infiltration of water. To sum up, the biocomposites prepared from small-diameter shrubs meet the requirement of the furniture and architectural decoration materials, suggesting that the proposed approach can be used to produce high-performance biocomposites.

Ultra-Thin Wood-Based Acoustic Diaphragms Fabricated via an Environmentally Friendly Strategy.

An acoustic diaphragm is a crucial component that regulates sound quality in earphones and loudspeakers. Natural wood with inherent good acoustic resonance and vibration spectrum is widely used in sound devices. However, using natural wood to produce an acoustic diaphragm is still a big challenge because making ultra-thin wood is hard and it warps easily. Therefore, this study introduces a new method for preparing ultra-thin wood acoustic diaphragms less than 10 µm in thickness, relying on delignification, sulfonation, and densifying techniques. The innovative sulfonation process increased the intermolecular hydrogen bond force, which significantly improved the tensile strength and Young's modulus of the wood diaphragm, up to 195 MPa and 27.1 GPa, respectively. Compared with the commonly used diaphragms in the market, this wood diaphragm exhibits an excellent specific dynamic elastic modulus up to 95.1 GPa/g cm3, indicating better acoustic properties. Also, the resonance frequency was up to 1240 Hz, 4.5 times higher than the titanium diaphragm among high-end products. Besides, the drying shrinkage rate of the ultra-thin wood diaphragm is only 1.2%, indicating excellent dimensional stability. This high-quality wood acoustic diaphragm has a very high application prospect and outstanding attributes for promoting the development of acoustic devices. Moreover, the reaction reagent can be recycled after preparation, and the selected reagents are green and environmentally friendly.

Components Interaction of Cotton Stalk under Low-Temperature Hydrothermal Conversion: A Bio-Oil Pyrolysis Behavior Perspective Analysis.

The conversion of agricultural and forestry waste biomass materials into bio-oil by mild hydro-thermal technology has a positive effect on extending the agricultural industry chain and alleviating the world energy crisis. The interaction investigation of biomass components during bio-oil formation can be significant for the efficient conversion of lignocellulose when different raw materials are fed together. In this paper, a bio-oil pyrolysis behavior (thermogravimetric analysis, TG) perspective component interaction investigation of cotton stalks under low-temperature hydro-thermal conversion (220 °C) was studied. Cellulose, hemi-cellulose, lignin, and protein were used as lignocellulose model components, by their simple binary blending and multi-variate blending and combined with thermo-gravimetric analysis and gas chromatography-mass spectrometry (GC-MS) characterization and analysis. The interaction of different model components and real biomass raw material components in the hydro-thermal process was explored. Results showed that the components of hydro-thermal bio-oil from cotton stalks were highly correlated with the interactions between cellulose, hemi-cellulose, lignin, and protein. During the hydro-thermal process, cellulose and hemi-cellulose inhibit each other, which reduces the content of ketones, aldehydes, ethers, and alcohols in bio-oil. Interaction between cellulose and lignin was obvious, which promotes the formation of oligomers, such as ketones, aldehydes, esters, phenols, and aliphatic, while inhibiting the production of aromatic and multi-hybrid compounds. Otherwise, there was no obvious interaction effect between hemi-cellulose and lignin or between lignin and protein. This research will guide the industrialization of lignocellulose, especially the possible co-feed hydro-thermal conversion technology.

Production of medium-chain fatty acid caproate from Chinese liquor distillers' grain using pit mud as the fermentation microbes.

Chinese liquor distillers' grain (CLDG) is an abundant industrial organic waste showing high potential as feedstock for biofuel conversion. In this study, CLDG was used as substrate by microbial community in pit mud to produce medium-chain fatty acids (especially caproate). Simulated and real fermentation were used to evaluate the effect of ethanol and lactic acid being the electronic donors (EDs) during the anaerobic chain elongation (CE). The caproate concentration was achieved at 449 mg COD/g VS, with the corresponding high carbon selectivity at 37.1%. Microbial analysis revealed that the domestication of pit mud increased the abundance of Caproiciproducens (converting lactic acid into caproate) and Lactobacillus (producing lactic acid), leading to enhanced caproate production. The lactic acid conversion facilitated in full utilization of ethanol through CE consumption. The coexistence of EDs benefited the CE system and that this green energy production can be a promising high-performance biofuel donor for sustainable industrial production development.

Enzymatic conversion of pretreated lignocellulosic biomass: A review on influence of structural changes of lignin.

The demands of energy sustainability drive efforts to bio-chemical conversion of biomass into biofuels through pretreatment, enzymatic hydrolysis, and microbial fermentation. Pretreatment leads to significant structural changes of the complex lignin polymer that affect yield and productivity of the enzymatic conversion of lignocellulosic biomass. Structural changes of lignin after pretreatment include functional groups, inter unit linkages and compositions. These changes influence non-productive adsorption of enzyme on lignin through hydrophobic interaction and electrostatic interaction as well as hydrogen bonding. This paper reviews the relationships between structural changes of lignin and enzymatic hydrolysis of pretreated lignocellulosic biomass. The formation of pseudo-lignin during dilute acid pretreatment is revealed, and their negative effect on enzymatic hydrolysis is discussed.

Bioconversion of 5-Hydroxymethylfurfural (HMF) to 2,5-Furandicarboxylic Acid (FDCA) by a Native Obligate Aerobic Bacterium, Acinetobacter calcoaceticus NL14.

2,5-Furandicarboxylic acid (FDCA), one of the top biomass-based platform chemical, is highly promising for resins and polymers, and it can be prepared from the bio-oxidation of hydroxymethyl furfural (HMF), which can be obtained mainly from lignocellulosic glucose that has a high production potential from not edible biomass.A native strain, Acinetobacter calcoaceticus NL14, that could convert HMF into FDCA is used for combining degradation and fermentation by consolidated bioprocessing (CBP). In this study, it was observed that the initial HMF concentration and pH neutralizer played important roles in the bioconversion of HMF, 5 g/L of HMF could be converted by 100% within 48 h with 0.5 g/L sodium carbonate (Na2CO3) with the production of 0.31 g/L FDCA. Extra glucose and hydrogen peroxide (H2O2) addition could further promote the production of FDCA to 0.54 g/L with 100% HMF conversion and a higher conversion rate. This report could provide a potential native bacterium for furan chemicals bioconversion and bioelimination, especially for FDCA bioproduction.